:root{
  --bg:#101420; --surface:#182033; --surface2:#23304a; --line:rgba(255,255,255,.12);
  --primary:#8ea2ff; --primary-2:#4f6df5; --accent:#ffb547;
  --text:#f8fbff; --muted:#c4cce0; --danger:#ff5a7a; --ok:#3ddc97;
  --r:14px; --r-sm:10px;
  --nav-h: calc(64px + env(safe-area-inset-bottom));
}
*{box-sizing:border-box;-webkit-tap-highlight-color:transparent}
html,body{margin:0;padding:0;background:var(--bg);color:var(--text);font-family:-apple-system,Segoe UI,Roboto,"Helvetica Neue",Arial,"Noto Sans Devanagari",sans-serif;overflow:hidden;height:100%;height:100dvh}
button{font:inherit;color:inherit;background:none;border:0;cursor:pointer}
input,textarea,select{font:inherit;color:inherit}
img{max-width:100%;display:block}
a{color:var(--primary)}
::-webkit-scrollbar{width:6px;height:6px}::-webkit-scrollbar-thumb{background:rgba(255,255,255,.15);border-radius:6px}

#dz-app{height:100dvh;display:flex;flex-direction:column;width:100%;max-width:560px;margin:0 auto;background:var(--bg);position:relative;overflow:hidden;box-shadow:0 0 60px rgba(0,0,0,.4)}
@media(min-width:900px){#dz-app{max-width:none;margin:0;border:0;box-shadow:none}}

.appbar{display:flex;align-items:center;justify-content:center;gap:10px;padding:14px 16px calc(12px + env(safe-area-inset-top));background:linear-gradient(135deg,var(--primary-2),var(--primary));position:relative;flex-shrink:0;color:#fff}
.appbar img{width:32px;height:32px}
.appbar h1{margin:0;font-size:18px;letter-spacing:.3px;font-weight:700;text-align:center}
.appbar .left,.appbar .right{position:absolute;top:50%;transform:translateY(-10%);padding:0 14px}
.appbar .left{left:0}.appbar .right{right:0}
.appbar .icon-btn{width:38px;height:38px;display:grid;place-items:center;border-radius:50%;background:rgba(255,255,255,.15)}

.screen{flex:1;overflow-y:auto;-webkit-overflow-scrolling:touch;padding:16px;padding-bottom:calc(var(--nav-h) + 16px)}

/* Bottom nav */
.bottom-nav{position:absolute;left:0;right:0;bottom:0;background:rgba(15,10,36,.95);backdrop-filter:blur(12px);border-top:1px solid var(--line);display:grid;grid-template-columns:repeat(5,1fr);padding:8px 6px calc(8px + env(safe-area-inset-bottom));z-index:10}
.nav-btn{display:flex;flex-direction:column;align-items:center;gap:3px;padding:6px 4px;color:var(--muted);font-size:11px;font-weight:600;border-radius:12px;transition:.2s}
.nav-btn svg{width:22px;height:22px;stroke-width:2}
.nav-btn.active{color:#fff;background:linear-gradient(135deg,var(--primary),var(--primary-2))}
.nav-btn.home-btn{position:relative;top:-14px;background:linear-gradient(135deg,var(--accent),#ff7a4d);color:#fff;border-radius:50%;width:54px;height:54px;justify-self:center;align-self:center;box-shadow:0 8px 20px rgba(255,122,77,.4);gap:0;padding:0;display:flex;align-items:center;justify-content:center}
.nav-btn.home-btn span:first-child{width:28px;height:28px;display:flex;align-items:center;justify-content:center;margin:0}
.nav-btn.home-btn svg{width:28px;height:28px;stroke-width:2.2;color:#fff;display:block;margin:0 auto}
.nav-btn.home-btn span:last-child{display:none}

/* Common */
.card{background:var(--surface);border:1px solid var(--line);border-radius:var(--r);padding:16px;margin-bottom:12px}
.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;padding:12px 18px;border-radius:var(--r-sm);background:linear-gradient(135deg,var(--primary),var(--primary-2));color:#fff;font-weight:600;transition:.2s}
.btn:active{transform:scale(.97)}
.btn.ghost{background:transparent;border:1px solid var(--line);color:var(--text)}
.btn.full{width:100%}
.btn[disabled]{opacity:.5;pointer-events:none}
.muted{color:var(--muted);font-size:13px}
.title{font-size:20px;font-weight:800;margin:0 0 4px;color:var(--text)}
.subtitle{font-size:13px;color:var(--muted);margin:0 0 14px}

