/* ===================================
   Design System & CSS Variables
   =================================== */

/* Dark Mode (Default) */
:root {
    /* Color Palette */
    --primary-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --secondary-gradient: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
    --success-gradient: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
    --warning-gradient: linear-gradient(135deg, #fa709a 0%, #fee140 100%);

    /* Dark Mode Colors */
    --bg-dark: #0f0f23;
    --bg-card: rgba(255, 255, 255, 0.05);
    --bg-input: rgba(255, 255, 255, 0.08);
    --text-primary: #ffffff;
    --text-secondary: rgba(255, 255, 255, 0.7);
    --text-muted: rgba(255, 255, 255, 0.5);

    /* Glassmorphism */
    --glass-bg: rgba(255, 255, 255, 0.1);
    --glass-border: rgba(255, 255, 255, 0.18);
    --glass-shadow: 0 8px 32px 0 rgba(31, 38, 135, 0.37);

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

    /* Border Radius */
    --radius-sm: 8px;
    --radius-md: 16px;
    --radius-lg: 24px;
    --radius-xl: 32px;

    /* Transitions */
    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s ease;
    --transition-slow: 0.5s ease;

    /* Shadows */
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.2);
    --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.3);
    --shadow-glow: 0 0 40px rgba(102, 126, 234, 0.4);

    /* Orb Colors for Dark Mode */
    --orb-1-color: linear-gradient(135deg, #667eea, #764ba2);
    --orb-2-color: linear-gradient(135deg, #f093fb, #f5576c);
    --orb-3-color: linear-gradient(135deg, #4facfe, #00f2fe);
}

/* Light Mode */
[data-theme="light"],
.light-mode {
    /* Light Mode Colors */
    --bg-dark: #f5f7fa;
    --bg-card: rgba(255, 255, 255, 0.9);
    --bg-input: rgba(255, 255, 255, 0.95);
    --text-primary: #1a202c;
    --text-secondary: rgba(26, 32, 44, 0.8);
    --text-muted: rgba(26, 32, 44, 0.6);

    /* Glassmorphism for Light */
    --glass-bg: rgba(255, 255, 255, 0.95);
    --glass-border: rgba(0, 0, 0, 0.15);
    --glass-shadow: 0 8px 32px 0 rgba(0, 0, 0, 0.1);

    /* Shadows for Light */
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.08);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.12);
    --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.15);
    --shadow-glow: 0 0 40px rgba(102, 126, 234, 0.2);

    /* Orb Colors for Light Mode (more subtle) */
    --orb-1-color: linear-gradient(135deg, rgba(102, 126, 234, 0.15), rgba(118, 75, 162, 0.15));
    --orb-2-color: linear-gradient(135deg, rgba(240, 147, 251, 0.15), rgba(245, 87, 108, 0.15));
    --orb-3-color: linear-gradient(135deg, rgba(79, 172, 254, 0.15), rgba(0, 242, 254, 0.15));
}

/* Auto detect system preference */
@media (prefers-color-scheme: light) {
    :root:not([data-theme="dark"]) {
        /* Light Mode Colors */
        --bg-dark: #f5f7fa;
        --bg-card: rgba(255, 255, 255, 0.9);
        --bg-input: rgba(255, 255, 255, 0.95);
        --text-primary: #1a202c;
        --text-secondary: rgba(26, 32, 44, 0.8);
        --text-muted: rgba(26, 32, 44, 0.6);

        /* Glassmorphism for Light */
        --glass-bg: rgba(255, 255, 255, 0.95);
        --glass-border: rgba(0, 0, 0, 0.15);
        --glass-shadow: 0 8px 32px 0 rgba(0, 0, 0, 0.1);

        /* Shadows for Light */
        --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.08);
        --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.12);
        --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.15);
        --shadow-glow: 0 0 40px rgba(102, 126, 234, 0.2);

