* { margin: 0; padding: 0; box-sizing: border-box; }
body { font-family: 'Poppins', sans-serif; background: linear-gradient(135deg, #1e3a8a 0%, #0f172a 50%, #1e293b 100%); min-height: 100vh; overflow-x: hidden; transition: background 0.5s ease; }
.screen { display: none; min-height: 100vh; padding: 20px; opacity: 0; transition: opacity 0.5s ease-in-out; }
.screen.active { display: block; opacity: 1; animation: fadeInScreen 0.6s ease-out; }
@keyframes fadeInScreen { from { opacity: 0; } to { opacity: 1; } }

/* Glassmorphism */
.glass-card, .glass-header { background: rgba(30, 58, 138, 0.2); backdrop-filter: blur(20px); border-radius: 20px; border: 1px solid rgba(59, 130, 246, 0.3); box-shadow: 0 20px 40px rgba(0,0,0,0.3); transition: all 0.3s ease; }

/* Login */
.login-card { max-width: 400px; margin: 100px auto; padding: 40px; text-align: center; animation: slideIn 0.8s cubic-bezier(0.34, 1.56, 0.64, 1); color: #f8fafc; }
.login-card h1 { color: #06b6d4; font-size: 40px; margin-bottom: 10px; text-shadow: 0 2px 8px rgba(6, 182, 212, 0.4); font-weight: 800; }
.login-card p { color: #cffafe; font-size: 14px; font-weight: 500; }
@keyframes slideIn { from { opacity: 0; transform: translateY(-50px); } to { opacity: 1; transform: translateY(0); } }
.role-tabs { display: flex; margin: 20px 0; background: rgba(15, 23, 42, 0.5); border-radius: 50px; overflow: hidden; transition: all 0.3s ease; border: 1px solid rgba(59, 130, 246, 0.2); }
.tab-btn { flex: 1; padding: 12px; border: none; background: none; color: #cbd5e1; font-weight: 600; cursor: pointer; transition: all 0.3s ease; border-radius: 50px; }
.tab-btn.active { background: linear-gradient(135deg, #3b82f6 0%, #1e40af 100%); color: #f8fafc; box-shadow: 0 8px 20px rgba(59, 130, 246, 0.4); font-weight: 700; transform: scale(1.05); }
.tab-btn:hover { background: rgba(59, 130, 246, 0.2); transform: scale(1.05); color: #f8fafc; }
input, textarea, select { width: 100%; padding: 15px; margin: 10px 0; border: 1px solid rgba(59, 130, 246, 0.3); border-radius: 12px; background: rgba(15, 23, 42, 0.6); font-size: 16px; transition: all 0.3s ease; font-family: inherit; color: #f8fafc; }
input::placeholder, textarea::placeholder { color: #94a3b8; }
input:focus, textarea:focus, select:focus { outline: none; transform: scale(1.02); box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.2); background: rgba(15, 23, 42, 0.8); border-color: #3b82f6; }
button { width: 100%; padding: 15px; margin: 10px 0; border: none; border-radius: 12px; background: linear-gradient(135deg, #3b82f6 0%, #1e40af 100%); color: #f8fafc; font-weight: 600; font-size: 16px; cursor: pointer; transition: all 0.3s cubic-bezier(0.34, 1.56, 0.64, 1); box-shadow: 0 5px 15px rgba(59, 130, 246, 0.3); }
button:hover { transform: translateY(-3px); box-shadow: 0 12px 30px rgba(59, 130, 246, 0.5); background: linear-gradient(135deg, #1e40af 0%, #1e3a8a 100%); }
button:active { transform: translateY(-1px); }

/* Logout Button */
.logout-btn { width: auto !important; padding: 10px 20px !important; margin: 0 !important; background: linear-gradient(135deg, #ef4444 0%, #b91c1c 100%) !important; border-radius: 8px !important; font-size: 14px !important; }
.logout-btn:hover { background: linear-gradient(135deg, #b91c1c 0%, #7f1d1d 100%) !important; transform: translateY(-2px) !important; }

