/* MATH BLITZ v2 — design system: graph-paper exercise book (light) + night (dark)
   Every colour is a token; SVG figures are styled by class so they follow the theme. */
*,*::before,*::after{box-sizing:border-box;margin:0;padding:0;-webkit-tap-highlight-color:transparent}
:root{
  --paper:#f7f3ea; --paper-grid:rgba(52,104,192,.085); --card:#fffdf8; --card2:#f5f0e4; --line:rgba(29,36,51,.10);
  --ink:#1c2333; --ink2:#4a5468; --ink3:#838b9c; --ink4:#b7bcc7;
  --blue:#2f6fe4; --blue-d:#1d52b5; --blue-t:rgba(47,111,228,.12);
  --red:#e0383e; --red-t:rgba(224,56,62,.12); --green:#15945a; --green-t:rgba(21,148,90,.12);
  --gold:#f0a91a; --gold-t:rgba(240,169,26,.16); --hl:#ffe45a; --violet:#7456f1; --violet-t:rgba(116,86,241,.12);
  --teal:#0f9b98; --orange:#ef7a22; --orange-t:rgba(239,122,34,.14);
  --shadow:0 1px 0 rgba(29,36,51,.04),0 8px 22px rgba(29,36,51,.07); --shadow-lg:0 2px 0 rgba(29,36,51,.05),0 18px 44px rgba(29,36,51,.13);
  /* figure tokens */
  --fig-ln:#1c2333; --fig-ln2:#4a5468; --fig-fill:rgba(47,111,228,.07); --fig-grid:rgba(52,104,192,.22); --fig-mk:#4a5468;
  --fig-hi:#ef7a22; --fig-tx:#1c2333; --fig-tx2:#4a5468; --fig-halo:#fffdf8; --fig-shade:rgba(47,111,228,.20);
  --fig-water:rgba(64,150,255,.34); --face1:#e9eef8; --face2:#d3dcee; --face3:#f4f7fc;
  --pie0:#9cc3ff; --pie1:#ffd27a; --pie2:#a8e3c4; --pie3:#ffb0b0; --pie4:#cdb9ff; --pie5:#9fe3e1;
  --bar-known:rgba(47,111,228,.14); --bar-unk:#fff1a8; --bar-hi:rgba(239,122,34,.22);
  --r:18px; --r-sm:12px; --font:'Lexend',system-ui,-apple-system,'Segoe UI',sans-serif; --hand:'Caveat','Comic Sans MS',cursive;
  color-scheme:light;
}
:root[data-theme="night"]{
  --paper:#0f1522; --paper-grid:rgba(120,160,230,.06); --card:#172033; --card2:#1d2840; --line:rgba(230,236,248,.09);
  --ink:#e8edf6; --ink2:#b3bdd0; --ink3:#7f8aa1; --ink4:#4b556a;
  --blue:#5b92ff; --blue-d:#3e78ee; --blue-t:rgba(91,146,255,.16); --red:#ff5a61; --red-t:rgba(255,90,97,.15);
  --green:#3ccf86; --green-t:rgba(60,207,134,.15); --gold:#ffc14d; --gold-t:rgba(255,193,77,.16); --hl:#f5d73b; --violet:#9b84ff; --violet-t:rgba(155,132,255,.16);
  --teal:#34c7c3; --orange:#ff9a4d; --orange-t:rgba(255,154,77,.16);
  --shadow:0 1px 0 rgba(0,0,0,.2),0 8px 24px rgba(0,0,0,.35); --shadow-lg:0 18px 48px rgba(0,0,0,.5);
  --fig-ln:#e8edf6; --fig-ln2:#b3bdd0; --fig-fill:rgba(91,146,255,.10); --fig-grid:rgba(140,170,230,.20); --fig-mk:#b3bdd0;
  --fig-hi:#ffae6b; --fig-tx:#e8edf6; --fig-tx2:#b3bdd0; --fig-halo:#172033; --fig-shade:rgba(91,146,255,.28);
  --fig-water:rgba(64,150,255,.40); --face1:#26334d; --face2:#1e2a40; --face3:#2e3d5a;
  --pie0:#3a6bc4; --pie1:#b98a2e; --pie2:#2f8a60; --pie3:#b04a4a; --pie4:#6a55c2; --pie5:#2a8f8c;
  --bar-known:rgba(91,146,255,.20); --bar-unk:rgba(245,215,59,.30); --bar-hi:rgba(255,154,77,.28);
  color-scheme:dark;
}
html,body{height:100%;overflow:hidden;background:var(--paper);color:var(--ink);font-family:var(--font);font-size:16px;line-height:1.45;
  -webkit-font-smoothing:antialiased;overscroll-behavior:none;-webkit-text-size-adjust:100%;touch-action:manipulation;user-select:none}
body{background-image:linear-gradient(var(--paper-grid) 1px,transparent 1px),linear-gradient(90deg,var(--paper-grid) 1px,transparent 1px);background-size:22px 22px;background-position:-1px -1px}
button{font:inherit;color:inherit;background:none;border:0;cursor:pointer}
button:focus-visible,[tabindex]:focus-visible{outline:3px solid var(--blue);outline-offset:2px}
.hidden{display:none!important}
b,strong{font-weight:700}

/* ================================================================ app shell */
#app{position:relative;height:100%;height:100dvh;max-width:600px;margin:0 auto;display:flex;flex-direction:column;overflow:hidden;
  padding:env(safe-area-inset-top,0) env(safe-area-inset-right,0) 0 env(safe-area-inset-left,0)}
.screen{position:absolute;inset:0;display:flex;flex-direction:column;background:transparent;opacity:1;visibility:visible;transition:opacity .28s ease,transform .28s ease,visibility 0s}
.screen.off{opacity:0;visibility:hidden;pointer-events:none;transform:translateY(8px);transition:opacity .2s,transform .2s,visibility 0s .2s}
.scroll{flex:1;overflow-y:auto;overflow-x:hidden;-webkit-overflow-scrolling:touch;padding:0 16px calc(24px + env(safe-area-inset-bottom,0))}
.scroll::-webkit-scrollbar{width:0}

