@font-face{font-family:'Luckiest Guy';font-style:normal;font-weight:400;font-display:swap;src:url(fonts/luckiest-guy-400.woff2) format('woff2')}
@font-face{font-family:'Nunito';font-style:normal;font-weight:400 600;font-display:swap;src:url(fonts/nunito-400-600.woff2) format('woff2')}
@font-face{font-family:'Nunito';font-style:normal;font-weight:700;font-display:swap;src:url(fonts/nunito-700.woff2) format('woff2')}
@font-face{font-family:'Nunito';font-style:normal;font-weight:800;font-display:swap;src:url(fonts/nunito-800.woff2) format('woff2')}
/* Layout: a student "tile desk". The board comes first (tray of tiles, then the board they move on),
   then the equation builder, then the strategy and answer. One column, phone-first. */
:root{
  --navy:#1D5B8D; --sky:#0B7CC9; --green:#3CC47C; --green-ink:#1E8A52;
  --bg:#EEF5FB; --paper:#FFFFFF; --ink:#16324A; --muted:#557089; --line:#CFE0EE; --field:#F7FBFE;
  --pill-good:#DDF5E8; --pill-mid:#FFF1CC; --pill-low:#FDE2DF;
  --pill-good-ink:#15693F; --pill-mid-ink:#7A5400; --pill-low-ink:#9A2A1F;
  --title-fill:#0B7CC9; --title-stroke:#12344F;
  --go:#3CC47C; --go-ink:#0B2A18; --track:#E6EFF7; --tile-edge:rgba(10,30,50,.38);
  /* tile colors: fill and the ink that reads on it. The same in both themes, like real plastic tiles. */
  --t1:#3CC47C; --i1:#0B2A18; --t2:#4FA8E6; --i2:#06243A; --t3:#F2762E; --i3:#2B1000; --t4:#F7A531; --i4:#2B1900;
  --t5:#A8D63F; --i5:#1F2B00; --t6:#FFDD3C; --i6:#2B2400; --t7:#E5484D; --i7:#FFFFFF; --t8:#F29BC1; --i8:#3A0A20;
  --t9:#2F6FD0; --i9:#FFFFFF; --t10:#9B4FC4; --i10:#FFFFFF; --t11:#18A7A0; --i11:#002422; --t12:#F4F6F8; --i12:#16324A;
  --shadow:0 1px 0 #d7e6f2, 0 10px 30px -18px rgba(29,91,141,.45);
  --f-display:"Luckiest Guy","Arial Rounded MT Bold","Trebuchet MS",sans-serif;
  --f-body:"Nunito",system-ui,-apple-system,"Segoe UI",sans-serif;
  color-scheme:light;
}
@media (prefers-color-scheme: dark){:root:not([data-theme="light"]){
  --bg:#0E1B27;--paper:#15283A;--ink:#E6F0F8;--muted:#9BB3C8;--line:#27425A;--field:#10202F;
  --navy:#5CADE2;--sky:#5CADE2;--green-ink:#5FD897;
  --pill-good:#153B2A;--pill-mid:#3B3013;--pill-low:#44211E;
  --pill-good-ink:#7FE3AE;--pill-mid-ink:#F4CF6E;--pill-low-ink:#F6A79E;
  --title-fill:#5CADE2;--title-stroke:#06121C;--track:#1B3147;--tile-edge:rgba(0,0,0,.55);
  --shadow:0 12px 30px -20px rgba(0,0,0,.8);color-scheme:dark}}
:root[data-theme="dark"]{
  --bg:#0E1B27;--paper:#15283A;--ink:#E6F0F8;--muted:#9BB3C8;--line:#27425A;--field:#10202F;
  --navy:#5CADE2;--sky:#5CADE2;--green-ink:#5FD897;
  --pill-good:#153B2A;--pill-mid:#3B3013;--pill-low:#44211E;
  --pill-good-ink:#7FE3AE;--pill-mid-ink:#F4CF6E;--pill-low-ink:#F6A79E;
  --title-fill:#5CADE2;--title-stroke:#06121C;--track:#1B3147;--tile-edge:rgba(0,0,0,.55);
  --shadow:0 12px 30px -20px rgba(0,0,0,.8);color-scheme:dark}