/* Navigation Menu */
.nav-menu { display: flex; gap: 0; margin: 0; padding: 0; background: linear-gradient(90deg, #1e3a8a 0%, #1e40af 100%); margin-bottom: 30px; width: 100%; border-bottom: 3px solid #0ea5e9; }
.nav-btn { padding: 15px 25px; border: none; background: transparent; color: #cffafe; font-weight: 600; cursor: pointer; transition: all 0.3s ease; border-radius: 0; flex: 1; text-align: center; border-right: 1px solid rgba(59, 130, 246, 0.2); white-space: nowrap; }
.nav-btn:last-child { border-right: none; }
.nav-btn:hover { background: rgba(59, 130, 246, 0.2); color: #f8fafc; }
.nav-btn.active { background: linear-gradient(135deg, #0ea5e9 0%, #0284c7 100%); color: #f8fafc; font-weight: 700; }

/* Tab Content */
.tab-content { display: none; animation: fadeInUp 0.6s ease-out; }
.tab-content.active { display: block; }

/* Global h3 Styling */
h3 { color: #0284c7; font-weight: 800; font-size: 20px; margin-bottom: 20px; text-shadow: 0 2px 4px rgba(0, 0, 0, 0.2); }

/* Dashboard */
.dashboard { color: #f8fafc; animation: fadeIn 0.6s ease-out; }
@keyframes fadeIn { from { opacity: 0; } to { opacity: 1; } }
.glass-header { display: flex; justify-content: space-between; align-items: center; padding: 20px 30px; margin-bottom: 30px; border-radius: 20px; background: linear-gradient(135deg, rgba(30, 58, 138, 0.3) 0%, rgba(30, 58, 138, 0.15) 100%); }
.glass-header h2 { color: #cffafe; text-shadow: 0 2px 8px rgba(0, 0, 0, 0.3); font-weight: 700; }

/* Welcome Banner */
.welcome-banner { padding: 40px 30px; text-align: center; margin-bottom: 30px; background: linear-gradient(135deg, rgba(59, 130, 246, 0.15) 0%, rgba(6, 182, 212, 0.1) 100%); }
.welcome-banner h2 { font-size: 32px; margin-bottom: 10px; color: #cffafe; font-weight: 800; }
.welcome-banner p { font-size: 16px; opacity: 0.95; color: #e0f2fe; font-weight: 500; }

/* Quick Stats */
.quick-stats { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; margin-bottom: 40px; max-width: 900px; margin-left: auto; margin-right: auto; }
.stat-card { background: linear-gradient(135deg, rgba(30, 58, 138, 0.3) 0%, rgba(6, 182, 212, 0.15) 100%); padding: 25px; border-radius: 15px; text-align: center; border: 1px solid rgba(59, 130, 246, 0.3); transition: all 0.3s ease; }
.stat-card:hover { background: linear-gradient(135deg, rgba(59, 130, 246, 0.3) 0%, rgba(6, 182, 212, 0.25) 100%); transform: translateY(-5px); box-shadow: 0 10px 30px rgba(59, 130, 246, 0.25); }
.stat-card h3 { font-size: 32px; color: #0ea5e9; margin-bottom: 10px; font-weight: 800; }
.stat-card p { opacity: 0.95; color: #cffafe; font-weight: 500; }

/* Subjects Grid */
.subjects-grid, #notifications { max-width: 900px; margin: 0 auto 30px; }
.cards-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 20px; margin-top: 20px; animation: slideUp 0.6s ease-out; }
@keyframes slideUp { from { opacity: 0; transform: translateY(20px); } to { opacity: 1; transform: translateY(0); } }
.subject-card { padding: 30px; text-align: center; cursor: pointer; transition: all 0.4s cubic-bezier(0.34, 1.56, 0.64, 1); background: linear-gradient(135deg, rgba(59, 130, 246, 0.15) 0%, rgba(6, 182, 212, 0.1) 100%); border-radius: 15px; border: 1px solid rgba(59, 130, 246, 0.3); color: #cffafe; font-weight: 700; }
.subject-card:hover { transform: translateY(-10px) scale(1.05); box-shadow: 0 20px 50px rgba(59, 130, 246, 0.3); background: linear-gradient(135deg, rgba(59, 130, 246, 0.25) 0%, rgba(6, 182, 212, 0.2) 100%); }
textarea { min-height: 100px; resize: vertical; }