/* top bars */
.topbar{display:flex;align-items:center;gap:10px;padding:12px 16px 8px;flex-shrink:0}
.topbar .spacer{flex:1}
.topbar h2{font-size:19px;font-weight:700;letter-spacing:-.01em}
.icon-btn{width:40px;height:40px;border-radius:12px;display:grid;place-items:center;color:var(--ink2);background:var(--card);box-shadow:var(--shadow);flex-shrink:0}
.icon-btn svg{width:21px;height:21px}
.icon-btn:active{transform:scale(.94)}
.chip{display:inline-flex;align-items:center;gap:6px;height:32px;padding:0 12px;border-radius:999px;background:var(--card);box-shadow:var(--shadow);font-size:13px;font-weight:600;color:var(--ink2);white-space:nowrap}
.chip b{color:var(--ink)}
.chip.fire b{color:var(--orange)}
.chip.xp b{color:var(--gold)}

/* ================================================================ home */
.home-hero{padding:6px 2px 4px;display:flex;align-items:flex-end;justify-content:space-between;gap:12px}
.wordmark{font-weight:800;font-size:38px;line-height:.9;letter-spacing:-.035em}
.wordmark span{display:block}
.wordmark .blitz{color:var(--blue);position:relative;display:inline-block;isolation:isolate}
.wordmark .blitz::after{content:'';position:absolute;left:-2px;right:-4px;bottom:3px;height:10px;background:var(--hl);opacity:.75;z-index:-1;transform:rotate(-1.5deg);border-radius:3px}
.tagline{font-size:13px;color:var(--ink2);margin-top:8px;font-weight:500}
.hand{font-family:var(--hand);font-weight:700}

.readiness{margin-top:16px;background:var(--card);border-radius:var(--r);box-shadow:var(--shadow);padding:16px;display:grid;grid-template-columns:auto 1fr;gap:16px;align-items:center}
.ring{--p:0;--c:var(--blue);width:94px;height:94px;border-radius:50%;background:conic-gradient(var(--c) calc(var(--p)*1%),var(--line) 0);display:grid;place-items:center;position:relative}
.ring::before{content:'';position:absolute;inset:9px;border-radius:50%;background:var(--card)}
.ring .rv{position:relative;text-align:center;line-height:1}
.ring .rv b{font-size:24px;font-weight:800;display:block}
.ring .rv small{font-size:10.5px;color:var(--ink3);font-weight:600;letter-spacing:.04em}
.readiness h3{font-size:15px;font-weight:700;margin-bottom:3px}
.readiness p{font-size:13px;color:var(--ink2)}
.al-badge{display:inline-flex;align-items:center;gap:6px;margin-top:8px;padding:5px 10px;border-radius:9px;background:var(--blue-t);color:var(--blue-d);font-weight:700;font-size:13px}
:root[data-theme="night"] .al-badge{color:var(--blue)}

.cta{margin-top:14px;width:100%;display:flex;align-items:center;gap:14px;padding:16px 18px;border-radius:var(--r);background:var(--blue);color:#fff;box-shadow:0 10px 26px rgba(47,111,228,.35);text-align:left;position:relative;overflow:hidden}
.cta::after{content:'';position:absolute;right:-30px;top:-30px;width:120px;height:120px;border-radius:50%;background:rgba(255,255,255,.12)}
.cta .ic{font-size:30px;line-height:1}
.cta b{display:block;font-size:18px}
.cta small{font-size:13px;opacity:.88}
.cta .go{margin-left:auto;font-size:22px;font-weight:700}
.cta:active{transform:scale(.985)}
.cta.done{background:var(--green);box-shadow:0 10px 26px rgba(21,148,90,.3)}

.sec-title{font-size:12px;font-weight:700;letter-spacing:.09em;text-transform:uppercase;color:var(--ink3);margin:22px 4px 10px}
.tiles{display:grid;grid-template-columns:1fr 1fr;gap:12px}
.tile{--c:var(--blue);background:var(--card);border-radius:var(--r);box-shadow:var(--shadow);padding:14px 14px 13px;text-align:left;display:flex;flex-direction:column;gap:6px;min-height:118px;position:relative;overflow:hidden;border:1px solid transparent}
.tile:active{transform:scale(.98)}
.tile .ti{width:40px;height:40px;border-radius:12px;display:grid;place-items:center;font-size:21px;background:color-mix(in srgb,var(--c) 14%,transparent);color:var(--c)}
.tile b{font-size:15.5px;line-height:1.2}
.tile small{font-size:12.2px;color:var(--ink2);line-height:1.3}
.tile .meta{margin-top:auto;font-size:11.5px;font-weight:600;color:var(--c)}
.tile.wide{grid-column:span 2;min-height:0;flex-direction:row;align-items:center;gap:12px}
.tile.wide .meta{margin:0 0 0 auto}

.stats-row{display:grid;grid-template-columns:repeat(3,1fr);gap:10px}
.stat{background:var(--card);border-radius:14px;box-shadow:var(--shadow);padding:12px 10px;text-align:center}
.stat b{display:block;font-size:22px;font-weight:800;line-height:1.1}
.stat small{font-size:11px;color:var(--ink3);font-weight:600}

