/* Pretendard 폰트 로드 */
@import url('https://cdn.jsdelivr.net/gh/orioncactus/pretendard@v1.3.8/dist/web/static/pretendard.css');

/* Lecturehub 커스텀 스타일 */

/* 한국어 폰트 시스템 스택 */
:root {
    --font-family: 'Pretendard', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    
    /* 부드러운 파스텔 컬러 팔레트 */
    --primary-color: #6366f1;
    --primary-light: #a5b4fc;
    --primary-dark: #4f46e5;
    --secondary-color: #8b5cf6;
    --secondary-light: #c4b5fd;
    --accent-color: #06b6d4;
    --accent-light: #67e8f9;
    
    --success-color: #10b981;
    --success-light: #6ee7b7;
    --warning-color: #f59e0b;
    --warning-light: #fcd34d;
    --danger-color: #ef4444;
    --danger-light: #fca5a5;
    
    --gray-50: #f9fafb;
    --gray-100: #f3f4f6;
    --gray-200: #e5e7eb;
    --gray-300: #d1d5db;
    --gray-400: #9ca3af;
    --gray-500: #6b7280;
    --gray-600: #4b5563;
    --gray-700: #374151;
    --gray-800: #1f2937;
    --gray-900: #111827;
    
    /* 라운드 크기 */
    --border-radius-sm: 0.5rem;
    --border-radius-md: 1rem;
    --border-radius-lg: 1.5rem;
    --border-radius-xl: 2rem;
    
    /* 그림자 */
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
    --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.1);
}

/* 전역 폰트 설정 */
body {
    font-family: var(--font-family);
    color: var(--gray-700);
    line-height: 1.6;
}

/* 네비게이션 스타일 */
.navbar {
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--gray-200);
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

.navbar-brand img {
    filter: drop-shadow(0 2px 4px rgba(99, 102, 241, 0.2));
}

/* 모바일 offcanvas 메뉴 개선 */
.navbar-toggler {
    border: none;
    padding: 0.25rem 0.5rem;
    border-radius: var(--border-radius-md);
    transition: all 0.3s ease;
}

.navbar-toggler:hover {
    background-color: rgba(99, 102, 241, 0.1);
}

.navbar-toggler:focus {
    box-shadow: 0 0 0 2px rgba(99, 102, 241, 0.25);
}

/* 네비게이션 링크 개선 */
.nav-link {
    color: var(--gray-600) !important;
    font-weight: 500;
    padding: 0.75rem 1rem !important;
    border-radius: var(--border-radius-md);
    transition: all 0.3s ease;
    margin: 0 0.25rem;
    position: relative;
    overflow: hidden;
}

.nav-link:hover {
    color: var(--primary-color) !important;
    background-color: rgba(99, 102, 241, 0.1);
    transform: translateY(-1px);
}

/* 활성 페이지 강조 - 밑줄 스타일 */
.nav-link.active {
    color: var(--primary-color) !important;
    background-color: rgba(99, 102, 241, 0.15);
    font-weight: 600;
}

.nav-link.active::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 70%;
    height: 3px;
    background: linear-gradient(90deg, var(--primary-color), var(--secondary-color));
    border-radius: 2px;
    animation: slideIn 0.3s ease;
}

@keyframes slideIn {
    from {
        width: 0;
    }
    to {
        width: 70%;
    }
}

/* 모바일에서는 pill 스타일 */
@media (max-width: 991px) {
    .nav-link.active::after {
        display: none;
    }
    
    .nav-link.active {
        background-color: var(--primary-color);
        color: white !important;
        border-radius: var(--border-radius-xl);
    }
}

/* 접근성 개선 */
.nav-link:focus {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}

/* 모바일 메뉴 접근성 */
.navbar-nav .nav-link[aria-expanded="true"] {
    background-color: rgba(99, 102, 241, 0.1);
}

