/* ============================================
   ChargedUP: Behind The Scenes of an RC Car
   Design System - December 20th
   ============================================ */

/* ============================================
   CSS Custom Properties (Design Tokens)
   ============================================ */
:root {
    /* Color Palette - Dark Theme (Default) */
    --color-bg-primary: #071733;
    --color-bg-secondary: #2F3E46;
    --color-bg-tertiary: #000000;
    --color-accent-cyan: #00D1FF;
    --color-accent-teal: #3EF1C6;
    --color-text-primary: #F8FAFC;
    --color-text-muted: #B6C0C9;
    --color-border: rgba(0, 209, 255, 0.2);
    --color-glow: rgba(0, 209, 255, 0.4);

    /* Typography */
    --font-primary: 'Inter', 'Segoe UI', system-ui, sans-serif;
    --font-mono: 'Fira Code', 'Consolas', monospace;
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.25rem;
    --font-size-2xl: 1.5rem;
    --font-size-3xl: 2rem;
    --font-size-4xl: 2.5rem;
    --font-size-5xl: 3.5rem;
    --line-height-tight: 1.2;
    --line-height-normal: 1.6;
    --line-height-relaxed: 1.8;

    /* Spacing */
    --space-xs: 0.25rem;
    --space-sm: 0.5rem;
    --space-md: 1rem;
    --space-lg: 1.5rem;
    --space-xl: 2rem;
    --space-2xl: 3rem;
    --space-3xl: 4rem;

    /* Border Radius */
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-xl: 20px;
    --radius-full: 9999px;

    /* Shadows */
    --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.5);
    --shadow-glow: 0 0 20px var(--color-glow);

    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-normal: 250ms ease;
    --transition-slow: 400ms ease;

    /* Layout */
    --header-height: 70px;
    --sidebar-width: 280px;
    --container-max: 1400px;
    --content-max: 900px;
}

/* ============================================
   Theme Variations
   ============================================ */

/* Light Theme */
[data-theme="light"] {
    --color-bg-primary: #F8FAFC;
    --color-bg-secondary: #E2E8F0;
    --color-bg-tertiary: #FFFFFF;
    --color-text-primary: #071733;
    --color-text-muted: #475569;
    --color-border: rgba(7, 23, 51, 0.15);
    --color-glow: rgba(0, 180, 216, 0.3);
    --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.15);
    --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.2);
    /* Darker accent colors for better readability in light mode */
    --color-accent-cyan: #0088aa;
    --color-accent-teal: #0d8a6f;
}

/* Light mode on non-home pages - even darker text for better contrast */
[data-theme="light"] .text-cyan,
[data-theme="light"] .text-teal {
    filter: brightness(0.7);
}

/* Light mode subheadings - ensure good contrast */
[data-theme="light"] h2,
[data-theme="light"] h3 {
    color: #071733;
}

/* Light mode settings panel - darker text for readability */
[data-theme="light"] .settings-panel {
    background: #F8FAFC !important;
    border-color: #CBD5E1 !important;
}

[data-theme="light"] .settings-panel div[style*="color: #3EF1C6"],
[data-theme="light"] .settings-panel div[style*="color:#3EF1C6"] {
    color: #0d8a6f !important;
}

[data-theme="light"] .settings-panel span[style*="color: #94A3B8"],
[data-theme="light"] .settings-panel span[style*="color:#94A3B8"] {
    color: #475569 !important;
}

[data-theme="light"] .settings-panel button[class*="settings-panel__btn"] {
    color: #071733 !important;
    border-color: #CBD5E1 !important;
}

[data-theme="light"] .settings-panel button[class*="settings-panel__btn"]:hover {
    background: rgba(0, 136, 170, 0.1) !important;
}

/* Light mode: Page navigation arrows */
[data-theme="light"] .page-nav-arrow {
    background: rgba(255, 255, 255, 0.9);
    border-color: #CBD5E1;
}

[data-theme="light"] .page-nav-arrow svg {
    stroke: #334155;
}

[data-theme="light"] .page-nav-arrow:hover {
    background: rgba(255, 255, 255, 1);
}

[data-theme="light"] .page-nav-arrow__label {
    background: rgba(30, 41, 59, 0.95);
    color: #fff;
    border-color: #475569;
}

/* High Contrast Theme */
[data-theme="high-contrast"] {
    --color-bg-primary: #000000;
    --color-bg-secondary: #1a1a1a;
    --color-bg-tertiary: #000000;
    --color-accent-cyan: #00FFFF;
    --color-accent-teal: #00FF99;
    --color-text-primary: #FFFFFF;
    --color-text-muted: #CCCCCC;
    --color-border: #FFFFFF;
}

/* Large Text Mode */
[data-text-size="large"] {
    --font-size-base: 1.25rem;
    --font-size-lg: 1.375rem;
    --font-size-xl: 1.5rem;
    --font-size-2xl: 1.875rem;
    --font-size-3xl: 2.5rem;
    --font-size-4xl: 3rem;
    --font-size-5xl: 4rem;
}

/* ============================================
   Reset & Base Styles
   ============================================ */
*,
*::before,
*::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    font-size: 16px;
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-primary);
    font-size: var(--font-size-base);
    line-height: var(--line-height-normal);
    color: var(--color-text-primary);
    background: var(--color-bg-primary);
    min-height: 100vh;
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* ============================================
   Typography
   ============================================ */
h1,
h2,
h3,
h4,
h5,
h6 {
    font-weight: 700;
    line-height: var(--line-height-tight);
    color: var(--color-text-primary);
    margin-bottom: var(--space-md);
}

h1 {
    font-size: var(--font-size-5xl);
    background: linear-gradient(135deg, var(--color-accent-cyan), var(--color-accent-teal));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

h2 {
    font-size: var(--font-size-3xl);
}

h3 {
    font-size: var(--font-size-2xl);
}

h4 {
    font-size: var(--font-size-xl);
}

p {
    margin-bottom: var(--space-md);
    color: var(--color-text-muted);
}

a {
    color: var(--color-accent-cyan);
    text-decoration: none;
    transition: color var(--transition-fast);
}

a:hover,
a:focus {
    color: var(--color-accent-teal);
    text-decoration: underline;
}

strong {
    font-weight: 600;
    color: var(--color-text-primary);
}

code {
    font-family: var(--font-mono);
    font-size: 0.9em;
    background: var(--color-bg-secondary);
    padding: 0.2em 0.4em;
    border-radius: var(--radius-sm);
    color: var(--color-accent-teal);
}

pre {
    font-family: var(--font-mono);
    background: var(--color-bg-tertiary);
    padding: var(--space-lg);
    border-radius: var(--radius-md);
    overflow-x: auto;
    margin-bottom: var(--space-lg);
    border: 1px solid var(--color-border);
}

pre code {
    background: none;
    padding: 0;
}

/* ============================================
   Layout Components
   ============================================ */
.container {
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 var(--space-lg);
}

