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

:root {
    --primary-color: #0a1628;
    --secondary-color: #1a2332;
    --accent-color: #8b5cf6;
    --accent-pink: #ec4899;
    --accent-blue: #3b82f6;
    --dark-color: #050a14;
    --light-color: #f8f9fa;
    --text-color: #1a1a1a;
    --text-light: #666;
    --border-color: #e0e0e0;
    --success-color: #28a745;
    --danger-color: #dc3545;
    --warning-color: #ffc107;
    --shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 40px rgba(139, 92, 246, 0.3);
    --glow: 0 0 20px rgba(139, 92, 246, 0.5);
}

body {
    font-family: 'Noto Sans KR', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    display: flex;
    flex-direction: column;
    background-color: #fff;
}

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

/* 헤더 */
.main-header {
    background: linear-gradient(135deg, rgba(10, 22, 40, 0.95), rgba(26, 35, 50, 0.95));
    backdrop-filter: blur(10px);
    color: white;
    padding: 1rem 0;
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: 0 4px 20px rgba(139, 92, 246, 0.2);
    border-bottom: 1px solid rgba(139, 92, 246, 0.3);
}

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

.logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 1.5rem;
    font-weight: 700;
}

.logo i {
    font-size: 2rem;
}

.logo-icon {
    position: relative;
    display: inline-block;
    width: 2rem;
    height: 2rem;
}

.logo-icon .fa-book {
    position: absolute;
    top: 0;
    left: 0;
    font-size: 2rem;
    color: white;
}

.logo-icon .logo-pen {
    position: absolute;
    top: 0.3rem;
    right: -0.3rem;
    font-size: 1rem;
    color: var(--accent-pink);
    transform: rotate(-45deg);
}

.logo-image {
    height: 40px;
    width: auto;
    object-fit: contain;
    /* 배경 제거하고 원본 색상 유지 */
}

/* ============================================
   네비게이션: 모바일 우선 설계
   - 기본: 숨김 (모바일)
   - 769px 이상: 가로 네비게이션 (PC)
   ============================================ */

/* 기본: 모바일 - 완전히 숨김 */
.main-nav {
    display: none !important; /* 모바일에서 기본 숨김 */
}

/* PC 전용: 가로 네비게이션 바 (769px 이상) */
@media (min-width: 769px) {
    .main-nav {
        display: flex !important;
        gap: 2rem;
        position: static !important;
        width: auto !important;
        height: auto !important;
        background: none !important;
        flex-direction: row !important;
        padding: 0 !important;
        right: auto !important;
        top: auto !important;
    }
}

.nav-link {
    color: white;
    text-decoration: none;
    font-weight: 500;
    transition: all 0.3s ease;
    padding: 0.5rem 0;
    border-bottom: 2px solid transparent;
}

.nav-link:hover,
.nav-link.active {
    border-bottom-color: var(--accent-color);
    text-shadow: 0 0 10px rgba(139, 92, 246, 0.8);
}

/* 햄버거 메뉴 버튼 (모바일에서만 표시) */
.mobile-menu-toggle {
    display: none; /* PC에서는 숨김 */
    background: none;
    border: none;
    color: white;
    font-size: 1.5rem;
    cursor: pointer;
    padding: 0.5rem;
    z-index: 1002;
    position: relative;
    transition: color 0.3s ease;
}

.mobile-menu-toggle:hover {
    color: var(--accent-color);
    transform: scale(1.1);
}

/* 메뉴 오버레이 (모바일 전용) */
.mobile-menu-overlay {
    display: none; /* PC에서는 완전히 숨김 */
}

/* 히어로 섹션 */
.hero-section {
    background: 
        radial-gradient(circle at 50% 50%, rgba(139, 92, 246, 0.15) 0%, transparent 50%),
        radial-gradient(circle at 80% 20%, rgba(236, 72, 153, 0.15) 0%, transparent 50%),
        radial-gradient(circle at 20% 80%, rgba(59, 130, 246, 0.15) 0%, transparent 50%),
        linear-gradient(135deg, #0a1628 0%, #1a2332 100%);
    color: white;
    padding: 8rem 0;
    text-align: center;
    position: relative;
    overflow: hidden;
}

#starfield {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 0;
}

.hero-section::before {
    content: '';
    position: absolute;
    width: 500px;
    height: 500px;
    background: radial-gradient(circle, rgba(139, 92, 246, 0.3) 0%, transparent 70%);
    border-radius: 50%;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    filter: blur(80px);
    animation: pulse 4s ease-in-out infinite;
}

@keyframes pulse {
    0%, 100% { opacity: 0.5; transform: translate(-50%, -50%) scale(1); }
    50% { opacity: 0.8; transform: translate(-50%, -50%) scale(1.1); }
}

.hero-content {
    max-width: 800px;
    margin: 0 auto;
    position: relative;
    z-index: 1;
}

.hero-title {
    font-size: 3.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
    background: linear-gradient(135deg, #ffffff 0%, #a78bfa 50%, #ec4899 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    animation: fadeInUp 0.8s ease;
    text-shadow: 0 0 40px rgba(139, 92, 246, 0.5);
}

