/* =============================================
   2bjarn - Custom Stylesheet
   Foundation 6.8 Overrides + Custom Design
   ============================================= */

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800&family=Noto+Sans+Thai:wght@300;400;500;600;700&display=swap');

/* =============================================
   CSS Variables
   ============================================= */
:root {
    --primary: #6C63FF;
    --primary-light: #8B83FF;
    --primary-dark: #5A52E0;
    --secondary: #3B82F6;
    --accent: #06D6A0;
    --danger: #EF4444;
    --warning: #F59E0B;
    --success: #10B981;
    
    --bg-dark: #0f0f23;
    --bg-card: #1a1a2e;
    --bg-card-hover: #222240;
    --bg-sidebar: #12122a;
    --bg-input: #252545;
    
    --text-primary: #E2E8F0;
    --text-secondary: #94A3B8;
    --text-muted: #64748B;
    
    --border-color: rgba(108, 99, 255, 0.15);
    --border-glow: rgba(108, 99, 255, 0.4);
    
    --glass-bg: rgba(26, 26, 46, 0.7);
    --glass-border: rgba(255, 255, 255, 0.08);
    
    --radius: 16px;
    --radius-sm: 10px;
    --radius-xs: 6px;
    
    --shadow: 0 8px 32px rgba(0, 0, 0, 0.3);
    --shadow-glow: 0 0 30px rgba(108, 99, 255, 0.15);
    
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    --font-th: 'Noto Sans Thai', sans-serif;
    --font-en: 'Inter', sans-serif;
}

/* =============================================
   Base & Reset
   ============================================= */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

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

body {
    font-family: var(--font-th);
    background: var(--bg-dark);
    color: var(--text-primary);
    line-height: 1.7;
    min-height: 100vh;
    overflow-x: hidden;
}

body.light-mode {
    --bg-dark: #f0f2f5;
    --bg-card: #ffffff;
    --bg-card-hover: #f8f9fa;
    --bg-input: #f1f3f5;
    --text-primary: #1a1a2e;
    --text-secondary: #4a5568;
    --text-muted: #718096;
    --border-color: rgba(0, 0, 0, 0.08);
    --glass-bg: rgba(255, 255, 255, 0.85);
    --glass-border: rgba(0, 0, 0, 0.06);
    --shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
}

a {
    color: var(--primary-light);
    text-decoration: none;
    transition: var(--transition);
}

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

/* =============================================
   Auth Pages (Login/Register)
   ============================================= */
.auth-wrapper {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, #0f0f23 0%, #1a1a3e 50%, #0f0f23 100%);
    position: relative;
    padding: 2rem;
}

.auth-wrapper::before {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle at 30% 50%, rgba(108, 99, 255, 0.08) 0%, transparent 50%),
                radial-gradient(circle at 70% 50%, rgba(59, 130, 246, 0.06) 0%, transparent 50%);
    animation: bgFloat 15s ease-in-out infinite;
}

@keyframes bgFloat {
    0%, 100% { transform: translate(0, 0) rotate(0deg); }
    33% { transform: translate(2%, -2%) rotate(1deg); }
    66% { transform: translate(-1%, 1%) rotate(-1deg); }
}

.auth-card {
    background: var(--glass-bg);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius);
    padding: 3rem;
    width: 100%;
    max-width: 440px;
    position: relative;
    z-index: 1;
    box-shadow: var(--shadow), var(--shadow-glow);
    animation: cardSlideUp 0.6s ease-out;
}

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

.auth-logo {
    text-align: center;
    margin-bottom: 2rem;
}

.auth-logo h1 {
    font-family: var(--font-en);
    font-size: 2.5rem;
    font-weight: 800;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    letter-spacing: -0.5px;
}

.auth-logo p {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-top: 0.25rem;
}

/* =============================================
   Form Styles
   ============================================= */
.form-group {
    margin-bottom: 1.25rem;
}

.form-group label {
    display: block;
    font-size: 0.85rem;
    font-weight: 500;
    color: var(--text-secondary);
    margin-bottom: 0.4rem;
}

