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

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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: #333;
    background-color: #fafafa;
}

img {
    max-width: 100%;
    height: auto;
}

a {
    text-decoration: none;
    color: inherit;
}

ul {
    list-style: none;
}

button {
    border: none;
    background: none;
    cursor: pointer;
    font-family: inherit;
}

/* CSS Variables */
:root {
    --primary-color: #ff6b6b;
    --secondary-color: #4ecdc4;
    --accent-color: #ffe66d;
    --dark-color: #2c3e50;
    --light-color: #ecf0f1;
    --success-color: #2ecc71;
    --warning-color: #f39c12;
    --error-color: #e74c3c;
    --gradient-primary: linear-gradient(135deg, #ff6b6b, #4ecdc4);
    --gradient-secondary: linear-gradient(135deg, #4ecdc4, #ffe66d);
    --shadow-light: 0 2px 10px rgba(0,0,0,0.1);
    --shadow-medium: 0 4px 20px rgba(0,0,0,0.15);
    --shadow-heavy: 0 8px 30px rgba(0,0,0,0.2);
    --border-radius: 8px;
    --transition: all 0.3s ease;
}

/* Container */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
    margin-bottom: 1rem;
    line-height: 1.3;
    color: var(--dark-color);
}

h1 {
    font-size: 2.5rem;
    font-weight: 700;
}

h2 {
    font-size: 2rem;
    font-weight: 600;
}

h3 {
    font-size: 1.5rem;
    font-weight: 600;
}

h4 {
    font-size: 1.25rem;
    font-weight: 500;
}

p {
    margin-bottom: 1rem;
    color: #666;
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 12px 24px;
    border-radius: var(--border-radius);
    font-weight: 500;
    text-align: center;
    transition: var(--transition);
    cursor: pointer;
    border: 2px solid transparent;
    font-size: 1rem;
}

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

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

.btn-secondary {
    background: var(--gradient-secondary);
    color: var(--dark-color);
    box-shadow: var(--shadow-light);
}

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

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

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

/* Header and Navigation */
.header {
    background: white;
    box-shadow: var(--shadow-light);
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
}

.nav {
    padding: 1rem 0;
}

.nav-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

.nav-brand a {
    display: flex;
    align-items: center;
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--dark-color);
}

.brand-icon {
    font-size: 2rem;
    margin-right: 0.5rem;
}

.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 4px;
}

.nav-toggle span {
    width: 25px;
    height: 3px;
    background: var(--dark-color);
    transition: var(--transition);
}

.nav-menu {
    display: flex;
    gap: 2rem;
    align-items: center;
}

.nav-link {
    color: var(--dark-color);
    font-weight: 500;
    transition: var(--transition);
    padding: 0.5rem 0;
    position: relative;
}

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

.nav-dropdown {
    position: relative;
}

.dropdown-arrow {
    font-size: 0.8rem;
    margin-left: 0.5rem;
    transition: var(--transition);
}

.dropdown-menu {
    position: absolute;
    top: 100%;
    left: 0;
    background: white;
    box-shadow: var(--shadow-medium);
    border-radius: var(--border-radius);
    padding: 0.5rem 0;
    min-width: 200px;
    opacity: 0;
    visibility: hidden;
    transform: translateY(-10px);
    transition: var(--transition);
}

.nav-dropdown:hover .dropdown-menu {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.nav-dropdown:hover .dropdown-arrow {
    transform: rotate(180deg);
}

.dropdown-menu li {
    padding: 0.5rem 1rem;
}

.dropdown-menu a {
    color: var(--dark-color);
    transition: var(--transition);
}

.dropdown-menu a:hover {
    color: var(--primary-color);
}

/* Main Content */
.main {
    margin-top: 80px;
}

/* Hero Section */
.hero {
    background: var(--gradient-primary);
    padding: 80px 0;
    display: flex;
    align-items: center;
    min-height: 600px;
    color: white;
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100"><defs><pattern id="grid" width="10" height="10" patternUnits="userSpaceOnUse"><path d="M 10 0 L 0 0 0 10" fill="none" stroke="rgba(255,255,255,0.1)" stroke-width="1"/></pattern></defs><rect width="100" height="100" fill="url(%23grid)"/></svg>');
    opacity: 0.3;
}