        /* Orb Colors for Light Mode */
        --orb-1-color: linear-gradient(135deg, rgba(102, 126, 234, 0.15), rgba(118, 75, 162, 0.15));
        --orb-2-color: linear-gradient(135deg, rgba(240, 147, 251, 0.15), rgba(245, 87, 108, 0.15));
        --orb-3-color: linear-gradient(135deg, rgba(79, 172, 254, 0.15), rgba(0, 242, 254, 0.15));
    }
}

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    background: var(--bg-dark);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    transition: background-color var(--transition-normal), color var(--transition-normal);
}

/* ===================================
   Background Animation
   =================================== */
.background-animation {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: -1;
    overflow: hidden;
}

.gradient-orb {
    position: absolute;
    border-radius: 50%;
    filter: blur(80px);
    opacity: 0.3;
    animation: float 20s infinite ease-in-out;
    transition: background var(--transition-slow);
}

.orb-1 {
    width: 500px;
    height: 500px;
    background: var(--orb-1-color);
    top: -250px;
    left: -250px;
    animation-delay: 0s;
}

.orb-2 {
    width: 400px;
    height: 400px;
    background: var(--orb-2-color);
    bottom: -200px;
    right: -200px;
    animation-delay: 7s;
}

.orb-3 {
    width: 350px;
    height: 350px;
    background: var(--orb-3-color);
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    animation-delay: 14s;
}

@keyframes float {

    0%,
    100% {
        transform: translate(0, 0) scale(1);
    }

    33% {
        transform: translate(50px, -50px) scale(1.1);
    }

    66% {
        transform: translate(-50px, 50px) scale(0.9);
    }
}

/* ===================================
   Container & Layout
   =================================== */
.container {
    max-width: 600px;
    margin: 0 auto;
    padding: var(--spacing-lg);
    position: relative;
    z-index: 1;
}

/* ===================================
   Header
   =================================== */
.header {
    text-align: center;
    margin-bottom: var(--spacing-xl);
    animation: fadeInDown 0.8s ease;
}

.logo {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-sm);
}

.logo svg {
    animation: rotate 20s linear infinite;
}

@keyframes rotate {
    from {
        transform: rotate(0deg);
    }

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

.logo h1 {
    font-size: 2.5rem;
    font-weight: 700;
    background: var(--primary-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.tagline {
    color: var(--text-secondary);
    font-size: 1rem;
    font-weight: 400;
}

/* ===================================
   Theme Toggle Button
   =================================== */
.theme-toggle {
    position: fixed;
    top: var(--spacing-lg);
    right: var(--spacing-lg);
    z-index: 1000;
    background: var(--glass-bg);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border: 1px solid var(--glass-border);
    border-radius: 50%;
    width: 50px;
    height: 50px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all var(--transition-normal);
    box-shadow: var(--shadow-md);
}

.theme-toggle:hover {
    transform: scale(1.1) rotate(15deg);
    box-shadow: var(--shadow-lg);
}

.theme-toggle:active {
    transform: scale(0.95);
}

.theme-toggle svg {
    width: 24px;
    height: 24px;
    color: var(--text-primary);
    transition: all var(--transition-normal);
}

.theme-toggle .sun-icon {
    display: none;
}

.theme-toggle .moon-icon {
    display: block;
}

[data-theme="light"] .theme-toggle .sun-icon,
.light-mode .theme-toggle .sun-icon {
    display: block;
}

[data-theme="light"] .theme-toggle .moon-icon,
.light-mode .theme-toggle .moon-icon {
    display: none;
}

@media (max-width: 768px) {
    .theme-toggle {
        top: var(--spacing-md);
        right: var(--spacing-md);
        width: 45px;
        height: 45px;
    }
}

/* ===================================
   Calculator Card
   =================================== */
.calculator-card {
    background: var(--glass-bg);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-xl);
    padding: var(--spacing-xl);
    box-shadow: var(--glass-shadow);
    position: relative;
    overflow: hidden;
    animation: fadeInUp 0.8s ease;
}

.card-glow {
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle, rgba(102, 126, 234, 0.1) 0%, transparent 70%);
    animation: rotateGlow 15s linear infinite;
    pointer-events: none;
}