/* Dashboard */
.greet{background:linear-gradient(135deg,var(--primary-2),var(--primary));border-radius:18px;padding:18px;margin-bottom:14px;color:#fff;display:flex;align-items:center;gap:14px}
.avatar{width:48px;height:48px;border-radius:50%;background:rgba(255,255,255,.2);display:grid;place-items:center;font-weight:700;font-size:18px}
.stats{display:grid;grid-template-columns:repeat(3,1fr);gap:10px;margin-bottom:14px}
.stat{background:var(--surface);border:1px solid var(--line);border-radius:var(--r);padding:14px 10px;text-align:center}
.stat .n{font-size:22px;font-weight:700;color:var(--primary)}
.stat .l{font-size:11px;color:var(--muted);margin-top:2px;text-transform:uppercase;letter-spacing:.5px}
.tiles{display:grid;grid-template-columns:1fr 1fr;gap:12px}
.tile{background:var(--surface);border:1px solid var(--line);border-radius:var(--r);padding:18px;display:flex;flex-direction:column;gap:10px;cursor:pointer;transition:.2s}
.tile:active{transform:scale(.97)}
.tile .ic{width:44px;height:44px;border-radius:12px;background:linear-gradient(135deg,var(--primary),var(--primary-2));display:grid;place-items:center}
.tile .ic svg{width:24px;height:24px;color:#fff}
.tile h3{margin:0;font-size:15px}
.tile p{margin:0;font-size:12px;color:var(--muted)}

/* Tabs / pills */
.pills{display:flex;flex-wrap:wrap;gap:8px;margin-bottom:14px}
.pill{padding:9px 14px;background:var(--surface);border:1px solid var(--line);border-radius:999px;font-size:13px;font-weight:600;color:var(--muted);cursor:pointer;transition:.15s}
.pill.active{background:linear-gradient(135deg,var(--primary),var(--primary-2));color:#fff;border-color:transparent}
.grid-4{display:grid;grid-template-columns:repeat(4,1fr);gap:8px}
.grid-3{display:grid;grid-template-columns:repeat(3,1fr);gap:8px}
.grid-2{display:grid;grid-template-columns:repeat(2,1fr);gap:8px}
.chip{padding:14px 8px;background:var(--surface);border:1px solid var(--line);border-radius:var(--r-sm);text-align:center;font-weight:600;font-size:14px;cursor:pointer;transition:.15s}
.chip.active{background:linear-gradient(135deg,var(--primary),var(--primary-2));border-color:transparent;color:#fff}
.stepper{display:flex;gap:6px;margin-bottom:14px}
.stepper .step{flex:1;height:4px;border-radius:4px;background:var(--surface2)}
.stepper .step.done{background:var(--primary)}
.section-label{font-size:12px;color:var(--muted);text-transform:uppercase;letter-spacing:.6px;margin:14px 0 8px;font-weight:700}

/* Chat */
.chat-wrap{display:flex;flex-direction:column;height:100%}
.chat-log{flex:1;overflow-y:auto;padding:14px 14px 6px;display:flex;flex-direction:column;gap:10px}
.bubble{max-width:82%;padding:10px 14px;border-radius:18px;line-height:1.5;font-size:14px;word-wrap:break-word;white-space:pre-wrap}
.bubble.user{align-self:flex-end;background:linear-gradient(135deg,var(--primary),var(--primary-2));color:#fff;border-bottom-right-radius:4px}
.bubble.bot{align-self:flex-start;background:var(--surface);border:1px solid var(--line);border-bottom-left-radius:4px}
.bubble.bot strong{color:#dfe6ff}
.bubble.bot h1,.bubble.bot h2,.bubble.bot h3{margin:8px 0 4px;font-size:15px;color:#ffffff}
.bubble.bot code{background:rgba(124,92,255,.15);padding:1px 5px;border-radius:4px;font-size:13px}
.bubble img{border-radius:10px;margin-top:6px}
.typing{display:inline-flex;gap:4px;padding:14px}
.typing span{width:7px;height:7px;border-radius:50%;background:var(--muted);animation:t 1.2s infinite}
.typing span:nth-child(2){animation-delay:.2s}.typing span:nth-child(3){animation-delay:.4s}
@keyframes t{0%,80%,100%{opacity:.3;transform:scale(.8)}40%{opacity:1;transform:scale(1)}}
.chat-form{display:flex;align-items:flex-end;gap:8px;padding:10px;border-top:1px solid var(--line);background:var(--bg)}
.chat-form .lang{display:flex;gap:4px;padding:4px;background:var(--surface);border-radius:999px;font-size:11px}
.chat-form .lang button{padding:5px 10px;border-radius:999px;color:var(--muted);font-weight:600}
.chat-form .lang button.active{background:var(--primary);color:#fff}
.chat-input-wrap{flex:1;display:flex;align-items:center;background:var(--surface);border:1px solid var(--line);border-radius:22px;padding:4px 4px 4px 14px;gap:6px}
.chat-input-wrap textarea{flex:1;background:none;border:0;outline:0;resize:none;max-height:100px;min-height:24px;padding:8px 0;font-size:14px}
.icon-btn-sm{width:36px;height:36px;border-radius:50%;display:grid;place-items:center;background:var(--surface2);color:var(--text);flex-shrink:0}
.icon-btn-sm.send{background:linear-gradient(135deg,var(--primary),var(--primary-2));color:#fff}
.icon-btn-sm.rec{background:var(--danger);color:#fff;animation:pulse 1s infinite}
@keyframes pulse{50%{box-shadow:0 0 0 8px rgba(255,90,122,.25)}}
.preview-img{max-width:160px;border-radius:10px;margin:0 10px 8px;position:relative}
.preview-img button{position:absolute;top:-6px;right:-6px;width:22px;height:22px;border-radius:50%;background:var(--danger);color:#fff;font-size:14px;display:grid;place-items:center}