.form-group input,
.form-group textarea,
.form-group select {
    width: 100%;
    padding: 0.75rem 1rem;
    background: var(--bg-input);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    color: var(--text-primary);
    font-family: var(--font-th);
    font-size: 0.95rem;
    transition: var(--transition);
    outline: none;
}

.form-group input:focus,
.form-group textarea:focus,
.form-group select:focus {
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(108, 99, 255, 0.15);
}

.form-group input::placeholder,
.form-group textarea::placeholder {
    color: var(--text-muted);
}

.form-group textarea {
    resize: vertical;
    min-height: 100px;
}

/* =============================================
   Buttons
   ============================================= */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: var(--radius-sm);
    font-family: var(--font-th);
    font-size: 0.95rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    text-decoration: none;
    line-height: 1.4;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    color: #fff;
    box-shadow: 0 4px 15px rgba(108, 99, 255, 0.3);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 25px rgba(108, 99, 255, 0.45);
    color: #fff;
}

.btn-success {
    background: linear-gradient(135deg, var(--success), #059669);
    color: #fff;
}

.btn-success:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(16, 185, 129, 0.35);
    color: #fff;
}

.btn-danger {
    background: linear-gradient(135deg, var(--danger), #DC2626);
    color: #fff;
}

.btn-danger:hover {
    transform: translateY(-2px);
    color: #fff;
}

.btn-outline {
    background: transparent;
    border: 1px solid var(--border-color);
    color: var(--text-primary);
}

.btn-outline:hover {
    border-color: var(--primary);
    background: rgba(108, 99, 255, 0.1);
    color: var(--primary-light);
}

.btn-sm {
    padding: 0.4rem 0.9rem;
    font-size: 0.82rem;
}

.btn-lg {
    padding: 0.9rem 2rem;
    font-size: 1.05rem;
}

.btn-block {
    width: 100%;
}

/* =============================================
   Layout: Sidebar + Main
   ============================================= */
.app-layout {
    display: flex;
    min-height: 100vh;
}

.sidebar {
    width: 280px;
    background: var(--bg-sidebar);
    border-right: 1px solid var(--border-color);
    position: fixed;
    top: 0;
    left: 0;
    height: 100vh;
    z-index: 100;
    display: flex;
    flex-direction: column;
    transition: var(--transition);
}

.sidebar-header {
    padding: 1.5rem;
    border-bottom: 1px solid var(--border-color);
}

.sidebar-header h1 {
    font-family: var(--font-en);
    font-size: 1.6rem;
    font-weight: 800;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.sidebar-header small {
    color: var(--text-muted);
    font-size: 0.75rem;
}

.sidebar-user {
    padding: 1.25rem 1.5rem;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.sidebar-user .avatar {
    width: 42px;
    height: 42px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 1rem;
    color: #fff;
    flex-shrink: 0;
}

.sidebar-user .user-info h4 {
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--text-primary);
    line-height: 1.3;
}

.sidebar-user .user-info span {
    font-size: 0.72rem;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.sidebar-nav {
    padding: 1rem 0;
    flex: 1;
    overflow-y: auto;
}

.sidebar-nav a {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.7rem 1.5rem;
    color: var(--text-secondary);
    font-size: 0.9rem;
    font-weight: 500;
    transition: var(--transition);
    border-left: 3px solid transparent;
}

.sidebar-nav a:hover {
    color: var(--text-primary);
    background: rgba(108, 99, 255, 0.06);
    border-left-color: var(--primary);
}

.sidebar-nav a.active {
    color: var(--primary-light);
    background: rgba(108, 99, 255, 0.1);
    border-left-color: var(--primary);
}

.sidebar-nav a .nav-icon {
    font-size: 1.15rem;
    width: 24px;
    text-align: center;
}

.sidebar-footer {
    padding: 1rem 1.5rem;
    border-top: 1px solid var(--border-color);
}

.sidebar-footer a {
    color: var(--text-muted);
    font-size: 0.85rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.sidebar-footer a:hover {
    color: var(--danger);
}

