/* topicwisepyqs — Telegram-inspired UI */
@import url('https://fonts.googleapis.com/css2?family=Nunito:wght@400;500;600;700;800&family=JetBrains+Mono:wght@400;600&display=swap');

/* ===== TOKENS ===== */
:root {
  --font: 'Nunito', sans-serif;
  --mono: 'JetBrains Mono', monospace;

  /* Light */
  --bg: #f1f3f5;
  --bg2: #ffffff;
  --bg3: #e8edf2;
  --sidebar: #ffffff;
  --sidebar-w: 260px;
  --text: #1c1e21;
  --text2: #65717b;
  --text3: #8a9bb0;
  --border: #dde2e8;
  --primary: #2481cc;
  --primary-h: #1a6fb5;
  --primary-t: rgba(36,129,204,.12);
  --green: #31a24c;
  --green-t: rgba(49,162,76,.12);
  --red: #e74c3c;
  --red-t: rgba(231,76,60,.12);
  --orange: #f39c12;
  --bubble-out: #effdde;
  --bubble-in: #ffffff;
  --shadow: 0 2px 12px rgba(0,0,0,.08);
  --shadow-sm: 0 1px 4px rgba(0,0,0,.06);
  --radius: 12px;
  --radius-sm: 8px;
  --radius-xs: 6px;
  --trans: .18s ease;
  --header-h: 56px;
}

[data-theme="dark"] {
  --bg: #0f1923;
  --bg2: #18222d;
  --bg3: #1e2c3a;
  --sidebar: #17212b;
  --text: #e8f0f8;
  --text2: #8b9caf;
  --text3: #5a6a7a;
  --border: #1f2f3f;
  --primary: #2b9fda;
  --primary-h: #1e8abf;
  --primary-t: rgba(43,159,218,.15);
  --green: #4caf73;
  --green-t: rgba(76,175,115,.15);
  --red: #f05545;
  --red-t: rgba(240,85,69,.15);
  --bubble-out: #2b5278;
  --bubble-in: #182533;
  --shadow: 0 2px 16px rgba(0,0,0,.3);
  --shadow-sm: 0 1px 6px rgba(0,0,0,.2);
}

/* ===== RESET ===== */
*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
html{font-size:15px;scroll-behavior:smooth}
body{font-family:var(--font);background:var(--bg);color:var(--text);transition:background var(--trans),color var(--trans);min-height:100vh;overflow-x:hidden}
a{text-decoration:none;color:var(--primary)}
img{max-width:100%;border-radius:var(--radius-xs)}
ul,ol{list-style:none}
button{cursor:pointer;font-family:var(--font)}
input,select,textarea{font-family:var(--font)}

/* ===== SCROLLBAR ===== */
::-webkit-scrollbar{width:5px;height:5px}
::-webkit-scrollbar-track{background:transparent}
::-webkit-scrollbar-thumb{background:var(--border);border-radius:10px}

/* ===== LAYOUT ===== */
.app{display:flex;height:100vh;overflow:hidden}
.sidebar{width:var(--sidebar-w);background:var(--sidebar);border-right:1px solid var(--border);display:flex;flex-direction:column;flex-shrink:0;transition:width var(--trans),transform var(--trans);z-index:100}
.sidebar.collapsed{width:64px}
.main{flex:1;display:flex;flex-direction:column;overflow:hidden}
.header{height:var(--header-h);background:var(--bg2);border-bottom:1px solid var(--border);display:flex;align-items:center;padding:0 20px;gap:12px;flex-shrink:0;position:sticky;top:0;z-index:50}
.content{flex:1;overflow-y:auto;padding:20px}

/* ===== LOGO ===== */
.logo{display:flex;align-items:center;gap:10px;padding:16px 18px;border-bottom:1px solid var(--border)}
.logo-icon{width:38px;height:38px;background:var(--primary);border-radius:10px;display:flex;align-items:center;justify-content:center;flex-shrink:0}
.logo-icon svg{width:22px;height:22px;fill:#fff}
.logo-text{overflow:hidden}
.logo-text strong{display:block;font-size:.92rem;font-weight:800;color:var(--text);letter-spacing:-.3px;white-space:nowrap}
.logo-text span{font-size:.72rem;color:var(--text3);white-space:nowrap}
.sidebar.collapsed .logo-text{display:none}

