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

:root {
    --primary-color: #2563eb;
    --secondary-color: #1e40af;
    --accent-color: #3b82f6;
    --text-dark: #1f2937;
    --text-light: #6b7280;
    --background: #ffffff;
    --background-light: #f9fafb;
    --border-color: #e5e7eb;
    --success-color: #10b981;
    --error-color: #ef4444;
}

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

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

/* Navigation */
.navbar {
    background-color: var(--background);
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
    position: sticky;
    top: 0;
    z-index: 1000;
    padding: 1rem 0;
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-brand h2 {
    color: var(--primary-color);
    font-weight: 700;
    font-size: 1.5rem;
}

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

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

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

/* Language Toggle */
.lang-toggle {
    background: none;
    border: 2px solid var(--primary-color);
    border-radius: 20px;
    padding: 0.4rem 0.8rem;
    cursor: pointer;
    font-weight: 600;
    font-size: 0.9rem;
    transition: all 0.3s;
    display: flex;
    align-items: center;
    gap: 0.3rem;
}

.lang-toggle:hover {
    background-color: var(--primary-color);
    color: white;
}

.lang-option {
    cursor: pointer;
    opacity: 0.5;
    transition: opacity 0.3s;
}

.lang-option.active {
    opacity: 1;
    color: var(--primary-color);
    font-weight: 700;
}

.lang-toggle:hover .lang-option.active {
    color: white;
}

.lang-divider {
    opacity: 0.3;
}

/* Auth Navigation */
.nav-auth {
    display: flex;
    align-items: center;
    gap: 0.8rem;
}

.welcome-user {
    font-size: 0.9rem;
    color: var(--text-dark);
    font-weight: 500;
}

.nav-auth-btn {
    padding: 0.4rem 1rem;
    border: 2px solid var(--primary-color);
    background: none;
    color: var(--primary-color);
    text-decoration: none;
    border-radius: 20px;
    font-weight: 600;
    font-size: 0.85rem;
    cursor: pointer;
    transition: all 0.3s;
    white-space: nowrap;
}

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

/* Hero Section */
.hero {
    position: relative;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    color: white;
    padding: 120px 0;
    text-align: center;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-image: url('/static/images/hero-bg.jpg');
    background-size: cover;
    background-position: center;
    opacity: 0.15;
    z-index: 0;
}

.hero-content {
    position: relative;
    z-index: 1;
}

.hero-title {
    font-size: 3rem;
    font-weight: 900;
    margin-bottom: 1rem;
    line-height: 1.2;
}

.hero-subtitle {
    font-size: 1.25rem;
    margin-bottom: 2rem;
    opacity: 0.9;
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 12px 32px;
    border-radius: 8px;
    text-decoration: none;
    font-weight: 600;
    transition: all 0.3s;
    border: none;
    cursor: pointer;
    font-size: 1rem;
}

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

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0,0,0,0.2);
}

.btn-secondary {
    background-color: rgba(255, 255, 255, 0.2);
    color: white;
    border: 2px solid white;
}

.btn-secondary:hover {
    background-color: white;
    color: var(--primary-color);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0,0,0,0.2);
}

.btn-block {
    width: 100%;
    text-align: center;
}

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

/* Sections */
.section {
    padding: 80px 0;
}

.section:nth-child(even) {
    background-color: var(--background-light);
}

.section-header {
    text-align: center;
    margin-bottom: 60px;
}

.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);
}

/* Introduction Section */
.intro-content {
    display: grid;
    grid-template-columns: 1fr 2fr;
    gap: 3rem;
    align-items: start;
}

.intro-card {
    background: white;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
    text-align: center;
}

.intro-icon {
    font-size: 4rem;
    margin-bottom: 1rem;
}

.instructor-photo {
    width: 200px;
    height: 200px;
    margin: 0 auto 1.5rem;
    border-radius: 50%;
    overflow: hidden;
    box-shadow: 0 4px 12px rgba(0,0,0,0.15);
    border: 4px solid var(--primary-color);
}

.instructor-photo img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    object-position: center;
    display: block;
    image-rendering: -webkit-optimize-contrast;
    -webkit-backface-visibility: hidden;
    transform: translateZ(0);
}

.intro-card h3 {
    font-size: 1.75rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
}

.intro-role {
    color: var(--primary-color);
    font-weight: 600;
    margin-bottom: 1.5rem;
}