.main-content {
    flex: 1;
    margin-left: 280px;
    padding: 2rem;
    min-height: 100vh;
}

/* Mobile sidebar toggle */
.sidebar-toggle {
    display: none;
    position: fixed;
    top: 1rem;
    left: 1rem;
    z-index: 200;
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-xs);
    padding: 0.5rem 0.7rem;
    color: var(--text-primary);
    font-size: 1.3rem;
    cursor: pointer;
}

.sidebar-overlay {
    display: none;
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.5);
    z-index: 90;
}

/* =============================================
   Page Header
   ============================================= */
.page-header {
    margin-bottom: 2rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    flex-wrap: wrap;
    gap: 1rem;
}

.page-header h2 {
    font-size: 1.6rem;
    font-weight: 700;
    color: var(--text-primary);
}

.page-header p {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-top: 0.15rem;
}

.breadcrumb {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.82rem;
    color: var(--text-muted);
    margin-bottom: 1rem;
}

.breadcrumb a {
    color: var(--text-secondary);
}

.breadcrumb a:hover {
    color: var(--primary-light);
}

.breadcrumb .sep {
    color: var(--text-muted);
}

/* =============================================
   Cards
   ============================================= */
.card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    padding: 1.5rem;
    transition: var(--transition);
    position: relative;
    overflow: hidden;
}

.card:hover {
    border-color: var(--border-glow);
    box-shadow: var(--shadow-glow);
    transform: translateY(-2px);
}

.card-header-color {
    height: 6px;
    margin: -1.5rem -1.5rem 1.25rem -1.5rem;
    border-radius: var(--radius) var(--radius) 0 0;
}

.card h3 {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 0.4rem;
}

.card p {
    color: var(--text-secondary);
    font-size: 0.85rem;
}

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

/* =============================================
   Stats Cards
   ============================================= */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1.25rem;
    margin-bottom: 2rem;
}

.stat-card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    padding: 1.5rem;
    display: flex;
    align-items: center;
    gap: 1rem;
    transition: var(--transition);
}

.stat-card:hover {
    border-color: var(--border-glow);
    transform: translateY(-2px);
}

.stat-icon {
    width: 50px;
    height: 50px;
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.4rem;
    flex-shrink: 0;
}

.stat-icon.purple {
    background: rgba(108, 99, 255, 0.15);
    color: var(--primary);
}

.stat-icon.blue {
    background: rgba(59, 130, 246, 0.15);
    color: var(--secondary);
}

.stat-icon.green {
    background: rgba(16, 185, 129, 0.15);
    color: var(--success);
}

.stat-icon.orange {
    background: rgba(245, 158, 11, 0.15);
    color: var(--warning);
}

.stat-info h3 {
    font-size: 1.5rem;
    font-weight: 700;
    line-height: 1.2;
    margin-bottom: 0;
}

.stat-info p {
    font-size: 0.8rem;
    color: var(--text-muted);
}

/* =============================================
   Classroom Grid
   ============================================= */
.classroom-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 1.25rem;
}

.classroom-card {
    cursor: pointer;
}

.classroom-card .class-code {
    display: inline-block;
    background: rgba(108, 99, 255, 0.12);
    color: var(--primary-light);
    padding: 0.2rem 0.6rem;
    border-radius: var(--radius-xs);
    font-family: var(--font-en);
    font-size: 0.78rem;
    font-weight: 600;
    letter-spacing: 1px;
}

.classroom-card .class-meta {
    display: flex;
    align-items: center;
    gap: 1rem;
    font-size: 0.8rem;
    color: var(--text-muted);
}

/* =============================================
   Assignment List
   ============================================= */
.assignment-list {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.assignment-item {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    padding: 1.25rem 1.5rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1rem;
    transition: var(--transition);
    flex-wrap: wrap;
}

.assignment-item:hover {
    border-color: var(--border-glow);
    background: var(--bg-card-hover);
}

.assignment-info h4 {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 0.25rem;
}

.assignment-info .meta {
    display: flex;
    align-items: center;
    gap: 1rem;
    font-size: 0.8rem;
    color: var(--text-muted);
}