.content-container {
    max-width: var(--content-max);
    margin: 0 auto;
}

.page-wrapper {
    min-height: calc(100vh - var(--header-height));
    padding-top: var(--header-height);
}

.section {
    padding: var(--space-3xl) 0;
}

.section--alt {
    background: var(--color-bg-secondary);
}

/* Grid System */
.grid {
    display: grid;
    gap: var(--space-lg);
}

.grid--2 {
    grid-template-columns: repeat(2, 1fr);
}

.grid--3 {
    grid-template-columns: repeat(3, 1fr);
}

.grid--4 {
    grid-template-columns: repeat(4, 1fr);
}

@media (max-width: 992px) {

    .grid--3,
    .grid--4 {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 768px) {

    .grid--2,
    .grid--3,
    .grid--4 {
        grid-template-columns: 1fr;
    }
}

/* Flex Utilities */
.flex {
    display: flex;
}

.flex--center {
    align-items: center;
    justify-content: center;
}

.flex--between {
    justify-content: space-between;
    align-items: center;
}

.flex--column {
    flex-direction: column;
}

.flex--wrap {
    flex-wrap: wrap;
}

.gap-sm {
    gap: var(--space-sm);
}

.gap-md {
    gap: var(--space-md);
}

.gap-lg {
    gap: var(--space-lg);
}

.gap-xl {
    gap: var(--space-xl);
}

/* ============================================
   Header & Navigation
   ============================================ */
.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: var(--header-height);
    background: rgba(7, 23, 51, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--color-border);
    z-index: 1000;
    transition: background var(--transition-normal);
}

[data-theme="light"] .header {
    background: rgba(248, 250, 252, 0.95);
}

.header__inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 100%;
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 var(--space-lg);
}

.header__logo {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    font-size: var(--font-size-xl);
    font-weight: 700;
    color: var(--color-text-primary);
    text-decoration: none;
}

.header__logo:hover {
    text-decoration: none;
}

.header__logo img,
.header__logo svg {
    height: 40px;
    width: auto;
}

.nav {
    display: flex;
    align-items: center;
    gap: var(--space-xl);
}

.nav__list {
    display: flex;
    list-style: none;
    gap: var(--space-lg);
}

.nav__link {
    color: var(--color-text-muted);
    font-weight: 500;
    padding: var(--space-sm) 0;
    position: relative;
    transition: color var(--transition-fast);
}

.nav__link:hover,
.nav__link--active {
    color: var(--color-accent-cyan);
    text-decoration: none;
}

.nav__link::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background: linear-gradient(90deg, var(--color-accent-cyan), var(--color-accent-teal));
    transition: width var(--transition-normal);
}

.nav__link:hover::after,
.nav__link--active::after {
    width: 100%;
}

/* Mode Toggle */
.mode-toggle {
    display: flex;
    background: var(--color-bg-secondary);
    border-radius: var(--radius-full);
    padding: 4px;
    border: 1px solid var(--color-border);
}

.mode-toggle__btn {
    padding: var(--space-sm) var(--space-md);
    border: none;
    background: transparent;
    color: var(--color-text-muted);
    font-size: var(--font-size-sm);
    font-weight: 500;
    border-radius: var(--radius-full);
    cursor: pointer;
    transition: all var(--transition-fast);
    display: flex;
    align-items: center;
    gap: var(--space-xs);
}

.mode-toggle__btn:hover {
    color: var(--color-text-primary);
}

.mode-toggle__btn--active {
    background: linear-gradient(135deg, var(--color-accent-cyan), var(--color-accent-teal));
    color: var(--color-bg-primary);
}

/* Mobile Navigation */
.nav-toggle {
    display: none;
    flex-direction: column;
    justify-content: center;
    gap: 5px;
    width: 32px;
    height: 32px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 4px;
}

.nav-toggle__bar {
    width: 100%;
    height: 2px;
    background: var(--color-text-primary);
    transition: all var(--transition-fast);
    border-radius: 2px;
}

.nav-toggle.active .nav-toggle__bar:nth-child(1) {
    transform: rotate(45deg) translate(5px, 5px);
}

.nav-toggle.active .nav-toggle__bar:nth-child(2) {
    opacity: 0;
}

.nav-toggle.active .nav-toggle__bar:nth-child(3) {
    transform: rotate(-45deg) translate(5px, -5px);
}

@media (max-width: 992px) {
    .nav-toggle {
        display: flex;
    }

    .nav__list {
        position: fixed;
        top: 70px;
        left: 0;
        right: 0;
        height: calc(100vh - 70px);
        height: calc(100dvh - 70px);
        flex-direction: column;
        background-color: #000000 !important;
        background: #000000 !important;
        padding: var(--space-lg) var(--space-xl);
        gap: var(--space-md);
        transform: translateX(100%);
        transition: transform var(--transition-normal);
        z-index: 9999;
        border-left: 2px solid rgba(0, 209, 255, 0.3);
        box-shadow: -10px 0 40px rgba(0, 0, 0, 0.8);
        overflow-y: auto;
    }

    .nav__list.active {
        transform: translateX(0);
        background-color: #000000 !important;
        background: #000000 !important;
    }

    .nav__link {
        font-size: var(--font-size-base);
        background: rgba(20, 30, 50, 0.95);
        padding: var(--space-md) var(--space-lg);
        border-radius: var(--radius-md);
        color: #FFFFFF !important;
        border: 1px solid rgba(0, 209, 255, 0.2);
        display: block;
        text-align: center;
    }

    .nav__link:hover {
        background: rgba(0, 209, 255, 0.15);
        border-color: var(--color-accent-cyan);
    }

    .mode-toggle {
        margin-top: var(--space-lg);
        display: flex;
        flex-direction: column;
        gap: var(--space-sm);
    }
}

/* ============================================
   Buttons
   ============================================ */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-sm);
    padding: var(--space-md) var(--space-xl);
    font-family: var(--font-primary);
    font-size: var(--font-size-base);
    font-weight: 600;
    border: none;
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition-fast);
    text-decoration: none;
}

.btn--primary {
    background: linear-gradient(135deg, var(--color-accent-cyan), var(--color-accent-teal));
    color: var(--color-bg-primary);
}

.btn--primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-glow);
    text-decoration: none;
    color: var(--color-bg-primary);
}

.btn--secondary {
    background: transparent;
    color: var(--color-accent-cyan);
    border: 2px solid var(--color-accent-cyan);
}

.btn--secondary:hover {
    background: var(--color-accent-cyan);
    color: var(--color-bg-primary);
    text-decoration: none;
}

.btn--ghost {
    background: rgba(0, 209, 255, 0.1);
    color: var(--color-accent-cyan);
    border: 1px solid var(--color-border);
}

.btn--ghost:hover {
    background: rgba(0, 209, 255, 0.2);
    text-decoration: none;
}