*{box-sizing:border-box}
body{background:var(--bg);color:var(--ink);font-family:var(--f-body);font-size:16px;line-height:1.5;margin:0}
.wrap{max-width:900px;margin:0 auto;padding-inline:clamp(16px,4vw,32px);padding-block:12px 40px}
button,input{font-family:inherit}
:focus-visible{outline:3px solid var(--green);outline-offset:2px}
.brandbar{display:flex;justify-content:space-between;align-items:center;gap:12px;font-weight:800;color:var(--navy);font-size:.9rem}
.brandbar a{color:inherit;text-decoration:none}
.kit{letter-spacing:.08em;text-transform:uppercase;font-size:.72rem;color:var(--muted)}
.hero{display:flex;align-items:center;margin-block:4px 8px}
.hero-text{flex:1;min-width:0;padding-bottom:clamp(8px,3vw,28px)}
.eyebrow{font-weight:800;color:var(--green-ink);letter-spacing:.08em;text-transform:uppercase;font-size:.78rem}
h1{font-family:var(--f-display);font-weight:400;font-size:clamp(2.2rem,7.2vw,4.2rem);line-height:.95;margin:4px 0 10px;color:var(--title-fill);-webkit-text-stroke:2px var(--title-stroke);paint-order:stroke fill;letter-spacing:.01em;text-wrap:balance;text-shadow:0 3px 0 var(--title-stroke)}
.tagline{margin:0;color:var(--muted);font-weight:700;max-width:46ch}
.roji{flex:0 0 auto;width:clamp(110px,24vw,210px);margin-left:-1.5%}
.roji img{width:100%;height:auto;display:block;filter:drop-shadow(0 8px 12px rgba(18,52,79,.18))}

.stack{display:grid;gap:18px}
.sheet{background:var(--paper);border-radius:18px;box-shadow:var(--shadow);padding:clamp(14px,3vw,24px);min-width:0;display:grid;gap:12px}
.sheet-head{display:flex;justify-content:space-between;align-items:center;gap:10px;flex-wrap:wrap}
h2{font-size:1.15rem;margin:0;font-weight:800;text-wrap:balance}
h3{font-size:1rem;margin:0;font-weight:800}
.hint{color:var(--muted);font-size:.92rem;margin:0;max-width:65ch}
.row{display:flex;gap:8px;flex-wrap:wrap;align-items:center}
.example{font-size:.72rem;font-weight:800;letter-spacing:.06em;text-transform:uppercase;color:var(--pill-mid-ink);background:var(--pill-mid);padding:3px 9px;border-radius:999px}

/* buttons */
.btn{appearance:none;border:2px solid var(--line);background:var(--paper);color:var(--ink);font:800 .92rem var(--f-body);padding:8px 14px;border-radius:12px;cursor:pointer;min-height:42px}
.btn:disabled{opacity:.45;cursor:default}
.btn.go{background:var(--go);border-color:var(--go);color:var(--go-ink);font-size:1rem;padding:10px 18px}
.btn.par{font-size:1.15rem;min-width:46px;padding-inline:10px}
.seg{display:inline-flex;border:2px solid var(--line);border-radius:999px;padding:2px;background:var(--field)}
.seg button{appearance:none;border:0;background:transparent;color:var(--ink);font:800 .92rem var(--f-body);padding:7px 16px;border-radius:999px;cursor:pointer;min-height:38px}
.seg button[aria-checked="true"]{background:var(--navy);color:var(--paper)}

/* textbook math (same classes the engine draws with) */
.m{font-variant-numeric:tabular-nums;line-height:1.2}
.fr{display:inline-flex;flex-direction:column;align-items:center;vertical-align:middle;margin:0 .12em;font-size:.86em}
.fn{border-bottom:2px solid currentColor;padding:0 .18em;line-height:1.15}
.fd{padding:0 .18em;line-height:1.15}
.mx{display:inline-flex;align-items:center;white-space:nowrap}
.op{margin:0 .28em}
.pa{color:var(--muted)}
.slot{display:inline-block;border:2px dashed var(--sky);color:var(--sky);border-radius:8px;padding:0 .4em;font-size:.8em;font-weight:800;vertical-align:middle;white-space:nowrap}