.assignment-actions {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    flex-shrink: 0;
}

.badge {
    display: inline-flex;
    align-items: center;
    padding: 0.2rem 0.65rem;
    border-radius: 50px;
    font-size: 0.72rem;
    font-weight: 600;
    letter-spacing: 0.3px;
}

.badge-success {
    background: rgba(16, 185, 129, 0.15);
    color: var(--success);
}

.badge-warning {
    background: rgba(245, 158, 11, 0.15);
    color: var(--warning);
}

.badge-danger {
    background: rgba(239, 68, 68, 0.15);
    color: var(--danger);
}

.badge-info {
    background: rgba(59, 130, 246, 0.15);
    color: var(--secondary);
}

/* =============================================
   Table
   ============================================= */
.table-wrapper {
    overflow-x: auto;
    border-radius: var(--radius-sm);
    border: 1px solid var(--border-color);
}

.data-table {
    width: 100%;
    border-collapse: collapse;
}

.data-table thead {
    background: var(--bg-input);
}

.data-table th {
    padding: 0.85rem 1rem;
    text-align: left;
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    border-bottom: 1px solid var(--border-color);
}

.data-table td {
    padding: 0.85rem 1rem;
    font-size: 0.9rem;
    border-bottom: 1px solid var(--border-color);
    color: var(--text-primary);
}

.data-table tbody tr {
    transition: var(--transition);
}

.data-table tbody tr:hover {
    background: rgba(108, 99, 255, 0.04);
}

.data-table tbody tr:last-child td {
    border-bottom: none;
}

/* =============================================
   Modal
   ============================================= */
.modal-overlay {
    display: none;
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.6);
    backdrop-filter: blur(4px);
    z-index: 500;
    align-items: center;
    justify-content: center;
    padding: 2rem;
    animation: fadeIn 0.2s ease;
}

.modal-overlay.active {
    display: flex;
}

.modal {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    padding: 2rem;
    width: 100%;
    max-width: 520px;
    max-height: 90vh;
    overflow-y: auto;
    animation: modalSlide 0.3s ease;
    box-shadow: var(--shadow);
}

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

@keyframes modalSlide {
    from { opacity: 0; transform: scale(0.95) translateY(10px); }
    to { opacity: 1; transform: scale(1) translateY(0); }
}

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

.modal-header h3 {
    font-size: 1.2rem;
    font-weight: 700;
}

.modal-close {
    background: none;
    border: none;
    color: var(--text-muted);
    font-size: 1.5rem;
    cursor: pointer;
    padding: 0.25rem;
    transition: var(--transition);
}

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

/* =============================================
   Share Link
   ============================================= */
.share-link-box {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    background: var(--bg-input);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    padding: 0.5rem 0.75rem;
}

.share-link-box input {
    flex: 1;
    background: none;
    border: none;
    color: var(--text-primary);
    font-family: var(--font-en);
    font-size: 0.82rem;
    outline: none;
}

.share-link-box .btn-copy {
    background: var(--primary);
    color: #fff;
    border: none;
    border-radius: var(--radius-xs);
    padding: 0.35rem 0.75rem;
    font-size: 0.78rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    white-space: nowrap;
}

.share-link-box .btn-copy:hover {
    background: var(--primary-dark);
}

/* =============================================
   Alert Messages
   ============================================= */
.alert {
    padding: 1rem 1.25rem;
    border-radius: var(--radius-sm);
    font-size: 0.9rem;
    margin-bottom: 1.25rem;
    display: flex;
    align-items: center;
    gap: 0.75rem;
    animation: cardSlideUp 0.4s ease;
}

.alert-success {
    background: rgba(16, 185, 129, 0.12);
    border: 1px solid rgba(16, 185, 129, 0.25);
    color: var(--success);
}

.alert-danger {
    background: rgba(239, 68, 68, 0.12);
    border: 1px solid rgba(239, 68, 68, 0.25);
    color: var(--danger);
}

.alert-warning {
    background: rgba(245, 158, 11, 0.12);
    border: 1px solid rgba(245, 158, 11, 0.25);
    color: var(--warning);
}

