/* ========================================
   OBESITY EDUCATION WEBSITE - DESIGN SYSTEM
   ======================================== */

/* Google Fonts */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&family=Poppins:wght@400;500;600;700&display=swap');

/* ========================================
   CSS RESET & BASE STYLES
   ======================================== */

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    /* Color Palette - Medical & Professional */
    --color-primary: #0066CC;
    --color-primary-dark: #004C99;
    --color-primary-light: #3385D6;
    --color-secondary: #00A896;
    --color-secondary-dark: #008576;
    --color-accent: #FF6B6B;
    --color-accent-light: #FF9999;
    
    /* Background Colors */
    --color-bg-primary: #FFFFFF;
    --color-bg-secondary: #F8F9FA;
    --color-bg-tertiary: #E8F4F8;
    --color-bg-dark: #1A2332;
    
    /* Text Colors */
    --color-text-primary: #2C3E50;
    --color-text-secondary: #5A6C7D;
    --color-text-light: #7F8C9A;
    --color-text-white: #FFFFFF;
    
    /* Alert & Status Colors */
    --color-success: #10B981;
    --color-warning: #F59E0B;
    --color-danger: #EF4444;
    --color-info: #3B82F6;
    
    /* Border & Shadow */
    --color-border: #E5E7EB;
    --color-border-light: #F3F4F6;
    --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.08);
    --shadow-lg: 0 10px 30px rgba(0, 0, 0, 0.12);
    --shadow-xl: 0 20px 50px rgba(0, 0, 0, 0.15);
    
    /* Typography */
    --font-primary: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    --font-heading: 'Poppins', sans-serif;
    
    /* Font Sizes */
    --text-xs: 0.75rem;     /* 12px */
    --text-sm: 0.875rem;    /* 14px */
    --text-base: 1rem;      /* 16px */
    --text-lg: 1.125rem;    /* 18px */
    --text-xl: 1.25rem;     /* 20px */
    --text-2xl: 1.5rem;     /* 24px */
    --text-3xl: 1.875rem;   /* 30px */
    --text-4xl: 2.25rem;    /* 36px */
    --text-5xl: 3rem;       /* 48px */
    
    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    --spacing-3xl: 4rem;
    
    /* Border Radius */
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-xl: 16px;
    --radius-full: 9999px;
    
    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 250ms ease;
    --transition-slow: 350ms ease;
    
    /* Z-index Layers */
    --z-dropdown: 1000;
    --z-sticky: 1020;
    --z-fixed: 1030;
    --z-modal-backdrop: 1040;
    --z-modal: 1050;
    --z-popover: 1060;
    --z-tooltip: 1070;
}

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

body {
    font-family: var(--font-primary);
    font-size: var(--text-base);
    line-height: 1.6;
    color: var(--color-text-primary);
    background-color: var(--color-bg-primary);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* ========================================
   TYPOGRAPHY
   ======================================== */

h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-heading);
    font-weight: 600;
    line-height: 1.3;
    color: var(--color-text-primary);
    margin-bottom: var(--spacing-md);
}

h1 { font-size: var(--text-5xl); }
h2 { font-size: var(--text-4xl); }
h3 { font-size: var(--text-3xl); }
h4 { font-size: var(--text-2xl); }
h5 { font-size: var(--text-xl); }
h6 { font-size: var(--text-lg); }

p {
    margin-bottom: var(--spacing-md);
    color: var(--color-text-secondary);
}

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

a:hover {
    color: var(--color-primary-dark);
}

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

/* ========================================
   LAYOUT COMPONENTS
   ======================================== */

.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

.container-wide {
    max-width: 1400px;
}

.container-narrow {
    max-width: 900px;
}

/* ========================================
   HEADER & NAVIGATION
   ======================================== */

.header {
    background: var(--color-bg-primary);
    box-shadow: var(--shadow-sm);
    position: sticky;
    top: 0;
    z-index: var(--z-sticky);
    transition: all var(--transition-base);
}

.header.scrolled {
    box-shadow: var(--shadow-md);
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-md) 0;
}

.logo {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-family: var(--font-heading);
    font-size: var(--text-2xl);
    font-weight: 700;
    color: var(--color-primary);
}

.logo-icon {
    width: 40px;
    height: 40px;
    background: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-weight: bold;
}

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

.nav a {
    color: var(--color-text-primary);
    font-weight: 500;
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--radius-md);
    transition: all var(--transition-fast);
}

.nav a:hover {
    background: var(--color-bg-tertiary);
    color: var(--color-primary);
}

.nav a.active {
    background: var(--color-primary);
    color: var(--color-text-white);
}

.mobile-menu-toggle {
    display: none;
    background: none;
    border: none;
    font-size: var(--text-2xl);
    color: var(--color-text-primary);
    cursor: pointer;
    padding: var(--spacing-sm);
}

/* ========================================
   HERO SECTION
   ======================================== */

.hero {
    background: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
    color: var(--color-text-white);
    padding: var(--spacing-3xl) 0;
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: url('data:image/svg+xml,<svg width="100" height="100" xmlns="http://www.w3.org/2000/svg"><circle cx="50" cy="50" r="2" fill="white" opacity="0.1"/></svg>');
    opacity: 0.3;
}

.hero-content {
    position: relative;
    z-index: 1;
    text-align: center;
    max-width: 900px;
    margin: 0 auto;
}

.hero h1 {
    color: var(--color-text-white);
    font-size: var(--text-5xl);
    margin-bottom: var(--spacing-lg);
    animation: fadeInUp 0.8s ease;
}

.hero p {
    font-size: var(--text-xl);
    color: rgba(255, 255, 255, 0.95);
    margin-bottom: var(--spacing-xl);
    animation: fadeInUp 0.8s ease 0.2s both;
}