/* 히어로 섹션 */
.hero-section {
    background: linear-gradient(135deg, var(--primary-light) 0%, var(--secondary-light) 100%);
    background-size: 400% 400%;
    animation: gradientShift 10s ease infinite;
    border-radius: var(--border-radius-xl);
    margin-bottom: 3rem;
    padding: 4rem 2rem;
    position: relative;
    overflow: hidden;
}

.hero-section::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: url('data:image/svg+xml,<svg width="60" height="60" viewBox="0 0 60 60" xmlns="http://www.w3.org/2000/svg"><g fill="none" fill-rule="evenodd"><g fill="%23ffffff" fill-opacity="0.1"><circle cx="30" cy="30" r="1.5"/></g></svg>');
    pointer-events: none;
}

@keyframes gradientShift {
    0%, 100% { background-position: 0% 50%; }
    50% { background-position: 100% 50%; }
}

.hero-title {
    font-size: 2.5rem;
    font-weight: 700;
    color: white;
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
    margin-bottom: 1rem;
}

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

/* 향상된 카드 스타일 */
.card {
    border: none;
    border-radius: var(--border-radius-lg) !important;
    box-shadow: var(--shadow-lg);
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    background: white;
    overflow: hidden;
    position: relative;
}

.card:hover {
    transform: translateY(-2px);
    box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    border: 1px solid rgba(99, 102, 241, 0.1);
}

/* 접근성 향상 - 포커스 가능한 카드 */
.card:focus-within {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
    transform: translateY(-2px);
    box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
}

/* 카드 링크 */
.card-link {
    text-decoration: none;
    color: inherit;
    display: block;
}

.card-link:hover {
    color: inherit;
    text-decoration: none;
}

/* 인터랙티브 카드 효과 */
.card-interactive {
    cursor: pointer;
    user-select: none;
}

.card-interactive:hover::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(135deg, rgba(99, 102, 241, 0.05), rgba(139, 92, 246, 0.05));
    pointer-events: none;
    z-index: 1;
}

.card-interactive:active {
    transform: translateY(-1px);
    transition: transform 0.1s ease;
}

.card-header {
    background: linear-gradient(135deg, var(--gray-50) 0%, white 100%);
    border-bottom: 1px solid var(--gray-200);
    border-radius: var(--border-radius-lg) var(--border-radius-lg) 0 0 !important;
    padding: 1.5rem;
}

.card-body {
    padding: 1.5rem;
}

.card-footer {
    background: var(--gray-50);
    border-top: 1px solid var(--gray-200);
    padding: 1rem 1.5rem;
}

/* 버튼 스타일 */
.btn {
    border-radius: var(--border-radius-md) !important;
    font-weight: 500;
    padding: 0.75rem 1.5rem;
    transition: all 0.3s ease;
    border: none;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    box-shadow: var(--shadow-md);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
    background: linear-gradient(135deg, var(--primary-dark) 0%, var(--secondary-color) 100%);
}

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

.btn-outline-primary:hover {
    background: var(--primary-color);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.btn-success {
    background: linear-gradient(135deg, var(--success-color) 0%, var(--accent-color) 100%);
}

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

/* 향상된 칩/배지 스타일 */
.chip, .badge {
    background: var(--primary-light);
    color: var(--primary-dark);
    padding: 0.5rem 1rem;
    border-radius: var(--border-radius-xl);
    font-size: 0.875rem;
    font-weight: 500;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    transition: all 0.3s ease;
    border: 2px solid transparent;
    cursor: default;
    user-select: none;
}

.chip:hover {
    background: var(--primary-color);
    color: white;
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

/* 필터 칩 스타일 */
.filter-chip {
    background: rgba(248, 250, 252, 0.8);
    color: var(--gray-600);
    border: 2px solid var(--gray-200);
    padding: 0.5rem 1rem;
    border-radius: var(--border-radius-xl);
    font-size: 0.875rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s ease;
    outline: none;
    backdrop-filter: blur(4px);
}