.btn--sm {
    padding: var(--space-sm) var(--space-md);
    font-size: var(--font-size-sm);
}

.btn--lg {
    padding: var(--space-lg) var(--space-2xl);
    font-size: var(--font-size-lg);
}

.btn--icon {
    width: 40px;
    height: 40px;
    padding: 0;
    border-radius: var(--radius-md);
}

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none;
}

/* ============================================
   Cards
   ============================================ */
.card {
    background: var(--color-bg-secondary);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--space-xl);
    transition: all var(--transition-normal);
}

.card:hover {
    border-color: var(--color-accent-cyan);
    box-shadow: var(--shadow-glow);
    transform: translateY(-4px);
}

.card__header {
    display: flex;
    align-items: center;
    gap: var(--space-md);
    margin-bottom: var(--space-lg);
}

.card__icon {
    width: 48px;
    height: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: rgba(0, 209, 255, 0.1);
    border-radius: var(--radius-md);
    color: var(--color-accent-cyan);
}

.card__title {
    font-size: var(--font-size-xl);
    margin: 0;
}

.card__content p:last-child {
    margin-bottom: 0;
}

/* Feature Card */
.feature-card {
    text-align: center;
    padding: var(--space-2xl);
}

.feature-card__icon {
    width: 80px;
    height: 80px;
    margin: 0 auto var(--space-lg);
    background: linear-gradient(135deg, rgba(0, 209, 255, 0.2), rgba(62, 241, 198, 0.2));
    border-radius: var(--radius-xl);
    display: flex;
    align-items: center;
    justify-content: center;
}

.feature-card__icon svg {
    width: 40px;
    height: 40px;
    color: var(--color-accent-cyan);
}

/* ============================================
   Forms & Inputs
   ============================================ */
.form-group {
    margin-bottom: var(--space-lg);
}

.form-label {
    display: block;
    margin-bottom: var(--space-sm);
    font-weight: 500;
    color: var(--color-text-primary);
}

.form-label--with-tooltip {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
}

.form-input,
.form-select,
.form-textarea {
    width: 100%;
    padding: var(--space-md);
    font-family: var(--font-primary);
    font-size: var(--font-size-base);
    color: var(--color-text-primary);
    background: var(--color-bg-tertiary);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    transition: all var(--transition-fast);
}

.form-input:focus,
.form-select:focus,
.form-textarea:focus {
    outline: none;
    border-color: var(--color-accent-cyan);
    box-shadow: 0 0 0 3px rgba(0, 209, 255, 0.2);
}

.form-input::placeholder {
    color: var(--color-text-muted);
}

.form-input--number {
    font-family: var(--font-mono);
}

/* Range Slider */
.range-slider,
input[type="range"] {
    width: 100%;
    height: 8px;
    -webkit-appearance: none;
    appearance: none;
    background: var(--color-bg-secondary);
    border-radius: var(--radius-full);
    outline: none;
    cursor: pointer;
    position: relative;
}

/* Track background - shows the entire range */
.range-slider::-webkit-slider-runnable-track,
input[type="range"]::-webkit-slider-runnable-track {
    width: 100%;
    height: 8px;
    background: linear-gradient(to right,
            rgba(0, 209, 255, 0.3) 0%,
            rgba(62, 241, 198, 0.1) 100%);
    border-radius: var(--radius-full);
    border: 1px solid var(--color-border);
}

.range-slider::-moz-range-track,
input[type="range"]::-moz-range-track {
    width: 100%;
    height: 8px;
    background: linear-gradient(to right,
            rgba(0, 209, 255, 0.3) 0%,
            rgba(62, 241, 198, 0.1) 100%);
    border-radius: var(--radius-full);
    border: 1px solid var(--color-border);
}

/* Slider thumb */
.range-slider::-webkit-slider-thumb,
input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 22px;
    height: 22px;
    background: linear-gradient(135deg, var(--color-accent-cyan), var(--color-accent-teal));
    border-radius: 50%;
    cursor: pointer;
    transition: transform var(--transition-fast), box-shadow var(--transition-fast);
    margin-top: -7px;
    box-shadow: 0 2px 8px rgba(0, 209, 255, 0.3);
}

.range-slider::-webkit-slider-thumb:hover,
input[type="range"]::-webkit-slider-thumb:hover {
    transform: scale(1.15);
    box-shadow: 0 4px 12px rgba(0, 209, 255, 0.5);
}

.range-slider::-moz-range-thumb,
input[type="range"]::-moz-range-thumb {
    width: 22px;
    height: 22px;
    background: linear-gradient(135deg, var(--color-accent-cyan), var(--color-accent-teal));
    border-radius: 50%;
    cursor: pointer;
    border: none;
    box-shadow: 0 2px 8px rgba(0, 209, 255, 0.3);
}

.range-slider::-moz-range-thumb:hover,
input[type="range"]::-moz-range-thumb:hover {
    transform: scale(1.15);
    box-shadow: 0 4px 12px rgba(0, 209, 255, 0.5);
}

/* Checkbox & Radio */
.form-check {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    cursor: pointer;
}

.form-check input {
    width: 20px;
    height: 20px;
    accent-color: var(--color-accent-cyan);
    cursor: pointer;
}

/* ============================================
   Calculator & Simulator Panels
   ============================================ */
.calculator-panel {
    background: var(--color-bg-secondary);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    overflow: hidden;
}

.calculator-panel__header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--space-lg);
    background: var(--color-bg-tertiary);
    border-bottom: 1px solid var(--color-border);
}

.calculator-panel__title {
    font-size: var(--font-size-xl);
    margin: 0;
    display: flex;
    align-items: center;
    gap: var(--space-sm);
}

.calculator-panel__body {
    padding: var(--space-xl);
}

.calculator-panel__footer {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: var(--space-md);
    padding: var(--space-lg);
    background: var(--color-bg-tertiary);
    border-top: 1px solid var(--color-border);
    flex-wrap: wrap;
}

/* Input Grid */
.input-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--space-lg);
}

@media (max-width: 600px) {
    .input-grid {
        grid-template-columns: 1fr;
    }
}

/* Results Display */
.results-panel {
    background: var(--color-bg-tertiary);
    border: 1px solid var(--color-accent-cyan);
    border-radius: var(--radius-md);
    padding: var(--space-lg);
    margin-top: var(--space-lg);
}

.result-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--space-sm) 0;
    border-bottom: 1px solid var(--color-border);
}

.result-item:last-child {
    border-bottom: none;
}

.result-item__label {
    color: var(--color-text-muted);
    display: flex;
    align-items: center;
    gap: var(--space-xs);
}

.result-item__value {
    font-family: var(--font-mono);
    font-weight: 600;
    color: var(--color-accent-teal);
}