.hero-subtitle {
    font-size: 1.5rem;
    margin-bottom: 2rem;
    opacity: 0.9;
    color: #e5e7eb;
    animation: fadeInUp 0.8s ease 0.2s both;
    min-height: 2.5rem;
}

.typing-text::after {
    content: '|';
    animation: blink 0.7s infinite;
    color: var(--accent-color);
}

@keyframes blink {
    0%, 100% { opacity: 1; }
    50% { opacity: 0; }
}

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

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

/* 버튼 */
.btn {
    display: inline-block;
    padding: 0.75rem 2rem;
    border-radius: 50px;
    text-decoration: none;
    font-weight: 600;
    transition: all 0.3s ease;
    border: none;
    cursor: pointer;
    font-size: 1rem;
}

.btn-primary {
    background: linear-gradient(135deg, #8b5cf6 0%, #ec4899 100%);
    color: white;
    box-shadow: 0 4px 15px rgba(139, 92, 246, 0.4);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(139, 92, 246, 0.6);
    background: linear-gradient(135deg, #a78bfa 0%, #f472b6 100%);
}

.btn-secondary {
    background-color: transparent;
    color: white;
    border: 2px solid rgba(139, 92, 246, 0.6);
    box-shadow: 0 0 15px rgba(139, 92, 246, 0.3);
}

.btn-secondary:hover {
    background: linear-gradient(135deg, #8b5cf6 0%, #ec4899 100%);
    color: white;
    border-color: transparent;
    box-shadow: 0 0 25px rgba(139, 92, 246, 0.6);
}

/* 섹션 공통 스타일 */
section {
    padding: 4rem 0;
}

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

.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--dark-color);
    margin-bottom: 0.5rem;
}

.section-subtitle {
    font-size: 1.2rem;
    color: var(--text-light);
}

/* ACU 섹션 */
.acu-section {
    background-color: var(--light-color);
}

.acu-intro {
    background: white;
    padding: 2rem;
    border-radius: 15px;
    box-shadow: var(--shadow);
    margin-bottom: 3rem;
}

.acu-logo-area {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-bottom: 1rem;
}

.acu-logo-area i {
    font-size: 3rem;
    color: var(--primary-color);
}

.acu-logo-area h3 {
    font-size: 2rem;
    color: var(--dark-color);
}

.acu-description {
    font-size: 1.1rem;
    line-height: 1.8;
    color: var(--text-color);
}

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

.acu-card {
    background: white;
    padding: 2rem;
    border-radius: 15px;
    box-shadow: var(--shadow);
    transition: all 0.3s ease;
}

.acu-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 40px rgba(139, 92, 246, 0.3);
    border: 1px solid var(--accent-color);
}

.acu-card-icon {
    width: 70px;
    height: 70px;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 1rem;
}

.acu-card-icon i {
    font-size: 2rem;
    color: white;
}

.acu-card h4 {
    font-size: 1.5rem;
    margin-bottom: 0.5rem;
    color: var(--dark-color);
}

.acu-card > p {
    color: var(--text-light);
    margin-bottom: 1rem;
}

.acu-features {
    list-style: none;
}

.acu-features li {
    padding: 0.5rem 0;
    color: var(--text-color);
}

.acu-features i {
    color: var(--success-color);
    margin-right: 0.5rem;
}

.acu-benefits {
    background: white;
    padding: 2rem;
    border-radius: 15px;
    box-shadow: var(--shadow);
    margin-bottom: 3rem;
}

.acu-benefits h3 {
    font-size: 1.8rem;
    margin-bottom: 2rem;
    text-align: center;
    color: var(--dark-color);
}

.benefits-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 2rem;
}

.benefit-item {
    text-align: center;
    padding: 1.5rem;
    background: var(--light-color);
    border-radius: 12px;
    transition: all 0.3s ease;
}

.benefit-item:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 25px rgba(139, 92, 246, 0.2);
}

.benefit-item i {
    font-size: 3rem;
    color: var(--accent-color);
    margin-bottom: 1rem;
}

.benefit-item h4 {
    font-size: 1.2rem;
    margin-bottom: 0.5rem;
    color: var(--dark-color);
}

.benefit-item p {
    color: var(--text-light);
}

.acu-info {
    background: white;
    padding: 2rem;
    border-radius: 15px;
    box-shadow: var(--shadow);
}

.acu-info h3 {
    font-size: 1.8rem;
    margin-bottom: 2rem;
    text-align: center;
    color: var(--dark-color);
}

.info-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 2rem;
}

.info-item {
    text-align: center;
    padding: 1.5rem;
    background: var(--light-color);
    border-radius: 10px;
}

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

.info-item p {
    font-size: 1.2rem;
    font-weight: 600;
    color: var(--dark-color);
}

/* ACU 시험 상세 정보 */
.acu-exam-details {
    background: white;
    padding: 2.5rem;
    border-radius: 15px;
    box-shadow: var(--shadow);
    margin-top: 3rem;
}

.acu-exam-details h3 {
    font-size: 1.8rem;
    margin-bottom: 2rem;
    text-align: center;
    color: var(--dark-color);
}