/* ===== NAV ===== */
.nav{flex:1;overflow-y:auto;padding:10px 8px}
.nav-item{display:flex;align-items:center;gap:12px;padding:10px 10px;border-radius:var(--radius-xs);color:var(--text2);font-size:.88rem;font-weight:600;transition:all var(--trans);cursor:pointer;white-space:nowrap;margin-bottom:2px}
.nav-item:hover{background:var(--primary-t);color:var(--primary)}
.nav-item.active{background:var(--primary-t);color:var(--primary)}
.nav-item i,.nav-item svg{width:18px;height:18px;flex-shrink:0;font-size:18px}
.nav-label{overflow:hidden;text-overflow:ellipsis}
.sidebar.collapsed .nav-label{display:none}
.nav-group{font-size:.7rem;font-weight:700;color:var(--text3);padding:8px 10px 4px;text-transform:uppercase;letter-spacing:.5px}
.sidebar.collapsed .nav-group{display:none}

/* ===== HEADER PARTS ===== */
.h-toggle{background:none;border:none;color:var(--text2);padding:6px;border-radius:8px;display:flex}
.h-toggle:hover{background:var(--bg3);color:var(--text)}
.h-title{font-size:1rem;font-weight:700;flex:1;color:var(--text)}
.h-actions{display:flex;align-items:center;gap:8px}
.h-btn{background:none;border:none;color:var(--text2);padding:7px;border-radius:8px;display:flex;align-items:center;justify-content:center;transition:all var(--trans);position:relative}
.h-btn:hover{background:var(--bg3);color:var(--text)}
.badge{position:absolute;top:3px;right:3px;width:8px;height:8px;background:var(--red);border-radius:50%;border:2px solid var(--bg2)}
.avatar-sm{width:34px;height:34px;border-radius:50%;background:var(--primary-t);display:flex;align-items:center;justify-content:center;overflow:hidden;cursor:pointer;font-weight:700;color:var(--primary);font-size:.85rem}

/* ===== CARDS ===== */
.card{background:var(--bg2);border-radius:var(--radius);border:1px solid var(--border);padding:20px;box-shadow:var(--shadow-sm)}
.card-header{display:flex;align-items:center;justify-content:space-between;margin-bottom:16px}
.card-title{font-size:.95rem;font-weight:700;color:var(--text)}

/* ===== STATS ===== */
.stats-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(180px,1fr));gap:14px;margin-bottom:20px}
.stat-card{background:var(--bg2);border-radius:var(--radius);border:1px solid var(--border);padding:18px;display:flex;align-items:center;gap:14px;box-shadow:var(--shadow-sm);transition:transform var(--trans)}
.stat-card:hover{transform:translateY(-2px)}
.stat-icon{width:44px;height:44px;border-radius:10px;display:flex;align-items:center;justify-content:center;flex-shrink:0;font-size:20px}
.stat-icon.blue{background:var(--primary-t);color:var(--primary)}
.stat-icon.green{background:var(--green-t);color:var(--green)}
.stat-icon.red{background:var(--red-t);color:var(--red)}
.stat-icon.orange{background:rgba(243,156,18,.12);color:var(--orange)}
.stat-val{font-size:1.5rem;font-weight:800;color:var(--text);line-height:1}
.stat-label{font-size:.78rem;color:var(--text3);margin-top:3px}

/* ===== TABLE ===== */
.tbl-wrap{overflow-x:auto}
table{width:100%;border-collapse:collapse;font-size:.875rem}
th{text-align:left;padding:10px 14px;font-size:.75rem;font-weight:700;text-transform:uppercase;letter-spacing:.4px;color:var(--text3);border-bottom:2px solid var(--border)}
td{padding:11px 14px;border-bottom:1px solid var(--border);color:var(--text2);vertical-align:middle}
tr:last-child td{border-bottom:none}
tbody tr:hover td{background:var(--bg3)}
.tbl-actions{display:flex;gap:6px}