.result-item--highlight {
    background: linear-gradient(90deg, rgba(0, 209, 255, 0.1), transparent);
    padding: var(--space-md);
    margin: var(--space-sm) calc(-1 * var(--space-lg));
    padding-left: var(--space-lg);
    padding-right: var(--space-lg);
    border-radius: var(--radius-sm);
}

/* Show Work Panel */
.show-work {
    margin-top: var(--space-lg);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    overflow: hidden;
}

.show-work__header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--space-md) var(--space-lg);
    background: var(--color-bg-tertiary);
    cursor: pointer;
    user-select: none;
}

.show-work__toggle {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    color: var(--color-accent-cyan);
}

.show-work__content {
    padding: var(--space-lg);
    display: none;
}

.show-work__content.active {
    display: block;
}

.work-step {
    display: flex;
    gap: var(--space-md);
    margin-bottom: var(--space-md);
    padding-bottom: var(--space-md);
    border-bottom: 1px dashed var(--color-border);
}

.work-step:last-child {
    border-bottom: none;
    margin-bottom: 0;
    padding-bottom: 0;
}

.work-step__number {
    flex-shrink: 0;
    width: 28px;
    height: 28px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--color-accent-cyan);
    color: var(--color-bg-primary);
    font-weight: 700;
    font-size: var(--font-size-sm);
    border-radius: 50%;
}

.work-step__content {
    flex: 1;
}

.work-step__formula {
    font-family: var(--font-mono);
    color: var(--color-accent-teal);
}

/* ============================================
   Presets
   ============================================ */
.presets {
    display: flex;
    gap: var(--space-sm);
    margin-bottom: var(--space-lg);
    flex-wrap: wrap;
}

.preset-btn {
    padding: var(--space-sm) var(--space-md);
    background: var(--color-bg-tertiary);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
    color: var(--color-text-muted);
    font-size: var(--font-size-sm);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.preset-btn:hover {
    border-color: var(--color-accent-cyan);
    color: var(--color-accent-cyan);
}

.preset-btn--active {
    background: var(--color-accent-cyan);
    border-color: var(--color-accent-cyan);
    color: var(--color-bg-primary);
}

/* ============================================
   Simulation Canvas
   ============================================ */
.simulation-container {
    position: relative;
    width: 100%;
    aspect-ratio: 16 / 9;
    background: var(--color-bg-tertiary);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    overflow: hidden;
}

.simulation-canvas {
    width: 100%;
    height: 100%;
    display: block;
}

.simulation-overlay {
    position: absolute;
    top: var(--space-md);
    right: var(--space-md);
    display: flex;
    gap: var(--space-sm);
}

.simulation-controls {
    position: absolute;
    bottom: var(--space-md);
    left: var(--space-md);
    right: var(--space-md);
    display: flex;
    align-items: center;
    gap: var(--space-md);
    background: rgba(0, 0, 0, 0.7);
    padding: var(--space-md);
    border-radius: var(--radius-md);
}

/* ============================================
   Tooltips
   ============================================ */
.tooltip-trigger {
    position: relative;
    cursor: help;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 16px;
    height: 16px;
    margin-left: 4px;
    border-radius: 50%;
    background: var(--color-accent-cyan);
    color: var(--color-bg-primary);
    font-size: 11px;
    font-weight: 600;
    vertical-align: middle;
}

.tooltip {
    position: absolute;
    bottom: 100%;
    left: 50%;
    transform: translateX(-50%);
    padding: var(--space-sm) var(--space-md);
    background: var(--color-bg-tertiary);
    border: 1px solid var(--color-accent-cyan);
    border-radius: var(--radius-sm);
    font-size: var(--font-size-sm);
    color: var(--color-text-primary);
    white-space: nowrap;
    opacity: 0;
    visibility: hidden;
    transition: all var(--transition-fast);
    z-index: 100;
    pointer-events: none;
}

.tooltip::after {
    content: '';
    position: absolute;
    top: 100%;
    left: 50%;
    transform: translateX(-50%);
    border: 6px solid transparent;
    border-top-color: var(--color-accent-cyan);
}

.tooltip-trigger:hover .tooltip,
.tooltip-trigger:focus .tooltip {
    opacity: 1;
    visibility: visible;
}

/* Info Icon */
.info-icon {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 18px;
    height: 18px;
    background: var(--color-bg-tertiary);
    border: 1px solid var(--color-border);
    border-radius: 50%;
    font-size: var(--font-size-xs);
    color: var(--color-text-muted);
    cursor: help;
}

.info-icon:hover {
    border-color: var(--color-accent-cyan);
    color: var(--color-accent-cyan);
}

/* ============================================
   Glossary
   ============================================ */
.glossary-list {
    list-style: none;
}

.glossary-item {
    padding: var(--space-lg);
    border-bottom: 1px solid var(--color-border);
    scroll-margin-top: calc(var(--header-height) + var(--space-lg));
}

.glossary-item:target {
    background: rgba(0, 209, 255, 0.1);
    border-left: 3px solid var(--color-accent-cyan);
    padding-left: calc(var(--space-lg) - 3px);
}

.glossary-term {
    font-size: var(--font-size-xl);
    color: var(--color-accent-cyan);
    margin-bottom: var(--space-sm);
}

.glossary-definition {
    color: var(--color-text-muted);
    margin-bottom: var(--space-sm);
}

.glossary-technical {
    font-size: var(--font-size-sm);
    color: var(--color-text-muted);
    font-style: italic;
    padding-left: var(--space-md);
    border-left: 2px solid var(--color-border);
}

.glossary-formula {
    font-family: var(--font-mono);
    font-size: var(--font-size-sm);
    color: var(--color-accent-teal);
    margin-top: var(--space-sm);
}

/* Glossary Filter */
.glossary-filter {
    display: flex;
    gap: var(--space-md);
    margin-bottom: var(--space-xl);
    flex-wrap: wrap;
}

.glossary-filter__search {
    flex: 1;
    min-width: 200px;
}

.glossary-filter__tabs {
    display: flex;
    background: var(--color-bg-secondary);
    border-radius: var(--radius-full);
    padding: 4px;
}

.glossary-filter__tab {
    padding: var(--space-sm) var(--space-lg);
    background: transparent;
    border: none;
    color: var(--color-text-muted);
    font-weight: 500;
    border-radius: var(--radius-full);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.glossary-filter__tab:hover {
    color: var(--color-text-primary);
}

.glossary-filter__tab--active {
    background: var(--color-accent-cyan);
    color: var(--color-bg-primary);
}

/* ============================================
   Hero Section
   ============================================ */
.hero {
    position: relative;
    min-height: calc(100vh - var(--header-height));
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    overflow: hidden;
    padding: var(--space-2xl);
}

.hero__background {
    position: absolute;
    inset: 0;
    z-index: 0;
}

.hero__content {
    position: relative;
    z-index: 1;
    max-width: 800px;
}

.hero__title {
    margin-bottom: var(--space-lg);
}

.hero__subtitle {
    font-size: var(--font-size-xl);
    color: var(--color-text-muted);
    margin-bottom: var(--space-2xl);
}