.filter-chip:hover {
    border-color: var(--primary-color);
    color: var(--primary-color);
    background: rgba(99, 102, 241, 0.05);
    transform: translateY(-1px);
    box-shadow: 0 4px 8px rgba(99, 102, 241, 0.15);
}

.filter-chip.active {
    background: var(--primary-color);
    color: white;
    border-color: var(--primary-dark);
    box-shadow: 0 4px 12px rgba(99, 102, 241, 0.3);
    font-weight: 600;
}

.filter-chip:focus {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}

/* 상태별 칩 색상 */
.chip-success {
    background: rgba(16, 185, 129, 0.1);
    color: var(--success-color);
    border-color: rgba(16, 185, 129, 0.2);
}

.chip-success:hover {
    background: var(--success-color);
    color: white;
    border-color: var(--success-color);
}

.chip-warning {
    background: rgba(245, 158, 11, 0.1);
    color: var(--warning-color);
    border-color: rgba(245, 158, 11, 0.2);
}

.chip-warning:hover {
    background: var(--warning-color);
    color: white;
    border-color: var(--warning-color);
}

.chip-danger {
    background: rgba(239, 68, 68, 0.1);
    color: var(--danger-color);
    border-color: rgba(239, 68, 68, 0.2);
}

.chip-danger:hover {
    background: var(--danger-color);
    color: white;
    border-color: var(--danger-color);
}

/* 상태 뱃지 부트스트랩 호환 스타일 */
.badge.bg-success, .status-badge-success {
    background-color: var(--success-color) !important;
    color: white;
}

.badge.bg-primary, .status-badge-primary {
    background-color: var(--primary-color) !important;
    color: white;
}

.badge.bg-secondary, .status-badge-secondary {
    background-color: var(--gray-500) !important;
    color: white;
}

.badge.bg-warning, .status-badge-warning {
    background-color: var(--warning-color) !important;
    color: white;
}

.badge.bg-info, .status-badge-info {
    background-color: var(--accent-color) !important;
    color: white;
}

/* 업로드 버튼 스타일 */
.upload-area {
    border: 2px dashed var(--gray-300);
    border-radius: var(--border-radius-lg);
    padding: 3rem 2rem;
    text-align: center;
    background: var(--gray-50);
    transition: all 0.3s ease;
    cursor: pointer;
}

.upload-area:hover {
    border-color: var(--primary-color);
    background: rgba(99, 102, 241, 0.05);
}

.upload-area.dragover {
    border-color: var(--primary-color);
    background: rgba(99, 102, 241, 0.1);
    transform: scale(1.02);
}

.upload-icon {
    font-size: 3rem;
    color: var(--gray-400);
    margin-bottom: 1rem;
}

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

/* 폼 스타일 */
.form-control, .form-select {
    border: 2px solid var(--gray-200);
    border-radius: var(--border-radius-md) !important;
    padding: 0.75rem 1rem;
    transition: all 0.3s ease;
    font-family: var(--font-family);
}

.form-control:focus, .form-select:focus {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 0.2rem rgba(99, 102, 241, 0.25);
}

.form-label {
    font-weight: 500;
    color: var(--gray-700);
    margin-bottom: 0.5rem;
}

/* 경고/정보 박스 */
.alert {
    border: none;
    border-radius: var(--border-radius-lg) !important;
    padding: 1rem 1.5rem;
    font-weight: 500;
}

.alert-info {
    background: rgba(6, 182, 212, 0.1);
    color: var(--accent-color);
    border-left: 4px solid var(--accent-color);
}

.alert-success {
    background: rgba(16, 185, 129, 0.1);
    color: var(--success-color);
    border-left: 4px solid var(--success-color);
}

.alert-warning {
    background: rgba(245, 158, 11, 0.1);
    color: var(--warning-color);
    border-left: 4px solid var(--warning-color);
}

.alert-danger {
    background: rgba(239, 68, 68, 0.1);
    color: var(--danger-color);
    border-left: 4px solid var(--danger-color);
}

