/* Roji Bar Model Builder.
   Layout: Roji brand header; the story stays beside the work on wide screens (stacked on phones);
   the work runs top to bottom as the four steps a student follows. */
:root{
  --navy:#1D5B8D; --sky:#0B7CC9; --green:#3CC47C; --green-ink:#1E8A52;
  --bg:#EEF5FB; --surface:#FFFFFF; --ink:#16324A; --muted:#557089; --line:#CFE0EE; --field:#F7FBFE; --tint:#E3EFF9;
  --on-navy:#FFFFFF; --warn-bg:#FFF1CC; --warn-ink:#7A5400; --ok-bg:#DDF5E8; --ok-ink:#15693F;
  --part:#D4E8F8; --part-line:#0B7CC9; --unit:#D3F3E1; --unit-line:#2FA869; --unk:#FFE9A3; --unk-line:#B97A00;
  --brace:#557089;
  --title-fill:#0B7CC9; --title-stroke:#12344F;
  --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; --surface:#15283A; --ink:#E6F0F8; --muted:#9BB3C8; --line:#27425A; --field:#10202F; --tint:#1B3247;
  --navy:#5CADE2; --sky:#5CADE2; --green-ink:#5FD897; --on-navy:#06121C;
  --warn-bg:#3B3013; --warn-ink:#F4CF6E; --ok-bg:#153B2A; --ok-ink:#7FE3AE;
  --part:#1E4466; --part-line:#5CADE2; --unit:#1A4A35; --unit-line:#5FD897; --unk:#4A3B10; --unk-line:#F4CF6E;
  --brace:#9BB3C8;
  --title-fill:#5CADE2; --title-stroke:#06121C; --shadow:0 12px 30px -20px rgba(0,0,0,.8); color-scheme:dark}}
:root[data-theme="dark"]{
  --bg:#0E1B27; --surface:#15283A; --ink:#E6F0F8; --muted:#9BB3C8; --line:#27425A; --field:#10202F; --tint:#1B3247;
  --navy:#5CADE2; --sky:#5CADE2; --green-ink:#5FD897; --on-navy:#06121C;
  --warn-bg:#3B3013; --warn-ink:#F4CF6E; --ok-bg:#153B2A; --ok-ink:#7FE3AE;
  --part:#1E4466; --part-line:#5CADE2; --unit:#1A4A35; --unit-line:#5FD897; --unk:#4A3B10; --unk-line:#F4CF6E;
  --brace:#9BB3C8;
  --title-fill:#5CADE2; --title-stroke:#06121C; --shadow:0 12px 30px -20px rgba(0,0,0,.8); color-scheme:dark}

*{box-sizing:border-box}
[hidden]{display:none!important}
html{-webkit-text-size-adjust:100%}
body{margin:0;background:var(--bg);color:var(--ink);font-family:var(--f-body);font-size:16px;line-height:1.5}
.wrap{max-width:1180px;margin:0 auto;padding-inline:clamp(16px,3vw,32px);padding-block:12px 40px}
button,input,select,textarea{font-family:inherit}
:focus-visible{outline:3px solid var(--green);outline-offset:2px}
p{margin:0}

/* ---------- brand header (same on every Roji tool) ---------- */
.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}
.brandbar .kit{letter-spacing:.08em;text-transform:uppercase;font-size:.72rem;color:var(--muted)}
.hero{display:flex;align-items:center;margin-block:4px 10px}
.hero-text{flex:1;min-width:0;padding-bottom:clamp(8px,2vw,20px)}
.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(2.1rem,6vw,3.8rem);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)}
h1 .grades{font-size:.5em;white-space:nowrap;-webkit-text-stroke:1.5px var(--title-stroke);text-shadow:0 2px 0 var(--title-stroke)}
.tagline{color:var(--muted);font-weight:700;max-width:52ch}
.roji{flex:0 0 auto;width:clamp(110px,20vw,200px);display:block}
.roji img{width:100%;height:auto;display:block;filter:drop-shadow(0 8px 12px rgba(18,52,79,.18))}