.hero__cta {
    display: flex;
    gap: var(--space-md);
    justify-content: center;
    flex-wrap: wrap;
}

/* Hero Animation Canvas */
.hero-canvas {
    position: absolute;
    inset: 0;
    width: 100%;
    height: 100%;
}

/* ============================================
   Worked Examples
   ============================================ */
.example {
    background: var(--color-bg-secondary);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    margin-bottom: var(--space-xl);
    overflow: hidden;
}

.example__header {
    display: flex;
    align-items: center;
    gap: var(--space-md);
    padding: var(--space-lg);
    background: var(--color-bg-tertiary);
    border-bottom: 1px solid var(--color-border);
}

.example__number {
    width: 36px;
    height: 36px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, var(--color-accent-cyan), var(--color-accent-teal));
    color: var(--color-bg-primary);
    font-weight: 700;
    border-radius: var(--radius-md);
}

.example__title {
    font-size: var(--font-size-lg);
    margin: 0;
}

.example__body {
    padding: var(--space-xl);
}

.example__problem {
    padding: var(--space-lg);
    background: rgba(0, 209, 255, 0.05);
    border-radius: var(--radius-md);
    margin-bottom: var(--space-lg);
    border-left: 3px solid var(--color-accent-cyan);
}

.example__solution {
    border-top: 1px solid var(--color-border);
    padding-top: var(--space-lg);
}

/* ============================================
   Tables
   ============================================ */
.table-container {
    overflow-x: auto;
    margin-bottom: var(--space-lg);
}

table {
    width: 100%;
    border-collapse: collapse;
    font-size: var(--font-size-sm);
}

th,
td {
    padding: var(--space-md);
    text-align: left;
    border-bottom: 1px solid var(--color-border);
}

th {
    background: var(--color-bg-secondary);
    font-weight: 600;
    color: var(--color-text-primary);
}

tr:hover td {
    background: rgba(0, 209, 255, 0.05);
}

/* ============================================
   Tabs
   ============================================ */
.tabs {
    margin-bottom: var(--space-xl);
}

.tabs__list {
    display: flex;
    border-bottom: 2px solid var(--color-border);
    margin-bottom: var(--space-lg);
}

.tabs__tab {
    padding: var(--space-md) var(--space-xl);
    background: transparent;
    border: none;
    color: var(--color-text-muted);
    font-weight: 500;
    cursor: pointer;
    position: relative;
    transition: color var(--transition-fast);
}

.tabs__tab:hover,
.tabs__tab--active {
    color: var(--color-accent-cyan);
}

.tabs__tab--active::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 0;
    right: 0;
    height: 2px;
    background: linear-gradient(90deg, var(--color-accent-cyan), var(--color-accent-teal));
}

.tabs__panel {
    display: none;
}

.tabs__panel--active {
    display: block;
}

/* ============================================
   Sankey Diagram Container
   ============================================ */
.sankey-container {
    background: var(--color-bg-tertiary);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    padding: var(--space-lg);
    min-height: 400px;
}

/* ============================================
   Settings Panel
   ============================================ */
.settings-panel {
    position: fixed;
    top: var(--header-height);
    right: 0;
    width: 320px;
    max-width: 100%;
    height: calc(100vh - var(--header-height));
    background: var(--color-bg-secondary);
    border-left: 1px solid var(--color-border);
    transform: translateX(100%);
    transition: transform var(--transition-normal);
    z-index: 999;
    overflow-y: auto;
}

.settings-panel.active {
    transform: translateX(0);
}

.settings-panel__header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--space-lg);
    border-bottom: 1px solid var(--color-border);
}

.settings-panel__body {
    padding: var(--space-lg);
}

.settings-group {
    margin-bottom: var(--space-xl);
}

.settings-group__title {
    font-size: var(--font-size-sm);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--color-text-muted);
    margin-bottom: var(--space-md);
}

/* ============================================
   Footer
   ============================================ */
.footer {
    background: var(--color-bg-secondary);
    border-top: 1px solid var(--color-border);
    padding: var(--space-2xl) 0;
}

.footer__inner {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: var(--space-lg);
}

.footer__links {
    display: flex;
    gap: var(--space-lg);
}

.footer__link {
    color: var(--color-text-muted);
    font-size: var(--font-size-sm);
}

.footer__link:hover {
    color: var(--color-accent-cyan);
}

.footer__copy {
    color: var(--color-text-muted);
    font-size: var(--font-size-sm);
}

/* ============================================
   Accessibility
   ============================================ */
.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

:focus-visible {
    outline: 2px solid var(--color-accent-cyan);
    outline-offset: 2px;
}

.skip-link {
    position: fixed;
    top: -100%;
    left: var(--space-md);
    padding: var(--space-md) var(--space-lg);
    background: var(--color-accent-cyan);
    color: var(--color-bg-primary);
    font-weight: 600;
    border-radius: 0 0 var(--radius-md) var(--radius-md);
    z-index: 10000;
    transition: top var(--transition-fast);
}

.skip-link:focus {
    top: 0;
}

/* ============================================
   Print Styles
   ============================================ */
@media print {
    :root {
        --color-bg-primary: #FFFFFF;
        --color-bg-secondary: #F8FAFC;
        --color-bg-tertiary: #FFFFFF;
        --color-text-primary: #000000;
        --color-text-muted: #333333;
        --color-accent-cyan: #0066CC;
        --color-accent-teal: #009966;
    }

    .header,
    .footer,
    .nav-toggle,
    .settings-panel,
    .btn--print-hide,
    .no-print {
        display: none !important;
    }

    .page-wrapper {
        padding-top: 0;
    }

    body {
        font-size: 12pt;
        line-height: 1.4;
    }

    h1 {
        font-size: 24pt;
        -webkit-text-fill-color: initial;
        background: none;
        color: #000000;
    }

    h2 {
        font-size: 18pt;
    }

    h3 {
        font-size: 14pt;
    }

    a {
        color: #0066CC;
        text-decoration: underline;
    }

    .card,
    .calculator-panel,
    .example {
        break-inside: avoid;
        border: 1px solid #CCCCCC;
        box-shadow: none;
    }

    .simulation-container {
        display: none;
    }
}

/* ============================================
   Animations
   ============================================ */
@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes pulse {

    0%,
    100% {
        opacity: 1;
    }

    50% {
        opacity: 0.5;
    }
}

@keyframes orbit {
    from {
        transform: rotate(0deg) translateX(40px) rotate(0deg);
    }

    to {
        transform: rotate(360deg) translateX(40px) rotate(-360deg);
    }
}

@keyframes fieldLine {
    0% {
        stroke-dashoffset: 100;
    }

    100% {
        stroke-dashoffset: 0;
    }
}

@keyframes glow {

    0%,
    100% {
        box-shadow: 0 0 10px var(--color-glow);
    }

    50% {
        box-shadow: 0 0 30px var(--color-glow), 0 0 60px var(--color-glow);
    }
}