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

.exam-detail-card {
    background: var(--light-color);
    padding: 2rem;
    border-radius: 12px;
    border: 2px solid transparent;
    transition: all 0.3s ease;
}

.exam-detail-card:hover {
    border-color: var(--accent-color);
    transform: translateY(-5px);
    box-shadow: 0 10px 30px rgba(139, 92, 246, 0.2);
}

.exam-detail-icon {
    width: 60px;
    height: 60px;
    background: linear-gradient(135deg, #8b5cf6 0%, #ec4899 100%);
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 1rem;
}

.exam-detail-icon i {
    font-size: 1.8rem;
    color: white;
}

.exam-detail-card h4 {
    font-size: 1.3rem;
    margin-bottom: 1rem;
    color: var(--dark-color);
}

.exam-detail-card ul {
    list-style: none;
    padding: 0;
}

.exam-detail-card ul li {
    padding: 0.5rem 0;
    color: var(--text-color);
    position: relative;
    padding-left: 1.5rem;
}

.exam-detail-card ul li:before {
    content: '•';
    position: absolute;
    left: 0;
    color: var(--accent-color);
    font-weight: bold;
    font-size: 1.2rem;
}

/* ACU 응시 절차 */
.acu-application {
    background: white;
    padding: 2.5rem;
    border-radius: 15px;
    box-shadow: var(--shadow);
    margin-top: 3rem;
}

.acu-application h3 {
    font-size: 1.8rem;
    margin-bottom: 2rem;
    text-align: center;
    color: var(--dark-color);
}

.application-steps {
    display: grid;
    gap: 1.5rem;
}

.step-item {
    display: flex;
    gap: 1.5rem;
    padding: 1.5rem;
    background: var(--light-color);
    border-radius: 12px;
    align-items: center;
    transition: all 0.3s ease;
}

.step-item:hover {
    transform: translateX(10px);
    box-shadow: 0 5px 20px rgba(139, 92, 246, 0.2);
}

.step-number {
    flex-shrink: 0;
    width: 50px;
    height: 50px;
    background: linear-gradient(135deg, #8b5cf6 0%, #ec4899 100%);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    font-weight: 700;
    color: white;
    box-shadow: 0 4px 15px rgba(139, 92, 246, 0.4);
}

.step-content h4 {
    font-size: 1.2rem;
    margin-bottom: 0.5rem;
    color: var(--dark-color);
}

.step-content p {
    color: var(--text-light);
    line-height: 1.6;
}

/* AI 융합교육 섹션 */
.ai-section {
    background: linear-gradient(180deg, #0a1628 0%, #1a2332 100%);
    color: white;
    padding: 5rem 0;
}

.ai-section .section-title {
    background: linear-gradient(135deg, #ffffff 0%, #a78bfa 50%, #ec4899 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.ai-section .section-subtitle {
    color: #e5e7eb;
}

.ai-intro {
    background: rgba(139, 92, 246, 0.1);
    border: 1px solid rgba(139, 92, 246, 0.3);
    padding: 2.5rem;
    border-radius: 20px;
    margin-bottom: 3rem;
    box-shadow: 0 0 30px rgba(139, 92, 246, 0.2);
}

.ai-intro h3 {
    font-size: 2rem;
    margin-bottom: 1rem;
    background: linear-gradient(135deg, #ffffff 0%, #a78bfa 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.ai-intro p {
    font-size: 1.1rem;
    line-height: 1.8;
    color: #d1d5db;
}

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

.ai-card {
    background: rgba(26, 35, 50, 0.6);
    backdrop-filter: blur(10px);
    border: 1px solid rgba(139, 92, 246, 0.3);
    padding: 2rem;
    border-radius: 20px;
    transition: all 0.4s ease;
}

.ai-card:hover {
    transform: translateY(-10px);
    box-shadow: 0 15px 50px rgba(139, 92, 246, 0.4);
    border-color: rgba(139, 92, 246, 0.6);
}

.ai-card-icon {
    width: 80px;
    height: 80px;
    background: linear-gradient(135deg, #8b5cf6 0%, #ec4899 100%);
    border-radius: 20px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 1.5rem;
    box-shadow: 0 10px 30px rgba(139, 92, 246, 0.4);
}

.ai-card-icon i {
    font-size: 2.5rem;
    color: white;
}

.ai-card h4 {
    font-size: 1.5rem;
    margin-bottom: 0.75rem;
    color: white;
}

.ai-card > p {
    color: #d1d5db;
    margin-bottom: 1.5rem;
    line-height: 1.6;
}

.ai-features {
    list-style: none;
}

.ai-features li {
    padding: 0.6rem 0;
    color: #e5e7eb;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.ai-features i {
    color: #a78bfa;
}

.ai-tools {
    background: rgba(139, 92, 246, 0.05);
    border: 1px solid rgba(139, 92, 246, 0.2);
    padding: 2.5rem;
    border-radius: 20px;
    margin-bottom: 3rem;
}

.ai-tools > h3 {
    font-size: 2rem;
    margin-bottom: 3rem;
    text-align: center;
    background: linear-gradient(135deg, #ffffff 0%, #a78bfa 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.tools-category {
    margin-bottom: 3rem;
}