/* Classes & Notes Grid */
.classes-grid, .notes-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); gap: 20px; margin-top: 20px; }
.class-card, .note-card { background: linear-gradient(135deg, rgba(30, 58, 138, 0.2) 0%, rgba(15, 23, 42, 0.3) 100%); padding: 25px; border-radius: 12px; border: 1.5px solid rgba(59, 130, 246, 0.4); transition: all 0.3s ease; animation: slideInLeft 0.5s ease-out; box-shadow: 0 4px 15px rgba(0, 0, 0, 0.2); }
.class-card:hover, .note-card:hover { background: linear-gradient(135deg, rgba(59, 130, 246, 0.15) 0%, rgba(6, 182, 212, 0.1) 100%); box-shadow: 0 8px 25px rgba(59, 130, 246, 0.3); transform: translateY(-5px); border-color: rgba(6, 182, 212, 0.6); }
.class-video { width: 100%; height: 160px; border-radius: 10px; object-fit: cover; margin-bottom: 15px; transition: transform 0.3s ease; border: 1px solid rgba(59, 130, 246, 0.2); }
.class-video:hover { transform: scale(1.02); }
.class-title, .note-title { font-weight: 800; font-size: 17px; margin-bottom: 12px; color: #cffafe; letter-spacing: 0.3px; }
.class-subject, .note-subject { font-size: 11px; opacity: 0.95; color: #0ea5e9; margin-bottom: 12px; font-weight: 600; text-transform: uppercase; letter-spacing: 0.5px; }
.class-description, .note-description { font-size: 13px; opacity: 0.95; line-height: 1.5; margin-bottom: 15px; color: #e0f2fe; font-weight: 500; }
.class-actions, .note-actions { display: flex; gap: 10px; margin-top: 18px; padding-top: 15px; border-top: 1px solid rgba(59, 130, 246, 0.15); }
.btn-action { flex: 1; padding: 10px 12px; border: 1.5px solid rgba(59, 130, 246, 0.5); border-radius: 8px; background: rgba(15, 23, 42, 0.6); color: #cffafe; cursor: pointer; font-weight: 700; transition: all 0.3s ease; font-size: 12px; text-transform: uppercase; letter-spacing: 0.3px; }
.btn-action:hover { background: linear-gradient(135deg, rgba(59, 130, 246, 0.2) 0%, rgba(6, 182, 212, 0.15) 100%); color: #e0f2fe; transform: translateY(-2px); border-color: rgba(6, 182, 212, 0.8); box-shadow: 0 4px 12px rgba(59, 130, 246, 0.2); }
.btn-primary { background: linear-gradient(135deg, #3b82f6 0%, #0ea5e9 100%) !important; border: none !important; color: #f8fafc !important; }
.btn-secondary { background: linear-gradient(135deg, #06b6d4 0%, #0891b2 100%) !important; border: none !important; color: #f8fafc !important; }

/* Upload Form */
.upload-form { padding: 30px; max-width: 600px; margin: 20px auto; }
.form-group { margin-bottom: 20px; }
.form-group label { display: block; margin-bottom: 8px; font-weight: 700; color: #cffafe; }
.form-group input[type="file"] { padding: 12px; border: 2px dashed rgba(59, 130, 246, 0.4); border-radius: 8px; cursor: pointer; background: rgba(15, 23, 42, 0.6); color: #cbd5e1; }
.form-group input[type="file"]::file-selector-button { background: linear-gradient(135deg, #3b82f6 0%, #0ea5e9 100%); padding: 8px 15px; border: none; border-radius: 6px; cursor: pointer; color: #f8fafc; font-weight: 600; transition: all 0.3s; }
.form-group input[type="file"]::file-selector-button:hover { background: linear-gradient(135deg, #1e40af 0%, #0284c7 100%); }