.animate-fade-in {
    animation: fadeIn 0.5s ease forwards;
}

.animate-pulse {
    animation: pulse 2s ease-in-out infinite;
}

.animate-glow {
    animation: glow 3s ease-in-out infinite;
}

/* Staggered animation delays */
.stagger-1 {
    animation-delay: 0.1s;
}

.stagger-2 {
    animation-delay: 0.2s;
}

.stagger-3 {
    animation-delay: 0.3s;
}

.stagger-4 {
    animation-delay: 0.4s;
}

.stagger-5 {
    animation-delay: 0.5s;
}

/* ============================================
   Utilities
   ============================================ */
.text-center {
    text-align: center;
}

.text-left {
    text-align: left;
}

.text-right {
    text-align: right;
}

.text-muted {
    color: var(--color-text-muted);
}

.text-cyan {
    color: var(--color-accent-cyan);
}

.text-teal {
    color: var(--color-accent-teal);
}

.font-mono {
    font-family: var(--font-mono);
}

.mb-0 {
    margin-bottom: 0;
}

.mb-sm {
    margin-bottom: var(--space-sm);
}

.mb-md {
    margin-bottom: var(--space-md);
}

.mb-lg {
    margin-bottom: var(--space-lg);
}

.mb-xl {
    margin-bottom: var(--space-xl);
}

.mb-2xl {
    margin-bottom: var(--space-2xl);
}

.mt-0 {
    margin-top: 0;
}

.mt-sm {
    margin-top: var(--space-sm);
}

.mt-md {
    margin-top: var(--space-md);
}

.mt-lg {
    margin-top: var(--space-lg);
}

.mt-xl {
    margin-top: var(--space-xl);
}

.mt-2xl {
    margin-top: var(--space-2xl);
}

.hidden {
    display: none;
}

.visible {
    visibility: visible;
}

.invisible {
    visibility: hidden;
}

/* ============================================
   Floating Settings Button (FAB)
   ============================================ */
.settings-fab {
    position: fixed;
    bottom: 24px;
    right: 24px;
    width: 56px;
    height: 56px;
    background: linear-gradient(135deg, var(--color-accent-cyan), var(--color-accent-teal));
    border: none;
    border-radius: 50%;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: var(--shadow-lg), var(--shadow-glow);
    z-index: 1001;
    transition: transform var(--transition-fast), box-shadow var(--transition-fast);
}

.settings-fab:hover {
    transform: scale(1.1);
    box-shadow: var(--shadow-lg), 0 0 30px var(--color-glow);
}

.settings-fab:active {
    transform: scale(0.95);
}

.settings-fab svg {
    width: 24px;
    height: 24px;
    fill: var(--color-bg-primary);
    transition: transform var(--transition-normal);
}

.settings-fab.active svg {
    transform: rotate(90deg);
}

/* Settings Panel */
.settings-panel {
    position: fixed;
    bottom: 90px;
    right: 24px;
    width: 280px;
    background: var(--color-bg-secondary);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--space-lg);
    box-shadow: var(--shadow-lg);
    z-index: 1000;
    opacity: 0;
    visibility: hidden;
    transform: translateY(20px);
    transition: all var(--transition-normal);
}

.settings-panel.active {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.settings-panel__title {
    font-size: var(--font-size-lg);
    font-weight: 600;
    margin-bottom: var(--space-lg);
    color: var(--color-text-primary);
    display: flex;
    align-items: center;
    gap: var(--space-sm);
}

.settings-panel__group {
    margin-bottom: var(--space-lg);
}

.settings-panel__group:last-child {
    margin-bottom: 0;
}

.settings-panel__label {
    display: block;
    font-size: var(--font-size-sm);
    font-weight: 500;
    color: var(--color-text-muted);
    margin-bottom: var(--space-sm);
}

.settings-panel__options {
    display: flex;
    gap: var(--space-xs);
}

.settings-panel__btn {
    flex: 1;
    padding: var(--space-sm) var(--space-md);
    background: var(--color-bg-tertiary);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    color: var(--color-text-muted);
    font-size: var(--font-size-sm);
    font-weight: 500;
    cursor: pointer;
    transition: all var(--transition-fast);
}

.settings-panel__btn:hover {
    border-color: var(--color-accent-cyan);
    color: var(--color-text-primary);
}

.settings-panel__btn.active {
    background: linear-gradient(135deg, var(--color-accent-cyan), var(--color-accent-teal));
    border-color: transparent;
    color: var(--color-bg-primary);
}

/* Small Text Mode */
[data-text-size="small"] {
    --font-size-base: 0.875rem;
    --font-size-lg: 1rem;
    --font-size-xl: 1.125rem;
    --font-size-2xl: 1.25rem;
    --font-size-3xl: 1.75rem;
    --font-size-4xl: 2.25rem;
    --font-size-5xl: 3rem;
}

/* ============================================
   Motor Speed Gauge
   ============================================ */
.motor-gauge {
    position: relative;
    width: 200px;
    height: 120px;
    margin: 0 auto;
}

.motor-gauge__dial {
    position: absolute;
    bottom: 0;
    left: 50%;
    width: 4px;
    height: 80px;
    background: linear-gradient(to top, var(--color-accent-cyan), var(--color-accent-teal));
    transform-origin: bottom center;
    transform: translateX(-50%) rotate(-90deg);
    transition: transform 0.5s ease-out;
    border-radius: 2px;
}

.motor-gauge__scale {
    position: absolute;
    bottom: 0;
    left: 50%;
    width: 160px;
    height: 80px;
    transform: translateX(-50%);
    border-radius: 80px 80px 0 0;
    border: 3px solid var(--color-border);
    border-bottom: none;
}

.motor-gauge__value {
    position: absolute;
    bottom: -30px;
    left: 50%;
    transform: translateX(-50%);
    font-family: var(--font-mono);
    font-size: var(--font-size-xl);
    font-weight: 700;
    color: var(--color-accent-cyan);
}

.motor-gauge__label {
    position: absolute;
    bottom: -50px;
    left: 50%;
    transform: translateX(-50%);
    font-size: var(--font-size-sm);
    color: var(--color-text-muted);
}

/* ============================================
   Battery Visualization
   ============================================ */
.battery-cell {
    position: relative;
    width: 60px;
    height: 120px;
    background: var(--color-bg-tertiary);
    border: 2px solid var(--color-border);
    border-radius: var(--radius-md);
    overflow: hidden;
}

.battery-cell__terminal {
    position: absolute;
    top: -8px;
    left: 50%;
    transform: translateX(-50%);
    width: 20px;
    height: 8px;
    background: var(--color-text-muted);
    border-radius: 4px 4px 0 0;
}