/* ========================================
   BUTTONS
   ======================================== */

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

.btn-primary {
    background: var(--color-primary);
    color: var(--color-text-white);
}

.btn-primary:hover {
    background: var(--color-primary-dark);
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.btn-secondary {
    background: var(--color-bg-primary);
    color: var(--color-primary);
}

.btn-secondary:hover {
    background: var(--color-bg-secondary);
    transform: translateY(-2px);
}

.btn-outline {
    background: transparent;
    color: var(--color-primary);
    border: 2px solid var(--color-primary);
}

.btn-outline:hover {
    background: var(--color-primary);
    color: var(--color-text-white);
}

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

/* ========================================
   CARDS
   ======================================== */

.card {
    background: var(--color-bg-primary);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    padding: var(--spacing-xl);
    transition: all var(--transition-base);
    border: 1px solid var(--color-border-light);
}

.card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-xl);
}

.card-header {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-lg);
}

.card-icon {
    width: 50px;
    height: 50px;
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: var(--text-2xl);
    background: linear-gradient(135deg, var(--color-primary-light), var(--color-primary));
    color: white;
}

.card-title {
    font-size: var(--text-xl);
    font-weight: 600;
    margin: 0;
}

.card-body p {
    margin: 0;
}

.card-footer {
    margin-top: var(--spacing-lg);
    padding-top: var(--spacing-lg);
    border-top: 1px solid var(--color-border-light);
}

/* ========================================
   GRID SYSTEM
   ======================================== */

.grid {
    display: grid;
    gap: var(--spacing-xl);
}

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

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

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

/* ========================================
   SECTIONS
   ======================================== */

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

.section-header {
    text-align: center;
    max-width: 800px;
    margin: 0 auto var(--spacing-2xl);
}

.section-title {
    font-size: var(--text-4xl);
    margin-bottom: var(--spacing-md);
    color: var(--color-text-primary);
}

.section-subtitle {
    font-size: var(--text-lg);
    color: var(--color-text-secondary);
}

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

/* ========================================
   ALERT BOXES
   ======================================== */

.alert {
    padding: var(--spacing-lg);
    border-radius: var(--radius-md);
    margin-bottom: var(--spacing-lg);
    border-left: 4px solid;
}

.alert-info {
    background: #EFF6FF;
    border-color: var(--color-info);
    color: #1E40AF;
}

.alert-success {
    background: #F0FDF4;
    border-color: var(--color-success);
    color: #166534;
}

.alert-warning {
    background: #FFFBEB;
    border-color: var(--color-warning);
    color: #92400E;
}

.alert-danger {
    background: #FEF2F2;
    border-color: var(--color-danger);
    color: #991B1B;
}

/* ========================================
   FOOTER
   ======================================== */

.footer {
    background: var(--color-bg-dark);
    color: rgba(255, 255, 255, 0.8);
    padding: var(--spacing-2xl) 0;
    margin-top: var(--spacing-3xl);
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-xl);
    margin-bottom: var(--spacing-xl);
}

.footer h4 {
    color: var(--color-text-white);
    margin-bottom: var(--spacing-md);
}

.footer a {
    color: rgba(255, 255, 255, 0.7);
    display: block;
    margin-bottom: var(--spacing-sm);
}

.footer a:hover {
    color: var(--color-text-white);
}

.footer-bottom {
    text-align: center;
    padding-top: var(--spacing-lg);
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    color: rgba(255, 255, 255, 0.6);
}

/* ========================================
   ANIMATIONS
   ======================================== */

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

.fade-in {
    animation: fadeIn 0.6s ease;
}

.fade-in-up {
    animation: fadeInUp 0.8s ease;
}

/* ========================================
   UTILITIES
   ======================================== */

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

.mt-sm { margin-top: var(--spacing-sm); }
.mt-md { margin-top: var(--spacing-md); }
.mt-lg { margin-top: var(--spacing-lg); }
.mt-xl { margin-top: var(--spacing-xl); }

.mb-sm { margin-bottom: var(--spacing-sm); }
.mb-md { margin-bottom: var(--spacing-md); }
.mb-lg { margin-bottom: var(--spacing-lg); }
.mb-xl { margin-bottom: var(--spacing-xl); }

.hidden { display: none; }

/* ========================================
   RESPONSIVE DESIGN
   ======================================== */

@media (max-width: 1024px) {
    :root {
        --text-5xl: 2.5rem;
        --text-4xl: 2rem;
        --text-3xl: 1.75rem;
    }
    
    .grid-4 {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .grid-3 {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 768px) {
    :root {
        --text-5xl: 2rem;
        --text-4xl: 1.75rem;
        --text-3xl: 1.5rem;
    }
    
    .mobile-menu-toggle {
        display: block;
    }
    
    .nav {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background: var(--color-bg-primary);
        flex-direction: column;
        padding: var(--spacing-lg);
        box-shadow: var(--shadow-lg);
        gap: 0;
    }
    
    .nav.active {
        display: flex;
    }
    
    .nav a {
        width: 100%;
        padding: var(--spacing-md);
    }
    
    .grid-2,
    .grid-3,
    .grid-4 {
        grid-template-columns: 1fr;
    }
    
    .hero {
        padding: var(--spacing-2xl) 0;
    }
    
    .section {
        padding: var(--spacing-2xl) 0;
    }
}

@media (max-width: 480px) {
    /* Kept root font size closer to 16px for better readability */
    html {
        font-size: 16px; 
    }
    
    .container {
        padding: 0 var(--spacing-md);
    }
    
    .card {
        padding: var(--spacing-lg);
    }
}

/* Ensure images and videos are always responsive */
img, video, iframe {
    max-width: 100%;
    height: auto;
}