.tools-category:last-child {
    margin-bottom: 0;
}

.category-title {
    font-size: 1.5rem;
    margin-bottom: 1.5rem;
    color: white;
    padding: 1rem 1.5rem;
    background: rgba(139, 92, 246, 0.2);
    border-left: 4px solid var(--accent-color);
    border-radius: 8px;
}

.tools-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 1.5rem;
}

.tool-item {
    text-align: center;
    padding: 1.5rem;
    background: rgba(26, 35, 50, 0.6);
    border: 1px solid rgba(139, 92, 246, 0.2);
    border-radius: 15px;
    transition: all 0.3s ease;
}

.tool-item:hover {
    transform: translateY(-5px);
    border-color: rgba(139, 92, 246, 0.5);
    box-shadow: 0 10px 30px rgba(139, 92, 246, 0.3);
}

.tool-item i {
    font-size: 2.5rem;
    color: var(--accent-color);
    margin-bottom: 0.75rem;
}

.tool-item h5 {
    font-size: 1.1rem;
    margin-bottom: 0.5rem;
    color: white;
    font-weight: 600;
}

.tool-item p {
    font-size: 0.9rem;
    color: #9ca3af;
}

.ai-benefits {
    background: rgba(139, 92, 246, 0.1);
    border: 1px solid rgba(139, 92, 246, 0.3);
    padding: 2.5rem;
    border-radius: 20px;
}

.ai-benefits h3 {
    font-size: 2rem;
    margin-bottom: 2rem;
    text-align: center;
    background: linear-gradient(135deg, #ffffff 0%, #a78bfa 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.benefits-list {
    display: grid;
    gap: 1.5rem;
}

.benefit-box {
    display: flex;
    gap: 1.5rem;
    padding: 1.5rem;
    background: rgba(26, 35, 50, 0.6);
    border: 1px solid rgba(139, 92, 246, 0.2);
    border-radius: 15px;
    transition: all 0.3s ease;
}

.benefit-box:hover {
    border-color: rgba(139, 92, 246, 0.5);
    transform: translateX(10px);
}

.benefit-icon {
    flex-shrink: 0;
    width: 60px;
    height: 60px;
    background: linear-gradient(135deg, #8b5cf6 0%, #ec4899 100%);
    border-radius: 15px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.benefit-icon i {
    font-size: 1.8rem;
    color: white;
}

.benefit-text h4 {
    font-size: 1.3rem;
    margin-bottom: 0.5rem;
    color: white;
}

.benefit-text p {
    color: #d1d5db;
    line-height: 1.6;
}

/* 학습자료 섹션 */
.materials-section {
    background: white;
}

.materials-actions {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2rem;
    flex-wrap: wrap;
    gap: 1rem;
}

.filter-controls {
    display: flex;
    gap: 1rem;
}

.filter-select {
    padding: 0.5rem 1rem;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    font-size: 1rem;
    cursor: pointer;
    transition: all 0.3s ease;
}

.filter-select:focus {
    outline: none;
    border-color: var(--primary-color);
}

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

.material-card {
    background: white;
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 1.5rem;
    box-shadow: var(--shadow);
    transition: all 0.3s ease;
}

.material-card:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-lg);
}

.material-header {
    display: flex;
    justify-content: space-between;
    align-items: start;
    margin-bottom: 1rem;
}

.material-category {
    display: inline-block;
    padding: 0.25rem 0.75rem;
    background: linear-gradient(135deg, #8b5cf6 0%, #ec4899 100%);
    color: white;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 500;
    box-shadow: 0 2px 10px rgba(139, 92, 246, 0.3);
}

.material-actions {
    display: flex;
    gap: 0.5rem;
}

.icon-btn {
    background: transparent;
    border: none;
    cursor: pointer;
    color: var(--text-light);
    font-size: 1.1rem;
    transition: color 0.3s ease;
}

.icon-btn:hover {
    color: var(--primary-color);
}

.icon-btn.delete:hover {
    color: var(--danger-color);
}

.material-title {
    font-size: 1.3rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--dark-color);
}

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

.material-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-top: 1rem;
    border-top: 1px solid var(--border-color);
}

.material-type {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--text-light);
    font-size: 0.9rem;
}

.material-download {
    padding: 0.5rem 1rem;
    background: linear-gradient(135deg, #8b5cf6 0%, #ec4899 100%);
    color: white;
    text-decoration: none;
    border-radius: 8px;
    font-size: 0.9rem;
    transition: all 0.3s ease;
    box-shadow: 0 2px 10px rgba(139, 92, 246, 0.3);
}

.material-download:hover {
    background: linear-gradient(135deg, #a78bfa 0%, #f472b6 100%);
    box-shadow: 0 4px 15px rgba(139, 92, 246, 0.5);
    transform: translateY(-2px);
}

.material-date {
    color: var(--text-light);
    font-size: 0.85rem;
    margin-top: 0.5rem;
}

.loading {
    grid-column: 1 / -1;
    text-align: center;
    padding: 3rem;
    color: var(--text-light);
}

.loading i {
    font-size: 2rem;
    margin-bottom: 1rem;
}

.empty-state {
    grid-column: 1 / -1;
    text-align: center;
    padding: 3rem;
}