/* 푸터 스타일 */
footer {
    background: var(--gray-50) !important;
    border-top: 1px solid var(--gray-200);
}

footer h6 {
    color: var(--gray-700);
    font-size: 0.9rem;
}

footer a {
    color: var(--gray-500) !important;
    transition: color 0.3s ease;
}

footer a:hover {
    color: var(--primary-color) !important;
}

/* 반응형 조정 */
@media (max-width: 768px) {
    .hero-title {
        font-size: 2rem;
    }
    
    .hero-subtitle {
        font-size: 1.1rem;
    }
    
    .hero-section {
        padding: 2rem 1rem;
        margin-bottom: 2rem;
    }
    
    .card-body {
        padding: 1rem;
    }
    
    .btn {
        padding: 0.6rem 1.2rem;
        font-size: 0.9rem;
    }
}

/* 스크롤바 스타일 (웹킷 브라우저) */
::-webkit-scrollbar {
    width: 8px;
}

::-webkit-scrollbar-track {
    background: var(--gray-100);
}

::-webkit-scrollbar-thumb {
    background: var(--gray-300);
    border-radius: var(--border-radius-sm);
}

::-webkit-scrollbar-thumb:hover {
    background: var(--primary-color);
}

/* 로딩 애니메이션 */
.loading {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 3px solid rgba(99, 102, 241, 0.3);
    border-radius: 50%;
    border-top-color: var(--primary-color);
    animation: spin 1s ease-in-out infinite;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

/* 새로운 큰 히어로 섹션 */
.hero-main {
    min-height: 60vh;
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
    overflow: hidden;
    background: white;
    text-align: center;
}

.hero-background {
    background: transparent;
    width: 100%;
    min-height: 60vh;
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
    text-align: center;
}

.floating-shapes {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    overflow: hidden;
    pointer-events: none;
}

.shape {
    position: absolute;
    border-radius: 50%;
    opacity: 0.6;
    animation: float 20s infinite linear;
}

.shape-1 {
    width: 60px;
    height: 60px;
    background: linear-gradient(135deg, #fbbf24, #f59e0b);
    top: 5%;
    left: 5%;
    animation-delay: 0s;
}

.shape-2 {
    width: 40px;
    height: 40px;
    background: linear-gradient(135deg, #60a5fa, #3b82f6);
    top: 8%;
    right: 5%;
    animation-delay: -5s;
}

.shape-3 {
    width: 80px;
    height: 80px;
    background: linear-gradient(135deg, #34d399, #10b981);
    bottom: 5%;
    left: 3%;
    animation-delay: -10s;
}

.shape-4 {
    width: 30px;
    height: 30px;
    background: linear-gradient(135deg, #a78bfa, #8b5cf6);
    bottom: 8%;
    right: 8%;
    animation-delay: -15s;
}

.shape-5 {
    width: 50px;
    height: 50px;
    background: linear-gradient(135deg, #fb7185, #f43f5e);
    top: 15%;
    right: 25%;
    animation-delay: -8s;
}

.shape-6 {
    width: 35px;
    height: 35px;
    background: linear-gradient(135deg, #06b6d4, #0891b2);
    bottom: 15%;
    left: 25%;
    animation-delay: -12s;
}

@keyframes float {
    0%, 100% {
        transform: translateY(0px) rotate(0deg);
    }
    33% {
        transform: translateY(-20px) rotate(120deg);
    }
    66% {
        transform: translateY(10px) rotate(240deg);
    }
}

.hero-main-title {
    font-size: 4.5rem;
    font-weight: 800;
    color: var(--gray-800);
    margin-bottom: 1.5rem;
    letter-spacing: -0.02em;
    line-height: 1.1;
    text-align: center;
    width: 100%;
}

.hero-main-subtitle {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--primary-color);
    margin-bottom: 1rem;
    text-align: center;
    width: 100%;
}

.hero-description {
    font-size: 1.1rem;
    color: var(--gray-600);
    margin-bottom: 2.5rem;
    line-height: 1.6;
    text-align: center;
    width: 100%;
}