.intro-details p {
    text-align: left;
    margin: 0.75rem 0;
    color: var(--text-dark);
}

.intro-description h3 {
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
    color: var(--text-dark);
}

.intro-description p {
    color: var(--text-light);
    margin-bottom: 1.5rem;
    line-height: 1.8;
}

.mt-4 {
    margin-top: 2.5rem;
}

.expertise-list {
    list-style: none;
    padding: 0;
}

.expertise-list li {
    padding: 0.75rem 0;
    border-bottom: 1px solid var(--border-color);
    color: var(--text-light);
}

.expertise-list li:last-child {
    border-bottom: none;
}

.expertise-list strong {
    color: var(--text-dark);
}

/* Courses Section */
.courses-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
}

.course-card {
    background: white;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: 0 2px 8px rgba(0,0,0,0.1);
    transition: transform 0.3s, box-shadow 0.3s;
    display: flex;
    flex-direction: column;
    position: relative;
}

.course-card.featured {
    border: 2px solid var(--primary-color);
}

.course-badge {
    position: absolute;
    top: -12px;
    right: 20px;
    background: var(--primary-color);
    color: white;
    padding: 6px 16px;
    border-radius: 20px;
    font-size: 0.875rem;
    font-weight: 600;
}

.course-card:hover {
    transform: translateY(-8px);
    box-shadow: 0 12px 24px rgba(0,0,0,0.15);
}

.course-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
    text-align: center;
}

.course-title {
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: 0.75rem;
    color: var(--text-dark);
}

.course-description {
    color: var(--text-light);
    margin-bottom: 1.25rem;
    line-height: 1.6;
    flex-grow: 1;
}

.course-features {
    list-style: none;
    padding: 0;
    margin-bottom: 1.5rem;
}

.course-features li {
    padding: 0.5rem 0;
    color: var(--text-dark);
    position: relative;
    padding-left: 1.5rem;
}

.course-features li::before {
    content: '✓';
    position: absolute;
    left: 0;
    color: var(--success-color);
    font-weight: 700;
}

.btn-course {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--accent-color) 100%);
    color: white;
    width: 100%;
    text-align: center;
    padding: 14px 24px;
    font-weight: 700;
    border-radius: 8px;
    transition: all 0.3s;
}

.btn-course:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 16px rgba(37, 99, 235, 0.3);
}

/* Reviews Section - Carousel */
.reviews-carousel-container {
    position: relative;
    max-width: 100%;
    overflow: hidden;
    padding: 0 50px;
}

.reviews-carousel {
    display: flex;
    gap: 2rem;
    overflow-x: hidden;
    scroll-behavior: smooth;
    padding: 20px 0;
}

.review-card {
    flex: 0 0 calc(33.333% - 1.5rem);
    background: white;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: 0 2px 8px rgba(0,0,0,0.1);
    transition: transform 0.3s, box-shadow 0.3s;
    min-width: 280px;
}

.review-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 8px 16px rgba(0,0,0,0.15);
}

.review-info {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
    padding-bottom: 0.5rem;
    border-bottom: 2px solid var(--primary-color);
}

.review-author {
    font-weight: 700;
    color: var(--text-dark);
    font-size: 1.1rem;
}

.review-meta {
    font-size: 0.875rem;
    color: var(--text-light);
    background: var(--background-light);
    padding: 0.25rem 0.75rem;
    border-radius: 12px;
}

.review-text {
    color: var(--text-light);
    line-height: 1.8;
    font-size: 0.95rem;
}

.carousel-btn {
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    background: var(--primary-color);
    color: white;
    border: none;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    font-size: 1.5rem;
    cursor: pointer;
    z-index: 10;
    transition: all 0.3s;
    display: flex;
    align-items: center;
    justify-content: center;
}

.carousel-btn:hover {
    background: var(--secondary-color);
    transform: translateY(-50%) scale(1.1);
}

.prev-btn {
    left: 0;
}

.next-btn {
    right: 0;
}

.carousel-indicators {
    display: flex;
    justify-content: center;
    gap: 0.5rem;
    margin-top: 2rem;
}

.carousel-indicator {
    width: 10px;
    height: 10px;
    border-radius: 50%;
    background: var(--border-color);
    cursor: pointer;
    transition: all 0.3s;
}

