*{box-sizing:border-box;margin:0;padding:0}:root{--bg: #f0f2f5;--bg-card: #fff;--text: #1a1a2e;--text-secondary: #555;--text-muted: #777;--border: #eee;--border-input: #ddd;--navbar-bg: #1a1a2e;--navbar-text: #fff;--navbar-link: #ccc;--navbar-link-hover: #fff;--input-bg: #fafafa;--input-bg-focus: #fff;--primary: #1a1a2e;--primary-hover: #2d2d5e;--accent: #4fc3f7;--accent-hover: #29b6f6;--danger: #e53935;--danger-hover: #c62828;--shadow: rgba(0,0,0,.06);--shadow-hover: rgba(0,0,0,.12);--hover-bg: #f8f9fa;--notif-bg: #eef6ff;--notif-hover: #e0edff;--room-bg: #e8f5e9;--room-text: #2e7d32;--status-pending-bg: #fff3e0;--status-pending-text: #e65100;--status-submitted-bg: #e3f2fd;--status-submitted-text: #1565c0;--status-checked-bg: #e8f5e9;--status-checked-text: #2e7d32}[data-theme=dark]{--bg: #121212;--bg-card: #1e1e1e;--text: #e0e0e0;--text-secondary: #aaa;--text-muted: #777;--border: #333;--border-input: #444;--navbar-bg: #000;--navbar-text: #e0e0e0;--navbar-link: #999;--navbar-link-hover: #fff;--input-bg: #2a2a2a;--input-bg-focus: #333;--primary: #bb86fc;--primary-hover: #a06cd5;--accent: #4fc3f7;--accent-hover: #29b6f6;--danger: #cf6679;--danger-hover: #b0003a;--shadow: rgba(0,0,0,.3);--shadow-hover: rgba(0,0,0,.5);--hover-bg: #2a2a2a;--notif-bg: #1a2a3a;--notif-hover: #1e3040;--room-bg: #1a2e1a;--room-text: #81c784;--status-pending-bg: #3a2a1a;--status-pending-text: #ffb74d;--status-submitted-bg: #1a2a3a;--status-submitted-text: #64b5f6;--status-checked-bg: #1a3a1a;--status-checked-text: #81c784}body{font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,sans-serif;background:var(--bg);color:var(--text);line-height:1.6;transition:background .3s,color .3s}a{color:inherit;text-decoration:none}a:hover{opacity:.8}.container{max-width:1100px;margin:0 auto;padding:0 20px}.theme-toggle{background:none;border:none;color:var(--navbar-text);cursor:pointer;font-size:1.1rem;padding:4px;display:flex;align-items:center;opacity:.7;transition:opacity .15s}.theme-toggle:hover{opacity:1}.navbar{background:var(--navbar-bg);color:var(--navbar-text);padding:10px 24px;display:flex;justify-content:space-between;align-items:center;flex-wrap:wrap;gap:10px}.navbar-brand{display:flex;align-items:center;gap:8px}.logo{color:var(--navbar-text);font-size:1.2rem;font-weight:600;letter-spacing:-.3px;font-family:Inter,-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,sans-serif;cursor:default}.nav-home-btn{font-weight:600!important}.navbar-role{font-size:1.1rem}.navbar-links{display:flex;align-items:center;gap:14px;flex-wrap:wrap}.navbar-links a{color:var(--navbar-link);font-size:.9rem}.navbar-links a:hover{color:var(--navbar-link-hover);opacity:1}.nav-home{font-size:1.2rem!important}.navbar-user{display:flex;align-items:center;gap:8px;font-weight:500;font-size:.9rem}.navbar-profile{display:flex;align-items:center;gap:6px;color:var(--accent)}.navbar-profile:hover{color:var(--accent-hover);opacity:1}.avatar-sm{width:28px;height:28px;border-radius:50%;object-fit:cover}.room-links{background:var(--room-bg);padding:6px 24px;display:flex;gap:16px;align-items:center;font-size:.85rem}.room-link{color:var(--room-text);font-weight:500}.room-link:hover{text-decoration:underline;opacity:1}.auth-page{display:flex;justify-content:center;align-items:center;min-height:100vh;padding:20px}.auth-card{background:var(--bg-card);border-radius:12px;padding:40px;width:100%;max-width:420px;box-shadow:0 2px 12px var(--shadow);animation:fadeIn .3s ease}.auth-card h1{font-size:1.5rem;margin-bottom:4px;color:var(--text);text-align:center}.auth-card