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

.btn-hero-primary {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    color: white;
    padding: 1rem 2rem;
    border-radius: var(--border-radius-lg);
    font-weight: 600;
    font-size: 1.1rem;
    border: none;
    text-decoration: none;
    transition: all 0.3s ease;
    box-shadow: var(--shadow-lg);
}

.btn-hero-primary:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-xl);
    color: white;
}

.btn-hero-secondary {
    background: white;
    color: var(--primary-color);
    padding: 1rem 2rem;
    border-radius: var(--border-radius-lg);
    font-weight: 600;
    font-size: 1.1rem;
    border: 2px solid var(--primary-color);
    text-decoration: none;
    transition: all 0.3s ease;
    box-shadow: var(--shadow-md);
}

.btn-hero-secondary:hover {
    background: var(--primary-color);
    color: white;
    transform: translateY(-3px);
    box-shadow: var(--shadow-lg);
}

/* 기능 타일 섹션 */
.feature-tiles {
    padding: 5rem 0;
    background: white;
}

.feature-tile-link {
    text-decoration: none;
    color: inherit;
}

.feature-tile {
    background: white;
    border-radius: var(--border-radius-xl);
    padding: 3rem 2rem;
    text-align: center;
    box-shadow: var(--shadow-md);
    transition: all 0.3s ease;
    height: 100%;
    border: 1px solid var(--gray-100);
}

.feature-tile:hover {
    transform: translateY(-8px) scale(1.02);
    box-shadow: var(--shadow-xl);
}

.feature-icon {
    margin-bottom: 1.5rem;
}

.icon-circle {
    width: 80px;
    height: 80px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto;
    transition: all 0.3s ease;
}

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

.icon-green {
    background: linear-gradient(135deg, #10b981, #059669);
}

.icon-blue {
    background: linear-gradient(135deg, #3b82f6, #2563eb);
}

.icon-blue-dark {
    background: linear-gradient(135deg, #1e40af, #1d4ed8);
}

.icon-orange {
    background: linear-gradient(135deg, #f59e0b, #d97706);
}

.feature-tile:hover .icon-circle {
    transform: scale(1.1);
}

.feature-title {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--gray-800);
    margin: 0;
}

/* 반응형 조정 */
@media (max-width: 1200px) {
    .hero-main-title {
        font-size: 4rem;
    }
}

@media (max-width: 992px) {
    .hero-main {
        min-height: 50vh;
    }
    
    .hero-background {
        min-height: 50vh;
    }
    
    .hero-main-title {
        font-size: 3.5rem;
    }
    
    .hero-main-subtitle {
        font-size: 1.3rem;
    }
    
    .feature-tiles {
        padding: 3rem 0;
    }
    
    .feature-tile {
        padding: 2.5rem 1.5rem;
    }
}

@media (max-width: 768px) {
    .hero-main {
        min-height: 45vh;
    }
    
    .hero-background {
        min-height: 45vh;
    }
    
    .hero-main-title {
        font-size: 2.8rem;
    }
    
    .hero-main-subtitle {
        font-size: 1.1rem;
    }
    
    .hero-description {
        font-size: 1rem;
    }
    
    .hero-buttons {
        flex-direction: column;
        align-items: center;
    }
    
    .btn-hero-primary,
    .btn-hero-secondary {
        width: 100%;
        max-width: 300px;
    }
    
    .feature-tile {
        padding: 2rem 1.5rem;
    }
    
    .icon-circle {
        width: 70px;
        height: 70px;
    }
    
    .icon-circle i {
        font-size: 1.8rem;
    }
    
    .feature-title {
        font-size: 1.3rem;
    }
}

@media (max-width: 576px) {
    .hero-main-title {
        font-size: 2.5rem;
    }
    
    .hero-buttons {
        padding: 0 1rem;
    }
    
    .shape {
        display: none; /* 모바일에서는 배경 도형 숨김 */
    }
}

/* 교육 자료 페이지 스타일 */
.filter-section {
    background: var(--gray-50);
    padding: 1.5rem;
    border-radius: var(--border-radius-lg);
    border: 1px solid var(--gray-200);
}