/* Doubt Items */
.doubt-item, .answer-item { background: linear-gradient(135deg, rgba(59, 130, 246, 0.1) 0%, rgba(6, 182, 212, 0.08) 100%); padding: 20px; border-radius: 15px; margin: 15px 0; animation: slideInLeft 0.5s ease-out; border: 1px solid rgba(59, 130, 246, 0.25); transition: all 0.3s ease; color: #cffafe; }
.doubt-item:hover, .answer-item:hover { background: linear-gradient(135deg, rgba(59, 130, 246, 0.2) 0%, rgba(6, 182, 212, 0.15) 100%); box-shadow: 0 10px 30px rgba(59, 130, 246, 0.15); }
@keyframes slideInLeft { from { opacity: 0; transform: translateX(-20px); } to { opacity: 1; transform: translateX(0); } }
.answer-video { width: 100%; height: 200px; border-radius: 10px; transition: transform 0.3s ease; margin: 15px 0; border: 1px solid rgba(59, 130, 246, 0.2); }
.answer-video:hover { transform: scale(1.02); }
.rating-stars { font-size: 24px; cursor: pointer; display: flex; gap: 5px; }
.rating-stars .star { color: #475569; transition: all 0.2s ease; transform-origin: center; }
.rating-stars .star:hover { transform: scale(1.3) rotate(15deg); color: #fbbf24; }
.rating-stars .star.filled { color: #06b6d4; animation: pulse 0.4s cubic-bezier(0.34, 1.56, 0.64, 1); }
@keyframes pulse { 0%, 100% { transform: scale(1); } 50% { transform: scale(1.3); } }
.hidden { display: none; opacity: 0; }
.show { display: block; animation: fadeIn 0.4s ease-out; }
.demo-note { font-size: 12px; opacity: 0.7; margin-top: 10px; transition: opacity 0.3s ease; color: #94a3b8; }
section { animation: fadeInUp 0.6s ease-out; }
@keyframes fadeInUp { from { opacity: 0; transform: translateY(15px); } to { opacity: 1; transform: translateY(0); } }

/* Video Player Section */
.video-player-section { background: linear-gradient(135deg, rgba(30, 58, 138, 0.4) 0%, rgba(15, 23, 42, 0.5) 100%); padding: 50px; border-radius: 15px; margin-bottom: 30px; position: relative; border: 1px solid rgba(59, 130, 246, 0.3); }
.video-player-section.hidden { display: none; }
.video-player-section h3 { color: #cffafe; font-weight: 800; font-size: 22px; margin-bottom: 15px; }
.video-player-section p { color: #e0f2fe; font-weight: 500; margin-bottom: 10px; }
.video-player-section strong { color: #0ea5e9; font-weight: 700; }
.close-video-btn { width: auto !important; padding: 8px 17px !important; margin: 0 0 20px 0 !important; background: linear-gradient(135deg, #ef4444 0%, #b91c1c 100%) !important; font-size: 14px !important; position: absolute; top: 10px; right: 10px; z-index: 10; }
.video-player-section iframe { border-radius: 12px; border: 1px solid rgba(59, 130, 246, 0.2); }

