:root{--bg:#f6f7f5;--card:#fff;--ink:#1c2321;--mute:#5f6b67;--line:#dfe4e1;--brand:#0f766e;--brand-ink:#fff;--ok:#15803d;--okbg:#e3f6e9;--bad:#b91c1c;--badbg:#fde8e8;--warn:#a16207;--warnbg:#fef3c7}
@media(prefers-color-scheme:dark){:root{--bg:#121816;--card:#1b2321;--ink:#e8eeeb;--mute:#9aa8a3;--line:#2c3834;--brand:#2dd4bf;--brand-ink:#06201c;--ok:#4ade80;--okbg:#14301f;--bad:#f87171;--badbg:#3a1a1a;--warn:#fbbf24;--warnbg:#3a2e10}}
*{box-sizing:border-box}
body{margin:0;background:var(--bg);color:var(--ink);font:16px/1.5 system-ui,-apple-system,Segoe UI,Roboto,sans-serif;padding-bottom:72px}
.top{position:sticky;top:0;z-index:5;display:flex;justify-content:space-between;align-items:center;gap:8px;background:var(--card);border-bottom:1px solid var(--line);padding:8px 16px}
.brand{background:none;border:0;color:var(--ink);font:700 17px inherit;cursor:pointer;text-align:left;padding:0}
.brand span{display:block;font:400 12px system-ui;color:var(--mute)}
.timer{font:700 18px ui-monospace,monospace;color:var(--brand)}
.timer.low{color:var(--bad)}
main{max-width:760px;margin:0 auto;padding:16px}
h1{font-size:24px;margin:8px 0}h2{font-size:19px;margin:20px 0 8px}h3{font-size:16px;margin:0 0 6px}
.tabs{position:fixed;bottom:0;left:0;right:0;display:flex;background:var(--card);border-top:1px solid var(--line);padding-bottom:env(safe-area-inset-bottom)}
.tabs button{flex:1;padding:14px 4px;background:none;border:0;color:var(--mute);font:600 14px inherit;cursor:pointer}
.tabs button.on{color:var(--brand);box-shadow:inset 0 3px 0 var(--brand)}
.card{background:var(--card);border:1px solid var(--line);border-radius:12px;padding:14px;margin:12px 0}
.card.lesson{display:block;width:100%;text-align:left;color:var(--ink);font:inherit;cursor:pointer}
.card.lesson:hover{border-color:var(--brand)}
.grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(150px,1fr));gap:10px}
.stat{text-align:center}.stat b{display:block;font-size:26px;color:var(--brand)}.stat small{color:var(--mute)}
.btn{background:var(--brand);color:var(--brand-ink);border:0;border-radius:10px;padding:11px 18px;font:600 15px inherit;cursor:pointer}
.btn.ghost{background:transparent;color:var(--brand);border:1.5px solid var(--brand)}
.btn.sm{padding:6px 12px;font-size:14px}
.btn:disabled{opacity:.5;cursor:default}
.row{display:flex;gap:8px;flex-wrap:wrap;align-items:center}
.chip{border:1.5px solid var(--line);background:var(--card);color:var(--ink);border-radius:999px;padding:6px 13px;font:500 14px inherit;cursor:pointer}
.chip.on{background:var(--brand);color:var(--brand-ink);border-color:var(--brand)}
.mute{color:var(--mute)}.small{font-size:13px}
.tag{display:inline-block;font:600 12px system-ui;background:var(--line);color:var(--mute);border-radius:6px;padding:2px 8px;margin-right:4px}
.instr{font-weight:600;margin:0 0 4px}
.bank{background:var(--warnbg);border-radius:8px;padding:6px 10px;margin:6px 0;font-weight:600;color:var(--warn)}
.q{margin:12px 0}
.q .stem{font-weight:500}
input[type=text],textarea{width:100%;font:inherit;color:var(--ink);background:var(--bg);border:1.5px solid var(--line);border-radius:8px;padding:9px 10px;margin-top:6px}
textarea{min-height:120px;resize:vertical}
input:focus,textarea:focus{outline:2px solid var(--brand);border-color:transparent}
.opt{display:block;border:1.5px solid var(--line);border-radius:8px;padding:9px 12px;margin:6px 0;cursor:pointer}
.opt input{margin-right:8px}
.opt.sel{border-color:var(--brand);background:color-mix(in srgb,var(--brand) 10%,transparent)}
.opt.right{border-color:var(--ok);background:var(--okbg)}.opt.wrong{border-color:var(--bad);background:var(--badbg)}
.fb{border-radius:8px;padding:8px 12px;margin-top:8px;font-size:15px}
.fb.ok{background:var(--okbg);color:var(--ok)}.fb.bad{background:var(--badbg);color:var(--bad)}.fb.self{background:var(--warnbg);color:var(--warn)}
.fb .ans{color:var(--ink);display:block;margin-top:2px}
details.passage{background:var(--card);border:1px solid var(--line);border-radius:12px;padding:10px 14px;margin:12px 0}
details.passage summary{cursor:pointer;font-weight:700}
details.passage p{margin:8px 0}
.tfrow{display:flex;gap:8px}
.bar{height:8px;background:var(--line);border-radius:6px;overflow:hidden}.bar i{display:block;height:100%;background:var(--brand)}
.sectitle{display:flex;justify-content:space-between;align-items:baseline}
.score{font:800 40px system-ui;color:var(--brand)}
.tips{margin:6px 0 0;padding-left:20px;color:var(--mute);font-size:14px}
.model{white-space:pre-wrap;background:var(--bg);border-radius:8px;padding:10px;margin-top:6px}
table{width:100%;border-collapse:collapse}td,th{text-align:left;padding:6px 4px;border-bottom:1px solid var(--line);font-size:14px}
.sticky-actions{position:sticky;bottom:60px;display:flex;gap:8px;justify-content:flex-end;padding:8px 0}
.fb.xp{background:var(--warnbg);color:var(--ink);margin-top:6px}