.carousel-indicator.active {
    background: var(--primary-color);
    width: 30px;
    border-radius: 5px;
}

/* Achievements Section */
.achievements-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin-bottom: 4rem;
}

.achievement-card {
    background: white;
    padding: 2.5rem 2rem;
    border-radius: 12px;
    text-align: center;
    box-shadow: 0 2px 8px rgba(0,0,0,0.1);
}

.achievement-number {
    font-size: 3rem;
    font-weight: 900;
    color: var(--primary-color);
    margin-bottom: 0.5rem;
}

.achievement-label {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text-dark);
    margin-bottom: 0.5rem;
}

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

.subsection-title {
    font-size: 2rem;
    font-weight: 700;
    text-align: center;
    margin-bottom: 2rem;
    color: var(--text-dark);
}

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

.story-card {
    background: white;
    padding: 2rem;
    border-radius: 12px;
    border-left: 4px solid var(--primary-color);
    box-shadow: 0 2px 8px rgba(0,0,0,0.1);
}

.story-card h4 {
    font-size: 1.25rem;
    font-weight: 700;
    margin-bottom: 1rem;
    color: var(--text-dark);
}

.story-card p {
    color: var(--text-light);
    line-height: 1.8;
    margin-bottom: 1rem;
}

.story-tag {
    display: inline-block;
    background-color: var(--accent-color);
    color: white;
    padding: 0.25rem 0.75rem;
    border-radius: 20px;
    font-size: 0.75rem;
    font-weight: 600;
}

/* Contact Section */
.contact-content {
    display: grid;
    grid-template-columns: 1fr 1.5fr;
    gap: 3rem;
}

.contact-info {
    background: white;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: 0 2px 8px rgba(0,0,0,0.1);
    height: fit-content;
}

.contact-info h3 {
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: 1.5rem;
    color: var(--text-dark);
}

.info-item {
    margin-bottom: 1.5rem;
}

.info-item strong {
    display: block;
    color: var(--primary-color);
    margin-bottom: 0.5rem;
    font-size: 1.1rem;
}

.info-item p {
    color: var(--text-light);
    line-height: 1.8;
}

.contact-form-wrapper {
    background: white;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: 0 2px 8px rgba(0,0,0,0.1);
}

.contact-form .form-group {
    margin-bottom: 1.5rem;
}

.contact-form label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 600;
    color: var(--text-dark);
}

.contact-form input,
.contact-form textarea {
    width: 100%;
    padding: 12px;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    font-family: inherit;
    font-size: 1rem;
    transition: border-color 0.3s;
}

.contact-form input:focus,
.contact-form textarea:focus {
    outline: none;
    border-color: var(--primary-color);
}

.contact-form textarea {
    resize: vertical;
}

.form-message {
    margin-top: 1rem;
    padding: 1rem;
    border-radius: 8px;
    display: none;
    text-align: center;
    font-weight: 600;
}

.form-message.success {
    display: block;
    background-color: #d1fae5;
    color: var(--success-color);
}

.form-message.error {
    display: block;
    background-color: #fee2e2;
    color: var(--error-color);
}

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

.footer p {
    margin: 0.5rem 0;
    opacity: 0.8;
}

/* Responsive Design */
@media (max-width: 768px) {
    .nav-menu {
        flex-direction: column;
        gap: 1rem;
    }
    
    .hero-title {
        font-size: 2rem;
    }
    
    .hero-subtitle {
        font-size: 1rem;
    }
    
    .section-title {
        font-size: 2rem;
    }
    
    .intro-content {
        grid-template-columns: 1fr;
    }
    
    .reviews-carousel-container {
        padding: 0 35px;
    }
    
    .review-card {
        flex: 0 0 100%;
        min-width: 0;
    }
    
    .carousel-btn {
        width: 35px;
        height: 35px;
        font-size: 1.25rem;
    }
    
    .achievements-grid {
        grid-template-columns: 1fr;
    }
    
    .stories-grid {
        grid-template-columns: 1fr;
    }
    
    .contact-content {
        grid-template-columns: 1fr;
    }
    
    .achievement-number {
        font-size: 2.5rem;
    }
}

@media (max-width: 480px) {
    .navbar .container {
        flex-direction: row;
        justify-content: space-between;
        align-items: center;
        flex-wrap: wrap;
        gap: 0.5rem;
    }
    
