:root{
  --bg:#EAF3FD;--surface:#FFFFFF;--ink:#0E2350;--ink-2:#36486B;--muted:#5D6B85;
  --line:#CFDDF0;--accent:#1B4FD8;--accent-soft:#E1EAFC;--cta:#0E2350;
  --ok:#1C7C45;--ok-soft:#E1F3E8;--bad:#B42318;--bad-soft:#FDE7E4;--warn:#8A5200;--warn-soft:#FFF1D6;
  --code:#0F1B33;--code-ink:#E6EDF7;
  --sans:"Plus Jakarta Sans",-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,Helvetica,Arial,sans-serif;
  --mono:ui-monospace,SFMono-Regular,Menlo,Consolas,"Liberation Mono",monospace;
  color-scheme:light;
}
*,*::before,*::after{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{margin:0;background:var(--bg);color:var(--ink);font-family:var(--sans);font-size:16px;line-height:1.5;-webkit-font-smoothing:antialiased;-webkit-tap-highlight-color:transparent}
button,input,textarea,select{font:inherit;color:inherit}
a{color:var(--accent)}
:focus-visible{outline:3px solid var(--accent);outline-offset:2px;border-radius:8px}
.app{max-width:560px;margin:0 auto;min-height:100vh;min-height:100dvh;display:flex;flex-direction:column;padding-top:env(safe-area-inset-top,0px)}
main.page{flex:1;padding:8px 18px calc(96px + env(safe-area-inset-bottom,0px))}
h1{margin:0;font-size:26px;line-height:1.15;letter-spacing:-.02em;font-weight:800}
h2{margin:0;font-size:20px;line-height:1.25;letter-spacing:-.01em;font-weight:800}
h3{margin:0;font-size:16px;font-weight:800}
p{margin:0}
.muted{color:var(--muted)}
.small{font-size:13px}
.sp{height:16px}

/* header */
.hdr{position:sticky;top:0;z-index:20;background:var(--bg);display:flex;align-items:center;gap:10px;padding:10px 14px}
.hdr .brand{font-weight:800;font-size:20px;letter-spacing:-.02em;flex:1}
.iconbtn{width:44px;height:44px;border:0;background:none;border-radius:12px;display:grid;place-items:center;cursor:pointer;flex:none}
.iconbtn svg{width:24px;height:24px}
.iconbtn svg path{fill:none;stroke:var(--ink);stroke-width:2.2;stroke-linecap:round;stroke-linejoin:round}
.streak{display:inline-flex;align-items:center;gap:6px;font-weight:800;font-size:15px;background:var(--surface);border:1px solid var(--line);border-radius:999px;padding:6px 12px}
.streak svg{width:18px;height:18px}

/* tab bar */
.tabs{position:fixed;left:0;right:0;bottom:0;z-index:20;background:var(--surface);border-top:1px solid var(--line);padding-bottom:env(safe-area-inset-bottom,0px)}
.tabs .in{max-width:560px;margin:0 auto;display:grid;grid-template-columns:repeat(4,1fr)}
.tab{display:flex;flex-direction:column;align-items:center;gap:2px;padding:9px 0 8px;font-size:12px;font-weight:700;color:var(--muted);text-decoration:none;min-height:56px}
.tab svg{width:24px;height:24px}
.tab svg path,.tab svg rect,.tab svg circle{fill:none;stroke:currentColor;stroke-width:2;stroke-linecap:round;stroke-linejoin:round}
.tab[aria-current="page"]{color:var(--accent)}

/* buttons */
.btn{display:flex;width:100%;align-items:center;justify-content:center;gap:8px;min-height:54px;padding:0 20px;border:0;border-radius:999px;background:var(--cta);color:#fff;font-weight:800;font-size:16px;cursor:pointer;text-decoration:none;text-align:center}
.btn:active{transform:translateY(1px)}
.btn[disabled]{background:#A5B0C4;cursor:not-allowed;transform:none}
.btn.secondary{background:var(--surface);color:var(--ink);border:2px solid var(--line)}
.btn.small{min-height:40px;font-size:14px;padding:0 14px;width:auto}
.linkbtn{background:none;border:0;color:var(--accent);font-weight:700;cursor:pointer;padding:8px 0;min-height:44px}