/* ===== BUTTONS ===== */
.btn{display:inline-flex;align-items:center;gap:7px;padding:8px 16px;border-radius:var(--radius-xs);font-size:.85rem;font-weight:700;border:none;transition:all var(--trans);cursor:pointer;white-space:nowrap}
.btn-primary{background:var(--primary);color:#fff}
.btn-primary:hover{background:var(--primary-h)}
.btn-outline{background:transparent;border:1.5px solid var(--border);color:var(--text2)}
.btn-outline:hover{border-color:var(--primary);color:var(--primary)}
.btn-danger{background:var(--red-t);color:var(--red)}
.btn-danger:hover{background:var(--red);color:#fff}
.btn-success{background:var(--green-t);color:var(--green)}
.btn-success:hover{background:var(--green);color:#fff}
.btn-sm{padding:5px 11px;font-size:.78rem}
.btn-icon{padding:7px;min-width:34px;justify-content:center}

/* ===== FORMS ===== */
.form-group{margin-bottom:16px}
label{display:block;font-size:.82rem;font-weight:700;color:var(--text2);margin-bottom:5px}
.inp{width:100%;padding:9px 13px;background:var(--bg3);border:1.5px solid var(--border);border-radius:var(--radius-xs);color:var(--text);font-size:.88rem;transition:border var(--trans)}
.inp:focus{outline:none;border-color:var(--primary);background:var(--bg2)}
.inp::placeholder{color:var(--text3)}
select.inp{cursor:pointer}
textarea.inp{resize:vertical;min-height:90px}
.form-row{display:grid;grid-template-columns:1fr 1fr;gap:16px}
.form-hint{font-size:.75rem;color:var(--text3);margin-top:4px}

/* ===== MODAL ===== */
.overlay{position:fixed;inset:0;background:rgba(0,0,0,.45);z-index:200;display:flex;align-items:center;justify-content:center;padding:16px;opacity:0;pointer-events:none;transition:opacity var(--trans)}
.overlay.show{opacity:1;pointer-events:all}
.modal{background:var(--bg2);border-radius:var(--radius);width:100%;max-width:540px;max-height:90vh;overflow-y:auto;box-shadow:0 8px 40px rgba(0,0,0,.25);transform:translateY(20px);transition:transform var(--trans)}
.overlay.show .modal{transform:translateY(0)}
.modal-header{padding:18px 20px;border-bottom:1px solid var(--border);display:flex;align-items:center;justify-content:space-between;position:sticky;top:0;background:var(--bg2);z-index:1}
.modal-title{font-size:.95rem;font-weight:700}
.modal-body{padding:20px}
.modal-footer{padding:14px 20px;border-top:1px solid var(--border);display:flex;gap:10px;justify-content:flex-end}

/* ===== BADGE/TAG ===== */
.tag{display:inline-flex;align-items:center;gap:4px;padding:3px 9px;border-radius:20px;font-size:.75rem;font-weight:700}
.tag-blue{background:var(--primary-t);color:var(--primary)}
.tag-green{background:var(--green-t);color:var(--green)}
.tag-red{background:var(--red-t);color:var(--red)}
.tag-gray{background:var(--bg3);color:var(--text3)}
.tag-orange{background:rgba(243,156,18,.12);color:var(--orange)}

/* ===== TOAST ===== */
#toast-wrap{position:fixed;bottom:24px;right:24px;z-index:999;display:flex;flex-direction:column;gap:10px}
.toast{background:var(--bg2);border:1px solid var(--border);border-radius:var(--radius-xs);padding:12px 16px;box-shadow:var(--shadow);font-size:.85rem;font-weight:600;display:flex;align-items:center;gap:10px;min-width:240px;animation:slideIn .25s ease;border-left:3px solid var(--primary)}
.toast.success{border-left-color:var(--green)}
.toast.error{border-left-color:var(--red)}
@keyframes slideIn{from{transform:translateX(60px);opacity:0}to{transform:translateX(0);opacity:1}}