.filter-label {
    color: var(--gray-700);
    font-weight: 600;
    margin-bottom: 0.75rem;
    font-size: 0.9rem;
}

.filter-chips {
    gap: 0.5rem;
}

.filter-chip {
    background: white;
    color: var(--gray-600);
    border: 2px solid var(--gray-200);
    padding: 0.5rem 1rem;
    border-radius: var(--border-radius-xl);
    font-size: 0.875rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s ease;
    outline: none;
}

.filter-chip:hover {
    border-color: var(--primary-color);
    color: var(--primary-color);
    transform: translateY(-1px);
}

.filter-chip.active {
    background: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
    box-shadow: var(--shadow-md);
}

/* 교육 카드 스타일 */
.education-card {
    background: white;
    border-radius: var(--border-radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-md);
    transition: all 0.3s ease;
    height: 100%;
    border: 1px solid var(--gray-100);
}

.education-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-xl);
}

.card-thumbnail {
    position: relative;
    height: 200px;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
}

.card-thumb-img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.card-thumb-placeholder {
    font-size: 3rem;
    opacity: 0.7;
}

.status-badge {
    position: absolute;
    top: 0.75rem;
    left: 0.75rem;
    background: var(--success-color);
    color: white;
    padding: 0.25rem 0.75rem;
    border-radius: var(--border-radius-md);
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.category-label {
    position: absolute;
    top: 0.75rem;
    right: 0.75rem;
    background: var(--primary-color);
    color: white;
    padding: 0.25rem 0.75rem;
    border-radius: var(--border-radius-md);
    font-size: 0.75rem;
    font-weight: 500;
}

.card-content {
    padding: 1.5rem;
}

.card-title {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--gray-800);
    margin-bottom: 0.75rem;
    line-height: 1.3;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.card-description {
    color: var(--gray-600);
    font-size: 0.9rem;
    line-height: 1.5;
    margin-bottom: 1.5rem;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.card-meta {
    display: flex;
    justify-content: space-between;
    align-items: flex-end;
    margin-top: auto;
}

.meta-left {
    display: flex;
    flex-direction: column;
    gap: 0.25rem;
}

.meta-item {
    display: flex;
    align-items: center;
    gap: 0.4rem;
    font-size: 0.8rem;
    color: var(--gray-500);
}

.meta-item i {
    font-size: 0.75rem;
}

.meta-right {
    flex-shrink: 0;
}

.btn-download {
    background: var(--primary-color);
    color: white;
    padding: 0.5rem 1rem;
    border-radius: var(--border-radius-md);
    font-size: 0.875rem;
    font-weight: 600;
    text-decoration: none;
    transition: all 0.3s ease;
    border: none;
}

.btn-download:hover {
    background: var(--primary-dark);
    color: white;
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

/* 결과 없음 메시지 */
.no-results-message {
    padding: 3rem 2rem;
    background: var(--gray-50);
    border-radius: var(--border-radius-lg);
    border: 1px solid var(--gray-200);
}

/* 반응형 조정 */
@media (max-width: 768px) {
    .filter-section {
        padding: 1rem;
    }
    
    .filter-chips {
        justify-content: center;
    }
    
    .card-thumbnail {
        height: 180px;
    }
    
    .card-content {
        padding: 1rem;
    }
    
    .card-title {
        font-size: 1.1rem;
    }
    
    .card-meta {
        flex-direction: column;
        align-items: flex-start;
        gap: 1rem;
    }
    
    .meta-left {
        width: 100%;
    }
    
    .meta-right {
        width: 100%;
    }
    
    .btn-download {
        width: 100%;
        text-align: center;
    }
}

@media (max-width: 576px) {
    .filter-group {
        margin-bottom: 1rem;
    }
    
