:root{
  --paper:#f6f1e7; --card:#fffdf8; --ink:#2b2622; --muted:#7a6f63; --line:#e6dccb;
  --accent:#c2553a; --accent-soft:#f6e1d8; --good:#3d7a57; --good-soft:#dcebdf; --bad-soft:#f5d9d3;
  --serif:"Iowan Old Style","Palatino Linotype",Palatino,Georgia,serif;
  --sans:"Avenir Next","Gill Sans","Trebuchet MS",system-ui,sans-serif;
  --safe-b:max(env(safe-area-inset-bottom),0px);
}
*{box-sizing:border-box;margin:0;-webkit-tap-highlight-color:transparent}
html,body{height:100%}
body{background:var(--paper);color:var(--ink);font-family:var(--sans);overscroll-behavior:none}
button{font-family:inherit;color:inherit}
.hidden{display:none!important}

/* ---------- App shell ---------- */
.app{max-width:1100px;margin:0 auto;min-height:100dvh;display:flex;flex-direction:column;
  padding:max(env(safe-area-inset-top),14px) 18px calc(var(--safe-b) + 60px)}
.bar{display:flex;align-items:center;gap:10px;min-height:44px;margin-bottom:12px}
.bar h2{font-family:var(--serif);font-weight:400;font-size:22px;flex:1;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.icon{width:44px;height:44px;border-radius:50%;border:1px solid var(--line);background:var(--card);display:grid;place-items:center;cursor:pointer;flex:none;font-size:18px}
.icon:active{transform:scale(.94)}
.screen{flex:1;display:flex;flex-direction:column;animation:in .28s ease both}
@keyframes in{from{opacity:0;transform:translateY(8px)}to{opacity:1;transform:none}}

/* ---------- Welcome / home ---------- */
.hero{padding:14px 2px 18px}
.hero h1{font-family:var(--serif);font-weight:400;font-size:clamp(34px,8vw,52px);line-height:1.02;letter-spacing:-.015em}
.hero h1 em{color:var(--accent)}
.hero p{color:var(--muted);margin-top:8px;font-size:16px;line-height:1.45;max-width:34ch}
.tooth-mark{font-size:40px;line-height:1;margin-bottom:8px}
.choices{display:grid;gap:10px}
@media(min-width:720px){.choices.two{grid-template-columns:repeat(2,minmax(0,1fr))}}
.choice{display:flex;align-items:center;gap:14px;text-align:left;padding:16px;border-radius:18px;border:1.5px solid var(--line);background:var(--card);cursor:pointer;transition:transform .12s,border-color .12s;min-height:72px}
.choice:hover{border-color:var(--ink)}
.choice:active{transform:scale(.985)}
.choice.on{border-color:var(--accent);background:var(--accent-soft)}
.choice .em{width:46px;height:46px;border-radius:14px;background:var(--paper);display:grid;place-items:center;font-size:22px;flex:none}
.choice b{display:block;font-weight:600;font-size:16px}
.choice small{display:block;color:var(--muted);font-size:13.5px;margin-top:2px;line-height:1.35}
.choice .go{margin-left:auto;color:var(--muted);font-size:20px}
.mini{display:flex;gap:10px;margin-top:14px}
.mini button{flex:1}
.kicker{font-size:11px;letter-spacing:.09em;text-transform:uppercase;color:var(--muted);margin:20px 2px 9px}
.streakline{display:flex;gap:8px;align-items:center;color:var(--muted);font-size:13.5px;margin-top:12px}
.dots{display:flex;gap:6px;justify-content:center;margin:4px 0 14px}
.dots i{width:7px;height:7px;border-radius:50%;background:var(--line)}
.dots i.on{background:var(--accent);width:20px;border-radius:7px}

/* ---------- Segmented control ---------- */
.seg{display:flex;background:var(--card);border:1px solid var(--line);border-radius:14px;padding:4px;gap:4px}
.seg button{flex:1;border:0;background:none;border-radius:10px;padding:11px 8px;font-weight:600;font-size:14px;color:var(--muted);cursor:pointer;min-height:42px}
.seg button.on{background:var(--ink);color:var(--paper)}

/* ---------- Buttons ---------- */
.btn{border:0;border-radius:14px;padding:15px 18px;font-weight:600;font-size:16px;cursor:pointer;background:var(--ink);color:var(--paper);min-height:52px;width:100%}
.btn:active{transform:scale(.985)}
.btn.ghost{background:var(--card);color:var(--ink);border:1.5px solid var(--line)}
.btn:disabled{opacity:.35;cursor:default}
.spacer{flex:1;min-height:16px}
.sticky{position:sticky;bottom:calc(var(--safe-b) + 56px);padding-top:10px;background:linear-gradient(transparent,var(--paper) 30%)}