.alert-info {
    background: rgba(59, 130, 246, 0.12);
    border: 1px solid rgba(59, 130, 246, 0.25);
    color: var(--secondary);
}

/* =============================================
   Public Page (Student Submit)
   ============================================= */
.public-wrapper {
    min-height: 100vh;
    background: linear-gradient(135deg, #0f0f23 0%, #1a1a3e 50%, #0f0f23 100%);
    position: relative;
}

.public-wrapper::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: radial-gradient(circle at 20% 20%, rgba(108, 99, 255, 0.06) 0%, transparent 50%),
                radial-gradient(circle at 80% 80%, rgba(59, 130, 246, 0.04) 0%, transparent 50%);
    pointer-events: none;
}

.public-header {
    background: var(--glass-bg);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--glass-border);
    padding: 1rem 2rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    position: relative;
    z-index: 1;
}

.public-header .logo {
    font-family: var(--font-en);
    font-size: 1.4rem;
    font-weight: 800;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.public-header .class-name {
    color: var(--text-secondary);
    font-size: 0.85rem;
}

.public-content {
    max-width: 640px;
    margin: 0 auto;
    padding: 2.5rem 1.5rem;
    position: relative;
    z-index: 1;
}

.submit-card {
    background: var(--glass-bg);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius);
    padding: 2rem;
    box-shadow: var(--shadow), var(--shadow-glow);
    animation: cardSlideUp 0.5s ease-out;
}

.submit-card .assignment-title {
    font-size: 1.4rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.submit-card .assignment-desc {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: 1.5rem;
    line-height: 1.7;
    white-space: pre-wrap;
}

.submit-card .due-info {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    background: rgba(245, 158, 11, 0.1);
    border: 1px solid rgba(245, 158, 11, 0.2);
    padding: 0.5rem 1rem;
    border-radius: var(--radius-xs);
    font-size: 0.85rem;
    color: var(--warning);
    margin-bottom: 1.5rem;
}

.submit-card .due-info.overdue {
    background: rgba(239, 68, 68, 0.1);
    border-color: rgba(239, 68, 68, 0.2);
    color: var(--danger);
}

.submit-card .score-info {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    background: rgba(108, 99, 255, 0.1);
    border: 1px solid rgba(108, 99, 255, 0.2);
    padding: 0.5rem 1rem;
    border-radius: var(--radius-xs);
    font-size: 0.85rem;
    color: var(--primary-light);
    margin-bottom: 1.5rem;
    margin-left: 0.5rem;
}

.divider {
    border: none;
    border-top: 1px solid var(--border-color);
    margin: 1.5rem 0;
}

/* File Upload Zone */
.upload-zone {
    border: 2px dashed var(--border-color);
    border-radius: var(--radius-sm);
    padding: 2rem;
    text-align: center;
    cursor: pointer;
    transition: var(--transition);
    position: relative;
}

.upload-zone:hover,
.upload-zone.dragover {
    border-color: var(--primary);
    background: rgba(108, 99, 255, 0.05);
}

.upload-zone .upload-icon {
    font-size: 2.5rem;
    margin-bottom: 0.75rem;
}

.upload-zone p {
    color: var(--text-secondary);
    font-size: 0.88rem;
}

.upload-zone small {
    color: var(--text-muted);
    font-size: 0.75rem;
}

.upload-zone input[type="file"] {
    position: absolute;
    inset: 0;
    opacity: 0;
    cursor: pointer;
}

.file-preview {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    background: var(--bg-input);
    padding: 0.75rem 1rem;
    border-radius: var(--radius-xs);
    margin-top: 0.75rem;
}

.file-preview .file-icon {
    font-size: 1.5rem;
}

.file-preview .file-info {
    flex: 1;
}

.file-preview .file-info span {
    font-size: 0.85rem;
    font-weight: 500;
}

.file-preview .file-info small {
    display: block;
    color: var(--text-muted);
    font-size: 0.75rem;
}

