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

:root {
    --primary-color: #4F46E5;
    --primary-dark: #4338CA;
    --secondary-color: #10B981;
    --text-dark: #1F2937;
    --text-light: #6B7280;
    --bg-light: #F9FAFB;
    --bg-white: #FFFFFF;
    --border-color: #E5E7EB;
    --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);
}

body {
    font-family: 'Noto Sans KR', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    color: var(--text-dark);
    line-height: 1.6;
    overflow-x: hidden;
}

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

/* 헤더 */
.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    box-shadow: var(--shadow-sm);
    z-index: 1000;
    transition: all 0.3s ease;
}

.navbar {
    padding: 1rem 0;
}

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

.logo {
    display: flex;
    align-items: baseline;
    gap: 8px;
}

.logo h1 {
    font-size: 1.75rem;
    font-weight: 700;
    color: var(--primary-color);
    margin: 0;
}

.logo-subtitle {
    font-size: 0.875rem;
    color: var(--text-light);
    font-weight: 400;
}

.nav-menu {
    display: flex;
    list-style: none;
    align-items: center;
    gap: 2rem;
}

.nav-menu li a {
    text-decoration: none;
    color: var(--text-dark);
    font-weight: 500;
    transition: color 0.3s ease;
}

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

.nav-buttons {
    display: flex;
    gap: 1rem;
    margin-left: 1rem;
}

.btn-login {
    padding: 0.5rem 1.5rem;
    text-decoration: none;
    color: var(--text-dark);
    font-weight: 500;
    transition: color 0.3s ease;
}

.btn-signup {
    padding: 0.5rem 1.5rem;
    background: var(--primary-color);
    color: white;
    text-decoration: none;
    border-radius: 8px;
    font-weight: 500;
    transition: background 0.3s ease;
}

.btn-signup:hover {
    background: var(--primary-dark);
}

.mobile-menu-toggle {
    display: none;
    flex-direction: column;
    gap: 4px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 8px;
}

.mobile-menu-toggle span {
    width: 25px;
    height: 3px;
    background: var(--text-dark);
    border-radius: 2px;
    transition: all 0.3s ease;
}

/* 히어로 섹션 */
.hero {
    position: relative;
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding-top: 80px;
    overflow: hidden;
}

.hero-background {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    z-index: -1;
}

.hero-overlay {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.3);
}

.hero-content {
    position: relative;
    z-index: 1;
    text-align: center;
    color: white;
    max-width: 800px;
    padding: 2rem;
}

.hero-title {
    font-size: 3.5rem;
    font-weight: 700;
    margin-bottom: 1.5rem;
    line-height: 1.2;
    animation: fadeInUp 0.8s ease;
}

.hero-subtitle {
    font-size: 1.25rem;
    margin-bottom: 2.5rem;
    opacity: 0.95;
    line-height: 1.8;
    animation: fadeInUp 0.8s ease 0.2s both;
}

.hero-buttons {
    display: flex;
    gap: 1rem;
    justify-content: center;
    margin-bottom: 4rem;
    animation: fadeInUp 0.8s ease 0.4s both;
}

.btn {
    padding: 1rem 2rem;
    border-radius: 8px;
    text-decoration: none;
    font-weight: 500;
    transition: all 0.3s ease;
    display: inline-block;
    font-size: 1rem;
}

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

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

.btn-secondary {
    background: transparent;
    color: white;
    border: 2px solid white;
}

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

.hero-stats {
    display: flex;
    justify-content: center;
    gap: 4rem;
    animation: fadeInUp 0.8s ease 0.6s both;
}

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

.stat-number {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
}

.stat-label {
    font-size: 1rem;
    opacity: 0.9;
}

/* 섹션 공통 스타일 */
section {
    padding: 5rem 0;
}

.section-header {
    text-align: center;
    margin-bottom: 3rem;
}

.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
    color: var(--text-dark);
}

.section-subtitle {
    font-size: 1.125rem;
    color: var(--text-light);
}

/* 강의 섹션 */
.courses {
    background: var(--bg-light);
}

.courses-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
    margin-bottom: 3rem;
}

.course-card {
    background: white;
    border-radius: 12px;
    overflow: hidden;
    box-shadow: var(--shadow-md);
    transition: all 0.3s ease;
}

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

.course-image {
    position: relative;
    width: 100%;
    height: 200px;
    overflow: hidden;
}

.course-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform 0.3s ease;
}

.course-card:hover .course-image img {
    transform: scale(1.05);
}

.course-badge {
    position: absolute;
    top: 1rem;
    right: 1rem;
    background: var(--primary-color);
    color: white;
    padding: 0.25rem 0.75rem;
    border-radius: 20px;
    font-size: 0.75rem;
    font-weight: 600;
}

.course-content {
    padding: 1.5rem;
}

.course-category {
    font-size: 0.875rem;
    color: var(--primary-color);
    font-weight: 600;
    margin-bottom: 0.5rem;
}

.course-title {
    font-size: 1.25rem;
    font-weight: 700;
    margin-bottom: 0.75rem;
    color: var(--text-dark);
}