/* ================================================================ lists (levels, topics, skills) */
.seg{display:flex;background:var(--card2);border-radius:12px;padding:4px;gap:4px;margin:4px 0 14px}
.seg button{flex:1;padding:9px 0;border-radius:9px;font-weight:700;font-size:14px;color:var(--ink2)}
.seg button.on{background:var(--card);color:var(--ink);box-shadow:var(--shadow)}
.list{display:flex;flex-direction:column;gap:10px}
.row{--c:var(--blue);display:flex;align-items:center;gap:12px;background:var(--card);border-radius:14px;box-shadow:var(--shadow);padding:13px 14px;text-align:left;width:100%}
.row:active{transform:scale(.99)}
.row .ri{width:38px;height:38px;border-radius:11px;display:grid;place-items:center;font-weight:800;font-size:17px;flex-shrink:0;background:color-mix(in srgb,var(--c) 13%,transparent);color:var(--c)}
.row .rt{flex:1;min-width:0}
.row .rt b{display:block;font-size:15px;line-height:1.25}
.row .rt small{font-size:12px;color:var(--ink3)}
.row .rr{font-size:12px;font-weight:700;color:var(--ink3);text-align:right;flex-shrink:0}
.bar-mini{height:6px;border-radius:9px;background:var(--line);overflow:hidden;margin-top:7px}
.bar-mini i{display:block;height:100%;background:var(--c);border-radius:9px;transition:width .6s}
.stars{letter-spacing:1px;font-size:12px;color:var(--ink4)}
.stars .on{color:var(--gold)}
.strand-head{display:flex;align-items:center;gap:8px;font-size:12px;font-weight:700;letter-spacing:.08em;text-transform:uppercase;color:var(--ink3);margin:18px 4px 8px}
.strand-head::after{content:'';flex:1;height:1px;background:var(--line)}

/* ================================================================ session (question player) */
.sbar{display:flex;align-items:center;gap:10px;padding:10px 14px 6px;flex-shrink:0}
.sbar .prog{flex:1;height:10px;border-radius:9px;background:var(--line);overflow:hidden}
.sbar .prog i{display:block;height:100%;width:0;background:var(--green);border-radius:9px;transition:width .4s cubic-bezier(.2,.8,.2,1)}
.sbar .timer{font-weight:800;font-variant-numeric:tabular-nums;font-size:17px;min-width:48px;text-align:right}
.sbar .timer.warn{color:var(--red);animation:pulse .7s infinite}
.sbar .score{font-weight:800;font-size:16px;font-variant-numeric:tabular-nums}
@keyframes pulse{50%{opacity:.55}}
.stage{flex:1;min-height:0;display:flex;flex-direction:column;padding:4px 14px calc(10px + env(safe-area-inset-bottom,0));position:relative;overflow:hidden;overflow:clip}
/* SAFE centering: auto margins clamp to 0 instead of clipping (never justify-content:center here) */
.qwrap{flex:1;min-height:0;display:flex;flex-direction:column;gap:9px;overflow-y:auto;overflow-x:hidden;scrollbar-width:none}
.qwrap::-webkit-scrollbar{display:none}
.qcard{flex:0 1 auto;min-height:0;margin-top:auto;display:flex;flex-direction:column;background:var(--card);border-radius:var(--r);box-shadow:var(--shadow);padding:clamp(12px,2vh,18px) 16px;overflow-y:auto;overflow-x:hidden;position:relative;scrollbar-width:thin}
.qtag{display:flex;align-items:center;gap:8px;font-size:11.5px;font-weight:700;letter-spacing:.06em;text-transform:uppercase;color:var(--ink3);margin-bottom:8px;flex-shrink:0}
.qtag .dot{width:7px;height:7px;border-radius:50%;background:var(--c,var(--blue))}
.qtag .marks{margin-left:auto;text-transform:none;letter-spacing:0;font-weight:600}
.qprompt{font-size:clamp(15.5px,min(4.4vw,2.5vh),20px);line-height:1.5;font-weight:500;flex-shrink:0}
.qprompt p+p{margin-top:6px}
.qprompt .eq{display:block;text-align:center;font-weight:800;font-size:clamp(34px,10vw,52px);letter-spacing:.01em;padding:6px 0;font-variant-numeric:tabular-nums}
.qfig{flex:1 1 auto;min-height:clamp(70px,14vh,120px);display:flex;align-items:center;justify-content:center;margin-top:10px;overflow:hidden;position:relative}
.qfig > svg,.qfig .fig-row > svg{width:100%;height:auto;max-height:100%;max-width:min(100%,var(--fw,420px))}
.qfig .fig-row{display:flex;gap:10px;align-items:center;justify-content:center;width:100%;height:100%}
.qfig .fig-row > svg{flex:1 1 0;min-width:0}
.qfig .ftbl{max-height:100%}
/* guided problems: the card scrolls, so the model keeps its readable size */
.qcard.guided .qfig{flex:0 0 auto;min-height:0}
.qcard.guided .qfig > svg{max-height:none}
.qright{flex:0 0 auto;display:flex;flex-direction:column;gap:9px;margin-bottom:auto}
.qparts{flex:0 0 auto;display:flex;flex-direction:column;gap:8px}
.qinput{flex:0 0 auto}

/* stacked fractions in text */
.fr{display:inline-flex;flex-direction:column;align-items:center;vertical-align:middle;line-height:1.05;margin:0 .12em;font-weight:inherit;font-variant-numeric:tabular-nums}
.fr .fr-n{border-bottom:.09em solid currentColor;padding:0 .18em .02em}
.fr .fr-d{padding:.04em .18em 0}
.qprompt .fr{font-size:.92em}
.mx{display:inline-flex;align-items:center;gap:.05em}