@keyframes rotateGlow {
    from {
        transform: rotate(0deg);
    }

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

/* ===================================
   Unit Toggle
   =================================== */
.unit-toggle {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-lg);
    background: var(--bg-input);
    padding: 6px;
    border-radius: var(--radius-md);
}

.toggle-btn {
    background: transparent;
    border: none;
    color: var(--text-secondary);
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: all var(--transition-normal);
    font-family: inherit;
    font-size: 0.95rem;
    font-weight: 500;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 4px;
}

.toggle-btn small {
    font-size: 0.75rem;
    opacity: 0.7;
}

.toggle-btn:hover {
    color: var(--text-primary);
    transform: translateY(-2px);
}

.toggle-btn.active {
    background: var(--primary-gradient);
    color: var(--text-primary);
    box-shadow: var(--shadow-md);
}

/* ===================================
   Form Styles
   =================================== */
.bmi-form {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
}

.input-group {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xs);
}

.input-label {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--text-primary);
}

.input-label svg {
    opacity: 0.7;
}

.optional {
    color: var(--text-muted);
    font-size: 0.85rem;
    font-weight: 400;
}

.input-wrapper {
    position: relative;
    display: flex;
    align-items: center;
}

.input-wrapper input {
    width: 100%;
    background: var(--bg-input);
    border: 2px solid transparent;
    border-radius: var(--radius-md);
    padding: var(--spacing-md);
    padding-right: 60px;
    color: var(--text-primary);
    font-family: inherit;
    font-size: 1.1rem;
    font-weight: 500;
    transition: all var(--transition-normal);
    outline: none;
}

.input-wrapper input:focus {
    border-color: #667eea;
    box-shadow: 0 0 0 4px rgba(102, 126, 234, 0.1);
    transform: translateY(-2px);
}

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

.unit-label {
    position: absolute;
    right: var(--spacing-md);
    color: var(--text-secondary);
    font-size: 0.9rem;
    font-weight: 500;
    pointer-events: none;
}

/* ===================================
   Calculate Button
   =================================== */
.calculate-btn {
    background: var(--primary-gradient);
    border: none;
    border-radius: var(--radius-md);
    padding: var(--spacing-md) var(--spacing-lg);
    color: var(--text-primary);
    font-family: inherit;
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    margin-top: var(--spacing-md);
    transition: all var(--transition-normal);
    box-shadow: var(--shadow-md);
    position: relative;
    overflow: hidden;
}

.calculate-btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
    transition: left 0.5s;
}

.calculate-btn:hover::before {
    left: 100%;
}

.calculate-btn:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-lg), var(--shadow-glow);
}

.calculate-btn:active {
    transform: translateY(-1px);
}

/* ===================================
   Result Container
   =================================== */
.result-container {
    margin-top: var(--spacing-xl);
    padding-top: var(--spacing-xl);
    border-top: 1px solid var(--glass-border);
    display: none;
    animation: fadeInUp 0.5s ease;
}

.result-container.show {
    display: block;
}

.result-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-lg);
}

.result-header h2 {
    font-size: 1.5rem;
    font-weight: 600;
}

.close-btn {
    background: var(--bg-input);
    border: none;
    border-radius: 50%;
    width: 36px;
    height: 36px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    color: var(--text-secondary);
    transition: all var(--transition-fast);
}

.close-btn:hover {
    background: var(--bg-card);
    color: var(--text-primary);
    transform: rotate(90deg);
}

/* ===================================
   BMI Value Display
   =================================== */
.bmi-value-display {
    text-align: center;
    margin-bottom: var(--spacing-xl);
    padding: var(--spacing-lg);
    background: var(--bg-input);
    border-radius: var(--radius-lg);
    position: relative;
    overflow: hidden;
}

.bmi-value-display::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: var(--primary-gradient);
}