.course-description {
    color: var(--text-light);
    font-size: 0.9375rem;
    margin-bottom: 1rem;
    line-height: 1.6;
}

.course-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.5rem;
    padding-bottom: 1rem;
    border-bottom: 1px solid var(--border-color);
}

.course-instructor {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.875rem;
    color: var(--text-light);
}

.instructor-icon {
    font-size: 1.25rem;
}

.course-rating {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.stars {
    color: #FBBF24;
    font-size: 0.875rem;
}

.rating-text {
    font-size: 0.875rem;
    color: var(--text-light);
}

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

.course-price {
    display: flex;
    flex-direction: column;
    gap: 0.25rem;
}

.price-current {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
}

.price-original {
    font-size: 0.875rem;
    color: var(--text-light);
    text-decoration: line-through;
}

.btn-course {
    padding: 0.75rem 1.5rem;
    background: var(--primary-color);
    color: white;
    border: none;
    border-radius: 8px;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s ease;
    font-size: 0.9375rem;
}

.btn-course:hover {
    background: var(--primary-dark);
    transform: translateY(-2px);
}

.courses-more {
    text-align: center;
}

.btn-outline {
    padding: 1rem 2.5rem;
    border: 2px solid var(--primary-color);
    color: var(--primary-color);
    background: transparent;
    border-radius: 8px;
    text-decoration: none;
    font-weight: 500;
    transition: all 0.3s ease;
    display: inline-block;
}

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

/* 특징 섹션 */
.features {
    background: white;
}

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

.feature-card {
    text-align: center;
    padding: 2rem;
    border-radius: 12px;
    transition: all 0.3s ease;
}

.feature-card:hover {
    background: var(--bg-light);
    transform: translateY(-5px);
}

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

.feature-title {
    font-size: 1.25rem;
    font-weight: 700;
    margin-bottom: 0.75rem;
    color: var(--text-dark);
}

.feature-description {
    color: var(--text-light);
    line-height: 1.6;
}

/* 소개 섹션 */
.about {
    background: var(--bg-light);
}

.about-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
    align-items: center;
}

.about-text {
    padding-right: 2rem;
}

.about-description {
    font-size: 1.125rem;
    color: var(--text-light);
    margin-bottom: 1.5rem;
    line-height: 1.8;
}

.about-stats {
    display: flex;
    gap: 3rem;
    margin-top: 2rem;
}

.about-stat {
    text-align: center;
}

.about-stat-number {
    font-size: 2rem;
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: 0.5rem;
}

.about-stat-label {
    font-size: 0.875rem;
    color: var(--text-light);
}

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

.about-image-placeholder {
    width: 100%;
    height: 400px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 6rem;
}

/* 푸터 */
.footer {
    background: var(--text-dark);
    color: white;
    padding: 4rem 0 2rem;
}

.footer-content {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr;
    gap: 3rem;
    margin-bottom: 3rem;
}

.footer-logo h3 {
    font-size: 1.5rem;
    margin-bottom: 0.5rem;
    color: white;
}

.footer-logo span {
    font-size: 0.875rem;
    opacity: 0.7;
}

.footer-description {
    margin: 1rem 0;
    opacity: 0.8;
    line-height: 1.6;
}

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

.social-link {
    color: white;
    text-decoration: none;
    opacity: 0.8;
    transition: opacity 0.3s ease;
}

.social-link:hover {
    opacity: 1;
}

.footer-title {
    font-size: 1.125rem;
    margin-bottom: 1rem;
    color: white;
}

.footer-links {
    list-style: none;
}

.footer-links li {
    margin-bottom: 0.75rem;
}

.footer-links a {
    color: white;
    text-decoration: none;
    opacity: 0.8;
    transition: opacity 0.3s ease;
}

.footer-links a:hover {
    opacity: 1;
}

.footer-bottom {
    text-align: center;
    padding-top: 2rem;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    opacity: 0.7;
}

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

/* 반응형 디자인 */
@media (max-width: 968px) {
    .nav-menu {
        position: fixed;
        top: 70px;
        left: -100%;
        flex-direction: column;
        background: white;
        width: 100%;
        padding: 2rem;
        box-shadow: var(--shadow-lg);
        transition: left 0.3s ease;
        gap: 1.5rem;
    }

    .nav-menu.active {
        left: 0;
    }

    .nav-buttons {
        flex-direction: column;
        width: 100%;
        margin-left: 0;
    }

    .mobile-menu-toggle {
        display: flex;
    }

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

    .hero-subtitle {
        font-size: 1.125rem;
    }

    .hero-stats {
        flex-direction: column;
        gap: 2rem;
    }

    .about-content {
        grid-template-columns: 1fr;
    }

    .about-text {
        padding-right: 0;
    }

    .footer-content {
        grid-template-columns: 1fr;
        gap: 2rem;
    }

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

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

@media (max-width: 640px) {
    .hero-title {
        font-size: 2rem;
    }

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

    .section-title {
        font-size: 2rem;
    }

    .about-stats {
        flex-direction: column;
        gap: 1.5rem;
    }
}

/* 스크롤 부드럽게 */
html {
    scroll-behavior: smooth;
}