/* answer fields */
.qasks{display:flex;flex-direction:column;gap:3px;margin-top:6px;font-size:.9em;color:var(--ink2);line-height:1.35}
.qasks b{color:var(--ink)} .qasks .mk{color:var(--ink3);font-size:.85em}
.field{display:flex;align-items:center;gap:10px;background:var(--card);border-radius:14px;box-shadow:var(--shadow);padding:8px 12px;border:2px solid transparent;min-height:clamp(46px,6.6vh,58px);cursor:pointer;transition:border-color .15s}
.field.focus{border-color:var(--blue)}
.field.ok{border-color:var(--green);background:color-mix(in srgb,var(--green) 7%,var(--card))}
.field.bad{border-color:var(--red);background:color-mix(in srgb,var(--red) 6%,var(--card));animation:shake .38s}
.field .flab{font-weight:700;color:var(--ink2);font-size:14px;flex-shrink:0}
.field .ftext{font-size:14px;color:var(--ink2);flex:1;min-width:0;line-height:1.3}
.field .fbox{display:flex;align-items:center;gap:6px;margin-left:auto;font-size:clamp(21px,3.2vh,27px);font-weight:700;font-variant-numeric:tabular-nums;flex-shrink:0}
.field .pre,.field .unit{color:var(--ink2);font-weight:600;font-size:.72em}
.field .unit.tight{margin-left:-5px}
.slot{min-width:1.1em;padding:0 3px;border-radius:7px;text-align:center;color:var(--ink);position:relative;line-height:1.15}
.slot.empty{color:var(--ink4);box-shadow:inset 0 0 0 1.5px var(--ink4);min-width:1.2em}
.slot.empty.on{box-shadow:inset 0 0 0 2px var(--blue)}
.field.ok .slot.empty,.field.bad .slot.empty,.field.locked .slot.empty{box-shadow:none}
.slot.on{background:var(--blue-t)}
.slot.on::after{content:'';position:absolute;right:1px;top:15%;bottom:15%;width:2px;background:var(--blue);animation:blink 1s steps(1) infinite}
@keyframes blink{50%{opacity:0}}
.frbox{display:inline-flex;flex-direction:column;align-items:center;gap:1px}
.frbox .bar{width:100%;min-width:30px;height:2.5px;background:currentColor;border-radius:2px}
.frbox .slot{font-size:.8em}
.sep{color:var(--ink3);font-weight:600}
.ampm{display:inline-flex;border-radius:9px;background:var(--card2);padding:2px;gap:2px;font-size:13px}
.ampm span{padding:4px 7px;border-radius:7px;color:var(--ink3);font-weight:700}
.ampm span.on{background:var(--blue);color:#fff}

/* keypad — phone layout: 1 2 3 on top */
.keypad{display:grid;grid-template-columns:repeat(4,1fr);gap:clamp(5px,1vh,8px);margin-top:clamp(7px,1.2vh,11px)}
.key{height:clamp(40px,6.4vh,56px);border-radius:13px;background:var(--card);box-shadow:0 1px 0 rgba(29,36,51,.07),0 3px 0 rgba(29,36,51,.08);font-size:clamp(19px,3vh,24px);font-weight:700;font-variant-numeric:tabular-nums;display:grid;place-items:center;color:var(--ink);transition:transform .06s}
.key:active{transform:translateY(2px);box-shadow:0 1px 0 rgba(29,36,51,.07)}
.key.fn{color:var(--blue);font-size:clamp(14px,2.2vh,17px);background:var(--card2)}
.key.fn.wide{font-size:13px}
.key.go{grid-column:span 4;background:var(--blue);color:#fff;font-size:17px;letter-spacing:.02em;box-shadow:0 4px 0 var(--blue-d)}
.key.go:disabled{opacity:.45;box-shadow:none}
.key.blank{visibility:hidden}
:root[data-theme="night"] .key{box-shadow:0 3px 0 rgba(0,0,0,.35)}

/* multiple choice */
.opts{display:grid;grid-template-columns:1fr 1fr;gap:9px}
.opts.col1{grid-template-columns:1fr}
.opt{display:flex;align-items:center;gap:10px;background:var(--card);border-radius:14px;box-shadow:var(--shadow);padding:clamp(9px,1.6vh,14px) 12px;min-height:clamp(48px,7vh,60px);text-align:left;border:2px solid transparent;font-weight:600;font-size:clamp(14.5px,2.2vh,17px);transition:border-color .12s,transform .06s}
.opt:active{transform:scale(.985)}
.opt .on{width:24px;height:24px;border-radius:50%;border:2px solid var(--ink4);display:grid;place-items:center;font-size:12px;font-weight:800;color:var(--ink3);flex-shrink:0}
.opt .oc{flex:1;min-width:0;display:block;text-align:center}
.opts.figs .opt .oc{display:flex;align-items:center;justify-content:center}
.opts.col1 .opt .oc{text-align:left}
.opt .oc svg{max-height:92px;width:100%;height:auto}
.opt.sel{border-color:var(--blue)}
.opt.ok{border-color:var(--green);background:color-mix(in srgb,var(--green) 9%,var(--card))}
.opt.ok .on{border-color:var(--green);background:var(--green);color:#fff}
.opt.bad{border-color:var(--red);background:color-mix(in srgb,var(--red) 7%,var(--card))}
.opt.bad .on{border-color:var(--red);background:var(--red);color:#fff}
.opt.dim{opacity:.45}
.opts.figs .opt{flex-direction:column;align-items:stretch;padding:8px}
.opts.figs .opt .on{align-self:flex-start}

/* widget controls */
.wbar{display:flex;align-items:center;justify-content:center;gap:12px;margin-top:10px;flex-wrap:wrap}
.tally{font-weight:700;color:var(--ink2);font-size:15px}
.tally b{color:var(--blue);font-size:19px}
.btn{height:50px;padding:0 18px;border-radius:14px;font-weight:700;font-size:16px;background:var(--card);box-shadow:var(--shadow);display:inline-flex;align-items:center;justify-content:center;gap:8px;white-space:nowrap}
.btn.primary{background:var(--blue);color:#fff;box-shadow:0 4px 0 var(--blue-d)}
.btn.primary:disabled{opacity:.45;box-shadow:none}
.btn.good{background:var(--green);color:#fff;box-shadow:0 4px 0 color-mix(in srgb,var(--green) 70%,#000)}
.btn.ghost{background:transparent;box-shadow:none;color:var(--ink2)}
.btn.block{width:100%}
.btn:active{transform:translateY(2px)}
.chips{display:flex;flex-wrap:wrap;gap:8px;justify-content:center}
.chipbtn{padding:10px 14px;border-radius:12px;background:var(--card);box-shadow:var(--shadow);font-weight:700;font-size:16px;border:2px solid var(--blue-t);font-variant-numeric:tabular-nums}
.slots-row{display:flex;flex-wrap:wrap;gap:8px;justify-content:center;margin:6px 0 10px}
.oslot{min-width:62px;height:48px;border-radius:12px;border:2px dashed var(--ink4);display:grid;place-items:center;font-weight:700;font-size:16px;color:var(--ink3);padding:0 8px}
.oslot.full{border-style:solid;border-color:var(--blue);color:var(--ink);background:var(--card)}
.ends{display:flex;justify-content:space-between;font-size:11px;font-weight:700;letter-spacing:.06em;color:var(--ink3);text-transform:uppercase}