h2{font-size:1.1rem;font-weight:400;color:var(--text-muted);margin-bottom:24px;text-align:center}.auth-link{margin-top:16px;text-align:center;font-size:.9rem;color:var(--text-muted)}.card{background:var(--bg-card);border-radius:10px;padding:24px;margin-bottom:20px;box-shadow:0 1px 4px var(--shadow);transition:box-shadow .2s,background .3s}.card:hover{box-shadow:0 2px 8px var(--shadow-hover)}.card h2{font-size:1.05rem;margin-bottom:16px;color:var(--text)}.stats{display:grid;grid-template-columns:repeat(auto-fit,minmax(140px,1fr));gap:16px;margin:20px 0}.stat-card{background:var(--bg-card);border-radius:10px;padding:20px;text-align:center;box-shadow:0 1px 4px var(--shadow)}.stat-number{font-size:2rem;font-weight:700;color:var(--text)}.stat-label{font-size:.85rem;color:var(--text-muted);margin-top:4px}.stat-warn .stat-number{color:#f57c00}.stat-ok .stat-number{color:#388e3c}.dashboard-grid{display:grid;grid-template-columns:1fr 1fr;gap:20px}@media (max-width: 700px){.dashboard-grid{grid-template-columns:1fr}}.search-bar{display:flex;gap:8px;align-items:center;margin-bottom:16px}.search-input{flex:1;padding:10px 12px 10px 36px;border:1px solid var(--border-input);border-radius:8px;font-size:.95rem;background:var(--input-bg);color:var(--text);transition:border-color .2s,background .3s}.search-input:focus{outline:none;border-color:var(--accent);background:var(--input-bg-focus)}.search-wrapper{position:relative;flex:1}.search-wrapper .search-icon{position:absolute;left:10px;top:50%;transform:translateY(-50%);color:var(--text-muted);pointer-events:none;font-size:1rem}.form-group{margin-bottom:14px}.form-group label{display:block;font-size:.85rem;font-weight:500;margin-bottom:4px;color:var(--text-secondary)}.form-group input,.form-group textarea,.form-group select{width:100%;padding:10px 12px;border:1px solid var(--border-input);border-radius:8px;font-size:.95rem;background:var(--input-bg);color:var(--text);transition:border-color .2s,background .3s}.form-group input:focus,.form-group textarea:focus,.form-group select:focus{outline:none;border-color:var(--accent);background:var(--input-bg-focus)}textarea{resize:vertical}.form-row{display:flex;gap:10px;flex-wrap:wrap}.form-row .form-group{flex:1}.input-sm{width:80px;padding:6px 8px;border:1px solid var(--border-input);border-radius:6px;font-size:.85rem;background:var(--input-bg);color:var(--text)}.btn{display:inline-flex;align-items:center;gap:6px;padding:10px 20px;border:none;border-radius:8px;font-size:.9rem;cursor:pointer;text-decoration:none;transition:background .15s,transform .1s}.btn:active{transform:scale(.97)}.btn-primary{background:var(--primary);color:#fff}.btn-primary:hover{background:var(--primary-hover);opacity:1}.btn-danger{background:var(--danger);color:#fff}.btn-danger:hover{background:var(--danger-hover);opacity:1}.btn-sm{padding:5px 12px;font-size:.82rem}.btn-full{width:100%;justify-content:center}.btn:disabled{opacity:.5;cursor:not-allowed}.btn-ghost{background:transparent;border:1px solid var(--border-input);color:var(--text)}.btn-ghost:hover{background:var(--hover-bg)}.table{width:100%;border-collapse:collapse;font-size:.9rem}.table th,.table td{padding:10px 12px;text-align:left;border-bottom:1px solid var(--border)}.table th{font-weight:600;color:var(--text-muted);font-size:.8rem;text-transform:uppercase}.table tr:hover{background:var(--hover-bg)}.item-list{list-style:none;margin-bottom:12px}.item-list li{display:flex;justify-content:space-between;padding:8px 0;border-bottom:1px solid var(--border);align-items:center}.status{display:inline-block;padding:2px 