:root{
  --bg:#0e0f1a;
  --panel:#161826;
  --panel-2:#1e2133;
  --ink:#eef0f8;
  --muted:#9aa0b8;
  --line:#2a2e44;
  --brand:#7c6cff;
  --brand-2:#a48bff;
  --good:#33c48d;
  --good-bg:rgba(51,196,141,.12);
  --warn:#ffb020;
  --warn-bg:rgba(255,176,32,.10);
  --bad:#e0556b;
  --bad-bg:rgba(224,85,107,.10);
  --coach:#20243a;
  --nav-w:244px;
  --guide-w:392px;
}
*{box-sizing:border-box}
html,body{margin:0;padding:0;height:100%}
body{
  background:var(--bg);
  color:var(--ink);
  font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,Helvetica,Arial,sans-serif;
  -webkit-font-smoothing:antialiased;
  height:100vh;overflow:hidden;
}

/* ---------- landing (signed-out) ---------- */
.landing-body{display:grid;place-items:center;min-height:100vh;padding:32px;overflow:auto}
.landing{max-width:560px;text-align:center}
.landing-mark{
  display:flex;align-items:center;justify-content:center;gap:10px;
  font-weight:700;font-size:18px;margin-bottom:36px;
}
.landing h1{font-size:30px;line-height:1.25;margin:0 0 18px;letter-spacing:-.4px}
.landing p{font-size:16px;line-height:1.6;color:var(--muted);margin:0 0 34px}
.landing-btn{
  display:inline-block;background:linear-gradient(135deg,var(--brand),var(--brand-2));
  color:#fff;text-decoration:none;font-weight:600;font-size:15px;
  padding:14px 30px;border-radius:11px;box-shadow:0 6px 20px rgba(124,108,255,.35);
}
.landing-btn:hover{filter:brightness(1.07)}
@media (max-width:520px){ .landing h1{font-size:25px} }

/* ---------- three-pane grid ---------- */
.app{
  display:grid;
  grid-template-columns:var(--nav-w) 5px 1fr 5px var(--guide-w);
  height:100vh;
  transition:grid-template-columns .22s ease;
}
.app.nav-collapsed{--nav-w:62px}
.app.resizing{transition:none;user-select:none}

/* ---------- drag handles between panels ---------- */
.resizer{background:transparent;cursor:col-resize;position:relative}
.resizer::after{content:"";position:absolute;top:0;bottom:0;left:1px;right:1px;background:var(--line)}
.resizer:hover::after,.resizer.dragging::after{background:var(--brand)}
.app.nav-collapsed #resizerNav{pointer-events:none}
.app.nav-collapsed #resizerNav::after{background:transparent}