.empty-state i {
    font-size: 4rem;
    color: var(--border-color);
    margin-bottom: 1rem;
}

.empty-state h3 {
    color: var(--text-light);
    margin-bottom: 0.5rem;
}

/* 과정소개 섹션 */
.about-section {
    background: var(--light-color);
}

.about-intro {
    background: white;
    padding: 2rem;
    border-radius: 15px;
    box-shadow: var(--shadow);
    margin-bottom: 3rem;
    text-align: center;
}

.about-intro p {
    font-size: 1.1rem;
    line-height: 1.8;
    color: var(--text-color);
    max-width: 900px;
    margin: 0 auto;
}

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

.feature-card {
    background: white;
    padding: 2rem;
    border-radius: 15px;
    box-shadow: var(--shadow);
    text-align: center;
    transition: all 0.3s ease;
}

.feature-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 40px rgba(139, 92, 246, 0.3);
    border: 1px solid rgba(139, 92, 246, 0.5);
}

.feature-card i {
    font-size: 3rem;
    color: var(--accent-color);
    margin-bottom: 1rem;
}

.feature-card h4 {
    font-size: 1.5rem;
    margin-bottom: 0.5rem;
    color: var(--dark-color);
}

.feature-card p {
    color: var(--text-light);
}

.curriculum {
    background: white;
    padding: 2rem;
    border-radius: 15px;
    box-shadow: var(--shadow);
}

.curriculum h3 {
    font-size: 2rem;
    margin-bottom: 2rem;
    text-align: center;
    color: var(--dark-color);
}

.curriculum-list {
    display: grid;
    gap: 1.5rem;
}

.curriculum-item {
    display: flex;
    gap: 1.5rem;
    padding: 1.5rem;
    background: var(--light-color);
    border-radius: 12px;
    transition: all 0.3s ease;
}

.curriculum-item:hover {
    background: #f5f5f5;
    border-left: 4px solid var(--accent-color);
}

.curriculum-number {
    flex-shrink: 0;
    width: 50px;
    height: 50px;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: var(--accent-color);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    font-weight: 700;
}

.curriculum-content h4 {
    font-size: 1.3rem;
    margin-bottom: 0.5rem;
    color: var(--dark-color);
}

.curriculum-content p {
    color: var(--text-light);
}

/* 모달 */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.7);
    z-index: 2000;
    animation: fadeIn 0.3s ease;
}

.modal.active {
    display: flex;
    align-items: center;
    justify-content: center;
}

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

.modal-content {
    background: white;
    padding: 2rem;
    border-radius: 15px;
    max-width: 600px;
    width: 90%;
    max-height: 90vh;
    overflow-y: auto;
    animation: slideUp 0.3s ease;
}

@keyframes slideUp {
    from {
        transform: translateY(50px);
        opacity: 0;
    }
    to {
        transform: translateY(0);
        opacity: 1;
    }
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.5rem;
    padding-bottom: 1rem;
    border-bottom: 2px solid var(--border-color);
}

.modal-header h3 {
    font-size: 1.8rem;
    color: var(--dark-color);
}

.modal-close {
    background: transparent;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--text-light);
    transition: color 0.3s ease;
}

.modal-close:hover {
    color: var(--danger-color);
}

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

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

.form-group input,
.form-group select,
.form-group textarea {
    width: 100%;
    padding: 0.75rem;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    font-size: 1rem;
    font-family: inherit;
    transition: border-color 0.3s ease;
}

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

.form-group small {
    display: block;
    margin-top: 0.25rem;
    color: var(--text-light);
    font-size: 0.85rem;
}

.form-actions {
    display: flex;
    gap: 1rem;
    justify-content: flex-end;
    margin-top: 2rem;
}

/* 푸터 */
.main-footer {
    background: var(--dark-color);
    color: white;
    padding: 3rem 0 1rem;
}

.footer-content {
    display: grid;
    grid-template-columns: 2fr 1fr 1.5fr;
    gap: 3rem;
    margin-bottom: 2rem;
}

.footer-info h4 {
    font-size: 1.5rem;
    margin-bottom: 0.5rem;
    background: linear-gradient(135deg, #8b5cf6, #ec4899);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.footer-info p {
    color: rgba(255, 255, 255, 0.7);
    font-size: 0.95rem;
}

/* 푸터 링크 섹션 */
.footer-links {
    display: flex;
    flex-direction: column;
    gap: 0.8rem;
}

.footer-links h5 {
    font-size: 1.1rem;
    margin-bottom: 0.5rem;
    color: #8b5cf6;
    font-weight: 600;
}

.footer-links a {
    color: rgba(255, 255, 255, 0.7);
    text-decoration: none;
    transition: all 0.3s ease;
    font-size: 0.95rem;
}

.footer-links a:hover {
    color: white;
    padding-left: 5px;
    color: #8b5cf6;
}

/* 문의하기 섹션 */
.footer-contact-section {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.footer-contact-section h5 {
    font-size: 1.1rem;
    margin-bottom: 0.5rem;
    color: #8b5cf6;
    font-weight: 600;
}