/* Test */
.test-runner{position:absolute;inset:0;background:var(--bg);z-index:20;display:flex;flex-direction:column}
.test-top{display:flex;justify-content:space-between;align-items:center;padding:14px 16px;background:linear-gradient(135deg,var(--primary-2),var(--primary));color:#fff}
.timer{font-variant-numeric:tabular-nums;font-weight:700;background:rgba(0,0,0,.25);padding:6px 12px;border-radius:999px}
.test-body{flex:1;overflow-y:auto;padding:18px}
.qnum{color:var(--muted);font-size:12px;text-transform:uppercase;letter-spacing:1px;margin-bottom:6px}
.qtxt{font-size:16px;line-height:1.5;margin-bottom:16px;font-weight:500}
.opt{display:block;background:var(--surface);border:2px solid var(--line);border-radius:var(--r-sm);padding:12px 14px;margin-bottom:10px;cursor:pointer;font-size:14px;transition:.15s}
.opt.sel{border-color:var(--primary);background:var(--surface2)}
.opt.right{border-color:var(--ok);background:rgba(61,220,151,.12)}
.opt.wrong{border-color:var(--danger);background:rgba(255,90,122,.12)}
.test-foot{display:flex;gap:8px;padding:12px;border-top:1px solid var(--line);background:var(--bg)}
.palette{display:grid;grid-template-columns:repeat(8,1fr);gap:6px;padding:0 16px 14px}
.palette button{aspect-ratio:1;border-radius:8px;background:var(--surface);border:1px solid var(--line);font-weight:700;font-size:12px}
.palette button.done{background:var(--primary);color:#fff;border-color:transparent}
.palette button.curr{outline:2px solid var(--accent)}

.result{padding:24px 18px;text-align:center}
.score-ring{width:160px;height:160px;border-radius:50%;background:conic-gradient(var(--primary) var(--pct), var(--surface2) 0);display:grid;place-items:center;margin:0 auto 18px;position:relative}
.score-ring::before{content:"";position:absolute;inset:14px;border-radius:50%;background:var(--bg)}
.score-ring span{position:relative;font-size:34px;font-weight:700;color:var(--primary)}
.result-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:8px;margin:16px 0}

/* Notes preview */
.notes-result{background:var(--surface);border:1px solid var(--line);border-radius:var(--r);padding:14px;margin:10px 0;font-size:13px;color:var(--muted);line-height:1.5;max-height:160px;overflow:auto}
.notes-review{position:absolute;inset:0;background:var(--bg);z-index:22;display:flex;flex-direction:column}
.review-top{display:flex;align-items:center;justify-content:space-between;gap:12px;padding:14px 16px;background:var(--surface);border-bottom:1px solid var(--line)}
.review-top strong{display:block;color:var(--text);font-size:16px}.review-top span{display:block;color:var(--muted);font-size:12px;margin-top:2px}
.review-format{border:1px solid var(--line);border-radius:999px;padding:6px 10px;color:var(--text)!important;font-weight:800}
.review-body{flex:1;overflow:auto;padding:18px;background:#e8edf5}
.notes-doc{max-width:820px;margin:0 auto;background:#ffffff;color:#1a1a2e;border-radius:14px;padding:28px 30px 32px;line-height:1.75;box-shadow:0 20px 60px rgba(0,0,0,.2);font-size:14px;font-family:'Segoe UI',Roboto,Arial,'Noto Sans Devanagari',sans-serif}
.notes-doc h1{font-size:23px;font-weight:800;color:#142044;margin:0 0 16px;padding-bottom:10px;border-bottom:3px solid var(--primary-2)}
.notes-doc h2{font-size:16.5px;font-weight:700;color:var(--primary-2);margin:22px 0 8px;padding:6px 12px;background:linear-gradient(90deg,rgba(79,109,245,.07),transparent);border-left:4px solid var(--primary-2);border-radius:0 6px 6px 0}
.notes-doc h3{font-size:14px;font-weight:700;color:#2d3560;margin:16px 0 6px}
.notes-doc p{margin:6px 0 10px}
.notes-doc ul{padding-left:0;margin:6px 0 12px;list-style:none}
.notes-doc li{position:relative;padding:5px 0 5px 22px;border-bottom:1px solid #f0f2f8;line-height:1.65}
.notes-doc li:last-child{border-bottom:none}
.notes-doc li::before{content:"▸";position:absolute;left:0;top:5px;color:var(--primary-2);font-size:12px;font-weight:700}
.notes-doc strong{color:#142044;font-weight:700}
.notes-doc em{color:#5563a0;font-style:italic}
.notes-doc code{background:#f0f2ff;padding:2px 6px;border-radius:4px;font-size:12.5px;color:#3730a3;font-family:'Consolas','Courier New',monospace}