/* ---------- left nav ---------- */
.nav{
  background:#101120;border-right:1px solid var(--line);
  display:flex;flex-direction:column;min-width:0;overflow:hidden;
}
.navtop{display:flex;align-items:center;justify-content:space-between;gap:8px;padding:16px 14px}
.wordmark{display:flex;align-items:center;gap:10px;font-weight:700;font-size:17px;min-width:0}
.logo{
  width:28px;height:28px;flex:none;border-radius:8px;
  background:linear-gradient(135deg,var(--brand),var(--brand-2));
  display:grid;place-items:center;font-size:14px;color:#fff;box-shadow:0 4px 14px rgba(124,108,255,.5);
}
.iconbtn{
  flex:none;width:28px;height:28px;border-radius:8px;cursor:pointer;
  background:var(--panel-2);border:1px solid var(--line);color:var(--muted);
  font-size:15px;line-height:1;transition:color .15s,transform .2s;
}
.iconbtn:hover{color:var(--ink)}
.app.nav-collapsed .iconbtn{transform:rotate(180deg)}
.navsec{padding:6px 10px}
.navsec-h{font-size:11px;text-transform:uppercase;letter-spacing:.6px;color:var(--muted);padding:8px 6px 6px}
.navlist{display:flex;flex-direction:column;gap:4px}
/* .nav is a fixed-height flex column with overflow:hidden, so only the
   Problems section scrolls internally — everything above it (miniset
   picker, progress button) stays put. min-height:0 overrides the flex
   default of min-height:auto, which otherwise refuses to shrink below the
   list's full content height and defeats the overflow-y:auto below. Two-
   line wrapped stems (see .navitem .txt .t) made this list tall enough to
   actually need it. */
.navsec-problems{flex:1;min-height:0;display:flex;flex-direction:column}
.navsec-problems .navlist{flex:1;min-height:0;overflow-y:auto}
.navitem{
  display:flex;align-items:center;gap:10px;width:100%;text-align:left;cursor:pointer;
  background:transparent;border:1px solid transparent;border-radius:10px;
  padding:10px;color:var(--ink);font-family:inherit;font-size:13.5px;line-height:1.35;min-width:0;
  transition:background .15s,border-color .15s;
}
.navitem:hover{background:var(--panel-2)}
.navitem.active{background:var(--panel-2);border-color:var(--line)}
.navitem .dot{
  flex:none;width:26px;height:26px;border-radius:8px;background:var(--panel);border:1px solid var(--line);
  display:grid;place-items:center;font-size:12px;font-weight:700;color:var(--brand-2);
}
.navitem .txt{min-width:0}
/* Character-count truncation and LaTeX don't mix — clipping mid-expression
   leaves an unclosed brace/unmatched $ that no renderer can recover. Wrap
   instead; stems are short and the sidebar has the vertical room. Line-height
   is generous so a stacked fraction/exponent isn't clipped top or bottom. */
.navitem .txt .t{display:block;overflow-wrap:break-word;line-height:1.5}
.navitem .txt .s{display:block;font-size:11px;color:var(--muted);margin-top:2px}
.navitem .s .live{color:var(--warn)}
.navitem .dot.clean{background:var(--good);color:#08240f;border-color:transparent}
.navitem .dot.assisted{background:var(--warn);color:#3a2600;border-color:transparent}
.navitem .dot.wrong{background:var(--bad);color:#2a0a10;border-color:transparent}
/* flex:0, not flex:1 — .navsec-problems is now the section that grows to
   fill remaining space and scrolls; this just collapses to nothing instead
   of competing with it for the same space. */
.navspacer{flex:0}
.navaccount{
  display:flex;align-items:center;gap:8px;padding:12px 14px 0;color:#9aa0b8;font-size:12px;
}
.navaccount #accountName{flex:1;min-width:0;overflow:hidden;text-overflow:ellipsis;white-space:nowrap;font-weight:600;color:var(--ink)}
.navaccount-btn{
  background:transparent;border:none;color:#6b7192;cursor:pointer;font-size:11px;
  padding:2px 4px;text-decoration:none;
}
.navaccount-btn:hover{color:var(--ink)}
.navfoot{padding:14px;color:#6b7192;font-size:11px;border-top:1px solid var(--line)}

/* miniset picker — v0 filters: topic / difficulty / random */
.mspicker{display:flex;gap:6px;margin:0 6px 8px}
.msselect{
  flex:1;min-width:0;background:var(--panel-2);border:1px solid var(--line);color:var(--ink);
  border-radius:8px;padding:7px 8px;font-size:12.5px;font-family:inherit;
}
.msselect:focus{outline:none;border-color:var(--brand)}
.msbtn{
  flex:none;cursor:pointer;font-family:inherit;font-size:12px;font-weight:600;color:var(--brand-2);
  background:var(--panel-2);border:1px solid var(--line);border-radius:8px;padding:7px 10px;
  transition:border-color .15s,background .15s;
}
.msbtn:hover{border-color:var(--brand);background:#23263c}
.msbtn.diffbtn{flex:1;text-align:center}
.msbtn.diffbtn.active{border-color:var(--brand);background:#23263c;color:var(--ink)}
.msbtn.wide{width:100%;margin:0 6px 4px;flex:none}
.msexit{
  display:block;width:calc(100% - 12px);margin:0 6px 8px;text-align:left;cursor:pointer;
  font-family:inherit;font-size:12px;color:var(--muted);background:transparent;border:none;padding:4px 0;
}
.msexit:hover{color:var(--ink)}
.msexit.hidden{display:none}

/* collapsed: hide text labels, center icons */
.app.nav-collapsed .label{display:none}
.app.nav-collapsed .navtop{justify-content:center;padding:16px 8px;flex-wrap:wrap;gap:12px}
.app.nav-collapsed .navsec-h{display:none}
.app.nav-collapsed .navitem{justify-content:center;padding:9px}
.app.nav-collapsed .navitem .txt{display:none}