/* cards */
.card{background:var(--surface);border:1px solid var(--line);border-radius:18px;padding:16px}
.card+.card{margin-top:10px}
.row{display:flex;gap:12px;align-items:center}
.grow{flex:1;min-width:0}
.pill{display:inline-flex;align-items:center;gap:6px;font-size:12px;font-weight:700;padding:4px 10px;border-radius:999px;background:var(--accent-soft);color:var(--accent)}
.pill.ok{background:var(--ok-soft);color:var(--ok)}
.pill.grey{background:#EEF1F6;color:var(--muted)}

/* path */
.path{display:grid;gap:8px;margin-top:12px}
.stop{display:flex;align-items:center;gap:12px;background:var(--surface);border:2px solid var(--line);border-radius:16px;padding:10px 12px;min-height:60px;text-decoration:none;color:inherit}
.stop .n{flex:none;width:26px;font-weight:800;font-size:18px}
.stop .tool{flex:none;width:34px;height:34px}
.stop .nm{flex:1;min-width:0;font-weight:800;text-transform:uppercase;font-size:15px;letter-spacing:.01em}
.stop .nm small{display:block;text-transform:none;letter-spacing:0;font-weight:500;font-size:13px;color:var(--muted)}
.stop.current{border-color:var(--accent)}
.stop.done .n{color:var(--ok)}
.bar{height:8px;border-radius:4px;background:var(--line);overflow:hidden}
.bar i{display:block;height:100%;background:var(--accent);border-radius:4px}
.next-card{background:var(--ink);color:#fff;border-radius:20px;padding:18px;margin-top:14px}
.next-card .muted{color:#B9C6DD}
.next-card .btn{background:#fff;color:var(--ink);margin-top:14px}
.maya{display:flex;gap:10px;align-items:flex-start;margin-top:10px}
.avatar{flex:none;width:36px;height:36px;border-radius:50%;background:#F6C343;color:var(--ink);display:grid;place-items:center;font-weight:800;font-size:15px}
.bubble{background:rgba(255,255,255,.12);border-radius:14px;border-top-left-radius:4px;padding:10px 12px;font-size:15px;line-height:1.4}

/* lesson list */
.lessons{display:grid;gap:8px;margin-top:14px}
.lesson-row{display:flex;align-items:center;gap:12px;background:var(--surface);border:1px solid var(--line);border-radius:14px;padding:12px 14px;text-decoration:none;color:inherit;min-height:60px}
.lesson-row .num{flex:none;width:38px;height:38px;border-radius:12px;display:grid;place-items:center;font-weight:800;font-size:13px;background:var(--accent-soft);color:var(--accent)}
.lesson-row.done .num{background:var(--ok-soft);color:var(--ok)}
.lesson-row.locked{opacity:.6}
.lesson-row.locked .num{background:#EEF1F6;color:var(--muted)}
.lesson-row .t{flex:1;min-width:0;font-weight:700;font-size:15px;line-height:1.3}
.lesson-row .t small{display:block;font-weight:500;color:var(--muted);font-size:13px}