/* Doubt Solver */
.doubt-frame{background:var(--surface);border:1px solid var(--line);border-radius:var(--r);padding:18px;color:var(--text);line-height:1.65;font-size:14.5px}
.doubt-iframe{width:100%;min-height:480px;border:0;border-radius:0;background:#fff;display:block}
.doubt-overlay{position:fixed;inset:0;background:#fff;color:#1a1a1a;display:flex;flex-direction:column;z-index:9999}
.doubt-top{display:flex;align-items:center;gap:12px;padding:12px 14px;background:linear-gradient(135deg,#6c47ff,#3b2cbb);color:#fff;box-shadow:0 4px 14px rgba(0,0,0,.18)}
.doubt-top .icon-btn-sm{background:rgba(255,255,255,.18);color:#fff;border:0}
.doubt-title strong{display:block;font-size:16px;font-weight:700;line-height:1.1}
.doubt-title span{display:block;font-size:12px;opacity:.85}
.doubt-body{flex:1;overflow:auto;background:#fff}
.doubt-body .card{margin:14px;color:#1a1a1a;background:#f7f8fc;border:1px solid #e2e8f0}
.review-actions{display:grid;grid-template-columns:1fr 2fr;gap:10px;padding:12px 16px calc(12px + env(safe-area-inset-bottom));background:var(--bg);border-top:1px solid var(--line)}

.skeleton{background:linear-gradient(90deg,var(--surface),var(--surface2),var(--surface));background-size:200% 100%;animation:sk 1.5s infinite;border-radius:8px;height:14px;margin:8px 0}
@keyframes sk{0%{background-position:200% 0}100%{background-position:-200% 0}}

.error-toast{position:fixed;bottom:calc(var(--nav-h) + 12px);left:50%;transform:translateX(-50%);background:var(--danger);color:#fff;padding:10px 16px;border-radius:999px;font-size:13px;z-index:30;animation:fadein .2s;max-width:90%;text-align:center}
@keyframes fadein{from{opacity:0;transform:translate(-50%,10px)}}

@media(min-width:900px){
  :root{--nav-h:76px}
  .appbar{padding:18px 40px}.appbar h1{font-size:22px}.appbar img{width:38px;height:38px}
  .screen{width:min(1180px,100%);margin:0 auto;padding:28px 36px calc(var(--nav-h) + 28px)}
  .tiles{grid-template-columns:repeat(4,1fr)}.grid-2{grid-template-columns:repeat(4,1fr)}.grid-3{grid-template-columns:repeat(5,1fr)}.grid-4{grid-template-columns:repeat(7,1fr)}
  .bottom-nav{left:50%;right:auto;transform:translateX(-50%);bottom:18px;width:min(760px,calc(100% - 48px));border:1px solid var(--line);border-radius:18px;padding:10px;background:rgba(24,32,51,.94);box-shadow:0 18px 50px rgba(0,0,0,.35)}
  .nav-btn{flex-direction:row;justify-content:center;font-size:13px;padding:10px 12px}.nav-btn.home-btn{top:0;width:auto;height:auto;border-radius:14px;padding:10px 14px;gap:6px}.nav-btn.home-btn span:first-child{width:auto;height:auto}.nav-btn.home-btn span:last-child{display:inline}
  .chat-wrap{width:min(980px,100%);margin:0 auto}.chat-log{padding:24px}.bubble{max-width:68%;font-size:15px}.chat-form{border:1px solid var(--line);border-radius:18px;margin:0 24px 96px;padding:12px;background:var(--surface)}
  .test-runner{position:absolute}.test-body{width:min(980px,100%);margin:0 auto;padding:30px 36px}.palette{width:min(980px,100%);margin:0 auto;grid-template-columns:repeat(16,1fr)}.test-foot{width:min(980px,100%);margin:0 auto 18px;border:1px solid var(--line);border-radius:16px;padding:12px}
}