/* ---------- center stage (fixed top bar + scrolling body) ---------- */
.stage{display:flex;flex-direction:column;min-width:0;min-height:0;overflow:hidden}
/* top bar — timer + session progress, fixed above the question */
.topbar{
  flex:none;display:flex;align-items:center;justify-content:space-between;gap:12px;
  padding:10px 26px;background:#12131f;border-bottom:1px solid var(--line);
}
.topbar.hidden{display:none}
/* footer bar — mirrors .topbar, fixed below the scrolling question body.
   Holds only the difficulty-reveal chip: off the stem entirely so nothing
   sits beside the question on the one screen that has to stay quiet. */
.stagefoot{
  flex:none;display:flex;justify-content:flex-end;padding:10px 26px;
  background:#12131f;border-top:1px solid var(--line);
}
.stagefoot.hidden{display:none}
.tbtn{
  display:inline-flex;align-items:center;gap:8px;cursor:pointer;font-family:inherit;
  font-size:12.5px;font-weight:600;color:var(--muted);
  background:var(--panel-2);border:1px solid var(--line);border-radius:9px;padding:7px 12px;
  transition:color .15s,border-color .15s,background .15s;
}
.tbtn:hover{color:var(--ink)}
.tbtn[aria-pressed="true"]{color:var(--brand-2);border-color:var(--brand);background:#23263c}
.tbtn .tdot{font-size:13px;line-height:1}
.tbar-left{display:flex;align-items:center;gap:8px}
/* difficulty badge colours (win over the generic pressed style) */
.tbtn.easy{color:var(--good);border-color:rgba(51,196,141,.45);background:var(--good-bg)}
.tbtn.medium{color:var(--warn);border-color:rgba(255,176,32,.45);background:var(--warn-bg)}
.tbtn.hard{color:var(--bad);border-color:rgba(224,85,107,.45);background:var(--bad-bg)}
.tbtn[aria-pressed="true"] #timerText{font-variant-numeric:tabular-nums}
.sessprog{font-size:12.5px;color:var(--muted);font-weight:600}
.sessprog b{color:var(--ink)}
/* the question body scrolls on its own; the top bar stays put */
.stage-body{flex:1;min-height:0;overflow-y:auto;padding:34px 26px 60px;display:flex;justify-content:center}
.stage-empty{display:grid;place-items:center;width:100%;min-height:100%}
.empty-card{text-align:center;max-width:340px;color:var(--muted)}
.empty-icon{font-size:40px;margin-bottom:10px}
.empty-card h1{color:var(--ink);font-size:22px;margin:0 0 8px}
.empty-card p{font-size:14px;line-height:1.55;margin:0}

.work{width:100%;max-width:640px}
.crumbs{font-size:12px;color:var(--muted);margin-bottom:14px;display:flex;gap:8px;align-items:center}
.crumbs .tag{border:1px solid var(--line);border-radius:999px;padding:3px 10px}

/* ---------- progress by tag ---------- */
.progoverall{font-size:13.5px;color:var(--muted);margin-bottom:18px;padding-bottom:14px;border-bottom:1px solid var(--line)}
.progoverall b{color:var(--ink);font-size:16px}
.progwhat{font-size:11px;text-decoration:underline dotted;cursor:help;margin-left:4px}
.progempty{color:var(--muted);font-size:13.5px;line-height:1.5}
.proglist{display:flex;flex-direction:column;gap:10px}
.progrow{display:grid;grid-template-columns:1fr 140px 42px 100px 80px;gap:12px;align-items:center;font-size:12.5px}
.progtag{color:var(--ink);font-weight:600;text-transform:capitalize}
.progbar{height:8px;border-radius:999px;background:var(--panel-2);overflow:hidden}
.progfill{height:100%;border-radius:999px;background:var(--bad)}
.progfill.warn{background:var(--warn)}
.progfill.good{background:var(--good)}
.progpct{color:var(--muted);text-align:right;font-variant-numeric:tabular-nums}
.progband{font-size:11px;font-weight:600;padding:3px 9px;border-radius:999px;border:1px solid var(--line);color:var(--muted);text-align:center}
.progband.good{color:var(--good);border-color:rgba(51,196,141,.45);background:var(--good-bg)}
.progband.warn{color:var(--warn);border-color:rgba(255,176,32,.45);background:var(--warn-bg)}
.progband.bad{color:var(--bad);border-color:rgba(224,85,107,.45);background:var(--bad-bg)}
.progn{color:var(--muted);font-size:11.5px}
@media (max-width:720px){
  .progrow{grid-template-columns:1fr 60px;grid-template-areas:"tag pct" "bar bar" "band n";row-gap:4px}
  .progtag{grid-area:tag}
  .progpct{grid-area:pct}
  .progbar{grid-area:bar}
  .progband{grid-area:band;justify-self:start}
  .progn{grid-area:n;justify-self:end}
}