    .nav-brand {
        flex: 0 0 auto;
    }
    
    .nav-brand h2 {
        font-size: 1.1rem;
    }
    
    .nav-menu {
        flex-direction: row;
        flex-wrap: nowrap;
        gap: 0.3rem;
        justify-content: flex-end;
        flex: 1 1 auto;
        order: 2;
    }
    
    .nav-menu li {
        white-space: nowrap;
    }
    
    .nav-menu a {
        font-size: 0.7rem;
        padding: 0.3rem 0.25rem;
        display: block;
    }
    
    .lang-toggle {
        padding: 0.3rem 0.5rem;
        font-size: 0.7rem;
        flex: 0 0 auto;
        order: 3;
    }
    
    .hero {
        padding: 60px 0;
    }
    
    .section {
        padding: 40px 0;
    }
    
    .container {
        padding: 0 10px;
    }
    
    .reviews-carousel-container {
        padding: 0 30px;
    }
    
    .review-card {
        min-width: 0;
        padding: 1.5rem;
    }
    
    .carousel-btn {
        width: 30px;
        height: 30px;
        font-size: 1.1rem;
    }
}

/* Case Studies Carousel Section */
.case-studies-section {
    background: linear-gradient(135deg, #f8fafc 0%, #e2e8f0 100%);
    padding: 60px 0;
}

.case-studies-carousel-wrapper {
    position: relative;
    max-width: 100%;
    margin: 0 auto;
    overflow: hidden;
    padding: 0 50px;
}

.case-studies-carousel {
    display: flex;
    gap: 20px;
    padding: 20px 0;
    transition: transform 0.5s ease;
}

.case-study-card {
    flex: 0 0 calc(33.333% - 14px);
    min-width: calc(33.333% - 14px);
    background: white;
    border-radius: 16px;
    overflow: hidden;
    box-shadow: 0 4px 12px rgba(0,0,0,0.1);
    transition: box-shadow 0.3s;
    cursor: pointer;
    text-decoration: none;
    color: inherit;
    display: block;
}

.case-study-card:hover {
    box-shadow: 0 12px 24px rgba(0,0,0,0.15);
}

.case-study-thumbnail {
    width: 100%;
    height: 180px;
    object-fit: cover;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--accent-color) 100%);
}

.case-study-content {
    padding: 1.25rem;
}

.case-study-title {
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--text-dark);
    margin-bottom: 0.5rem;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
    line-height: 1.4;
}

.case-study-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 0.85rem;
    color: var(--text-light);
}

.case-study-date {
    display: flex;
    align-items: center;
    gap: 0.3rem;
}

.case-carousel-btn {
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    background: white;
    border: none;
    width: 44px;
    height: 44px;
    border-radius: 50%;
    cursor: pointer;
    font-size: 1.3rem;
    color: var(--primary-color);
    box-shadow: 0 4px 12px rgba(0,0,0,0.15);
    transition: all 0.3s;
    z-index: 10;
}

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

.case-prev-btn {
    left: 0;
}

.case-next-btn {
    right: 0;
}

.case-carousel-indicators {
    display: flex;
    justify-content: center;
    gap: 0.5rem;
    margin-top: 1.5rem;
}

.case-carousel-indicators .indicator {
    width: 10px;
    height: 10px;
    border-radius: 50%;
    background: var(--border-color);
    cursor: pointer;
    transition: all 0.3s;
}

.case-carousel-indicators .indicator.active {
    background: var(--primary-color);
    transform: scale(1.2);
}

.case-studies-cta {
    text-align: center;
    margin-top: 2rem;
}

.btn-outline {
    display: inline-block;
    padding: 12px 32px;
    border: 2px solid var(--primary-color);
    color: var(--primary-color);
    background: transparent;
    border-radius: 8px;
    font-weight: 600;
    text-decoration: none;
    transition: all 0.3s;
}

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

@media (max-width: 992px) {
    .case-study-card {
        flex: 0 0 calc(50% - 0.75rem);
    }
}

@media (max-width: 576px) {
    .case-study-card {
        flex: 0 0 100%;
    }
    
    .case-studies-carousel-wrapper {
        padding: 0 35px;
    }
    
    .case-carousel-btn {
        width: 32px;
        height: 32px;
        font-size: 1rem;
    }
    
    .case-study-thumbnail {
        height: 150px;
    }
}