/* Note Preview Section */
.note-preview-section { background: linear-gradient(135deg, rgba(30, 58, 138, 0.4) 0%, rgba(15, 23, 42, 0.5) 100%); padding: 30px; border-radius: 15px; margin-bottom: 30px; position: relative; border: 1px solid rgba(59, 130, 246, 0.3); }
.note-preview-section.hidden { display: none; }
.note-preview-section h3 { color: #cffafe; font-weight: 800; font-size: 22px; margin-bottom: 15px; }
.note-preview-section p { color: #e0f2fe; font-weight: 500; margin-bottom: 10px; }
.note-preview-section strong { color: #0ea5e9; font-weight: 700; }
.preview-controls { display: flex; gap: 10px; margin-bottom: 20px; flex-wrap: wrap; }
.close-preview-btn { width: auto !important; padding: 8px 15px !important; margin: 0 0 20px 0 !important; background: linear-gradient(135deg, #ef4444 0%, #b91c1c 100%) !important; font-size: 14px !important; position: absolute; top: 10px; right: 10px; z-index: 10; }
.note-content-viewer { background: rgba(15, 23, 42, 0.7); padding: 20px; border-radius: 12px; max-height: 800px; overflow: auto; transition: transform 0.3s ease; border: 1px solid rgba(59, 130, 246, 0.2); }
.note-content-viewer embed { border-radius: 8px; border: 1px solid rgba(59, 130, 246, 0.2); }
.note-content-viewer pre { font-size: 14px; line-height: 1.6; color: #cffafe; background: rgba(15, 23, 42, 0.5); padding: 15px 5px 10px 10px; border-radius: 8px; border-left: 4px solid #06b6d4; }
.note-content-viewer h3 { margin-bottom: 10px; color: #06b6d4; text-shadow: 0 2px 4px rgba(0, 0, 0, 0.3); }

/* Empty State */
.empty-state { text-align: center; padding: 40px 20px; opacity: 0.8; }
.empty-state p { font-size: 16px; color: #e0f2fe; font-weight: 500; }

/* Responsive */
/* Responsive */
@media (max-width: 768px) { 
    .glass-header { flex-direction: column; gap: 10px; text-align: center; } 
    .cards-grid { grid-template-columns: repeat(2, 1fr); }
    .login-card { margin: 50px auto; padding: 30px; }
    button { padding: 12px; font-size: 14px; }
    .nav-menu { gap: 0; }
    .nav-btn { padding: 12px 10px; font-size: 13px; }
    .quick-stats { grid-template-columns: repeat(2, 1fr); }
    .classes-grid, .notes-grid { grid-template-columns: repeat(auto-fill, minmax(200px, 1fr)); }
    .welcome-banner { padding: 25px 20px; }
    .welcome-banner h2 { font-size: 24px; }
}

@media (max-width: 480px) {
    .cards-grid { grid-template-columns: 1fr; }
    .glass-header { padding: 15px 20px; }
    .subject-card { padding: 20px; }
    .nav-menu { flex-direction: row; overflow-x: auto; }
    .nav-btn { padding: 12px 8px; font-size: 11px; min-width: max-content; }
    .quick-stats { grid-template-columns: 1fr; }
    .classes-grid, .notes-grid { grid-template-columns: 1fr; }
    .welcome-banner { padding: 20px; }
    .welcome-banner h2 { font-size: 20px; }
    .upload-form { padding: 20px; }
}

/* Live Class Notification */
.live-notification { background: linear-gradient(135deg, rgba(239, 68, 68, 0.2) 0%, rgba(220, 38, 38, 0.15) 100%); border: 2px solid rgba(239, 68, 68, 0.6); border-radius: 15px; padding: 25px; margin-bottom: 30px; animation: slideInDown 0.5s ease-out; }
.live-notification strong { color: #fca5a5; font-size: 16px; }
.live-notification p { color: #f5d5d5; margin-bottom: 8px; }

@keyframes pulse-red { 0%, 100% { opacity: 1; } 50% { opacity: 0.5; } }
@keyframes slideInDown { from { opacity: 0; transform: translateY(-20px); } to { opacity: 1; transform: translateY(0); } }

/* Start Live Class Section */
.live-class-form { background: linear-gradient(135deg, rgba(239, 68, 68, 0.15) 0%, rgba(239, 68, 68, 0.1) 100%); border: 1.5px solid rgba(239, 68, 68, 0.4); border-radius: 15px; padding: 25px; margin: 25px 0; }
.live-class-form h4 { color: #fca5a5; font-size: 16px; font-weight: 700; margin-bottom: 15px; display: flex; align-items: center; gap: 10px; }
.live-class-form .btn-secondary { background: linear-gradient(135deg, #ef4444 0%, #dc2626 100%) !important; border: none !important; color: #fff !important; }