.bmi-number {
    font-size: 4rem;
    font-weight: 700;
    background: var(--primary-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    line-height: 1;
    margin-bottom: var(--spacing-sm);
    animation: scaleIn 0.5s ease;
}

.bmi-category {
    font-size: 1.3rem;
    font-weight: 600;
    color: var(--text-primary);
    animation: fadeIn 0.5s ease 0.2s both;
}

/* ===================================
   BMI Scale
   =================================== */
.bmi-scale {
    margin-bottom: var(--spacing-xl);
}

.scale-bar {
    height: 12px;
    background: linear-gradient(to right,
            #4facfe 0%,
            #00f2fe 25%,
            #43e97b 50%,
            #fa709a 75%,
            #fee140 100%);
    border-radius: 100px;
    position: relative;
    margin-bottom: var(--spacing-sm);
    box-shadow: var(--shadow-sm);
}

.scale-indicator {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 24px;
    height: 24px;
    background: white;
    border: 3px solid var(--bg-dark);
    border-radius: 50%;
    box-shadow: var(--shadow-md);
    transition: left var(--transition-slow);
    animation: pulse 2s infinite;
}

@keyframes pulse {

    0%,
    100% {
        box-shadow: 0 0 0 0 rgba(255, 255, 255, 0.7);
    }

    50% {
        box-shadow: 0 0 0 10px rgba(255, 255, 255, 0);
    }
}

.scale-labels {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: var(--spacing-xs);
    font-size: 0.75rem;
    color: var(--text-muted);
    text-align: center;
}

/* ===================================
   Health Info Cards
   =================================== */
.health-info {
    display: grid;
    gap: var(--spacing-md);
}

.info-card {
    background: var(--bg-input);
    padding: var(--spacing-md);
    border-radius: var(--radius-md);
    border-left: 4px solid transparent;
    transition: all var(--transition-normal);
    animation: fadeIn 0.5s ease;
}

.info-card:hover {
    transform: translateX(4px);
    border-left-color: #667eea;
}

.info-card h3 {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: var(--spacing-xs);
    color: var(--text-primary);
}

.info-card p {
    font-size: 0.9rem;
    color: var(--text-secondary);
    line-height: 1.6;
}

/* ===================================
   Instant Result Preview
   =================================== */
.instant-result {
    display: none;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    margin-top: var(--spacing-lg);
    padding: var(--spacing-md);
    background: var(--bg-input);
    border-radius: var(--radius-md);
    border: 2px solid transparent;
    transition: all var(--transition-normal);
    animation: fadeIn 0.3s ease;
}

.instant-result.show {
    display: flex;
}

.instant-label {
    font-size: 0.9rem;
    color: var(--text-secondary);
    font-weight: 500;
}

.instant-value {
    font-size: 2rem;
    font-weight: 700;
    background: var(--primary-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

/* ===================================
   Health Tips Section
   =================================== */
.health-tips {
    margin-top: var(--spacing-xl);
    padding-top: var(--spacing-xl);
    border-top: 1px solid var(--glass-border);
    animation: fadeInUp 0.5s ease;
}

.health-tips h3 {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    font-size: 1.2rem;
    font-weight: 600;
    margin-bottom: var(--spacing-md);
    color: var(--text-primary);
}

.health-tips h3 svg {
    color: #43e97b;
}

.tips-container {
    display: grid;
    gap: var(--spacing-sm);
}

.tip-item {
    display: flex;
    align-items: flex-start;
    gap: var(--spacing-sm);
    padding: var(--spacing-md);
    background: var(--bg-input);
    border-radius: var(--radius-md);
    border-left: 3px solid #667eea;
    transition: all var(--transition-normal);
    animation: slideInLeft 0.3s ease;
}

.tip-item:hover {
    transform: translateX(4px);
    background: rgba(255, 255, 255, 0.12);
}

.tip-icon {
    font-size: 1.5rem;
    flex-shrink: 0;
}

.tip-text {
    font-size: 0.9rem;
    color: var(--text-secondary);
    line-height: 1.6;
}