/* ---------- layout ---------- */
.app{display:grid;grid-template-columns:minmax(0,340px) minmax(0,1fr);gap:20px;align-items:start}
.work{display:grid;gap:16px;min-width:0}
.story{position:sticky;top:calc(env(safe-area-inset-top,0px) + 12px)}
@media (max-width:900px){.app{grid-template-columns:minmax(0,1fr)}.story{position:static}}
.panel{background:var(--surface);border-radius:18px;box-shadow:var(--shadow);padding:16px 20px 20px;min-width:0;display:grid;gap:12px}
.panel h2{font-size:1.05rem;font-weight:800;margin:0;color:var(--navy);display:flex;align-items:center;gap:10px}
.num{display:inline-grid;place-items:center;width:30px;height:30px;border-radius:50%;background:var(--navy);color:var(--on-navy);font-family:var(--f-display);font-size:1.05rem;padding-top:2px;flex:none}
label{display:block;font-size:.9rem;font-weight:800;color:var(--muted)}
.hint{font-weight:600;font-size:.84rem;color:var(--muted)}
input,textarea{font-size:1rem;font-weight:700;color:var(--ink);background:var(--field);border:2px solid var(--line);border-radius:10px;padding:9px 10px;min-height:44px;min-width:0}
textarea{width:100%;resize:vertical;line-height:1.4}
input:focus,textarea:focus{border-color:var(--sky)}

.btn{display:inline-flex;align-items:center;justify-content:center;font-size:.95rem;font-weight:800;border:2px solid var(--navy);background:var(--navy);color:var(--on-navy);
  border-radius:12px;padding:9px 16px;min-height:44px;cursor:pointer;text-decoration:none}
.btn.ghost{background:transparent;color:var(--navy)}
.btn.small{font-size:.86rem;padding:6px 12px}
.btn.big{font-size:1.05rem;padding:10px 22px}
.btn[aria-pressed="true"]{background:var(--navy);color:var(--on-navy)}
.btn:disabled{opacity:.45;cursor:not-allowed}
.actions{display:flex;flex-wrap:wrap;gap:8px}
.actions:has(> :not([hidden])) {margin-top:2px}
.seg-row{display:flex;flex-wrap:wrap;gap:6px}
.chip{font-size:.9rem;font-weight:800;border:2px solid var(--line);background:var(--surface);color:var(--ink);border-radius:999px;padding:8px 13px;min-height:44px;cursor:pointer}
.chip[aria-pressed="true"]{background:var(--navy);color:var(--on-navy);border-color:var(--navy)}

/* ---------- story ---------- */
.storytext{font-size:1.2rem;font-weight:700;line-height:1.45;background:var(--tint);border-radius:14px;padding:14px 16px;overflow-wrap:break-word;white-space:pre-wrap}
.own{display:grid;gap:8px;border-top:2px dashed var(--line);padding-top:12px}
.ask{margin:0;padding-left:1.2em;display:grid;gap:4px;font-size:.92rem;font-weight:600;color:var(--muted)}
.ask b{color:var(--unk-line)}

.example{display:flex;flex-wrap:wrap;gap:8px 14px;align-items:center;justify-content:space-between;background:var(--warn-bg);color:var(--warn-ink);border-radius:12px;padding:8px 12px;font-weight:700}
.example .btn.ghost{color:var(--warn-ink);border-color:currentColor}

/* ---------- pieces ---------- */
.tray{display:flex;flex-wrap:wrap;gap:8px;align-items:center}
.tray-tip{font-size:.84rem;font-weight:700;color:var(--muted)}
.piece{font-size:.95rem;font-weight:800;min-height:46px;min-width:86px;padding:8px 14px;border-radius:8px;border:2.5px solid var(--part-line);background:var(--part);color:var(--ink);cursor:grab;touch-action:none}
.piece.unk{background:var(--unk);border-color:var(--unk-line)}
.piece.unit{background:var(--unit);border-color:var(--unit-line)}
.ghost-piece{position:fixed;left:0;top:0;z-index:50;pointer-events:none;min-width:70px;height:46px;border-radius:8px;display:grid;place-items:center;font-weight:800;padding:0 12px;
  border:2.5px solid var(--part-line);background:var(--part);color:var(--ink);opacity:.92;box-shadow:0 10px 20px -8px rgba(0,0,0,.45)}
.ghost-piece.unk{background:var(--unk);border-color:var(--unk-line)}
.ghost-piece.unit{background:var(--unit);border-color:var(--unit-line)}