/* interactive figure parts */
.w-seg{cursor:pointer;fill:var(--card);stroke:var(--fig-ln);stroke-width:2;transition:fill .12s}
.w-seg.on{fill:color-mix(in srgb,var(--blue) 55%,transparent)}
.f-tap,.w-cell{cursor:pointer}
.w-cell{fill:transparent;stroke:none}
.w-cell.on{fill:color-mix(in srgb,var(--green) 45%,transparent)}
.w-cell.given{fill:var(--fig-shade)}
.w-cell.user{fill:color-mix(in srgb,var(--blue) 45%,transparent)}
.w-handle{fill:var(--fig-hi);stroke:var(--card);stroke-width:3;cursor:grab}

/* tools: protractor overlay & calculator */
.tool-btns{position:absolute;right:8px;top:8px;display:flex;gap:6px;z-index:5}
.tool-btn{height:32px;padding:0 10px;border-radius:10px;background:var(--card2);font-size:12px;font-weight:700;color:var(--ink2);display:inline-flex;align-items:center;gap:5px}
.tool-btn.on{background:var(--blue);color:#fff}
.proto-ov{position:absolute;left:50%;top:50%;width:230px;touch-action:none;cursor:grab;transform-origin:50% 88%;opacity:.92;z-index:4}
.proto-ov svg{width:100%;height:auto;display:block;filter:drop-shadow(0 3px 8px rgba(0,0,0,.18))}
.proto-ov .rot{position:absolute;right:-6px;top:-6px;width:30px;height:30px;border-radius:50%;background:var(--blue);color:#fff;display:grid;place-items:center;font-size:15px;box-shadow:var(--shadow)}

/* feedback sheet (red-pen marking) */
.fb{position:absolute;left:10px;right:10px;bottom:calc(10px + env(safe-area-inset-bottom,0));z-index:20;background:var(--card);border-radius:20px;box-shadow:var(--shadow-lg);padding:14px 16px 14px;transform:translateY(calc(100% + 40px));visibility:hidden;transition:transform .32s cubic-bezier(.2,.9,.2,1),visibility 0s .32s;max-height:72%;display:flex;flex-direction:column}
.fb.show{transform:none;visibility:visible;transition:transform .32s cubic-bezier(.2,.9,.2,1),visibility 0s}
.fb .fbh{display:flex;align-items:center;gap:12px}
.fb .mark{width:54px;height:54px;flex-shrink:0}
.fb .mark path{fill:none;stroke-width:7;stroke-linecap:round;stroke-linejoin:round;stroke-dasharray:120;stroke-dashoffset:120;animation:draw .5s .05s ease-out forwards}
.fb.good .mark path{stroke:var(--green)}
.fb.bad .mark path{stroke:var(--red)}
.fb.half .mark path{stroke:var(--orange)}
.fb.half .fbt b{color:var(--orange)}
@keyframes draw{to{stroke-dashoffset:0}}
.fb .fbt b{display:block;font-size:19px;font-weight:800}
.fb.good .fbt b{color:var(--green)}
.fb.bad .fbt b{color:var(--red)}
.fb .fbt small{font-size:13.5px;color:var(--ink2)}
.fb .ans{margin-top:4px;font-size:15px}
.fb .ans .k{font-weight:800;color:var(--ink)}
.fb .why{margin-top:10px;font-size:14.5px;line-height:1.55;color:var(--ink);overflow-y:auto;border-top:1px dashed var(--line);padding-top:10px;display:none}
.fb .why.open{display:block}
.fb .fba{display:flex;gap:10px;margin-top:12px}
.fb .fba .btn{flex:1}
.fb .xp{margin-left:auto;font-family:var(--hand);font-size:26px;color:var(--gold);font-weight:700}
@keyframes shake{0%,100%{transform:translateX(0)}20%{transform:translateX(-7px)}40%{transform:translateX(7px)}60%{transform:translateX(-5px)}80%{transform:translateX(5px)}}

/* guided steps (problem solving) */
.steps{display:flex;flex-direction:column;gap:6px;margin-top:10px}
.step{display:flex;gap:10px;align-items:flex-start;font-size:14.5px;line-height:1.45}
.step .sn{width:22px;height:22px;border-radius:7px;background:var(--violet-t);color:var(--violet);font-size:12px;font-weight:800;display:grid;place-items:center;flex-shrink:0;margin-top:1px}
.step.done .sn{background:var(--green);color:#fff}
.step.now{font-weight:600}
.step .sw{color:var(--green);font-weight:700}
.step.later{opacity:.4}

/* results */
.res-hero{text-align:center;padding:10px 0 4px}
.res-hero .big{font-size:58px;font-weight:800;line-height:1;letter-spacing:-.03em}
.res-hero .sub{color:var(--ink2);font-weight:600;margin-top:4px}
.grade{display:inline-block;margin-top:10px;padding:7px 16px;border-radius:12px;font-weight:800;font-size:16px;background:var(--green-t);color:var(--green)}
.grade.al3,.grade.al4{background:var(--gold-t);color:#b87a05}
.grade.al5,.grade.al6,.grade.al7,.grade.al8{background:var(--red-t);color:var(--red)}
.mastery-up{background:var(--card);border-radius:14px;box-shadow:var(--shadow);padding:12px 14px;margin-top:12px}
.mastery-up h4{font-size:12px;letter-spacing:.08em;text-transform:uppercase;color:var(--ink3);margin-bottom:6px}
.mastery-up li{list-style:none;display:flex;justify-content:space-between;gap:10px;font-size:14px;padding:4px 0;border-top:1px dashed var(--line)}
.mastery-up li:first-of-type{border-top:0}