/* lesson player */
.lhdr{position:sticky;top:0;z-index:20;background:var(--bg);display:flex;align-items:center;gap:10px;padding:10px 14px}
.lhdr .bar{flex:1}
.stage{animation:in .22s ease-out}
@keyframes in{from{opacity:0;transform:translateY(6px)}to{opacity:1;transform:none}}
.kicker{font-size:13px;font-weight:700;color:var(--accent);margin-bottom:6px}
.msg{display:flex;gap:10px;align-items:flex-start;margin-top:14px}
.msg .bubble{background:var(--surface);border:1px solid var(--line);color:var(--ink)}
.concept p+p{margin-top:10px}
.concept .ex{margin-top:14px;background:var(--surface);border:1px solid var(--line);border-radius:14px;padding:12px 14px;font-size:15px}
code,.code{font-family:var(--mono);font-size:13.5px}
p code,li code,.concept code{background:#E6ECF7;border-radius:6px;padding:1px 6px}
.cta-bar{position:fixed;left:0;right:0;bottom:0;z-index:25;background:linear-gradient(to top,var(--bg) 75%,transparent);padding:14px 18px calc(12px + env(safe-area-inset-bottom,0px))}
.cta-bar .in{max-width:524px;margin:0 auto;display:flex;gap:10px}
.cta-bar .btn.tutor{width:auto;flex:none;background:var(--surface);color:var(--ink);border:2px solid var(--line);padding:0 16px}

/* sheet grid */
.sheet{margin-top:12px;border:1px solid var(--line);border-radius:12px;overflow:auto;max-height:46vh;background:var(--surface);-webkit-overflow-scrolling:touch}
.sheet table{border-collapse:separate;border-spacing:0;font-size:13px;min-width:100%}
.sheet th,.sheet td{padding:6px 9px;border-right:1px solid #E3EAF4;border-bottom:1px solid #E3EAF4;white-space:nowrap;text-align:left}
.sheet thead th{position:sticky;top:0;background:#F1F5FB;font-weight:700;color:var(--muted);z-index:1;font-size:12px}
.sheet thead tr.hdrrow th{top:27px;color:var(--ink)}
.sheet .rn{position:sticky;left:0;background:#F1F5FB;color:var(--muted);font-weight:600;text-align:right;z-index:1}
.sheet td.num{text-align:right;font-variant-numeric:tabular-nums}
.sheet td.hl{background:#FFF6D8}
.sheet th.sortable{cursor:pointer}
.toolbar{display:flex;gap:8px;flex-wrap:wrap;margin-top:10px;align-items:center}
.toolbar select{min-height:40px;border:1px solid var(--line);border-radius:10px;background:var(--surface);padding:0 10px}
.fx{display:flex;align-items:center;gap:0;margin-top:12px;border:2px solid var(--line);border-radius:12px;background:var(--surface);overflow:hidden}
.fx label{flex:none;padding:0 10px;font-family:var(--mono);font-weight:700;color:var(--muted);background:#F1F5FB;align-self:stretch;display:flex;align-items:center;border-right:1px solid var(--line)}
.fx input{flex:1;min-width:0;border:0;padding:12px;font-family:var(--mono);font-size:15px;background:transparent}
.fx input:focus{outline:none}
.fx:focus-within{border-color:var(--accent)}
.result{margin-top:10px;font-size:14px;padding:10px 12px;border-radius:12px;background:#F1F5FB}
.result.ok{background:var(--ok-soft);color:var(--ok);font-weight:700}
.result.bad{background:var(--bad-soft);color:var(--bad)}

/* editor */
.editor{margin-top:12px;border-radius:14px;overflow:hidden;border:2px solid var(--code)}
.editor textarea{display:block;width:100%;min-height:120px;border:0;background:var(--code);color:var(--code-ink);font-family:var(--mono);font-size:15px;line-height:1.5;padding:12px;resize:vertical}
.editor textarea:focus{outline:none}
.editor .ebar{display:flex;justify-content:space-between;align-items:center;background:#16264A;padding:6px 8px 6px 12px;color:#9FB2D6;font-size:12px}
.schema{margin-top:10px;font-size:13px}
.schema summary{cursor:pointer;font-weight:700;color:var(--accent);min-height:36px;display:flex;align-items:center}
.schema pre{margin:6px 0 0;background:var(--surface);border:1px solid var(--line);border-radius:10px;padding:10px;overflow:auto;font-size:12.5px}