    .filter-chip {
        padding: 0.4rem 0.8rem;
        font-size: 0.8rem;
    }
    
    .status-badge,
    .category-label {
        font-size: 0.7rem;
        padding: 0.2rem 0.6rem;
    }
}

/* 애니메이션 향상 */
.material-card {
    transition: all 0.3s ease;
}

.material-card[style*="display: none"] {
    opacity: 0;
    transform: scale(0.95);
}

.material-card:not([style*="display: none"]) {
    opacity: 1;
    transform: scale(1);
}

/* about.php 전용 스타일 */
.instructor-hero {
    padding: 4rem 0;
    background: linear-gradient(135deg, #f8fafc 0%, #e2e8f0 100%);
    position: relative;
    overflow: hidden;
}

.hero-background-instructor {
    position: relative;
    z-index: 2;
}

.instructor-main-title {
    font-size: 3.5rem;
    font-weight: 800;
    color: var(--gray-800);
    margin-bottom: 1rem;
    letter-spacing: -0.02em;
}

.instructor-subtitle {
    font-size: 1.4rem;
    font-weight: 600;
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.instructor-description {
    font-size: 1.1rem;
    color: var(--gray-600);
    margin-bottom: 0;
}

/* 프로필 섹션 */
.profile-section {
    padding: 4rem 0;
    background: white;
}

.profile-card {
    background: white;
    border-radius: var(--border-radius-xl);
    box-shadow: var(--shadow-xl);
    padding: 3rem;
    border: 1px solid var(--gray-100);
}

.profile-avatar {
    margin-bottom: 2rem;
}

.avatar-circle {
    width: 225px;
    height: 225px;
    border-radius: 20px;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto;
    box-shadow: var(--shadow-lg);
}

.avatar-circle i {
    font-size: 4rem;
    color: white;
}

/* 프로필 이미지 스타일 */
.profile-image {
    width: 100%;
    height: 100%;
    object-fit: cover;
    border-radius: 20px;
}

.instructor-badges {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
    align-items: center;
}

.instructor-badge {
    padding: 0.5rem 1rem;
    border-radius: var(--border-radius-xl);
    font-size: 0.875rem;
    font-weight: 500;
    text-decoration: none;
    transition: all 0.3s ease;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
}

.instructor-badge.external {
    background: var(--success-light);
    color: var(--success-color);
    border: 2px solid var(--success-color);
}

.instructor-badge.channel {
    background: var(--accent-light);
    color: var(--accent-color);
    border: 2px solid var(--accent-color);
}

.instructor-badge:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
    text-decoration: none;
}

.instructor-badge.channel:hover {
    color: white;
    background: var(--accent-color);
}

.profile-name {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--gray-800);
    margin-bottom: 0.5rem;
}

.profile-title {
    font-size: 1.2rem;
    color: var(--primary-color);
    font-weight: 600;
    margin-bottom: 2rem;
}

.profile-details {
    margin-bottom: 2rem;
}

.detail-item {
    display: flex;
    align-items: flex-start;
    gap: 1rem;
    margin-bottom: 1.5rem;
    padding: 1rem;
    background: var(--gray-50);
    border-radius: var(--border-radius-md);
    border-left: 4px solid var(--primary-color);
}

.detail-item i {
    font-size: 1.2rem;
    margin-top: 0.2rem;
    flex-shrink: 0;
}

.detail-item div {
    flex: 1;
}

.detail-item strong {
    display: block;
    color: var(--gray-700);
    margin-bottom: 0.25rem;
    font-weight: 600;
}

.detail-item span {
    color: var(--gray-600);
    line-height: 1.5;
}

.profile-actions {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
}

/* 교육 모듈 섹션 */
.education-modules {
    padding: 5rem 0;
    background: var(--gray-50);
}

.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--gray-800);
    margin-bottom: 1rem;
}

.section-subtitle {
    font-size: 1.1rem;
    color: var(--gray-600);
    margin-bottom: 0;
}