/* ---------- Session: the 3D view gets most of the screen ---------- */
.session{display:grid;grid-template-columns:minmax(0,1fr);gap:10px;flex:1}
@media(min-width:860px){.session{grid-template-columns:minmax(0,2.1fr) minmax(300px,1fr);align-items:start;gap:16px}}
.stage{position:relative;border-radius:22px;background:var(--card);border:1px solid var(--line);overflow:hidden;height:clamp(260px,46dvh,560px);min-width:0}
/* Phone: leave room only for the question and answer controls below */
.stage.in-session{height:clamp(300px,calc(100dvh - 330px),820px)}
@media(min-width:860px){
  .stage{height:clamp(380px,70dvh,620px);position:sticky;top:14px}
  .stage.in-session{height:calc(100dvh - 96px);max-height:none;min-height:420px}
}
.stage.in-session .badge{display:none}
.stage canvas{width:100%;height:100%;display:block;touch-action:none;cursor:grab}
.stage .tools{position:absolute;left:10px;top:10px;display:flex;gap:6px;flex-wrap:wrap}
.stage .badge{position:absolute;right:10px;top:10px;font-size:10.5px;letter-spacing:.06em;text-transform:uppercase;color:var(--accent);background:var(--accent-soft);padding:5px 9px;border-radius:999px}
.stage .hint{position:absolute;left:50%;transform:translateX(-50%);bottom:10px;font-size:12px;color:var(--muted);background:rgba(255,253,248,.88);padding:5px 11px;border-radius:999px;white-space:nowrap}
.stage .timer{position:absolute;left:0;bottom:0;height:4px;background:var(--accent);transition:width .25s linear}
.chip{border:1px solid var(--line);background:rgba(255,253,248,.92);border-radius:999px;font-weight:600;font-size:12.5px;padding:8px 12px;cursor:pointer;min-height:36px}
.chip.on{background:var(--ink);color:var(--paper);border-color:var(--ink)}
.panel{min-width:0;display:flex;flex-direction:column}
.qhead{display:flex;align-items:baseline;gap:10px}
.q{font-family:var(--serif);font-size:clamp(18px,4.6vw,22px);line-height:1.2;margin:0;flex:1}
.q .target{color:var(--accent)}
.count{font-size:12.5px;color:var(--muted);white-space:nowrap;font-variant-numeric:tabular-nums}
.prog{height:3px;background:var(--line);border-radius:3px;overflow:hidden;margin:8px 0 10px}
.prog i{display:block;height:100%;background:var(--accent);transition:width .3s}
.opts{display:grid;gap:7px}
@media(max-width:859px){.opts.grid2{grid-template-columns:repeat(2,minmax(0,1fr))}}
.opt{text-align:left;border:1.5px solid var(--line);background:#fff;border-radius:13px;padding:11px 13px;font-size:15px;font-weight:500;cursor:pointer;min-height:48px;transition:transform .1s,border-color .1s}
.opt:hover:not(:disabled){border-color:var(--ink)}
.opt:active:not(:disabled){transform:scale(.98)}
.opt.right{background:var(--good-soft);border-color:var(--good)}
.opt.wrong{background:var(--bad-soft);border-color:var(--accent)}
.opt:disabled{cursor:default}
/* Write-in answers */
.typed{display:flex;gap:8px;padding:6px;border:1.5px solid var(--line);border-radius:16px;background:#fff;transition:border-color .15s,background .15s}
.typed:focus-within{border-color:var(--ink)}
.typed input{flex:1;min-width:0;border:0;outline:0;background:transparent;font:500 20px var(--sans);color:var(--ink);padding:8px 10px;letter-spacing:.02em}
.typed input::placeholder{color:#b8ad9f}
.typed .btn{width:auto;min-height:46px;padding:10px 18px;font-size:15px}
.typed.right{background:var(--good-soft);border-color:var(--good)}
.typed.wrong{background:var(--bad-soft);border-color:var(--accent)}
.typed-help{font-size:13px;color:var(--muted);margin:7px 4px 0;min-height:18px}
.typed-help.warn{color:var(--accent)}
.fb{margin-top:12px;padding:14px;border-radius:14px;background:var(--card);border:1px solid var(--line);font-size:14.5px;line-height:1.5;animation:in .2s ease both}
.fb .tag{display:inline-block;font-size:11px;letter-spacing:.07em;text-transform:uppercase;font-weight:600;margin-bottom:4px}
.fb .tag.ok{color:var(--good)} .fb .tag.no{color:var(--accent)}
.fb .why{margin-top:8px;padding-top:8px;border-top:1px dashed var(--line);color:var(--ink)}
.fb .why b{color:var(--accent);font-weight:600}
.fb small{display:block;color:var(--muted);margin-top:6px;font-size:12.5px}
.row{display:flex;gap:8px;margin-top:10px}
.row .btn{flex:1;min-height:48px;padding:12px 16px}
/* Session screen: slimmer top bar */
.screen.in-session .bar{min-height:40px;margin-bottom:8px}
.screen.in-session .bar h2{font-size:18px}
.screen.in-session .icon{width:40px;height:40px}

/* ---------- Practice filters ---------- */
.filter-row{display:grid;grid-template-columns:62px minmax(0,1fr);align-items:center;gap:10px;margin-top:10px}
.filter-row>span{font-size:12px;letter-spacing:.06em;text-transform:uppercase;color:var(--muted)}
.chips{display:flex;gap:6px;flex-wrap:wrap}
.chips .chip{background:var(--card)}
.pick{margin-top:12px;background:var(--card);border:1px solid var(--line)}
.pick-actions{display:flex;gap:6px;flex-wrap:wrap;margin-bottom:8px}
.pick .study-list{padding-bottom:12px}