.bank{border:2px solid var(--warn)}
.bankhd{display:block;font-size:12px;font-weight:700;margin-bottom:2px}

.lbank .bi{display:inline-block;margin:3px 10px 3px 0;font-weight:600}
.lbank .bi b{display:inline-block;min-width:22px;text-align:center;background:var(--warn);color:#fff;border-radius:6px;padding:0 4px;margin-right:4px}
.letters{display:flex;flex-wrap:wrap;gap:6px;margin:6px 0}
.lt{min-width:44px;text-align:center;padding:10px 12px;border:2px solid var(--line,#cbd5e1);border-radius:8px;font-weight:700;cursor:pointer}
.lt input{position:absolute;opacity:0;pointer-events:none}
.lt.sel{background:var(--brand);color:#fff;border-color:var(--brand)}

.lin{width:64px;text-align:center;font-size:20px;font-weight:700;text-transform:uppercase;margin-left:6px;display:inline-block}
.letterbox{margin:6px 0;font-weight:600}

.letterbox .lin{width:72px !important;max-width:72px}

/* the word list follows the student while they scroll through the questions */
.bank{position:sticky;top:var(--hh,64px);z-index:4;max-height:32vh;overflow:auto;background-color:var(--card);background-image:linear-gradient(var(--warnbg),var(--warnbg));box-shadow:0 3px 8px rgba(0,0,0,.18)}

/* reading comprehension: the text stays in view while students answer */
.rd .bank{position:static;max-height:none;box-shadow:none}
.rtext{position:sticky;top:var(--hh,52px);z-index:4;background:var(--card);border:1px solid var(--line);border-radius:12px;padding:8px 14px;margin:8px 0;overflow-y:auto;box-shadow:0 3px 8px rgba(0,0,0,.18)}
.rtext.rz0{height:24vh}.rtext.rz1{height:40vh}.rtext.rz2{height:62vh}
.rtext p{margin:8px 0}
.rthd{display:flex;justify-content:space-between;align-items:center;gap:8px;position:sticky;top:-8px;background:var(--card);padding:4px 0;margin-bottom:4px;border-bottom:1px solid var(--line)}
.rbtns{display:flex;gap:4px;flex-shrink:0}
@media (min-width:900px){
  main.wide{max-width:1180px}
  .rd{display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1fr);gap:18px;align-items:start}
  .rtext,.rtext.rz0,.rtext.rz1,.rtext.rz2{height:auto;max-height:calc(100vh - var(--hh,52px) - 24px);margin:0}
  .rbtns{display:none}
}

.rthd b{flex:1;min-width:0;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.rbtns .btn{padding:4px 12px;min-width:40px}