.battery-cell__level {
    position: absolute;
    bottom: 4px;
    left: 4px;
    right: 4px;
    background: linear-gradient(to top, var(--color-accent-teal), var(--color-accent-cyan));
    border-radius: 4px;
    transition: height 0.5s ease-out;
}

.battery-cell__label {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    font-family: var(--font-mono);
    font-size: var(--font-size-xs);
    font-weight: 700;
    color: var(--color-text-primary);
    z-index: 1;
}

.battery-pack {
    display: flex;
    gap: var(--space-sm);
    justify-content: center;
    align-items: flex-end;
    padding: var(--space-lg);
}

/* Battery discharge curve */
.discharge-curve {
    width: 100%;
    height: 150px;
    background: var(--color-bg-tertiary);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    position: relative;
}

/* ============================================
   RC Car specific animations
   ============================================ */
@keyframes motorSpin {
    from {
        transform: rotate(0deg);
    }

    to {
        transform: rotate(360deg);
    }
}

@keyframes electronFlow {
    0% {
        transform: translateX(0);
        opacity: 1;
    }

    100% {
        transform: translateX(100px);
        opacity: 0;
    }
}

.motor-coil {
    animation: motorSpin 1s linear infinite;
    animation-play-state: paused;
}

.motor-coil.spinning {
    animation-play-state: running;
}

/* Electron particles */
.electron-particle {
    position: absolute;
    width: 8px;
    height: 8px;
    background: var(--color-accent-cyan);
    border-radius: 50%;
    box-shadow: 0 0 8px var(--color-accent-cyan);
}

/* ============================================
   Mobile Responsiveness Enhancements
   ============================================ */

/* Fix navigation menu background on mobile */
@media (max-width: 992px) {
    .nav__list {
        background-color: #000000 !important;
        background: #000000 !important;
    }

    .nav__list.active {
        background-color: #000000 !important;
        background: #000000 !important;
    }

    /* Improve header layout on mobile */
    .header__inner {
        padding: 0 var(--space-md);
    }

    .header__logo span {
        font-size: var(--font-size-base);
    }

    /* Hide mode toggle on mobile header - it's redundant */
    .mode-toggle {
        display: none;
    }

    /* Larger touch targets for nav links */
    .nav__link {
        padding: var(--space-md) var(--space-lg);
        min-height: 48px;
        display: flex;
        align-items: center;
    }
}

/* Smaller screen fixes */
@media (max-width: 768px) {

    /* Increase button touch targets */
    .btn {
        min-height: 44px;
        padding: var(--space-md) var(--space-lg);
    }

    .btn--sm {
        min-height: 40px;
        padding: var(--space-sm) var(--space-md);
    }

    /* Larger preset buttons */
    .preset-btn,
    [data-motor-preset],
    [data-battery-preset] {
        min-height: 44px;
        padding: var(--space-sm) var(--space-md);
        font-size: var(--font-size-sm);
    }

    /* Fix chemical equation overflow */
    pre,
    code {
        overflow-x: auto;
        max-width: 100%;
        font-size: var(--font-size-xs);
        word-wrap: break-word;
    }

    .card pre {
        padding: var(--space-sm);
        margin: var(--space-sm) 0;
    }

    /* Larger checkbox/radio touch targets */
    input[type="checkbox"],
    input[type="radio"] {
        width: 24px;
        height: 24px;
        min-width: 24px;
        min-height: 24px;
    }

    /* Better label alignment with checkbox */
    label {
        display: flex;
        align-items: center;
        gap: var(--space-sm);
        min-height: 44px;
    }

    /* Improve range slider touch area */
    input[type="range"] {
        height: 32px;
    }

    /* Settings FAB adjustments */
    .settings-fab {
        width: 48px;
        height: 48px;
        bottom: 16px;
        right: 16px;
    }

    .settings-panel {
        right: 16px;
        bottom: 76px;
        width: calc(100vw - 32px);
        max-width: 300px;
    }

    /* Better spacing for mobile */
    .section {
        padding: var(--space-lg) 0;
    }

    .container {
        padding: 0 var(--space-md);
    }

    /* Card improvements for mobile */
    .card {
        padding: var(--space-md);
    }

    .card h3,
    .card h4 {
        font-size: var(--font-size-base);
    }

    /* Results panel improvements */
    .results-panel {
        padding: var(--space-md);
    }

    .result-item {
        flex-direction: column;
        align-items: flex-start;
        gap: var(--space-xs);
    }

    /* Heading sizes for mobile */
    h1 {
        font-size: var(--font-size-2xl);
    }

    h2 {
        font-size: var(--font-size-xl);
    }

    /* Fun facts cards on mobile */
    .grid--3 .card,
    .grid--2 .card {
        padding: var(--space-md);
    }

    /* Canvas responsiveness */
    canvas {
        max-width: 100%;
        height: auto !important;
    }

    /* Calculator panel improvements */
    .calculator-panel {
        margin: 0 calc(-1 * var(--space-md));
        border-radius: 0;
    }

    .calculator-panel__header {
        flex-direction: column;
        gap: var(--space-md);
        align-items: flex-start;
    }

    .calculator-panel__header .flex {
        flex-wrap: wrap;
        width: 100%;
    }
}

/* Very small screens (phones in portrait) */
@media (max-width: 480px) {
    body {
        font-size: 14px;
    }

    h1 {
        font-size: var(--font-size-xl);
    }

    h2 {
        font-size: var(--font-size-lg);
    }

    h3,
    h4 {
        font-size: var(--font-size-base);
    }

    /* Stack all result items */
    .grid--2,
    .grid--3 {
        gap: var(--space-md);
    }

    /* Even larger touch targets */
    .btn {
        width: 100%;
        justify-content: center;
    }

    /* Stacked buttons */
    .flex.gap-md,
    .flex.gap-sm {
        flex-direction: column;
    }

    .flex.gap-md>*,
    .flex.gap-sm>* {
        width: 100%;
    }

    /* Results grid to single column */
    .results-panel .grid--2,
    .results-panel .grid--3 {
        grid-template-columns: 1fr;
    }

    /* Better collapsible button */
    .collapsible-toggle {
        font-size: var(--font-size-sm) !important;
    }

    /* Form group spacing */
    .form-group {
        margin-bottom: var(--space-md);
    }

    /* Footer */
    .footer {
        padding: var(--space-lg) 0;
        text-align: center;
    }
}

/* ============================================
   Page Transitions & Scroll Animations
   ============================================ */