/* teach / library cards */
.teach{background:var(--card);border-radius:var(--r);box-shadow:var(--shadow);padding:16px;font-size:15px;line-height:1.6}
.teach h3{font-size:18px;margin-bottom:8px;line-height:1.25}
.teach p{margin-bottom:8px}
.teach .eg{background:var(--gold-t);border-left:4px solid var(--gold);padding:9px 12px;border-radius:8px;font-weight:500}
.teach ul,.teach ol{padding-left:20px;margin-bottom:8px}
.teach .trap,.teach .warn{background:var(--red-t);border-left:4px solid var(--red);padding:9px 12px;border-radius:8px}
.teach table{border-collapse:collapse;margin:6px 0}
.teach td,.teach th{border:1px solid var(--line);padding:4px 8px;text-align:center}
.tagline-sm{font-size:12px;color:var(--ink3);font-weight:600;margin-bottom:6px}

/* mock exam */
.nav-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(40px,1fr));gap:7px}
.nav-grid button{height:40px;border-radius:10px;background:var(--card);box-shadow:var(--shadow);font-weight:700;font-size:14px}
.nav-grid button.ans{background:var(--blue-t);color:var(--blue-d)}
.nav-grid button.cur{outline:2.5px solid var(--blue)}
.nav-grid button.flag{box-shadow:inset 0 -4px 0 var(--orange),var(--shadow)}
.nav-grid button.ok{background:var(--green-t);color:var(--green)}
.nav-grid button.no{background:var(--red-t);color:var(--red)}
.paper-card{background:var(--card);border-radius:var(--r);box-shadow:var(--shadow);padding:16px;text-align:left;width:100%;display:block}
.paper-card b{font-size:17px;display:block}
.paper-card small{color:var(--ink2);font-size:13px;display:block;margin-top:3px;line-height:1.4}
.paper-card .pc-meta{display:flex;gap:8px;margin-top:10px;flex-wrap:wrap}
.pill{font-size:11.5px;font-weight:700;padding:4px 9px;border-radius:8px;background:var(--card2);color:var(--ink2)}

/* sheets / modals */
.sheet-bg{position:fixed;inset:0;background:rgba(15,20,30,.4);z-index:50;opacity:0;visibility:hidden;transition:opacity .2s,visibility 0s .2s}
.sheet-bg.show{opacity:1;visibility:visible;transition:opacity .2s}
.sheet{position:fixed;left:50%;bottom:0;width:min(600px,100%);transform:translate(-50%,105%);z-index:51;background:var(--card);border-radius:22px 22px 0 0;box-shadow:var(--shadow-lg);padding:14px 16px calc(18px + env(safe-area-inset-bottom,0));max-height:88dvh;overflow-y:auto;transition:transform .3s cubic-bezier(.2,.9,.2,1)}
.sheet.show{transform:translate(-50%,0)}
/* a sheet's main button stays in view even when the lesson above it is long */
.sheet-cta{position:sticky;bottom:calc(-18px - env(safe-area-inset-bottom,0));display:flex;gap:10px;margin:14px -16px calc(-18px - env(safe-area-inset-bottom,0));padding:10px 16px calc(14px + env(safe-area-inset-bottom,0));background:var(--card);border-top:1px solid var(--line);z-index:2}
.sheet .grab{width:44px;height:5px;border-radius:9px;background:var(--line);margin:0 auto 12px}
.sheet h3{font-size:19px;margin-bottom:10px}
.opt-row{display:flex;align-items:center;justify-content:space-between;gap:12px;padding:12px 0;border-top:1px solid var(--line);font-weight:600}
.opt-row:first-of-type{border-top:0}
.switch{width:50px;height:30px;border-radius:99px;background:var(--line);position:relative;transition:background .2s;flex-shrink:0}
.switch::after{content:'';position:absolute;left:3px;top:3px;width:24px;height:24px;border-radius:50%;background:#fff;box-shadow:0 1px 3px rgba(0,0,0,.25);transition:transform .2s}
.switch.on{background:var(--green)}
.switch.on::after{transform:translateX(20px)}

/* calculator */
.calc{display:grid;grid-template-columns:repeat(5,1fr);gap:7px}
.calc .disp{grid-column:span 5;background:var(--card2);border-radius:12px;padding:10px 12px;text-align:right;min-height:64px}
.calc .disp .ex{font-size:14px;color:var(--ink3);min-height:18px;word-break:break-all}
.calc .disp .val{font-size:28px;font-weight:800;font-variant-numeric:tabular-nums;word-break:break-all}
.calc button{height:48px;border-radius:12px;background:var(--card2);font-weight:700;font-size:18px}
.calc button.op{color:var(--blue)}
.calc button.eq{background:var(--blue);color:#fff}

/* toasts, fx */
.toast{position:fixed;left:50%;top:calc(14px + env(safe-area-inset-top,0));transform:translate(-50%,-160%);z-index:80;background:var(--ink);color:var(--card);padding:10px 16px;border-radius:14px;font-weight:700;font-size:14px;box-shadow:var(--shadow-lg);transition:transform .35s cubic-bezier(.2,.9,.2,1),visibility 0s .35s;visibility:hidden;max-width:calc(100% - 28px);white-space:normal;text-align:center}
.toast.show{transform:translate(-50%,0);visibility:visible;transition:transform .35s cubic-bezier(.2,.9,.2,1)}
.fx-layer{position:fixed;inset:0;pointer-events:none;z-index:90;overflow:hidden}
.confetti{position:absolute;width:9px;height:14px;border-radius:2px}
.float-xp{position:absolute;font-family:var(--hand);font-weight:700;font-size:30px;color:var(--gold);text-shadow:0 2px 0 rgba(0,0,0,.08);animation:floatUp 1.1s ease-out forwards}
@keyframes floatUp{0%{opacity:0;transform:translate(-50%,0) scale(.6)}20%{opacity:1;transform:translate(-50%,-10px) scale(1.1)}100%{opacity:0;transform:translate(-50%,-80px)}}
.streak-pop{position:absolute;left:50%;top:18%;transform:translateX(-50%);background:var(--orange);color:#fff;padding:9px 16px;border-radius:14px;font-weight:800;box-shadow:var(--shadow-lg);animation:pop .9s ease-out forwards}
@keyframes pop{0%{opacity:0;transform:translate(-50%,10px) scale(.8)}20%{opacity:1;transform:translate(-50%,0) scale(1.05)}80%{opacity:1}100%{opacity:0;transform:translate(-50%,-14px)}}