@keyframes slideInLeft {
    from {
        opacity: 0;
        transform: translateX(-20px);
    }

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

/* ===================================
   Content Sections
   =================================== */
.content-section {
    max-width: 800px;
    margin: var(--spacing-xl) auto;
    padding: var(--spacing-xl);
    background: var(--glass-bg);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-xl);
    animation: fadeInUp 0.8s ease;
}

.content-section h2 {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: var(--spacing-md);
    background: var(--primary-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.content-section p {
    font-size: 1rem;
    color: var(--text-secondary);
    line-height: 1.8;
    margin-bottom: var(--spacing-md);
}

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

/* ===================================
   Category Grid
   =================================== */
.category-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-md);
    margin-top: var(--spacing-lg);
}

.category-card {
    padding: var(--spacing-lg);
    background: var(--bg-input);
    border-radius: var(--radius-lg);
    border-top: 4px solid;
    transition: all var(--transition-normal);
    text-align: center;
}

.category-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-lg);
}

.underweight-card {
    border-top-color: #4facfe;
}

.normal-card {
    border-top-color: #43e97b;
}

.overweight-card {
    border-top-color: #fa709a;
}

.obese-card {
    border-top-color: #fee140;
}

.category-icon {
    font-size: 3rem;
    margin-bottom: var(--spacing-sm);
}

.category-card h3 {
    font-size: 1.3rem;
    font-weight: 600;
    margin-bottom: var(--spacing-xs);
    color: var(--text-primary);
}

.category-range {
    font-size: 0.95rem;
    color: var(--text-secondary);
    font-weight: 600;
    margin-bottom: var(--spacing-sm);
    padding: var(--spacing-xs) var(--spacing-sm);
    background: rgba(255, 255, 255, 0.05);
    border-radius: var(--radius-sm);
    display: inline-block;
}

.category-card p {
    font-size: 0.9rem;
    color: var(--text-secondary);
    line-height: 1.6;
}

/* ===================================
   Benefits Grid
   =================================== */
.benefits-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: var(--spacing-md);
    margin-top: var(--spacing-lg);
}

.benefit-item {
    padding: var(--spacing-md);
    background: var(--bg-input);
    border-radius: var(--radius-md);
    transition: all var(--transition-normal);
}

.benefit-item:hover {
    transform: translateY(-4px);
    background: rgba(255, 255, 255, 0.12);
}

.benefit-icon {
    font-size: 2.5rem;
    margin-bottom: var(--spacing-sm);
}

.benefit-item h3 {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: var(--spacing-xs);
    color: var(--text-primary);
}

.benefit-item p {
    font-size: 0.9rem;
    color: var(--text-secondary);
    line-height: 1.6;
    margin: 0;
}

/* ===================================
   BMI Table
   =================================== */
.table-responsive {
    overflow-x: auto;
    margin-top: var(--spacing-lg);
}

.bmi-table {
    width: 100%;
    border-collapse: collapse;
    background: var(--bg-input);
    border-radius: var(--radius-md);
    overflow: hidden;
}

.bmi-table thead {
    background: rgba(102, 126, 234, 0.2);
}

.bmi-table th {
    padding: var(--spacing-md);
    text-align: left;
    font-weight: 600;
    color: var(--text-primary);
    font-size: 0.9rem;
}

.bmi-table td {
    padding: var(--spacing-md);
    border-top: 1px solid var(--glass-border);
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.bmi-table tbody tr {
    transition: background var(--transition-fast);
}

.bmi-table tbody tr:hover {
    background: rgba(255, 255, 255, 0.05);
}

/* ===================================
   FAQ Section
   =================================== */
.faq-container {
    margin-top: var(--spacing-lg);
}

.faq-item {
    margin-bottom: var(--spacing-sm);
    background: var(--bg-input);
    border-radius: var(--radius-md);
    overflow: hidden;
    transition: all var(--transition-normal);
}