10px;border-radius:12px;font-size:.8rem;font-weight:500}.status-pending{background:var(--status-pending-bg);color:var(--status-pending-text)}.status-submitted{background:var(--status-submitted-bg);color:var(--status-submitted-text)}.status-checked{background:var(--status-checked-bg);color:var(--status-checked-text)}.tags{display:flex;gap:4px;flex-wrap:wrap}.tag{display:inline-block;padding:1px 8px;border-radius:10px;font-size:.72rem;font-weight:500;background:var(--hover-bg);color:var(--text-secondary);border:1px solid var(--border)}.tag-filter{cursor:pointer;transition:background .15s}.tag-filter:hover,.tag-filter.active{background:var(--accent);color:#fff;border-color:var(--accent)}.deadline{font-size:.78rem;font-weight:500}.deadline-urgent{color:var(--danger)}.deadline-soon{color:#f57c00}.deadline-ok,.deadline-done{color:var(--status-checked-text)}.student-comment{padding:12px;border-radius:8px;background:var(--notif-bg);margin-top:8px;font-size:.9rem;color:var(--text-secondary)}.student-comment strong{color:var(--text)}.alert{padding:12px;border-radius:8px;margin-bottom:16px;font-size:.9rem}.alert-error{background:#ffebee;color:#c62828;border:1px solid #ffcdd2}[data-theme=dark] .alert-error{background:#3a1a1a;color:#ef9a9a;border:1px solid #5a2a2a}.file-link{color:inherit}.file-link:hover{text-decoration:underline;opacity:1}.text-muted{color:var(--text-muted);font-size:.9rem}.flex-between{display:flex;justify-content:space-between;align-items:center;flex-wrap:wrap;gap:8px}.checkbox-label{display:flex;align-items:center;gap:6px;font-size:.9rem;color:var(--text-muted);cursor:pointer}.stat-link{display:block;text-decoration:none;color:inherit;transition:transform .15s,box-shadow .15s;cursor:pointer}.stat-link:hover{transform:translateY(-2px);box-shadow:0 4px 12px var(--shadow-hover);opacity:1}.card-title-link{text-decoration:none;color:inherit;display:inline-block}.card-title-link:hover h2{color:var(--accent)}.card-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(320px,1fr));gap:14px;margin-bottom:20px}.card-grid-item{background:var(--bg-card);border-radius:10px;padding:16px 18px;box-shadow:0 1px 4px var(--shadow);display:flex;flex-direction:column;gap:6px;animation:fadeIn .25s ease;transition:box-shadow .2s,transform .15s,background .3s}.card-grid-item:hover{box-shadow:0 3px 12px var(--shadow-hover);transform:translateY(-1px)}.card-grid-title{font-weight:600;font-size:1rem;color:var(--text);text-decoration:none}.card-grid-title:hover{color:var(--accent);opacity:1}.card-grid-desc{font-size:.85rem;color:var(--text-secondary);line-height:1.4}.card-grid-meta{font-size:.82rem;color:var(--text-muted)}.card-grid-footer{display:flex;align-items:center;gap:8px;flex-wrap:wrap;margin-top:auto;padding-top:8px;border-top:1px solid var(--border)}.notif-bell{position:relative;cursor:pointer;font-size:1.1rem;-webkit-user-select:none;user-select:none;display:flex;align-items:center}.notif-badge{position:absolute;top:-6px;right:-8px;background:var(--danger);color:#fff;font-size:.65rem;font-weight:700;min-width:16px;height:16px;border-radius:8px;display:flex;align-items:center;justify-content:center;padding:0 4px}.notif-dropdown{position:absolute;top:100%;right:0;width:340px;max-height:360px;overflow-y:auto;background:var(--bg-card);border-radius:10px;box-shadow:0 4px 20px var(--shadow-hover);z-index:100;margin-top:8px;color:var(--text);border:1px solid var(--border)}.notif-header{display:flex;justify-content:space-between;align-items:center;padding:12px 14px;border-bottom:1px solid