/* mode toggle — Try it myself / Coach me */
.modebar{display:flex;align-items:center;justify-content:space-between;gap:12px;margin-bottom:14px}
.seg{display:inline-flex;background:var(--panel);border:1px solid var(--line);border-radius:11px;padding:3px}
.seg button{
  cursor:pointer;font-family:inherit;font-size:13px;font-weight:600;border:none;background:transparent;
  color:var(--muted);padding:8px 14px;border-radius:8px;transition:background .15s,color .15s;
}
.seg button:hover{color:var(--ink)}
.seg button.active{background:linear-gradient(135deg,var(--brand),var(--brand-2));color:#fff;box-shadow:0 4px 12px rgba(124,108,255,.35)}
.modehint{font-size:12px;color:var(--muted)}

/* coaching option buttons inside the guide (Coach me stages) */
.gopts{display:flex;flex-direction:column;gap:8px;margin:4px 0 12px;animation:rise .3s ease both}
.gopt{
  text-align:left;width:100%;cursor:pointer;font-family:inherit;
  background:var(--panel-2);border:1px solid var(--line);color:var(--ink);
  padding:11px 13px;border-radius:10px;font-size:13.5px;line-height:1.4;transition:transform .1s,border-color .15s,background .15s;
}
.gopt:hover:not(:disabled){border-color:var(--brand);transform:translateY(-1px);background:#23263c}
.gopt:disabled{cursor:default}
.gopt.correct{border-color:var(--good);background:var(--good-bg)}
.gopt.wrong{border-color:var(--bad);background:var(--bad-bg)}
.gopt .k{display:inline-block;width:20px;height:20px;border-radius:6px;background:#2c3050;color:var(--brand-2);font-size:11px;font-weight:700;text-align:center;line-height:20px;margin-right:8px}
.coach.walk{border-left-color:var(--brand-2);background:rgba(164,139,255,.08)}
.coach.walk .who{color:var(--brand-2)}
/* targeted nudge (branch-on-the-wrong-answer fork) */
.coach.nudge{border-left-color:var(--warn);background:var(--warn-bg)}
.coach.nudge .who{color:var(--warn)}
.nudgetag{font-size:10.5px;color:var(--warn);text-transform:uppercase;letter-spacing:.5px;margin-bottom:5px;font-weight:700}

.problem{background:var(--panel);border:1px solid var(--line);border-radius:16px;padding:22px 22px 18px;box-shadow:0 12px 40px rgba(0,0,0,.35)}
/* Stem + flag button share a row — the control belongs on the thing it
   acts on, not floating as detached page chrome. */
.qrow{display:flex;align-items:flex-start;justify-content:space-between;gap:14px;margin-bottom:14px}
.qrow .q{margin-bottom:0}
.problem .q{font-size:19px;line-height:1.5;font-weight:600;margin-bottom:14px}
/* Quiet by design — a grey chip, not a badge. Lives in the stage footer, off
   the stem entirely. Collapsed ("Show difficulty") until tapped or answered. */
.diffchip{
  display:inline-block;font-size:11px;font-weight:600;color:var(--muted);font-family:inherit;
  background:var(--panel-2);border:1px solid var(--line);border-radius:999px;
  padding:3px 11px;cursor:pointer;transition:border-color .15s,color .15s;
}
.diffchip:hover:not(:disabled){border-color:var(--brand);color:var(--ink)}
.diffchip:disabled{cursor:default}
.stmt{display:flex;gap:10px;padding:11px 13px;background:#12142099;border:1px solid var(--line);border-radius:10px;margin:8px 0;font-size:15px}
.stmt .n{color:var(--brand-2);font-weight:700;flex:none}