/* tiles */
.c1{--tf:var(--t1);--ti:var(--i1)}.c2{--tf:var(--t2);--ti:var(--i2)}.c3{--tf:var(--t3);--ti:var(--i3)}.c4{--tf:var(--t4);--ti:var(--i4)}
.c5{--tf:var(--t5);--ti:var(--i5)}.c6{--tf:var(--t6);--ti:var(--i6)}.c7{--tf:var(--t7);--ti:var(--i7)}.c8{--tf:var(--t8);--ti:var(--i8)}
.c9{--tf:var(--t9);--ti:var(--i9)}.c10{--tf:var(--t10);--ti:var(--i10)}.c11{--tf:var(--t11);--ti:var(--i11)}.c12{--tf:var(--t12);--ti:var(--i12)}
.tray{display:grid;grid-template-columns:repeat(12,minmax(0,1fr));gap:6px}
@media (max-width:640px){.tray{grid-template-columns:repeat(6,minmax(0,1fr))}}
.tile{appearance:none;background:var(--tf);color:var(--ti);border:1.5px solid var(--tile-edge);border-radius:9px;font:800 1.05rem var(--f-body);min-height:48px;display:grid;place-items:center;cursor:pointer;padding:2px;user-select:none;-webkit-user-select:none;box-shadow:0 2px 0 var(--tile-edge)}
#tray .tile{cursor:grab;touch-action:none}
.ghost{position:fixed;z-index:50;pointer-events:none;width:56px;transform:translate(-50%,-50%) rotate(-4deg);opacity:.92}

.board{position:relative;background:var(--field);border:2px dashed var(--line);border-radius:14px;overflow:hidden;user-select:none;-webkit-user-select:none}
.track{position:absolute;background:var(--track);border-radius:7px}
.piece{position:absolute;display:grid;place-items:center;border-radius:7px;background:var(--tf);color:var(--ti);font-weight:800;font-size:1rem;border:1.5px solid var(--tile-edge);cursor:grab;touch-action:none;box-shadow:0 2px 0 var(--tile-edge);overflow:hidden}
.piece.small{font-size:.78rem}
.piece.sel{outline:3px solid var(--ink);outline-offset:1px}
.piece.drag,.cp.drag path{cursor:grabbing}
.piece.drag{box-shadow:0 8px 16px -6px rgba(0,0,0,.45)}
.plate{position:absolute;border-radius:50%;background:var(--track);border:2px dashed var(--line)}
.cp path:focus-visible,.cp circle:focus-visible{outline:none;stroke:var(--green);stroke-width:4}
.cp{position:absolute;pointer-events:none;overflow:visible}
.cp path,.cp circle{pointer-events:auto;fill:var(--tf);stroke:var(--tile-edge);stroke-width:1.5;cursor:grab;touch-action:none}
.cp text{fill:var(--ti);font-family:var(--f-body);font-weight:800;pointer-events:none;text-anchor:middle}
.cp line{stroke:var(--ti);stroke-width:1.5;pointer-events:none}
.cp.sel path,.cp.sel circle{stroke:var(--ink);stroke-width:3.5}
.board.over,.eqzone.over{border-color:var(--green);border-style:solid}
.compare{background:var(--field);border-left:5px solid var(--sky);border-radius:10px;padding:10px 14px;font-weight:700;min-height:52px;display:flex;align-items:center}
.compare p{margin:0}

/* equation builder */
.ops{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:8px}
.opbtn{appearance:none;border:2px solid var(--line);background:var(--paper);color:var(--ink);border-radius:12px;padding:6px 4px;cursor:pointer;display:grid;justify-items:center;font:800 .82rem var(--f-body);min-height:56px}
.opbtn b{font-size:1.5rem;line-height:1}
.opbtn[aria-checked="true"]{background:var(--navy);border-color:var(--navy);color:var(--paper)}
.eqzone{border:2px dashed var(--line);border-radius:14px;background:var(--field);padding:14px;min-height:92px;display:flex;align-items:center;overflow-x:auto}
.eq{display:flex;flex-wrap:wrap;align-items:center;gap:6px 4px;font-size:1.6rem;font-weight:800;min-width:0}
.eq .empty{font-size:1rem;color:var(--muted);font-weight:700}
.term{appearance:none;background:var(--tf);color:var(--ti);border:1.5px solid var(--tile-edge);border-radius:10px;font:inherit;padding:4px 10px;min-width:46px;min-height:54px;cursor:pointer;box-shadow:0 2px 0 var(--tile-edge)}
.opchip{appearance:none;border:0;background:transparent;color:var(--ink);font:inherit;cursor:pointer;padding:4px 6px;border-radius:8px;min-height:44px}
.eq .pa{font-size:2.2rem;font-weight:600;line-height:1}
.eq .q{color:var(--muted)}
.howmany{border:2px solid var(--sky);border-radius:14px;padding:12px;display:grid;gap:10px;background:var(--field)}
.howmany p{margin:0;font-weight:800;font-size:1.05rem}
.hm-nums{display:grid;grid-template-columns:repeat(6,minmax(0,1fr));gap:6px}
.hm-nums button{appearance:none;border:2px solid var(--line);background:var(--paper);color:var(--ink);border-radius:10px;font:800 1.15rem var(--f-body);min-height:58px;cursor:pointer;display:grid;justify-items:center;padding:4px 2px}
.hm-nums small{font-size:.7rem;color:var(--muted);font-weight:800}
.err{margin:0;color:var(--pill-low-ink);font-weight:800}
.err:empty{display:none}