var(--border);font-weight:600;font-size:.9rem}.notif-empty{padding:24px;text-align:center;color:var(--text-muted);font-size:.85rem}.notif-item{padding:10px 14px;border-bottom:1px solid var(--border);cursor:default}.notif-unread{background:var(--notif-bg);cursor:pointer}.notif-unread:hover{background:var(--notif-hover)}.notif-text{font-size:.85rem;line-height:1.4}.notif-time{font-size:.72rem;color:var(--text-muted);margin-top:2px}.btn-avatar-upload{position:absolute;bottom:0;right:0;cursor:pointer;background:var(--accent);color:#fff;border-radius:50%;width:34px;height:34px;display:flex;align-items:center;justify-content:center;font-size:.95rem;border:2px solid var(--bg-card);transition:background .15s}.btn-avatar-upload:hover{background:var(--accent-hover)}@keyframes shimmer{0%{background-position:-200px 0}to{background-position:calc(200px + 100%) 0}}.skeleton{background:linear-gradient(90deg,var(--border) 25%,var(--hover-bg) 50%,var(--border) 75%);background-size:200px 100%;animation:shimmer 1.5s infinite;border-radius:6px;height:1em}.skeleton-card{height:120px;margin-bottom:14px}@keyframes fadeIn{0%{opacity:0;transform:translateY(6px)}to{opacity:1;transform:translateY(0)}}@keyframes slideIn{0%{opacity:0;transform:translate(-10px)}to{opacity:1;transform:translate(0)}}.fade-in{animation:fadeIn .25s ease}.slide-in{animation:slideIn .2s ease}.hamburger{display:none;background:none;border:none;cursor:pointer;padding:4px;flex-direction:column;gap:4px}.hamburger span{display:block;width:22px;height:2px;background:var(--navbar-text);border-radius:2px;transition:transform .2s,opacity .2s}.hamburger.open span:nth-child(1){transform:translateY(6px) rotate(45deg)}.hamburger.open span:nth-child(2){opacity:0}.hamburger.open span:nth-child(3){transform:translateY(-6px) rotate(-45deg)}.mobile-menu{display:none}.mobile-menu.open{display:flex;position:fixed;top:0;right:0;bottom:0;left:0;z-index:200;background:var(--navbar-bg);color:var(--navbar-text);padding:70px 24px 24px;animation:fadeIn .15s ease}.mobile-menu-links{display:flex;flex-direction:column;gap:16px;width:100%}.mobile-menu-links a{display:flex;align-items:center;gap:10px;color:var(--navbar-link);font-size:1.05rem;padding:8px 0}.mobile-menu-links a:hover{color:var(--navbar-link-hover);opacity:1}.mobile-menu-links hr{border:none;border-top:1px solid rgba(255,255,255,.1);margin:8px 0}.mobile-profile-link .navbar-profile{color:var(--accent);font-size:1rem}.mobile-logout{color:var(--navbar-link)!important;border-color:#fff3!important;justify-content:center;margin-top:8px}@media (max-width: 768px){.navbar{position:relative}.navbar-links{display:none}.hamburger{display:flex}.navbar-user .navbar-profile span,.navbar-user .btn-ghost{display:none}.container{padding:0 12px}main.container{margin-top:12px}.card{padding:16px}.card-grid{grid-template-columns:1fr}.card-grid-item{padding:12px 14px}.dashboard-grid{grid-template-columns:1fr}.stats{grid-template-columns:repeat(2,1fr);gap:10px}.stat-card{padding:14px}.stat-number{font-size:1.5rem}.form-row{flex-direction:column}.form-row .form-group{flex:none}.auth-card{padding:24px;margin:0 10px}.auth-page{padding:10px}.notif-dropdown{position:fixed;top:56px;left:0;right:0;width:100%;max-height:60vh;border-radius:0 0 10px 10px}.search-input{font-size:16px}h1{font-size:1.3rem}h2{font-size:1rem}.btn{padding:8px 16px}.room-links{flex-direction:column;gap:6px;padding:8px 12px}.dashboard-grid{gap:12px}.stats{gap:8px}.navbar .theme-toggle{order:-1}}@media (max-width: 480px){.stats{grid-template-columns:repeat(2,1fr);gap:6px}.stat-card{padding:10px}.stat-number{font-size:1.3rem}.card-grid-item .card-grid-footer .form-row{flex-direction:column;align-items:stretch}.card-grid-item .card-grid-footer .form-row .input-sm{width:100%}}@media (pointer: coarse){.btn{min-height:44px}.btn-sm{min-height:36px;padding:8px 14px}.navbar-links a,.navbar-profile,.notif-bell{min-height:44px;display:flex;align-items:center}input,select,textarea{font-size:16px!important}}.lesson-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(320px,1fr));gap:14px}.lesson-card{transition:transform .15s,box-shadow .2s;overflow:hidden}.lesson-card:hover{transform:translateY(-2px);box-shadow:0 4px 12px var(--shadow-hover)}.lesson-card-header{display:flex;justify-content:space-between;align-items:flex-start;gap:8px}.lesson-card-header h3{font-size:1rem;font-weight:600;margin:0;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}.lesson-meta{display:flex;gap:12px;flex-wrap:wrap;font-size:.82rem;color:var(--text-muted);margin-top:4px}.lesson-meta span{display:inline-flex;align-items:center;gap:4px;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}.lesson-desc{margin-top:8px;font-size:.85rem;line-height:1.4;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}.lesson-link-item{display:block;padding:8px 12px;border-radius:6px;background:var(--hover-bg);color:var(--text);font-size:.9rem;margin-bottom:6px;transition:background .12s}.lesson-link-item:hover{background:var(--notif-bg);opacity:1}.chat-layout{display:flex;gap:1px;background:var(--border);border-radius:10px;overflow:hidden;min-height:500px;margin-top:16px}.chat-conversations{flex:0 0 280px;background:var(--bg-card);overflow-y:auto}.chat-conv-item{padding:14px 16px;cursor:pointer;border-bottom:1px solid var(--border);transition:background .12s}.chat-conv-item:hover{background:var(--hover-bg)}.chat-conv-item.active{background:var(--notif-bg);border-left:3px solid var(--accent)}.chat-conv-name{font-weight:600;font-size:.9rem;color:var(--text);display:flex;align-items:center}.chat-conv-preview{font-size:.8rem;color:var(--text-muted);margin-top:2px;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}.chat-main{flex:1;background:var(--bg-card);display:flex;flex-direction:column}.chat-header{padding:12px 16px;font-weight:600;font-size:.95rem;border-bottom:1px solid var(--border);display:flex;align-items:center;gap:8px}.chat-back-btn{display:none}.chat-thread{flex:1;overflow-y:auto;padding:16px;display:flex;flex-direction:column;gap:8px}.chat-msg{max-width:75%;padding:8px 14px;border-radius:12px;background:var(--hover-bg);align-self:flex-start;animation:fadeIn .15s ease}.chat-msg-own{align-self:flex-end;background:var(--notif-bg);border-bottom-right-radius:4px}.chat-msg-text{font-size:.9rem;color:var(--text);line-height:1.4}.chat-msg-time{font-size:.7rem;color:var(--text-muted);margin-top:2px}.chat-form{display:flex;gap:8px;padding:12px 16px;border-top:1px solid var(--border)}.chat-form input{flex:1;padding:10px 14px;border:1px solid var(--border-input);border-radius:24px;font-size:.9rem;background:var(--input-bg);color:var(--text);outline:none}.chat-form input:focus{border-color:var(--accent);background:var(--input-bg-focus)}.chat-empty{display:flex;flex-direction:column;align-items:center;justify-content:center;height:100%;color:var(--text-muted);font-size:1rem;gap:8px;min-height:400px}@media (max-width: 768px){.chat-conversations{flex:0 0 100%}.chat-conversations:has(~.chat-main :not(.chat-empty)){display:none}.chat-back-btn{display:flex}}@media (max-width: 480px){.lesson-grid{grid-template-columns:1fr}.chat-msg{max-width:90%}}