/* ===================================
   Bridge Course - Main Stylesheet
   Educational Theme - SEE Exam Preparation
   =================================== */

/* ===================================
   CSS Variables & Theme Configuration
   =================================== */
:root {
    /* Primary Colors - Educational Theme */
    --primary-color: #3B82F6;
    --primary-dark: #2563EB;
    --primary-light: #60A5FA;
    --primary-gradient: linear-gradient(135deg, #3B82F6 0%, #1D4ED8 100%);
    
    /* Secondary Colors */
    --secondary-color: #f59e0b;
    --secondary-dark: #d97706;
    --secondary-light: #fbbf24;
    
    /* Success & Accent Colors */
    --success-color: #10b981;
    --success-light: #34d399;
    --accent-color: #ec4899;
    --accent-light: #f472b6;
    
    /* Neutral Colors */
    --text-primary: #1f2937;
    --text-secondary: #6b7280;
    --text-light: #9ca3af;
    --white: #ffffff;
    --black: #000000;
    
    /* Background Colors */
    --bg-primary: #ffffff;
    --bg-secondary: #f9fafb;
    --bg-tertiary: #f3f4f6;
    --bg-dark: #111827;
    
    /* Border & Shadow Colors */
    --border-color: #e5e7eb;
    --border-light: #f3f4f6;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
    --shadow-2xl: 0 25px 50px -12px rgba(0, 0, 0, 0.25);
    
    /* Typography */
    --font-primary: 'Poppins', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --font-secondary: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    
    /* Font Sizes */
    --text-xs: 0.75rem;
    --text-sm: 0.875rem;
    --text-base: 1rem;
    --text-lg: 1.125rem;
    --text-xl: 1.25rem;
    --text-2xl: 1.5rem;
    --text-3xl: 1.875rem;
    --text-4xl: 2.25rem;
    --text-5xl: 3rem;
    --text-6xl: 3.75rem;
    
    /* 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: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    --radius-2xl: 1.5rem;
    --radius-full: 9999px;
    
    /* Transitions */
    --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-base: 300ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-slow: 500ms cubic-bezier(0.4, 0, 0.2, 1);
    
    /* Z-Index Layers */
    --z-dropdown: 1000;
    --z-sticky: 1020;
    --z-fixed: 1030;
    --z-modal-backdrop: 1040;
    --z-modal: 1050;
    --z-tooltip: 1070;
}

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

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

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

/* ===================================
   Typography
   =================================== */
h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-primary);
    font-weight: 700;
    line-height: 1.2;
    color: var(--text-primary);
}

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(--text-secondary);
}

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

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

/* ===================================
   Utility Classes
   =================================== */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

.gradient-text {
    background: var(--primary-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.section-badge {
    display: inline-block;
    padding: var(--spacing-sm) var(--spacing-lg);
    background: linear-gradient(135deg, rgba(59, 130, 246, 0.1) 0%, rgba(37, 99, 235, 0.1) 100%);
    border: 1px solid rgba(59, 130, 246, 0.2);
    border-radius: var(--radius-full);
    color: var(--primary-color);
    font-size: var(--text-sm);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: var(--spacing-md);
}

.section-header {
    text-align: center;
    margin-bottom: var(--spacing-3xl);
}

.section-title {
    font-size: var(--text-4xl);
    margin-bottom: var(--spacing-md);
    font-weight: 800;
}

.section-description {
    font-size: var(--text-lg);
    color: var(--text-secondary);
    max-width: 700px;
    margin: 0 auto;
}

/* ===================================
   Button Styles
   =================================== */
.btn {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: 0.875rem 1.75rem;
    font-size: var(--text-base);
    font-weight: 600;
    border-radius: var(--radius-lg);
    border: none;
    cursor: pointer;
    transition: all var(--transition-base);
    text-decoration: none;
    font-family: var(--font-primary);
}

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

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-xl);
}

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

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

.btn-large {
    padding: 1.125rem 2.25rem;
    font-size: var(--text-lg);
}

.btn-primary-nav {
    background: var(--primary-gradient);
    color: var(--white) !important;
    padding: 0.625rem 1.5rem;
    border-radius: var(--radius-lg);
}

.btn-primary-nav:hover {
    transform: translateY(-1px);
    box-shadow: var(--shadow-lg);
}

/* ===================================
   Header & Navigation
   =================================== */
.header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    background: var(--white);
    box-shadow: var(--shadow-sm);
    z-index: var(--z-fixed);
    transition: all var(--transition-base);
}

.header.scrolled {
    box-shadow: var(--shadow-md);
    padding: 0.5rem 0;
}

.navbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem var(--spacing-lg);
}

.nav-brand {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-size: var(--text-xl);
    font-weight: 800;
    color: var(--primary-color);
    font-family: var(--font-primary);
}

.nav-brand .logo-img {
    height: 80px;
    width: auto;
    object-fit: contain;
}

.nav-brand i {
    font-size: var(--text-2xl);
}

.nav-menu {
    display: flex;
    align-items: center;
    gap: var(--spacing-xl);
    list-style: none;
}

.nav-link {
    color: var(--text-primary);
    font-weight: 500;
    font-size: var(--text-base);
    transition: color var(--transition-base);
    position: relative;
}

.nav-link:hover,
.nav-link.active {
    color: var(--primary-color);
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--primary-gradient);
    transition: width var(--transition-base);
}

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

.hamburger {
    display: none;
    flex-direction: column;
    gap: 5px;
    cursor: pointer;
}