.contact-description {
    color: rgba(255, 255, 255, 0.7);
    font-size: 0.9rem;
    line-height: 1.6;
    margin-bottom: 1rem;
}

.contact-btn {
    background: linear-gradient(135deg, #8b5cf6, #ec4899);
    color: white;
    border: none;
    padding: 0.8rem 1.5rem;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    margin-bottom: 1rem;
    box-shadow: 0 4px 15px rgba(139, 92, 246, 0.3);
    text-decoration: none;
}

.contact-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(139, 92, 246, 0.5);
    color: white;
}

.contact-btn i {
    font-size: 1.1rem;
}

.contact-item {
    display: flex;
    align-items: flex-start;
    gap: 0.8rem;
}

.contact-item i {
    color: #8b5cf6;
    font-size: 1.2rem;
    margin-top: 0.2rem;
}

.contact-info {
    display: flex;
    flex-direction: column;
    gap: 0.2rem;
}

.contact-label {
    font-size: 0.85rem;
    color: rgba(255, 255, 255, 0.5);
    font-weight: 500;
}

.contact-info a,
.contact-info span {
    color: rgba(255, 255, 255, 0.8);
    text-decoration: none;
    transition: all 0.3s ease;
    font-size: 0.95rem;
}

.contact-info a:hover {
    color: #8b5cf6;
    text-shadow: 0 0 10px rgba(139, 92, 246, 0.5);
}

/* 문의하기 - 간단한 mailto 링크 사용 */

/* 푸터 하단 */
.footer-bottom {
    text-align: center;
    padding-top: 1.5rem;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
}

.footer-bottom p {
    color: rgba(255, 255, 255, 0.5);
    font-size: 0.9rem;
    line-height: 1.6;
}

/* ============================
   과제 제출 섹션
   ============================ */
.assignment-section {
    background: linear-gradient(to bottom, var(--light-color), white);
    padding: 6rem 0;
}

/* 모드 전환 버튼 */
.assignment-mode-switch {
    display: flex;
    justify-content: center;
    gap: 1rem;
    margin: 2rem 0;
}

.mode-btn {
    padding: 1rem 2rem;
    font-size: 1.1rem;
    font-weight: 600;
    border: 2px solid var(--border-color);
    background: white;
    color: var(--text-color);
    cursor: pointer;
    border-radius: 10px;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.mode-btn i {
    font-size: 1.2rem;
}

.mode-btn:hover {
    border-color: var(--accent-color);
    transform: translateY(-2px);
    box-shadow: 0 5px 20px rgba(139, 92, 246, 0.3);
}

.mode-btn.active {
    background: linear-gradient(135deg, var(--accent-color), var(--accent-pink));
    color: white;
    border-color: transparent;
    box-shadow: 0 5px 20px rgba(139, 92, 246, 0.5);
}

/* 모드 콘텐츠 */
.mode-content {
    display: none;
}

.mode-content.active {
    display: block;
}

/* 강사 로그인 */
.teacher-login {
    display: flex;
    justify-content: center;
    padding: 3rem 0;
}

.login-box {
    background: white;
    padding: 3rem;
    border-radius: 20px;
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.1);
    text-align: center;
    max-width: 400px;
    width: 100%;
}

.login-box i {
    font-size: 3rem;
    color: var(--accent-color);
    margin-bottom: 1.5rem;
}

.login-box h3 {
    font-size: 1.8rem;
    color: var(--dark-color);
    margin-bottom: 0.5rem;
}

.login-box p {
    color: var(--text-light);
    margin-bottom: 1.5rem;
}

.login-box input[type="password"] {
    width: 100%;
    padding: 1rem;
    font-size: 1rem;
    border: 2px solid var(--border-color);
    border-radius: 10px;
    margin-bottom: 1rem;
    transition: all 0.3s ease;
}

.login-box input[type="password"]:focus {
    outline: none;
    border-color: var(--accent-color);
    box-shadow: 0 0 0 3px rgba(139, 92, 246, 0.1);
}

.password-hint {
    font-size: 0.85rem;
    color: var(--text-light);
    margin-top: 1rem;
    line-height: 1.6;
}

.password-hint code {
    background: var(--light-color);
    padding: 0.2rem 0.5rem;
    border-radius: 5px;
    color: var(--accent-color);
    font-weight: 600;
    font-family: 'Courier New', monospace;
}

.password-hint small {
    display: block;
    margin-top: 0.5rem;
    font-size: 0.75rem;
}

/* 강사 대시보드 */
.teacher-dashboard {
    padding: 2rem 0;
}

.teacher-section {
    background: white;
    padding: 2rem;
    border-radius: 15px;
    box-shadow: var(--shadow);
    margin-bottom: 2rem;
}

.teacher-section h3 {
    font-size: 1.5rem;
    color: var(--dark-color);
    margin-bottom: 1.5rem;
}

.section-header-with-btn {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.5rem;
}

.section-header-with-btn h3 {
    margin: 0;
}

/* 통계 카드 */
.submissions-stats {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1.5rem;
    margin-bottom: 2rem;
}