.hero-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
    align-items: center;
    position: relative;
    z-index: 1;
}

.hero-title {
    font-size: 3.5rem;
    margin-bottom: 1.5rem;
    color: white;
}

.hero-subtitle {
    font-size: 1.25rem;
    margin-bottom: 2rem;
    color: rgba(255,255,255,0.9);
}

.hero-buttons {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
}

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

.korean-text-animation {
    display: flex;
    gap: 1rem;
    font-size: 4rem;
    font-weight: 700;
}

.korean-char {
    animation: float 3s ease-in-out infinite;
    text-shadow: 2px 2px 4px rgba(0,0,0,0.3);
}

.korean-char:nth-child(2) {
    animation-delay: 0.5s;
}

.korean-char:nth-child(3) {
    animation-delay: 1s;
}

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

/* Section Styles */
section {
    padding: 60px 0;
}

.section-title {
    text-align: center;
    margin-bottom: 3rem;
    position: relative;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: -10px;
    left: 50%;
    transform: translateX(-50%);
    width: 60px;
    height: 3px;
    background: var(--gradient-primary);
    border-radius: 2px;
}

/* Features Section */
.features {
    background: white;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.feature-card {
    background: white;
    padding: 2rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-light);
    text-align: center;
    transition: var(--transition);
    border: 1px solid #eee;
}

.feature-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-medium);
}

.feature-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.feature-card h3 {
    margin-bottom: 1rem;
    color: var(--dark-color);
}

.feature-card p {
    margin-bottom: 1.5rem;
    color: #666;
}

.feature-link {
    color: var(--primary-color);
    font-weight: 500;
    transition: var(--transition);
}

.feature-link:hover {
    text-decoration: underline;
}

/* Quick Access Section */
.quick-access {
    background: var(--light-color);
}

.quick-access-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.quick-card {
    background: white;
    padding: 2rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-light);
}

.quick-card h3 {
    margin-bottom: 1.5rem;
    color: var(--dark-color);
}

.daily-phrase {
    background: var(--gradient-secondary);
    padding: 1.5rem;
    border-radius: var(--border-radius);
    margin-bottom: 1rem;
}

.phrase-korean {
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    color: var(--dark-color);
}

.phrase-romanization {
    font-style: italic;
    margin-bottom: 0.5rem;
    color: #666;
}

.phrase-english {
    color: #555;
}

.phrase-loading {
    text-align: center;
    color: #666;
}

.featured-song h4 {
    color: var(--primary-color);
    margin-bottom: 1rem;
}

/* Learning Path Section */
.learning-path {
    background: white;
}

.path-timeline {
    display: flex;
    flex-direction: column;
    gap: 2rem;
    max-width: 800px;
    margin: 0 auto;
}

.path-step {
    display: flex;
    align-items: center;
    gap: 2rem;
    padding: 1.5rem;
    background: var(--light-color);
    border-radius: var(--border-radius);
    transition: var(--transition);
}

.path-step:hover {
    background: #e8f4fd;
    transform: translateX(10px);
}

.step-number {
    width: 60px;
    height: 60px;
    background: var(--gradient-primary);
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    font-weight: 700;
    flex-shrink: 0;
}

.step-content {
    flex: 1;
}

.step-content h3 {
    margin-bottom: 0.5rem;
    color: var(--dark-color);
}

.step-content p {
    margin-bottom: 1rem;
}

.step-link {
    color: var(--primary-color);
    font-weight: 500;
    transition: var(--transition);
}

.step-link:hover {
    text-decoration: underline;
}

/* Footer */
.footer {
    background: var(--dark-color);
    color: white;
    padding: 40px 0 20px;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin-bottom: 2rem;
}

.footer-section h3,
.footer-section h4 {
    margin-bottom: 1rem;
    color: white;
}