/* choices */
.choices{display:grid;gap:8px;margin-top:14px}
.choice{display:flex;align-items:center;gap:12px;min-height:54px;padding:10px 14px;background:var(--surface);border:2px solid var(--line);border-radius:14px;text-align:left;cursor:pointer;font-weight:600}
.choice[aria-checked="true"]{border-color:var(--accent);background:var(--accent-soft)}
.choice.right{border-color:var(--ok);background:var(--ok-soft)}
.choice.wrong{border-color:var(--bad);background:var(--bad-soft)}
.feedback{margin-top:12px;border-radius:14px;padding:12px 14px;font-size:15px}
.feedback.ok{background:var(--ok-soft);color:#14532D}
.feedback.bad{background:var(--bad-soft);color:#7A1C12}

/* pivot builder */
.pivot{margin-top:12px;display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:8px}
.pivot label{font-size:12px;font-weight:700;color:var(--muted);display:grid;gap:4px}
.pivot select{min-height:44px;border:1px solid var(--line);border-radius:10px;background:var(--surface);padding:0 8px;font-weight:600}

textarea.free{width:100%;min-height:130px;margin-top:12px;border:2px solid var(--line);border-radius:14px;padding:12px;background:var(--surface);font-size:15px;line-height:1.5;resize:vertical}
textarea.free:focus{outline:none;border-color:var(--accent)}

.procheck{margin-top:14px;background:var(--warn-soft);color:#5A3700;border-radius:14px;padding:14px;font-size:15px}

/* tutor drawer */
.veil{position:fixed;inset:0;z-index:50;background:rgba(14,35,80,.4);display:flex;align-items:flex-end;justify-content:center}
.drawer{width:100%;max-width:560px;max-height:82vh;display:flex;flex-direction:column;background:var(--bg);border-radius:22px 22px 0 0;padding:14px 16px calc(12px + env(safe-area-inset-bottom,0px));animation:up .22s ease-out}
@keyframes up{from{transform:translateY(30px);opacity:.6}}
.drawer .head{display:flex;align-items:center;gap:10px}
.drawer .head h2{flex:1}
.chat{flex:1;overflow:auto;display:grid;gap:8px;align-content:start;padding:12px 2px}
.cb{max-width:88%;padding:10px 12px;border-radius:14px;font-size:15px;line-height:1.45;white-space:pre-wrap}
.cb.ai{background:var(--surface);border:1px solid var(--line);border-bottom-left-radius:4px}
.cb.me{justify-self:end;background:var(--accent);color:#fff;border-bottom-right-radius:4px}
.quick{display:flex;gap:6px;flex-wrap:wrap}
.quick button{border:1px solid var(--line);background:var(--surface);border-radius:999px;padding:8px 12px;font-size:13px;font-weight:700;cursor:pointer;min-height:40px}
.ask{display:flex;gap:8px;margin-top:8px}
.ask input{flex:1;min-width:0;min-height:46px;border:2px solid var(--line);border-radius:999px;padding:0 14px;background:var(--surface)}

/* done screen */
.done{text-align:center;padding-top:30px}
.done .big{font-size:56px;font-weight:800;letter-spacing:-.03em}
.stars{display:flex;justify-content:center;gap:6px;margin-top:12px}
.stars button{width:48px;height:48px;border:0;background:none;cursor:pointer;font-size:34px;color:#C9D3E3;line-height:1}
.stars button.on{color:#F5B400}

.field{display:grid;gap:6px;margin-top:14px}
.field label{font-weight:700;font-size:14px}
.field input,.field select{min-height:50px;border:2px solid var(--line);border-radius:12px;padding:0 12px;background:var(--surface)}
.cert{position:relative;background:#fff;border:2px solid var(--ink);border-radius:8px;padding:22px 18px;text-align:center;margin-top:14px}
.cert::before{content:"";position:absolute;inset:6px;border:1px solid var(--line);border-radius:4px;pointer-events:none}
.toast{position:fixed;left:50%;bottom:90px;transform:translateX(-50%);background:var(--ink);color:#fff;padding:10px 16px;border-radius:999px;font-size:14px;font-weight:700;z-index:60}
@media (prefers-reduced-motion:reduce){*{animation:none!important;transition:none!important}}