/* ---------- board ---------- */
.board{display:grid;gap:14px;background:var(--field);border:2px dashed var(--line);border-radius:14px;padding:14px;min-width:0}
.barrow{display:grid;gap:4px;min-width:0;border-radius:10px;padding:2px}
.barrow.drop{background:var(--tint)}
.barhead{display:flex;gap:8px;align-items:center}
.barname{flex:0 1 220px;min-height:36px;padding:4px 8px;font-size:.9rem;border-style:dashed;background:transparent}
.rmbar{margin-left:auto;border:0;background:transparent;color:var(--muted);font-weight:800;font-size:.82rem;min-height:36px;padding:0 6px;cursor:pointer;text-decoration:underline}
.lane{display:grid;gap:3px;min-width:0}
.track{display:flex;align-items:stretch;min-width:0}
.bar{display:flex;min-width:0;min-height:52px}
.bar.empty{border:2.5px dashed var(--line);border-radius:8px;align-items:center;justify-content:center;color:var(--muted);font-weight:700;font-size:.88rem;flex:1}
.seg{position:relative;min-width:0;display:flex;background:var(--part);border:2.5px solid var(--part-line);margin-right:-2.5px;touch-action:none;cursor:grab}
.seg:first-child{border-radius:8px 0 0 8px}
.seg:last-child{border-radius:0 8px 8px 0;margin-right:0}
.seg:only-child{border-radius:8px}
.seg.unit{background:var(--unit);border-color:var(--unit-line)}
.seg.unk{background:var(--unk);border-color:var(--unk-line)}
.seg.sel{z-index:2;box-shadow:0 0 0 3px var(--surface),0 0 0 6px var(--navy)}
.seg.pick{outline:3px dashed var(--navy);outline-offset:-6px}
.seg.ins-before::before,.seg.ins-after::after{content:"";position:absolute;top:-6px;bottom:-6px;width:5px;border-radius:3px;background:var(--navy);z-index:3}
.seg.ins-before::before{left:-5px}
.seg.ins-after::after{right:-5px}
.seg .lbl{width:100%;border:0;background:transparent;text-align:center;padding:4px 2px;min-height:47px;font-weight:800;font-size:1.05rem;border-radius:0}
.seg .lbl::placeholder{color:var(--muted);opacity:.55;font-weight:700}
.grip{position:absolute;right:-9px;top:0;bottom:0;width:18px;cursor:ew-resize;z-index:4;touch-action:none}
.seg.sel .grip::after{content:"";position:absolute;left:6px;top:25%;bottom:25%;width:6px;border-radius:3px;background:var(--navy)}
.diff{flex:0 0 auto;min-width:54px;display:flex;align-items:center;border:2.5px dashed var(--brace);border-left:0;border-radius:0 8px 8px 0}
.diff input,.brk input,.whole input,.grand input{border:0;border-bottom:2px solid var(--line);border-radius:0;background:transparent;text-align:center;min-height:36px;padding:2px;font-weight:800}
.diff input{width:100%;border-bottom:0}
.tops{display:grid;gap:2px;min-width:0}
.brk{display:grid;justify-items:center;min-width:0;position:relative}
.brk input{width:min(100%,8.5em)}
.brk .rm{position:absolute;right:0;top:0;border:0;background:transparent;color:var(--muted);font-weight:800;min-width:30px;min-height:32px;cursor:pointer}
.brk::after,.whole::before{content:"";display:block;width:100%;height:9px;border:2.5px solid var(--brace)}
.brk::after{border-bottom:0;border-radius:6px 6px 0 0}
.whole{display:grid;justify-items:center;min-width:0}
.whole::before{border-top:0;border-radius:0 0 6px 6px}
.whole input{width:min(100%,8.5em)}
.grand{display:flex;flex-wrap:wrap;align-items:center;gap:8px;border-top:2.5px solid var(--brace);padding-top:8px;font-weight:800;color:var(--muted);font-size:.9rem}
.grand input{width:8.5em}
.note{font-size:.88rem;font-weight:700;color:var(--warn-ink);background:var(--warn-bg);border-radius:10px;padding:6px 10px}