/* ===== QUIZ SOLVING UI (Telegram-like) ===== */
.quiz-wrap{max-width:700px;margin:0 auto}
.q-bubble{background:var(--bubble-in);border-radius:0 var(--radius) var(--radius) var(--radius);padding:16px 18px;margin-bottom:4px;box-shadow:var(--shadow-sm);border:1px solid var(--border)}
.q-num{font-size:.75rem;font-weight:700;color:var(--primary);margin-bottom:6px}
.q-text{font-size:.95rem;line-height:1.6;color:var(--text)}
.q-img{margin-top:10px;border-radius:var(--radius-xs);max-height:260px;object-fit:contain}
.opts{display:flex;flex-direction:column;gap:8px;margin-top:16px}
.opt{display:flex;align-items:center;gap:12px;padding:11px 16px;background:var(--bg2);border:1.5px solid var(--border);border-radius:var(--radius);cursor:pointer;transition:all .15s;user-select:none}
.opt:hover:not(.locked){border-color:var(--primary);background:var(--primary-t)}
.opt-key{width:28px;height:28px;border-radius:50%;background:var(--bg3);border:1.5px solid var(--border);display:flex;align-items:center;justify-content:center;font-size:.78rem;font-weight:700;flex-shrink:0;transition:all .15s}
.opt-text{font-size:.88rem;color:var(--text);font-weight:500;flex:1}
.opt.correct{border-color:var(--green);background:var(--green-t)}
.opt.correct .opt-key{background:var(--green);border-color:var(--green);color:#fff}
.opt.wrong{border-color:var(--red);background:var(--red-t)}
.opt.wrong .opt-key{background:var(--red);border-color:var(--red);color:#fff}
.opt.locked{cursor:default}

/* Explanation bubble (telegram out-bubble style) */
.exp-bubble{background:var(--bubble-out);border-radius:var(--radius) 0 var(--radius) var(--radius);padding:12px 16px;margin-top:6px;margin-left:40px;font-size:.85rem;line-height:1.55;color:var(--text);box-shadow:var(--shadow-sm);animation:popIn .2s ease;border:1px solid var(--border)}
.exp-label{font-size:.72rem;font-weight:700;color:var(--primary);margin-bottom:5px;display:flex;align-items:center;gap:5px}
@keyframes popIn{from{transform:scale(.95);opacity:0}to{transform:scale(1);opacity:1}}

/* Progress bar */
.q-progress{height:3px;background:var(--bg3);border-radius:2px;overflow:hidden;margin-bottom:16px}
.q-progress-fill{height:100%;background:var(--primary);border-radius:2px;transition:width .4s ease}

/* Timer */
.q-timer{display:flex;align-items:center;gap:6px;font-family:var(--mono);font-size:.9rem;font-weight:600;color:var(--text2);background:var(--bg3);padding:5px 12px;border-radius:20px}
.q-timer.warn{color:var(--red);animation:pulse 1s infinite}
@keyframes pulse{0%,100%{opacity:1}50%{opacity:.5}}

/* Nav dots */
.q-dots{display:flex;flex-wrap:wrap;gap:5px;margin-bottom:16px}
.q-dot{width:28px;height:28px;border-radius:6px;background:var(--bg3);border:1.5px solid var(--border);display:flex;align-items:center;justify-content:center;font-size:.72rem;font-weight:700;cursor:pointer;transition:all .15s;color:var(--text3)}
.q-dot.answered{background:var(--green-t);border-color:var(--green);color:var(--green)}
.q-dot.wrong{background:var(--red-t);border-color:var(--red);color:var(--red)}
.q-dot.current{background:var(--primary);border-color:var(--primary);color:#fff}