/* ---------- Tooth facts + Read more ---------- */
.fb b,.review b,.key b{font-weight:700}
.why b{color:var(--ink)}
.key{margin-top:8px;padding:10px 12px;border-radius:10px;background:var(--paper);font-size:14px;line-height:1.5}
.props{display:grid;grid-template-columns:auto minmax(0,1fr);gap:6px 12px;margin:12px 0 0;padding-top:10px;border-top:1px dashed var(--line);font-size:13.5px}
.props dt{color:var(--muted);font-size:11.5px;letter-spacing:.05em;text-transform:uppercase;padding-top:2px;white-space:nowrap}
.props dd{margin:0;line-height:1.4}
.more{margin-top:12px;border-radius:12px;background:var(--paper);padding:0 12px}
.more summary{cursor:pointer;font-weight:600;font-size:14px;padding:12px 0;list-style:none;display:flex;justify-content:space-between;align-items:center;min-height:44px}
.more summary::-webkit-details-marker{display:none}
.more summary::after{content:"+";font-size:18px;color:var(--accent)}
.more[open] summary::after{content:"−"}
.more h4{font-size:11.5px;letter-spacing:.07em;text-transform:uppercase;color:var(--accent);margin:4px 0 4px;font-weight:600}
.more ul,.more ol{margin:0 0 12px;padding-left:18px;font-size:14px;line-height:1.5}
.more li+li{margin-top:3px}
.more .src{font-size:11.5px;color:var(--muted);padding-bottom:12px}
.steps{margin-top:16px;background:var(--card);border:1px solid var(--line)}

/* ---------- Results ---------- */
.big{font-family:var(--serif);font-size:72px;line-height:1;text-align:center;margin:18px 0 4px}
.sub{color:var(--muted);text-align:center;margin-bottom:18px}
.review{display:grid;gap:8px}
.review div{background:var(--card);border:1px solid var(--line);border-radius:14px;padding:12px 14px;font-size:14px;line-height:1.45}
.review b{font-weight:600}
.review .x{color:var(--accent)} .review .v{color:var(--good)}

/* ---------- Progress chart ---------- */
.chart{background:var(--card);border:1px solid var(--line);border-radius:18px;padding:14px 10px;overflow-x:auto}
.chart .lab{display:flex;justify-content:space-between;font-size:11px;color:var(--muted);padding:0 4px 6px;letter-spacing:.06em;text-transform:uppercase}
.teethrow{display:grid;gap:3px;min-width:0}
.teethrow+.teethrow{margin-top:10px}
.cell{aspect-ratio:3/4;border-radius:7px;display:grid;place-items:center;font-size:10.5px;font-weight:600;border:1px solid var(--line);background:#fff;cursor:pointer;min-width:0}
.cell.l0{background:#fff;color:var(--muted)}
.cell.l1{background:#f2c9bd} .cell.l2{background:#f3e3c4} .cell.l3{background:#d3e6d8}
.legend{display:flex;gap:12px;justify-content:center;font-size:12px;color:var(--muted);margin-top:12px;flex-wrap:wrap}
.legend span::before{content:"";display:inline-block;width:10px;height:10px;border-radius:3px;margin-right:5px;vertical-align:-1px;background:var(--c)}
.confuse{display:grid;gap:8px}
.confuse div{background:var(--card);border:1px solid var(--line);border-radius:14px;padding:12px 14px;font-size:14px;line-height:1.45}

/* ---------- Settings ---------- */
.setting{background:var(--card);border:1px solid var(--line);border-radius:16px;padding:14px;margin-bottom:10px}
.setting>b{display:block;font-weight:600;font-size:15px}
.setting>small{display:block;color:var(--muted);font-size:13px;margin:2px 0 10px}
.toggle{display:flex;align-items:center;justify-content:space-between;gap:16px;cursor:pointer}
.toggle b{display:block;font-weight:600;font-size:15px}
.toggle small{display:block;color:var(--muted);font-size:13px;margin-top:2px}
.toggle input{position:absolute;opacity:0;pointer-events:none}
.toggle i{flex:none;width:50px;height:30px;border-radius:999px;background:var(--line);position:relative;transition:background .15s}
.toggle i::after{content:"";position:absolute;top:3px;left:3px;width:24px;height:24px;border-radius:50%;background:#fff;box-shadow:0 1px 2px rgba(0,0,0,.2);transition:transform .15s}
.toggle input:checked+i{background:var(--accent)}
.toggle input:checked+i::after{transform:translateX(20px)}
.toggle input:focus-visible+i{outline:2px solid var(--ink);outline-offset:2px}
.note{font-size:12.5px;color:var(--muted);line-height:1.5;margin-top:14px}
.study-list{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:6px}
.study-list .chip{text-align:left;border-radius:12px;padding:10px 12px;background:var(--card)}