.toolbar{display:flex;flex-wrap:wrap;gap:6px;align-items:center;min-height:44px}
.toolbar .tip{font-size:.88rem;font-weight:700;color:var(--muted)}
.toolbar .what{font-size:.82rem;font-weight:800;text-transform:uppercase;letter-spacing:.06em;color:var(--muted);margin-right:2px}
.tb{font-size:.88rem;font-weight:800;border:2px solid var(--line);background:var(--surface);color:var(--ink);border-radius:10px;padding:6px 11px;min-height:44px;min-width:44px;cursor:pointer}
.tb:disabled{opacity:.4;cursor:not-allowed}
.boardtools{display:flex;flex-wrap:wrap;gap:6px;border-top:2px dashed var(--line);padding-top:12px}
.checkrow{display:flex;flex-wrap:wrap;gap:10px 14px;align-items:center}
.checkrow .fb{flex:1 1 260px}

/* ---------- feedback and steps ---------- */
.fb{border-radius:12px;padding:10px 14px;font-weight:700;background:var(--tint);color:var(--ink);max-width:65ch}
.fb.ok{background:var(--ok-bg);color:var(--ok-ink)}
.fb.warn{background:var(--warn-bg);color:var(--warn-ink)}
.lock{font-weight:700;color:var(--muted)}
.step.locked h2{color:var(--muted)}
.step.locked .num{background:var(--line);color:var(--muted)}
.step.locked .stepbody{display:none}
.step:not(.locked) .lock{display:none}
.stepbody{display:grid;gap:10px}
.inrow{display:flex;flex-wrap:wrap;gap:8px;align-items:center}
.inrow input{flex:1 1 160px;font-size:1.2rem;font-weight:800}
#ans-input{flex:0 1 150px}
.q{font-weight:800;font-size:1.3rem;color:var(--unk-line)}
.unit{font-weight:800;color:var(--muted)}
.keys{display:flex;flex-wrap:wrap;gap:6px}
.key{font-size:1.2rem;font-weight:800;min-width:46px;min-height:46px;border-radius:10px;border:2px solid var(--line);background:var(--surface);color:var(--ink);cursor:pointer}

.how{background:var(--surface);border-radius:14px;padding:12px 16px;box-shadow:var(--shadow)}
.how summary{cursor:pointer;font-weight:800;color:var(--navy)}
.how ul{margin:8px 0 0;padding-left:1.2em;display:grid;gap:5px;max-width:70ch}
.toast{position:fixed;left:50%;transform:translateX(-50%);bottom:calc(env(safe-area-inset-bottom,0px) + 16px);z-index:60;background:var(--ink);color:var(--bg);border-radius:12px;padding:10px 16px;font-weight:800;max-width:calc(100% - 32px);box-shadow:0 10px 24px -10px rgba(0,0,0,.5)}

footer.site{margin-top:28px;display:flex;justify-content:space-between;gap:12px;flex-wrap:wrap;color:var(--muted);font-size:.85rem;font-weight:700}
footer.site a{color:var(--navy)}
@media (max-width:520px){
  .panel{padding:14px 14px 16px}
  .board{padding:10px}
  .storytext{font-size:1.08rem}
  .seg .lbl{font-size:.95rem}
}
@media (prefers-reduced-motion:reduce){*{transition:none!important;animation:none!important}}