/* Result screen */
.result-circle{width:140px;height:140px;border-radius:50%;display:flex;flex-direction:column;align-items:center;justify-content:center;margin:0 auto 20px;border:6px solid var(--primary);background:var(--primary-t)}
.result-pct{font-size:2rem;font-weight:800;color:var(--primary);line-height:1}
.result-label{font-size:.75rem;color:var(--text3);margin-top:3px}
.result-stats{display:grid;grid-template-columns:repeat(3,1fr);gap:12px;margin-top:20px}
.rs-item{background:var(--bg3);border-radius:var(--radius-sm);padding:14px;text-align:center}
.rs-val{font-size:1.4rem;font-weight:800}
.rs-key{font-size:.75rem;color:var(--text3);margin-top:3px}

/* ===== CATEGORY TREE ===== */
.cat-tree{display:flex;flex-direction:column;gap:2px}
.cat-row{display:flex;align-items:center;gap:8px;padding:8px 10px;border-radius:var(--radius-xs);transition:background var(--trans);cursor:pointer}
.cat-row:hover{background:var(--bg3)}
.cat-indent{display:flex;align-items:center;gap:8px;flex:1}
.cat-toggle{width:20px;height:20px;display:flex;align-items:center;justify-content:center;color:var(--text3);flex-shrink:0;transition:transform var(--trans)}
.cat-toggle.open{transform:rotate(90deg)}
.cat-icon{width:28px;height:28px;border-radius:6px;display:flex;align-items:center;justify-content:center;font-size:14px;flex-shrink:0}
.cat-name{font-size:.88rem;font-weight:600;color:var(--text);flex:1}
.cat-count{font-size:.75rem;color:var(--text3)}

/* ===== DRAG AREA ===== */
.drop-zone{border:2px dashed var(--border);border-radius:var(--radius);padding:30px;text-align:center;transition:all var(--trans);cursor:pointer}
.drop-zone:hover,.drop-zone.drag-over{border-color:var(--primary);background:var(--primary-t)}
.drop-zone i{font-size:2rem;color:var(--text3);margin-bottom:8px;display:block}
.drop-zone p{font-size:.85rem;color:var(--text2)}
.drop-zone span{color:var(--primary);font-weight:700}

/* ===== STUDENT SIDEBAR (quiz session) ===== */
.session-sidebar{width:220px;background:var(--bg2);border-left:1px solid var(--border);padding:16px;flex-shrink:0;overflow-y:auto}

/* ===== SEARCH BAR ===== */
.search-bar{display:flex;align-items:center;gap:8px;background:var(--bg3);border:1.5px solid var(--border);border-radius:var(--radius-xs);padding:7px 12px;flex:1;max-width:320px}
.search-bar input{background:none;border:none;outline:none;color:var(--text);font-size:.875rem;width:100%}
.search-bar i{color:var(--text3)}

/* ===== PAGINATION ===== */
.pagination{display:flex;align-items:center;gap:6px;margin-top:16px;justify-content:center}
.page-btn{width:34px;height:34px;border-radius:var(--radius-xs);background:var(--bg3);border:1.5px solid var(--border);display:flex;align-items:center;justify-content:center;font-size:.82rem;font-weight:700;color:var(--text2);cursor:pointer;transition:all var(--trans)}
.page-btn:hover,.page-btn.active{background:var(--primary);border-color:var(--primary);color:#fff}

/* ===== ALERTS ===== */
.alert{padding:12px 16px;border-radius:var(--radius-xs);font-size:.85rem;font-weight:600;display:flex;align-items:flex-start;gap:10px;margin-bottom:16px}
.alert-info{background:var(--primary-t);color:var(--primary);border-left:3px solid var(--primary)}
.alert-success{background:var(--green-t);color:var(--green);border-left:3px solid var(--green)}
.alert-danger{background:var(--red-t);color:var(--red);border-left:3px solid var(--red)}
.alert-warn{background:rgba(243,156,18,.12);color:var(--orange);border-left:3px solid var(--orange)}