.hamburger span {
    width: 25px;
    height: 3px;
    background: var(--primary-color);
    border-radius: var(--radius-sm);
    transition: all var(--transition-base);
}

/* ===================================
   Hero Section
   =================================== */
.hero {
    position: relative;
    min-height: 100vh;
    display: flex;
    align-items: center;
    padding: 8rem 0 4rem;
    overflow: hidden;
}

.hero-background {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: -1;
    overflow: hidden;
}

.hero-shape {
    position: absolute;
    border-radius: 50%;
    opacity: 0.1;
}

.hero-shape.shape-1 {
    width: 600px;
    height: 600px;
    background: var(--primary-gradient);
    top: -200px;
    right: -150px;
    animation: float 20s infinite ease-in-out;
}

.hero-shape.shape-2 {
    width: 400px;
    height: 400px;
    background: linear-gradient(135deg, #60A5FA 0%, #3B82F6 100%);
    bottom: -100px;
    left: -100px;
    animation: float 15s infinite ease-in-out reverse;
}

.hero-shape.shape-3 {
    width: 300px;
    height: 300px;
    background: linear-gradient(135deg, #93C5FD 0%, #2563EB 100%);
    top: 50%;
    left: 30%;
    animation: float 18s infinite ease-in-out;
}

@keyframes float {
    0%, 100% { transform: translate(0, 0) rotate(0deg); }
    33% { transform: translate(30px, -30px) rotate(120deg); }
    66% { transform: translate(-20px, 20px) rotate(240deg); }
}

.hero-container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-3xl);
    align-items: center;
}

.hero-content {
    animation: fadeInUp 1s ease-out;
}

.hero-badge {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm) var(--spacing-lg);
    background: linear-gradient(135deg, rgba(59, 130, 246, 0.1) 0%, rgba(37, 99, 235, 0.1) 100%);
    border-radius: var(--radius-full);
    color: var(--primary-color);
    font-size: var(--text-sm);
    font-weight: 600;
    margin-bottom: var(--spacing-lg);
}

.hero-badge i {
    color: var(--secondary-color);
}

.hero-title {
    font-size: var(--text-5xl);
    font-weight: 800;
    line-height: 1.1;
    margin-bottom: var(--spacing-lg);
}

.hero-description {
    font-size: var(--text-lg);
    color: var(--text-secondary);
    margin-bottom: var(--spacing-xl);
    line-height: 1.8;
}

.hero-features-list {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-xl);
}

.hero-feature-item {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    color: var(--text-primary);
    font-weight: 500;
}

.hero-feature-item i {
    color: var(--success-color);
    font-size: var(--text-lg);
}

.hero-cta {
    display: flex;
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-2xl);
}

.hero-stats {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--spacing-xl);
    padding-top: var(--spacing-xl);
    border-top: 1px solid var(--border-color);
}

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

.stat-number {
    font-size: var(--text-4xl);
    font-weight: 800;
    background: var(--primary-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: var(--spacing-xs);
}

.stat-number::after {
    content: '+';
}

.stat-label {
    font-size: var(--text-sm);
    color: var(--text-secondary);
    margin: 0;
}

.hero-image {
    position: relative;
    animation: fadeInRight 1s ease-out;
}

.phone-mockup {
    position: relative;
    width: 100%;
    max-width: 400px;
    margin: 0 auto;
    will-change: transform;
}

.phone-frame {
    position: relative;
    width: 100%;
    padding-top: 200%;
    background: linear-gradient(135deg, #3B82F6 0%, #1D4ED8 100%);
    border-radius: 3rem;
    box-shadow: var(--shadow-2xl);
    overflow: hidden;
}

.phone-screen {
    position: absolute;
    top: 3%;
    left: 3%;
    right: 3%;
    bottom: 3%;
    background: var(--bg-secondary);
    border-radius: 2.5rem;
    overflow: hidden;
    display: flex;
    align-items: center;
    justify-content: center;
}

.phone-screen img {
    width: 100%;
    height: 100%;
    object-fit: contain;
    background: linear-gradient(180deg, #f8f9fa 0%, #ffffff 100%);
}

.phone-screen::before {
    content: 'App Preview';
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    color: var(--text-light);
    font-size: 1.5rem;
    font-weight: 600;
    z-index: -1;
}

.floating-card {
    position: absolute;
    background: var(--white);
    padding: var(--spacing-md) var(--spacing-lg);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-xl);
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-weight: 600;
    animation: floatCard 3s infinite ease-in-out;
}

.floating-card i {
    font-size: var(--text-xl);
    color: var(--primary-color);
}

.floating-card.card-1 {
    top: 10%;
    right: -10%;
    animation-delay: 0s;
}

.floating-card.card-2 {
    top: 40%;
    left: -15%;
    animation-delay: 1s;
}

.floating-card.card-3 {
    bottom: 15%;
    right: -5%;
    animation-delay: 2s;
}

@keyframes floatCard {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-20px); }
}

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

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

/* ===================================
   Scroll to Top Button
   =================================== */
.scroll-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 50px;
    height: 50px;
    background: var(--primary-gradient);
    color: var(--white);
    border: none;
    border-radius: 50%;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: var(--text-xl);
    box-shadow: var(--shadow-lg);
    opacity: 0;
    visibility: hidden;
    transition: all var(--transition-base);
    z-index: var(--z-fixed);
}

.scroll-to-top.visible {
    opacity: 1;
    visibility: visible;
}

.scroll-to-top:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-xl);
}