.stat-card {
    background: linear-gradient(135deg, var(--light-color), white);
    padding: 1.5rem;
    border-radius: 15px;
    box-shadow: var(--shadow);
    display: flex;
    align-items: center;
    gap: 1rem;
    transition: all 0.3s ease;
}

.stat-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.15);
}

.stat-card i {
    font-size: 2.5rem;
    color: var(--accent-color);
}

.stat-info h4 {
    font-size: 2rem;
    font-weight: 700;
    color: var(--dark-color);
    margin: 0;
}

.stat-info p {
    font-size: 0.9rem;
    color: var(--text-light);
    margin: 0;
}

/* 과제 목록 */
.assignments-list-section,
.my-submissions-section {
    margin-bottom: 3rem;
}

.assignments-list-section h3,
.my-submissions-section h3 {
    font-size: 1.5rem;
    color: var(--dark-color);
    margin-bottom: 1.5rem;
}

.assignments-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: 1.5rem;
}

.assignment-card {
    background: white;
    padding: 1.5rem;
    border-radius: 15px;
    box-shadow: var(--shadow);
    transition: all 0.3s ease;
    border: 2px solid transparent;
}

.assignment-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 30px rgba(139, 92, 246, 0.3);
    border-color: var(--accent-color);
}

.assignment-card.expired {
    opacity: 0.6;
    background: var(--light-color);
}

.assignment-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
}

.assignment-category {
    background: linear-gradient(135deg, var(--accent-color), var(--accent-pink));
    color: white;
    padding: 0.4rem 1rem;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 600;
}

.assignment-actions {
    display: flex;
    gap: 0.5rem;
}

.badge-active {
    background: linear-gradient(135deg, #10b981, #059669);
    color: white;
    padding: 0.4rem 1rem;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 600;
}

.badge-expired {
    background: linear-gradient(135deg, #ef4444, #dc2626);
    color: white;
    padding: 0.4rem 1rem;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 600;
}

.assignment-title {
    font-size: 1.3rem;
    font-weight: 700;
    color: var(--dark-color);
    margin-bottom: 0.8rem;
}

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

.assignment-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: 1rem;
    padding-top: 1rem;
    border-top: 1px solid var(--border-color);
}

.assignment-deadline {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--text-light);
    font-size: 0.9rem;
}

.assignment-deadline i {
    color: var(--accent-color);
}

.btn-sm {
    padding: 0.6rem 1.2rem;
    font-size: 0.9rem;
}

/* 제출 현황 필터 */
.submission-filter {
    display: flex;
    gap: 1rem;
    margin-bottom: 1.5rem;
}

.submission-filter input {
    flex: 1;
    padding: 0.8rem 1rem;
    font-size: 1rem;
    border: 2px solid var(--border-color);
    border-radius: 10px;
    transition: all 0.3s ease;
}

.submission-filter input:focus {
    outline: none;
    border-color: var(--accent-color);
    box-shadow: 0 0 0 3px rgba(139, 92, 246, 0.1);
}

/* 제출 목록 */
.submissions-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 1.5rem;
}

.submission-card {
    background: white;
    padding: 1.5rem;
    border-radius: 15px;
    box-shadow: var(--shadow);
    transition: all 0.3s ease;
}

.submission-card:hover {
    transform: translateY(-3px);
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.15);
}

.submission-card h4 {
    font-size: 1.2rem;
    color: var(--dark-color);
    margin-bottom: 1rem;
}

.submission-card p {
    color: var(--text-light);
    margin-bottom: 0.5rem;
    font-size: 0.95rem;
}

.submission-card strong {
    color: var(--text-color);
}

/* 제출 현황 테이블 */
.submissions-table {
    width: 100%;
    border-collapse: collapse;
    background: white;
    border-radius: 10px;
    overflow: hidden;
    box-shadow: var(--shadow);
}

.submissions-table thead {
    background: linear-gradient(135deg, var(--accent-color), var(--accent-pink));
}

.submissions-table th {
    padding: 1rem;
    text-align: left;
    color: white;
    font-weight: 600;
    font-size: 0.95rem;
}

.submissions-table tbody tr {
    border-bottom: 1px solid var(--border-color);
    transition: background 0.2s ease;
}

.submissions-table tbody tr:hover {
    background: var(--light-color);
}

.submissions-table td {
    padding: 1rem;
    color: var(--text-color);
    font-size: 0.95rem;
}

.badge {
    background: linear-gradient(135deg, var(--accent-color), var(--accent-pink));
    color: white;
    padding: 0.3rem 0.8rem;
    border-radius: 15px;
    font-size: 0.8rem;
    font-weight: 600;
}

.text-muted {
    color: var(--text-light);
    font-size: 0.95rem;
}

.text-error {
    color: #ef4444;
    font-size: 0.95rem;
}

/* 맨 위로 가기 버튼 */
.scroll-to-top {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    width: 50px;
    height: 50px;
    background: linear-gradient(135deg, var(--accent-color), var(--accent-pink));
    color: white;
    border: none;
    border-radius: 50%;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.2rem;
    box-shadow: var(--shadow-lg);
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s ease;
    z-index: 9999 !important; /* 모든 요소보다 최상위 */
    pointer-events: auto !important;
}