.faq-item:hover {
    background: rgba(255, 255, 255, 0.12);
}

.faq-question {
    width: 100%;
    padding: var(--spacing-md);
    background: transparent;
    border: none;
    color: var(--text-primary);
    font-family: inherit;
    font-size: 1rem;
    font-weight: 600;
    text-align: left;
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: var(--spacing-sm);
    transition: all var(--transition-fast);
}

.faq-question:hover {
    color: #667eea;
}

.faq-question svg {
    flex-shrink: 0;
    transition: transform var(--transition-normal);
}

.faq-item.active .faq-question svg {
    transform: rotate(180deg);
}

.faq-answer {
    max-height: 0;
    overflow: hidden;
    transition: max-height var(--transition-normal);
}

.faq-item.active .faq-answer {
    max-height: 500px;
}

.faq-answer p {
    padding: 0 var(--spacing-md) var(--spacing-md);
    color: var(--text-secondary);
    line-height: 1.8;
    font-size: 0.95rem;
    margin: 0;
}

/* ===================================
   Footer
   =================================== */
.footer {
    margin-top: var(--spacing-xl);
    padding: var(--spacing-xl) var(--spacing-lg);
    background: var(--glass-bg);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-xl);
    text-align: center;
    animation: fadeIn 1s ease;
}

.footer-content {
    max-width: 800px;
    margin: 0 auto;
}

.disclaimer {
    font-size: 0.85rem;
    color: var(--text-secondary);
    line-height: 1.8;
    margin-bottom: var(--spacing-md);
    padding: var(--spacing-md);
    background: rgba(255, 255, 255, 0.05);
    border-radius: var(--radius-md);
    border-left: 3px solid #fa709a;
}

.copyright {
    font-size: 0.8rem;
    color: var(--text-muted);
}

.footer a {
    color: #667eea;
    text-decoration: none;
    transition: color var(--transition-fast);
}

.footer a:hover {
    color: #764ba2;
    text-decoration: underline;
}

/* ===================================
   Animations
   =================================== */
@keyframes fadeInDown {
    from {
        opacity: 0;
        transform: translateY(-30px);
    }

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

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }

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

@keyframes fadeIn {
    from {
        opacity: 0;
    }

    to {
        opacity: 1;
    }
}

@keyframes scaleIn {
    from {
        opacity: 0;
        transform: scale(0.5);
    }

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

/* ===================================
   Responsive Design
   =================================== */
@media (max-width: 768px) {
    .container {
        padding: var(--spacing-md);
    }

    .logo h1 {
        font-size: 2rem;
    }

    .calculator-card {
        padding: var(--spacing-lg);
    }

    .bmi-number {
        font-size: 3rem;
    }

    .scale-labels {
        font-size: 0.7rem;
    }

    .content-section {
        padding: var(--spacing-lg);
    }

    .content-section h2 {
        font-size: 1.5rem;
    }

    .category-grid {
        grid-template-columns: 1fr;
    }

    .benefits-grid {
        grid-template-columns: 1fr;
    }

    .bmi-table {
        font-size: 0.8rem;
    }

    .bmi-table th,
    .bmi-table td {
        padding: var(--spacing-sm);
    }
}

@media (max-width: 480px) {
    .logo h1 {
        font-size: 1.75rem;
    }

    .calculator-card {
        padding: var(--spacing-md);
    }

    .bmi-number {
        font-size: 2.5rem;
    }

    .unit-toggle {
        gap: 6px;
    }

    .toggle-btn {
        padding: var(--spacing-xs) var(--spacing-sm);
        font-size: 0.85rem;
    }

    .content-section {
        padding: var(--spacing-md);
    }

    .instant-value {
        font-size: 1.5rem;
    }

    .category-icon {
        font-size: 2rem;
    }

    .benefit-icon {
        font-size: 2rem;
    }
}

/* ===================================
   Accessibility
   =================================== */
@media (prefers-reduced-motion: reduce) {

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

/* Focus visible for keyboard navigation */
*:focus-visible {
    outline: 2px solid #667eea;
    outline-offset: 2px;
}