/* Keyframe Animations */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes fadeIn {
    from {
        opacity: 0;
    }

    to {
        opacity: 1;
    }
}

@keyframes slideInLeft {
    from {
        opacity: 0;
        transform: translateX(-30px);
    }

    to {
        opacity: 1;
        transform: translateX(0);
    }
}

@keyframes slideInRight {
    from {
        opacity: 0;
        transform: translateX(30px);
    }

    to {
        opacity: 1;
        transform: translateX(0);
    }
}

@keyframes scaleIn {
    from {
        opacity: 0;
        transform: scale(0.95);
    }

    to {
        opacity: 1;
        transform: scale(1);
    }
}

/* Page wrapper animation - applies to main content */
.page-wrapper {
    animation: fadeInUp 0.6s ease-out forwards;
}

/* Animate on load classes - for elements that animate on page load */
.animate-on-load {
    opacity: 0;
    animation: fadeInUp 0.6s ease-out forwards;
}

.animate-on-load.delay-1 {
    animation-delay: 0.1s;
}

.animate-on-load.delay-2 {
    animation-delay: 0.2s;
}

.animate-on-load.delay-3 {
    animation-delay: 0.3s;
}

.animate-on-load.delay-4 {
    animation-delay: 0.4s;
}

.animate-on-load.delay-5 {
    animation-delay: 0.5s;
}

.animate-on-load.delay-6 {
    animation-delay: 0.6s;
}

/* Scroll-triggered animation classes */
.animate-on-scroll {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.6s ease-out, transform 0.6s ease-out;
}

.animate-on-scroll.visible {
    opacity: 1;
    transform: translateY(0);
}

/* Slide variations for scroll */
.animate-slide-left {
    opacity: 0;
    transform: translateX(-30px);
    transition: opacity 0.6s ease-out, transform 0.6s ease-out;
}

.animate-slide-left.visible {
    opacity: 1;
    transform: translateX(0);
}

.animate-slide-right {
    opacity: 0;
    transform: translateX(30px);
    transition: opacity 0.6s ease-out, transform 0.6s ease-out;
}

.animate-slide-right.visible {
    opacity: 1;
    transform: translateX(0);
}

/* Scale animation for cards */
.animate-scale {
    opacity: 0;
    transform: scale(0.95);
    transition: opacity 0.5s ease-out, transform 0.5s ease-out;
}

.animate-scale.visible {
    opacity: 1;
    transform: scale(1);
}

/* Stagger delays for scroll animations */
.stagger-1 {
    transition-delay: 0.1s;
}

.stagger-2 {
    transition-delay: 0.2s;
}

.stagger-3 {
    transition-delay: 0.3s;
}

.stagger-4 {
    transition-delay: 0.4s;
}

.stagger-5 {
    transition-delay: 0.5s;
}

/* Header entrance animation */
.header {
    animation: fadeIn 0.4s ease-out forwards;
}

/* Hero section staggered animations */
.hero__content>* {
    opacity: 0;
    animation: fadeInUp 0.6s ease-out forwards;
}

.hero__content>*:nth-child(1) {
    animation-delay: 0.2s;
}

.hero__content>*:nth-child(2) {
    animation-delay: 0.4s;
}

.hero__content>*:nth-child(3) {
    animation-delay: 0.6s;
}

.hero__content>*:nth-child(4) {
    animation-delay: 0.8s;
}

/* Card hover enhancement with animation */
.card {
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.card:hover {
    transform: translateY(-4px);
}

/* Section headings animate */
.section>h1,
.section>h2 {
    opacity: 0;
    animation: fadeInUp 0.6s ease-out forwards;
    animation-delay: 0.1s;
}

/* Reduce motion for accessibility */
@media (prefers-reduced-motion: reduce) {

    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }

    .animate-on-scroll,
    .animate-slide-left,
    .animate-slide-right,
    .animate-scale {
        opacity: 1;
        transform: none;
    }
}

/* ============================================
   Page Navigation Arrows
   ============================================ */

.page-nav-arrow {
    position: fixed;
    top: 50%;
    transform: translateY(-50%);
    z-index: 1000;
    width: 50px;
    height: 80px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, rgba(0, 209, 255, 0.1), rgba(62, 241, 198, 0.1));
    border: 1px solid var(--color-border);
    cursor: pointer;
    transition: all 0.3s ease;
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
}

.page-nav-arrow--prev {
    left: 0;
    border-radius: 0 var(--radius-lg) var(--radius-lg) 0;
    border-left: none;
}

.page-nav-arrow--next {
    right: 0;
    border-radius: var(--radius-lg) 0 0 var(--radius-lg);
    border-right: none;
}

.page-nav-arrow:hover {
    background: linear-gradient(135deg, rgba(0, 209, 255, 0.25), rgba(62, 241, 198, 0.25));
    box-shadow: 0 0 20px var(--color-glow);
}

.page-nav-arrow--prev:hover {
    padding-left: 5px;
}

.page-nav-arrow--next:hover {
    padding-right: 5px;
}

.page-nav-arrow svg {
    width: 24px;
    height: 24px;
    fill: none;
    stroke: var(--color-accent-cyan);
    stroke-width: 2;
    stroke-linecap: round;
    stroke-linejoin: round;
    transition: transform 0.3s ease;
}

.page-nav-arrow--prev:hover svg {
    transform: translateX(-3px);
}

.page-nav-arrow--next:hover svg {
    transform: translateX(3px);
}

/* Arrow label - shows page name on hover */
.page-nav-arrow__label {
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    padding: var(--space-xs) var(--space-sm);
    font-size: var(--font-size-sm);
    color: var(--color-text-primary);
    white-space: nowrap;
    opacity: 0;
    transition: opacity 0.3s ease, transform 0.3s ease;
    pointer-events: none;
    background: rgba(7, 23, 51, 0.95);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
}

/* Position label to the right of prev arrow */
.page-nav-arrow--prev .page-nav-arrow__label {
    left: 100%;
    margin-left: var(--space-sm);
}

/* Position label to the left of next arrow */
.page-nav-arrow--next .page-nav-arrow__label {
    right: 100%;
    margin-right: var(--space-sm);
}

.page-nav-arrow:hover .page-nav-arrow__label {
    opacity: 1;
}

/* Mobile arrow styles */
@media (max-width: 768px) {
    .page-nav-arrow {
        width: 36px;
        height: 50px;
    }

    .page-nav-arrow svg {
        width: 18px;
        height: 18px;
    }

    .page-nav-arrow__label {
        font-size: var(--font-size-xs);
        padding: 4px 8px;
    }
}

/* ============================================
   SVG Drawing Animation Classes
   ============================================ */

.svg-draw path,
.svg-draw line,
.svg-draw polyline,
.svg-draw polygon,
.svg-draw circle,
.svg-draw rect {
    fill: none;
    stroke-dasharray: var(--path-length, 1000);
    stroke-dashoffset: var(--path-length, 1000);
}

.svg-draw.visible path,
.svg-draw.visible line,
.svg-draw.visible polyline,
.svg-draw.visible polygon,
.svg-draw.visible circle,
.svg-draw.visible rect {
    stroke-dashoffset: 0;
    transition: stroke-dashoffset 1.5s ease-out;
}