/* onboarding */
.onb{display:flex;flex-direction:column;align-items:center;text-align:center;padding:40px 22px 24px;gap:14px}
.onb .levels{display:grid;grid-template-columns:1fr 1fr;gap:12px;width:100%;margin-top:6px}
.onb .levels button{background:var(--card);box-shadow:var(--shadow);border-radius:16px;padding:18px 10px;font-weight:800;font-size:20px}
.onb .levels button small{display:block;font-size:12px;color:var(--ink3);font-weight:600;margin-top:2px}

/* ================================================================ SVG figure styles */
.fig{font-family:var(--font);overflow:visible}
.fig text{fill:var(--fig-tx);paint-order:stroke;stroke:var(--fig-halo);stroke-width:3.5px;stroke-linejoin:round}
.fig .f-tx{fill:var(--fig-tx)} .fig .f-tx2{fill:var(--fig-tx2)} .fig .f-tx3{fill:var(--ink3)} .fig .f-txh{fill:var(--fig-hi);font-weight:800}
.f-ln{stroke:var(--fig-ln);stroke-width:2;stroke-linejoin:round;stroke-linecap:round;fill:none}
.f-ln2{stroke:var(--fig-ln2);stroke-width:1.4;fill:none}
.f-tick{stroke:var(--fig-ln2);stroke-width:.8;fill:none}
.f-grid{stroke:var(--fig-grid);stroke-width:1;fill:none}
.f-dash{stroke:var(--fig-ln2);stroke-width:1.6;stroke-dasharray:5 4;fill:none}
.f-mk{stroke:var(--fig-mk);stroke-width:1.6;fill:none;stroke-linecap:round;stroke-linejoin:round}
.f-hi{stroke:var(--fig-hi);stroke-width:2.2;fill:none}
.f-arcw{stroke-width:2.4}
.f-nofill{fill:none}
.f-fill{fill:var(--fig-fill)}
.f-shade{fill:url(#hatch);stroke:none}
.f-dot{fill:var(--fig-ln);stroke:none}
.f-mk-fill{fill:var(--fig-mk)} .f-hi-fill{fill:var(--fig-hi)}
.f-bar{stroke:var(--fig-ln);stroke-width:1.6}
.f-bar-known{fill:var(--bar-known)} .f-bar-unk{fill:var(--bar-unk)} .f-bar-hi{fill:var(--bar-hi)} .f-bar-shade{fill:url(#hatch)}
.f-bar-ghost{fill:none;stroke-dasharray:4 3;stroke:var(--ink3)} .f-bar-blank{fill:var(--card)}
.f-plot{stroke:var(--blue);stroke-width:2.6;fill:none;stroke-linejoin:round} .f-plotdot{fill:var(--blue);stroke:var(--card);stroke-width:1.5}
.f-pie{stroke:var(--card);stroke-width:2} .f-pie0{fill:var(--pie0)} .f-pie1{fill:var(--pie1)} .f-pie2{fill:var(--pie2)} .f-pie3{fill:var(--pie3)} .f-pie4{fill:var(--pie4)} .f-pie5{fill:var(--pie5)} .f-pie-hot{stroke:var(--fig-hi);stroke-width:3}
.f-cell{fill:var(--fig-shade);stroke:var(--fig-ln2);stroke-width:1.2} .f-cell2{fill:var(--gold-t);stroke:var(--gold);stroke-width:1.2}
.f-axis{stroke:var(--red);stroke-width:2;stroke-dasharray:7 5}
.f-water{fill:var(--fig-water);stroke:none} .f-water2{filter:brightness(.92)} .f-water3{fill:color-mix(in srgb,var(--fig-water) 70%,#fff)}
.f-glass{fill:rgba(160,190,230,.08)}
.f-face1{fill:var(--face1)} .f-face2{fill:var(--face2)} .f-face3{fill:var(--face3)}
.f-net{fill:var(--face1)}
.f-proto{fill:rgba(160,200,255,.14)}
.f-arm{stroke:var(--fig-ln);stroke-width:2.4;stroke-linecap:round}
.f-hand-h{stroke:var(--fig-ln);stroke-width:5;stroke-linecap:round} .f-hand-m{stroke:var(--fig-ln);stroke-width:3;stroke-linecap:round} .f-hand-s{stroke:var(--red);stroke-width:1.5;stroke-linecap:round}
.f-clockface{fill:var(--card)} .f-lcd{fill:#1d2a1f} .fig .f-lcdtx{fill:#9cf59c;stroke:none;font-family:'JetBrains Mono',monospace}
.f-needle{stroke:var(--red);stroke-width:2.6;stroke-linecap:round}
.f-stick{stroke:#c98a3c;stroke-width:3.2;stroke-linecap:round} .f-tile{fill:var(--face1);stroke:var(--fig-ln2)} .f-dotfill{fill:var(--fig-ln)}
.ftbl{border-collapse:collapse;font-size:14px;background:var(--card);border-radius:10px;overflow:hidden;margin:0 auto;font-variant-numeric:tabular-nums}
.ftbl th,.ftbl td{border:1px solid var(--line);padding:6px 11px;text-align:center}
.ftbl thead th{background:var(--card2);font-weight:700;font-size:13px}
.ftbl tbody th{font-weight:600;text-align:left}
.ftbl caption{font-size:12.5px;color:var(--ink2);padding-bottom:6px;font-weight:600}
.blank{display:inline-block;min-width:34px;border-bottom:2px solid var(--blue);color:var(--blue);font-weight:800}