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

.scroll-to-top:hover {
    transform: translateY(-5px);
    box-shadow: 0 15px 50px rgba(139, 92, 246, 0.5);
}

.scroll-to-top:active {
    transform: translateY(-2px);
}

/* 섹션 순서 제어 */
.main-header {
    order: 0;
}

.hero-section {
    order: 1;
}

.about-section {
    order: 2;
}

.ai-section {
    order: 3;
}

.acu-section {
    order: 4;
}

.materials-section {
    order: 5;
}

.assignment-section {
    order: 6;
}

.main-footer {
    order: 7;
}

/* 반응형 디자인 */
@media (max-width: 768px) {
    .hero-title {
        font-size: 2.5rem;
    }

    .hero-subtitle {
        font-size: 1.2rem;
    }
    
    /* 모바일 햄버거 메뉴 */
    .mobile-menu-toggle {
        display: block;
    }
    
    /* 모바일 메뉴 오버레이 */
    .mobile-menu-overlay {
        display: block;
        position: fixed;
        top: 0;
        left: 0;
        width: 100%;
        height: 100%;
        background: rgba(0, 0, 0, 0.5);
        z-index: 998;
        opacity: 0;
        visibility: hidden;
        transition: opacity 0.3s ease, visibility 0.3s ease;
    }
    
    .mobile-menu-overlay.active {
        opacity: 1;
        visibility: visible;
    }
    
    /* 모바일 슬라이드 메뉴 */
    .main-nav {
        display: none; /* 기본적으로 완전히 숨김 */
        position: fixed !important;
        top: 70px;
        right: -100% !important;
        width: 250px !important;
        height: calc(100vh - 70px);
        background: linear-gradient(135deg, rgba(10, 22, 40, 0.98), rgba(26, 35, 50, 0.98)) !important;
        backdrop-filter: blur(10px);
        flex-direction: column !important;
        padding: 2rem 1rem;
        gap: 0;
        box-shadow: -5px 0 20px rgba(0, 0, 0, 0.3);
        transition: right 0.3s ease;
        z-index: 1001 !important;
        overflow-y: auto;
        border-left: 2px solid rgba(139, 92, 246, 0.3);
    }
    
    .main-nav.active {
        display: flex !important; /* 활성화시에만 표시 */
        right: 0 !important;
    }
    
    /* 푸터 모바일 반응형 */
    .footer-content {
        grid-template-columns: 1fr;
        gap: 2rem;
    }
    
    .footer-links,
    .footer-contact-section {
        text-align: left;
    }
    
    .footer-links a {
        display: block;
    }
    
    .footer-bottom p {
        font-size: 0.85rem;
        line-height: 1.8;
    }
    
    .nav-link {
        display: block !important;
        color: #ffffff !important;
        background: transparent !important;
        font-size: 1.1rem !important;
        padding: 1.2rem 1rem !important;
        width: 100% !important;
        text-align: left !important;
        border-bottom: 1px solid rgba(139, 92, 246, 0.3) !important;
        border-left: 3px solid transparent !important;
        min-height: 50px !important;
        line-height: 1.5 !important;
    }
    
    .nav-link:hover,
    .nav-link.active {
        border-bottom-color: transparent !important;
        border-left-color: var(--accent-color) !important;
        background: rgba(139, 92, 246, 0.1) !important;
    }
    
    /* 모바일 맨 위로 버튼 */
    .scroll-to-top {
        bottom: 5rem !important;
        left: 1.5rem !important;
        right: auto !important;
        width: 60px !important;
        height: 60px !important;
        font-size: 1.4rem !important;
        z-index: 9999 !important;
    }

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

    .acu-programs,
    .benefits-grid,
    .about-features {
        grid-template-columns: 1fr;
    }

    .materials-list {
        grid-template-columns: 1fr;
    }

    .materials-actions {
        flex-direction: column;
        align-items: stretch;
    }

    .filter-controls {
        width: 100%;
    }

    .filter-select {
        width: 100%;
    }

    .assignment-mode-switch {
        flex-direction: column;
    }

    .mode-btn {
        width: 100%;
        justify-content: center;
    }

    .assignments-grid,
    .submissions-grid {
        grid-template-columns: 1fr;
    }

    .submission-filter {
        flex-direction: column;
    }

    .submissions-stats {
        grid-template-columns: 1fr;
    }

    .submissions-table {
        display: block;
        overflow-x: auto;
    }

    .assignment-footer {
        flex-direction: column;
        align-items: flex-start;
        gap: 1rem;
    }

    .section-header-with-btn {
        flex-direction: column;
        align-items: stretch;
        gap: 1rem;
    }

    .footer-content {
        flex-direction: column;
        text-align: center;
    }

    .footer-links {
        flex-direction: column;
        gap: 1rem;
    }
}

@media (max-width: 480px) {
    .hero-title {
        font-size: 2rem;
    }

    .hero-subtitle {
        font-size: 1rem;
    }

    .logo {
        font-size: 1.2rem;
    }

    .logo i {
        font-size: 1.5rem;
    }

    .main-nav {
        display: none;
    }

    .btn {
        padding: 0.6rem 1.5rem;
        font-size: 0.9rem;
    }
}