/* ===== SWITCH TOGGLE ===== */
.switch{position:relative;display:inline-flex;align-items:center;gap:8px;cursor:pointer;font-size:.85rem;font-weight:600;color:var(--text2)}
.switch input{opacity:0;width:0;height:0}
.switch-track{width:42px;height:24px;background:var(--border);border-radius:12px;position:relative;transition:background var(--trans);flex-shrink:0}
.switch input:checked+.switch-track{background:var(--primary)}
.switch-track::after{content:'';position:absolute;width:18px;height:18px;background:#fff;border-radius:50%;top:3px;left:3px;transition:left var(--trans);box-shadow:0 1px 4px rgba(0,0,0,.2)}
.switch input:checked+.switch-track::after{left:21px}

/* ===== EMPTY STATE ===== */
.empty{text-align:center;padding:50px 20px;color:var(--text3)}
.empty i{font-size:3rem;margin-bottom:12px;display:block}
.empty p{font-size:.9rem}

/* ===== LOGIN PAGE ===== */
.login-page{min-height:100vh;display:flex;align-items:center;justify-content:center;background:var(--bg);padding:20px}
.login-box{background:var(--bg2);border-radius:var(--radius);border:1px solid var(--border);padding:36px;width:100%;max-width:400px;box-shadow:var(--shadow)}
.login-logo{text-align:center;margin-bottom:28px}
.login-logo .logo-icon{width:56px;height:56px;margin:0 auto 10px;border-radius:14px}
.login-logo h1{font-size:1.3rem;font-weight:800;color:var(--text)}
.login-logo p{font-size:.82rem;color:var(--text3);margin-top:3px}

/* ===== RESPONSIVE ===== */
@media(max-width:768px){
  .sidebar{position:fixed;left:-260px;height:100%;box-shadow:var(--shadow);transition:left var(--trans)}
  .sidebar.mobile-open{left:0}
  .sidebar.collapsed{width:260px;left:-260px}
  .form-row{grid-template-columns:1fr}
  .stats-grid{grid-template-columns:1fr 1fr}
  .content{padding:14px}
  .session-sidebar{display:none}
}
@media(max-width:480px){
  .stats-grid{grid-template-columns:1fr}
}

/* ===== STUDENT FRONT SPECIFIC ===== */
.hero{background:var(--primary);color:#fff;border-radius:var(--radius);padding:28px 24px;margin-bottom:20px;position:relative;overflow:hidden}
.hero::after{content:'';position:absolute;top:-30px;right:-30px;width:180px;height:180px;background:rgba(255,255,255,.08);border-radius:50%}
.hero h2{font-size:1.3rem;font-weight:800}
.hero p{font-size:.85rem;opacity:.85;margin-top:6px}
.quiz-card{background:var(--bg2);border:1px solid var(--border);border-radius:var(--radius);padding:16px;transition:all var(--trans);cursor:pointer}
.quiz-card:hover{border-color:var(--primary);box-shadow:0 4px 20px rgba(36,129,204,.15);transform:translateY(-2px)}
.quiz-card h4{font-size:.9rem;font-weight:700;color:var(--text);margin-bottom:6px}
.quiz-meta{display:flex;flex-wrap:wrap;gap:8px;margin-top:10px}
.quiz-meta span{display:flex;align-items:center;gap:4px;font-size:.75rem;color:var(--text3)}

/* PWA install banner */
#pwa-banner{position:fixed;bottom:0;left:0;right:0;background:var(--primary);color:#fff;padding:12px 20px;display:flex;align-items:center;justify-content:space-between;z-index:998;transform:translateY(100%);transition:transform .4s ease;gap:12px}
#pwa-banner.show{transform:translateY(0)}
#pwa-banner p{font-size:.85rem;font-weight:600;flex:1}
#pwa-banner .btn-install{background:#fff;color:var(--primary);padding:7px 16px;border-radius:20px;font-weight:700;font-size:.82rem;border:none;cursor:pointer}
#pwa-banner .btn-dismiss{background:rgba(255,255,255,.2);border:none;color:#fff;padding:7px 12px;border-radius:20px;cursor:pointer;font-size:.82rem}

/* ===== DARK MODE TOGGLE ===== */
.theme-btn{background:none;border:none;cursor:pointer;padding:7px;border-radius:8px;color:var(--text2);display:flex;transition:all var(--trans)}
.theme-btn:hover{background:var(--bg3);color:var(--text)}