/* ================================================================ landscape / very short screens: question left, input right */
/* auto-fit: app.js adds fit1..fit4 (cumulative) to #qwrap until the question needs no scrolling */
.qwrap.fit1 .opt .oc svg{max-height:74px}
.qwrap.fit2 .opt .oc svg{max-height:58px} .qwrap.fit2 .opts{gap:6px}
.qwrap.fit3 .opt .oc svg{max-height:46px} .qwrap.fit3 .opts.figs .opt{flex-direction:row;align-items:center;padding:4px 8px}
.qwrap.fit4 .opt .oc svg{max-height:36px} .qwrap.fit4 .opt{min-height:30px;font-size:14px}
.mstrip{display:flex;gap:8px;margin-top:8px;flex-shrink:0} .mstrip .btn{flex:1;height:42px}
.qwrap.fit2 .mstrip{margin-top:5px} .qwrap.fit2 .mstrip .btn{height:36px}
.qwrap.fit3 .mstrip .btn{height:32px;font-size:14px} .qwrap.fit4 .mstrip{margin-top:3px} .qwrap.fit4 .mstrip .btn{height:29px}
.qwrap.fit5 .qfig{min-height:22px;margin-top:3px} .qwrap.fit5 .qprompt{font-size:12px} .qwrap.fit5 .qasks{margin-top:3px;gap:1px}
/* last resort on the tiniest screens (mock papers): Save moves on, and ▦ in the header reaches every question */
.qwrap.fit6 .mstrip{display:none}
.qasks.alt{display:none} .qwrap.asks .qasks.alt{display:flex} .qwrap.asks .field .ftext{display:none}

.qwrap.fit1 .qcard{padding:10px 12px} .qwrap.fit1 .qtag{margin-bottom:4px}
.qwrap.fit1 .qprompt{font-size:14.5px;line-height:1.4} .qwrap.fit1 .qfig{min-height:56px;margin-top:6px}
.qwrap.fit1 .field .ftext{font-size:12.5px;line-height:1.25} .qwrap.fit1 .qasks{font-size:.86em}
.qwrap.fit2 .key{height:34px} .qwrap.fit2 .key:not(.fn):not(.go){font-size:18px} .qwrap.fit2 .keypad{gap:4px;margin-top:5px}
.qwrap.fit2 .field{min-height:36px;padding:3px 10px} .qwrap.fit2 .qparts{gap:5px}
.qwrap.fit2 .qprompt{font-size:14px} .qwrap.fit2 .qfig{min-height:46px}
.qwrap.fit2 .ftbl{font-size:12px} .qwrap.fit2 .ftbl th,.qwrap.fit2 .ftbl td{padding:3px 7px} .qwrap.fit2 .ftbl thead th{font-size:11.5px}
.qwrap.fit2 .opt{min-height:38px;padding:5px 9px}
.qwrap.fit3 .qtag{font-size:10px;margin-bottom:2px} .qwrap.fit3 .qprompt{font-size:13px;line-height:1.35}
.qwrap.fit3 .qfig{min-height:38px;margin-top:4px} .qwrap.fit3 .key{height:31px} .qwrap.fit3 .key:not(.fn):not(.go){font-size:17px}
.qwrap.fit3 .opt{min-height:34px;padding:3px 8px}
.qwrap.fit4 .qprompt{font-size:12.5px;line-height:1.28} .qwrap.fit4 .qcard{padding:7px 10px} .qwrap.fit4 .qtag{margin-bottom:1px} .qwrap.fit4 .qfig{min-height:30px}
.qwrap.fit4 .key{height:29px} .qwrap.fit4 .key:not(.fn):not(.go){font-size:16px} .qwrap.fit4 .field{min-height:33px}
.qwrap.fit4 .field .ftext{font-size:11.5px} .qwrap.fit4 .ftbl{font-size:11px} .qwrap.fit4 .ftbl th,.qwrap.fit4 .ftbl td{padding:2px 5px}
/* when the question card has to scroll, fade its bottom edge so the child knows there is more */
.qcard.more{-webkit-mask-image:linear-gradient(#000 calc(100% - 34px),transparent);mask-image:linear-gradient(#000 calc(100% - 34px),transparent)}
/* short portrait phones (iPhone SE, small Android): tighter spacing so more of the question fits */
@media (max-height:640px) and (orientation:portrait){
  .qcard{padding:10px 13px}
  .qtag{margin-bottom:5px}
  .qprompt{font-size:15px;line-height:1.42}
  .qfig{min-height:64px;margin-top:6px}
  .field{min-height:40px;padding:4px 10px}
  .field .ftext{font-size:13px;line-height:1.25}
  .key{height:38px}
  .keypad{gap:5px;margin-top:6px}
  .qparts{gap:6px}
}
@media (max-height:500px) and (orientation:landscape){
  #app{max-width:none}
  .sbar{padding:5px 14px 3px}
  .stage{padding:3px 14px calc(6px + env(safe-area-inset-bottom,0))}
  .qwrap{flex-direction:row;align-items:center;gap:14px}
  .qwrap>.qcard{margin:0;flex:1 1 55%;min-width:0;max-height:100%}
  .qwrap>.qright{flex:1 1 45%;max-width:400px;display:flex;flex-direction:column;max-height:100%;overflow-y:auto}
  .qinput{margin-bottom:0}
  .keypad{margin-top:5px;gap:4px}
  .key{height:34px;font-size:17px}
  .field{min-height:40px;padding:5px 10px}
  .opt{min-height:40px;padding:6px 10px}
  .fb{left:auto;width:min(420px,48%)}
}
@media (min-width:700px){
  #app{max-width:640px}
  .tiles{grid-template-columns:1fr 1fr 1fr}
  .tile.wide{grid-column:span 3}
}
@media (prefers-reduced-motion:reduce){*{animation-duration:.01ms!important;transition-duration:.01ms!important}}