.module-card {
    background: white;
    border-radius: var(--border-radius-xl);
    padding: 2.5rem;
    box-shadow: var(--shadow-lg);
    transition: all 0.3s ease;
    height: 100%;
    border: 1px solid var(--gray-100);
    position: relative;
    overflow: hidden;
}

.module-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-xl);
}

.module-card.corporate {
    border-left: 4px solid var(--success-color);
}

.module-card.adult {
    border-left: 4px solid var(--primary-color);
}

.module-card.youth {
    border-left: 4px solid var(--secondary-color);
}

.module-icon {
    width: 80px;
    height: 80px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 1.5rem;
    font-size: 2.5rem;
    color: white;
}

.module-card.corporate .module-icon {
    background: linear-gradient(135deg, var(--success-color), #059669);
}

.module-card.adult .module-icon {
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
}

.module-card.youth .module-icon {
    background: linear-gradient(135deg, var(--secondary-color), #7c3aed);
}

.module-title {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--gray-800);
    text-align: center;
    margin-bottom: 1rem;
}

.module-description {
    color: var(--gray-600);
    text-align: center;
    margin-bottom: 2rem;
    line-height: 1.6;
}

.module-features {
    margin-bottom: 2rem;
}

.feature-item {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-bottom: 0.75rem;
    font-size: 0.9rem;
}

.feature-item i {
    font-size: 1rem;
}

.module-stats {
    display: flex;
    justify-content: space-between;
    margin-top: auto;
    padding-top: 1.5rem;
    border-top: 1px solid var(--gray-200);
}

.stat-item {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.875rem;
    color: var(--gray-500);
    font-weight: 500;
}

.stat-item i {
    color: var(--primary-color);
}

/* 반응형 조정 */
@media (max-width: 768px) {
    .instructor-main-title {
        font-size: 2.5rem;
    }
    
    .instructor-subtitle {
        font-size: 1.2rem;
    }
    
    .profile-card {
        padding: 2rem;
    }
    
    .profile-name {
        font-size: 2rem;
    }
    
    .detail-item {
        flex-direction: column;
        gap: 0.5rem;
        text-align: center;
    }
    
    .profile-actions {
        flex-direction: column;
        align-items: center;
    }
    
    .profile-actions .btn {
        width: 100%;
        max-width: 300px;
    }
    
    .module-card {
        padding: 2rem;
    }
    
    .module-stats {
        flex-direction: column;
        gap: 0.5rem;
        text-align: center;
    }
}

/* 접근성 개선 */
.btn:focus {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}

.form-control:focus, .form-select:focus {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 0.2rem rgba(99, 102, 241, 0.25);
    outline: none;
}

/* 스크린 리더 전용 텍스트 */
.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

/* 유틸리티 클래스 */
.rounded-4 {
    border-radius: var(--border-radius-xl) !important;
}

.shadow-soft {
    box-shadow: var(--shadow-lg);
}

.text-gradient {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

/* 연락처 정보 스타일 */
.contact-info {
    padding: 1.5rem;
    background: linear-gradient(135deg, rgba(79, 172, 254, 0.08), rgba(0, 242, 254, 0.08));
    border-radius: var(--border-radius-lg);
    border: 1px solid rgba(79, 172, 254, 0.15);
    backdrop-filter: blur(10px);
}

.contact-item {
    display: flex;
    align-items: flex-start;
    gap: 0.75rem;
    margin-bottom: 1.25rem;
}

.contact-item:last-child {
    margin-bottom: 0;
}

.contact-icon {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 2.5rem;
    height: 2.5rem;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    border-radius: 50%;
    color: white;
    font-size: 1rem;
    flex-shrink: 0;
}

.contact-text {
    flex: 1;
    font-size: 0.9rem;
    line-height: 1.5;
}

.contact-text strong {
    color: var(--gray-800);
    font-weight: 600;
    margin-bottom: 0.25rem;
    display: block;
}

.contact-text span {
    color: var(--gray-600);
    display: inline-block;
    margin-bottom: 0.125rem;
}