/* strategy, answer, steps */
.pemdas{display:flex;gap:6px;flex-wrap:wrap;list-style:none;margin:0;padding:0}
.pemdas li{border:2px solid var(--line);border-radius:10px;padding:4px 10px;font-weight:800;font-size:.85rem;color:var(--muted)}
.pemdas li b{font-family:var(--f-display);font-weight:400;font-size:1.05rem;margin-right:6px;letter-spacing:.04em}
.pemdas li.on{background:var(--navy);border-color:var(--navy);color:var(--paper)}
.bigeq{font-size:1.5rem;font-weight:800;overflow-x:auto;padding-block:4px}
.steps{list-style:none;margin:0;padding:0;display:grid;gap:12px}
.steps>li{border:2px solid var(--line);border-radius:14px;padding:12px 14px;display:grid;gap:8px;min-width:0}
.st-h{display:flex;gap:8px;align-items:baseline;flex-wrap:wrap;font-weight:800}
.st-n{background:var(--pill-good);color:var(--pill-good-ink);border-radius:999px;padding:1px 10px;font-size:.8rem;white-space:nowrap}
.st-eq{font-size:1.3rem;font-weight:800;overflow-x:auto;padding-block:2px}
.part{display:grid;gap:2px;min-width:0}
.part .pt{font-weight:800;color:var(--navy);font-size:.92rem}
.part .pm{font-size:1.05rem;overflow-x:auto;padding-block:2px}
.now{color:var(--muted);font-weight:700;overflow-x:auto}
.answer{display:flex;gap:12px;align-items:center;flex-wrap:wrap}
.boxes{display:flex;align-items:center;gap:8px}
.boxes input{width:62px;height:50px;text-align:center;font:800 1.3rem var(--f-body);border:2px solid var(--line);border-radius:10px;background:var(--field);color:var(--ink)}
.boxes .stackbox{display:grid;gap:4px}
.boxes .stackbox hr{border:0;border-top:3px solid var(--ink);margin:0;width:100%}
.lbl{font-size:.75rem;color:var(--muted);font-weight:800;text-align:center}
.dots{display:flex;gap:6px;align-items:center;font-weight:800;color:var(--muted);font-size:.9rem}
.dot{width:14px;height:14px;border-radius:50%;border:2px solid var(--line);background:var(--paper)}
.dot.used{background:var(--pill-low-ink);border-color:var(--pill-low-ink)}
.dot.won{background:var(--green);border-color:var(--green)}
.fb{margin:0;border-radius:12px;padding:10px 14px;font-weight:800}
.fb:empty{display:none}
.fb.good{background:var(--pill-good);color:var(--pill-good-ink)}
.fb.mid{background:var(--pill-mid);color:var(--pill-mid-ink)}
.fb.low{background:var(--pill-low);color:var(--pill-low-ink)}
.reveal{display:grid;gap:12px}
.final{font-size:1.4rem;font-weight:800;background:var(--pill-good);color:var(--pill-good-ink);border-radius:12px;padding:10px 14px;overflow-x:auto}
details>summary{cursor:pointer;font-weight:800;color:var(--navy);padding-block:6px}
details[open]>summary{margin-bottom:8px}

footer{margin-top:28px;display:flex;justify-content:space-between;gap:12px;flex-wrap:wrap;color:var(--muted);font-size:.85rem;font-weight:700}
footer a{color:var(--navy)}
.privacy{max-width:62ch}
.privacy b{color:var(--ink)}
@media (max-width:480px){.eq{font-size:1.3rem}.term{min-height:48px;padding-inline:8px}.boxes input{width:54px}}
@media (prefers-reduced-motion:reduce){*{transition:none!important;animation:none!important}}