.footer-section p {
    color: #bbb;
    margin-bottom: 1rem;
}

.footer-section ul li {
    margin-bottom: 0.5rem;
}

.footer-section ul li a {
    color: #bbb;
    transition: var(--transition);
}

.footer-section ul li a:hover {
    color: var(--primary-color);
}

.social-links {
    display: flex;
    gap: 1rem;
    margin-top: 1rem;
}

.social-links a {
    font-size: 1.5rem;
    transition: var(--transition);
}

.social-links a:hover {
    transform: scale(1.2);
}

.footer-bottom {
    text-align: center;
    padding-top: 2rem;
    border-top: 1px solid #444;
    color: #bbb;
}

/* Responsive Design (Mobile First) */
@media (max-width: 768px) {
    /* Navigation Menu */
    .nav-toggle {
        display: flex;
    }
    
    .nav-menu {
        position: fixed;
        top: 80px; /* Adjusting to header height */
        left: 0;
        right: 0;
        background: white;
        flex-direction: column;
        gap: 0;
        padding: 1rem 0;
        box-shadow: var(--shadow-medium);
        transform: translateY(-100%);
        opacity: 0;
        visibility: hidden;
        transition: transform 0.4s ease-in-out, opacity 0.4s ease-in-out;
    }
    
    .nav-menu.active {
        transform: translateY(0);
        opacity: 1;
        visibility: visible;
    }
    
    .nav-link {
        padding: 1rem 2rem;
        border-bottom: 1px solid #eee;
        text-align: center;
    }
    
    .dropdown-menu {
        position: static;
        opacity: 1;
        visibility: visible;
        transform: none;
        box-shadow: none;
        background: #f8f9fa;
        margin-top: 0.5rem;
    }
    
    /* Hero Section */
    .hero-content {
        grid-template-columns: 1fr;
        text-align: center;
        gap: 2rem;
    }

    .hero-title {
        font-size: 2.5rem;
    }

    .hero-visual {
        order: -1; /* Move visual to the top for better mobile flow */
    }

    .korean-text-animation {
        font-size: 3rem;
    }

    .hero {
        min-height: auto;
        padding: 60px 0;
    }
    
    /* Section Grids */
    .features-grid,
    .quick-access-grid {
        grid-template-columns: 1fr;
    }
    
    /* Learning Path Timeline */
    .path-timeline {
        flex-direction: column;
        align-items: center;
    }
    
    .path-step {
        width: 100%;
        text-align: left;
        flex-direction: column;
        align-items: center;
        text-align: center;
    }

    .step-number {
        margin-bottom: 1rem;
    }
    
    /* Footer */
    .footer-content {
        grid-template-columns: 1fr;
        text-align: center;
    }

    .footer-section {
        margin-bottom: 2rem;
    }

    .footer-section ul {
        display: flex;
        flex-wrap: wrap;
        justify-content: center;
        gap: 10px;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 15px;
    }
    
    .hero {
        padding: 40px 0;
    }
    
    .hero-title {
        font-size: 2rem;
    }
    
    .korean-text-animation {
        font-size: 2.5rem;
    }
    
    .hero-buttons {
        justify-content: center;
    }
    
    section {
        padding: 40px 0;
    }
    
    .feature-card,
    .quick-card {
        padding: 1.5rem;
    }
}

/* Accessibility */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

/* Focus styles for keyboard navigation */
a:focus,
button:focus,
input:focus,
textarea:focus,
select:focus {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}

/* Skip link for screen readers */
.skip-link {
    position: absolute;
    top: -40px;
    left: 6px;
    background: var(--dark-color);
    color: white;
    padding: 8px;
    text-decoration: none;
    border-radius: 4px;
    z-index: 9999;
}

.skip-link:focus {
    top: 6px;
}

/* Print styles */
@media print {
    .header,
    .footer,
    .nav,
    .btn {
        display: none !important;
    }
    
    .main {
        margin-top: 0 !important;
    }
    
    * {
        background: white !important;
        color: black !important;
        box-shadow: none !important;
    }
}