.file-preview .remove-file {
    background: none;
    border: none;
    color: var(--danger);
    cursor: pointer;
    font-size: 1.2rem;
    padding: 0.25rem;
}

/* =============================================
   Success Page
   ============================================= */
.success-card {
    text-align: center;
    padding: 3rem 2rem;
}

.success-card .success-icon {
    font-size: 4rem;
    margin-bottom: 1rem;
    animation: bounceIn 0.6s ease;
}

@keyframes bounceIn {
    0% { transform: scale(0); }
    50% { transform: scale(1.2); }
    100% { transform: scale(1); }
}

.success-card h2 {
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    color: var(--success);
}

.success-card p {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

/* =============================================
   Gallery / Show All Works
   ============================================= */
.gallery-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 1.25rem;
}

.work-card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    overflow: hidden;
    transition: var(--transition);
}

.work-card:hover {
    border-color: var(--border-glow);
    transform: translateY(-3px);
    box-shadow: var(--shadow-glow);
}

.work-card .work-preview {
    height: 180px;
    background: var(--bg-input);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 3rem;
    color: var(--text-muted);
    overflow: hidden;
}

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

.work-card .work-info {
    padding: 1rem 1.25rem;
}

.work-card .work-info h4 {
    font-size: 0.95rem;
    font-weight: 600;
    margin-bottom: 0.25rem;
}

.work-card .work-info .meta {
    font-size: 0.78rem;
    color: var(--text-muted);
}

/* =============================================
   Empty State
   ============================================= */
.empty-state {
    text-align: center;
    padding: 4rem 2rem;
    color: var(--text-muted);
}

.empty-state .empty-icon {
    font-size: 3.5rem;
    margin-bottom: 1rem;
    opacity: 0.5;
}

.empty-state h3 {
    font-size: 1.1rem;
    margin-bottom: 0.5rem;
    color: var(--text-secondary);
}

.empty-state p {
    font-size: 0.85rem;
}

/* =============================================
   Utilities
   ============================================= */
.text-center { text-align: center; }
.text-right { text-align: right; }
.text-muted { color: var(--text-muted); }
.text-success { color: var(--success); }
.text-danger { color: var(--danger); }
.text-warning { color: var(--warning); }
.mt-1 { margin-top: 0.5rem; }
.mt-2 { margin-top: 1rem; }
.mt-3 { margin-top: 1.5rem; }
.mb-1 { margin-bottom: 0.5rem; }
.mb-2 { margin-bottom: 1rem; }
.mb-3 { margin-bottom: 1.5rem; }
.gap-1 { gap: 0.5rem; }
.d-flex { display: flex; }
.items-center { align-items: center; }
.justify-between { justify-content: space-between; }
.flex-wrap { flex-wrap: wrap; }

/* =============================================
   Responsive
   ============================================= */
@media (max-width: 768px) {
    .sidebar {
        transform: translateX(-100%);
    }
    
    .sidebar.open {
        transform: translateX(0);
    }
    
    .sidebar-toggle {
        display: block;
    }
    
    .sidebar-overlay.active {
        display: block;
    }
    
    .main-content {
        margin-left: 0;
        padding: 1.25rem;
        padding-top: 4rem;
    }
    
    .page-header {
        flex-direction: column;
        align-items: flex-start;
    }
    
    .classroom-grid {
        grid-template-columns: 1fr;
    }
    
    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .auth-card {
        padding: 2rem 1.5rem;
    }
    
    .public-content {
        padding: 1.5rem 1rem;
    }
    
    .submit-card {
        padding: 1.5rem;
    }
    
    .assignment-item {
        flex-direction: column;
        align-items: flex-start;
    }
    
    .gallery-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .stats-grid {
        grid-template-columns: 1fr;
    }
}

/* =============================================
   Scrollbar
   ============================================= */
::-webkit-scrollbar {
    width: 6px;
}

::-webkit-scrollbar-track {
    background: var(--bg-dark);
}

::-webkit-scrollbar-thumb {
    background: var(--border-color);
    border-radius: 3px;
}

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

/* =============================================
   Join Classroom (Short URL) Page
   ============================================= */
.join-classroom-card {
    padding: 0 !important;
    overflow: hidden;
}

.join-cover {
    height: 8px;
    border-radius: var(--radius-sm) var(--radius-sm) 0 0;
}

.join-header {
    padding: 1.5rem 2rem 0;
}

.join-title {
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: 0.25rem;
}

.join-desc {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: 0.5rem;
}

.join-meta {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    font-size: 0.82rem;
    color: var(--text-muted);
    margin-bottom: 0.5rem;
}

.join-code {
    background: var(--bg-input);
    padding: 0.15rem 0.6rem;
    border-radius: var(--radius-xs);
    font-family: var(--font-en);
    font-weight: 600;
    letter-spacing: 0.5px;
}

.join-classroom-card > .divider {
    margin: 0.5rem 2rem;
}

.join-section-title {
    font-size: 1rem;
    font-weight: 600;
    padding: 0.5rem 2rem;
    color: var(--text-secondary);
}

.join-assignment-list {
    padding: 0 1rem 1.5rem;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.join-assignment-item {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 1rem 1.25rem;
    background: var(--bg-input);
    border-radius: var(--radius-sm);
    text-decoration: none !important;
    color: var(--text-primary);
    transition: var(--transition);
    border: 1px solid transparent;
}

.join-assignment-item:hover {
    background: var(--bg-card-hover);
    border-color: var(--border-glow);
    transform: translateY(-2px);
    box-shadow: var(--shadow-glow);
    color: var(--text-primary);
}

.join-assignment-item.overdue {
    opacity: 0.6;
}

.join-assignment-item.overdue:hover {
    opacity: 0.8;
}

.join-assign-icon {
    font-size: 1.8rem;
    flex-shrink: 0;
    width: 44px;
    height: 44px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: rgba(108, 99, 255, 0.1);
    border-radius: var(--radius-xs);
}

.join-assignment-item.overdue .join-assign-icon {
    background: rgba(239, 68, 68, 0.1);
}

.join-assign-info {
    flex: 1;
    min-width: 0;
}

.join-assign-info h4 {
    font-size: 0.95rem;
    font-weight: 600;
    margin-bottom: 0.2rem;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.join-assign-meta {
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
    font-size: 0.78rem;
    color: var(--text-muted);
}

.join-assign-meta .text-danger {
    color: var(--danger);
}

.join-assign-desc {
    font-size: 0.8rem;
    color: var(--text-muted);
    margin-top: 0.25rem;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.join-assign-arrow {
    flex-shrink: 0;
}

.join-submit-badge {
    display: inline-block;
    padding: 0.35rem 0.85rem;
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    color: #fff;
    font-size: 0.78rem;
    font-weight: 600;
    border-radius: 20px;
    white-space: nowrap;
    transition: var(--transition);
}

.join-assignment-item:hover .join-submit-badge {
    background: linear-gradient(135deg, var(--primary-light), var(--primary));
    box-shadow: 0 0 12px rgba(108, 99, 255, 0.4);
}

.badge-danger-sm {
    display: inline-block;
    padding: 0.3rem 0.7rem;
    background: rgba(239, 68, 68, 0.15);
    color: var(--danger);
    font-size: 0.75rem;
    font-weight: 600;
    border-radius: 20px;
    white-space: nowrap;
}

@media (max-width: 600px) {
    .join-header {
        padding: 1.25rem 1.25rem 0;
    }

    .join-classroom-card > .divider {
        margin: 0.5rem 1.25rem;
    }

    .join-section-title {
        padding: 0.5rem 1.25rem;
    }

    .join-assignment-list {
        padding: 0 0.75rem 1.25rem;
    }

    .join-assignment-item {
        padding: 0.85rem 1rem;
        gap: 0.75rem;
    }

    .join-assign-icon {
        width: 36px;
        height: 36px;
        font-size: 1.4rem;
    }

    .join-assign-info h4 {
        font-size: 0.88rem;
    }

    .join-submit-badge {
        padding: 0.3rem 0.65rem;
        font-size: 0.72rem;
    }
}