.answers-h{font-size:11px;color:var(--muted);text-transform:uppercase;letter-spacing:.6px;margin:18px 0 10px}
.answers{display:flex;flex-direction:column;gap:9px}
.ans{
  display:flex;align-items:center;gap:12px;text-align:left;width:100%;cursor:pointer;font-family:inherit;
  background:var(--panel-2);border:1px solid var(--line);color:var(--ink);
  padding:13px 15px;border-radius:12px;font-size:14.5px;line-height:1.4;
  transition:transform .1s,border-color .15s,background .15s;
}
.ans:hover:not(:disabled){border-color:var(--brand);transform:translateY(-1px);background:#23263c}
.ans:disabled{cursor:default}
.ans .k{
  flex:none;width:26px;height:26px;border-radius:8px;background:var(--panel);border:1px solid var(--line);
  color:var(--brand-2);font-size:13px;font-weight:700;display:grid;place-items:center;
}
.ans.selected{border-color:var(--brand);background:#23263c;box-shadow:0 0 0 1px var(--brand) inset}
.ans.selected .k{background:var(--brand);color:#fff;border-color:transparent}
.ans.correct{border-color:var(--good);background:var(--good-bg);box-shadow:none}
.ans.correct .k{background:var(--good);color:#08240f;border-color:transparent}
.ans.wrong{border-color:var(--bad);background:var(--bad-bg);box-shadow:none}
.ans.wrong .k{background:var(--bad);color:#2a0a10;border-color:transparent}
.ans.dim{opacity:.45}

/* center actions (Submit / New similar / Continue) + verdict banner */
.centeractions{display:flex;gap:10px;align-items:center;margin-top:16px;flex-wrap:wrap}
.centeractions .btn{width:auto}
.cbtn{
  cursor:pointer;font-family:inherit;font-size:14px;font-weight:600;
  border-radius:11px;padding:12px 20px;border:1px solid var(--line);background:var(--panel-2);color:var(--ink);
  transition:transform .1s,background .15s,opacity .15s;
}
.cbtn:hover:not(:disabled){transform:translateY(-1px)}
.cbtn.primary{background:linear-gradient(135deg,var(--brand),var(--brand-2));border:none;color:#fff;box-shadow:0 6px 18px rgba(124,108,255,.4)}
.cbtn.ghost{background:transparent;color:var(--muted)}
.cbtn.ghost:hover{color:var(--ink)}
.cbtn:disabled{opacity:.4;cursor:default}
.verdict{
  display:flex;align-items:center;gap:12px;margin-top:16px;padding:14px 16px;border-radius:12px;
  border:1px solid var(--line);animation:rise .25s ease both;
}
.verdict .vh{font-size:15px;font-weight:700}
.verdict .vsub{font-size:13px;color:var(--muted)}
.verdict.good{border-color:rgba(51,196,141,.4);background:var(--good-bg)}
.verdict.good .vh{color:var(--good)}
.verdict.bad{border-color:rgba(224,85,107,.4);background:var(--bad-bg)}
.verdict.bad .vh{color:var(--bad)}
.verdict.warn{border-color:rgba(255,176,32,.4);background:var(--warn-bg)}
.verdict.warn .vh{color:var(--warn)}
.verdict .grow{flex:1}
.verdict .cbtn{padding:8px 14px;font-size:13px}

/* ---------- right guide ---------- */
.guide{background:#12131f;border-left:1px solid var(--line);display:flex;flex-direction:column;min-width:0;min-height:0;overflow:hidden}
/* The header carried its own top padding; without it the first coach bubble
   would sit flush against the top edge. */
.guide-stream{flex:1;min-height:0;overflow-y:auto;padding:20px 18px 8px}
.guide-actions{padding:14px 18px 10px;border-top:1px solid var(--line);display:flex;flex-direction:column;gap:9px}
.guide-actions:empty{display:none}

/* flag toggle + inline flag panel */
.flagtoggle{
  background:none;border:1px solid var(--line);color:var(--muted);border-radius:8px;
  width:28px;height:28px;font-size:13px;cursor:pointer;line-height:1;
}
.flagtoggle:hover{color:var(--warn);border-color:var(--warn)}
.flagbar{padding:12px 16px;border:1px solid var(--line);border-radius:10px;background:var(--panel-2);margin-bottom:14px}
.flagbar.hidden{display:none}
.flagbar-row{display:flex;flex-direction:column;gap:7px}
.flagbtn{
  text-align:left;background:var(--panel);border:1px solid var(--line);color:var(--ink);
  border-radius:8px;padding:8px 12px;font-size:12.5px;cursor:pointer;
}
.flagbtn:hover{border-color:var(--warn)}
.flagbtn.picked{border-color:var(--warn);background:var(--warn-bg)}
.flagcomment{
  width:100%;box-sizing:border-box;margin-top:8px;background:var(--panel);border:1px solid var(--line);
  color:var(--ink);border-radius:8px;padding:8px 10px;font:inherit;font-size:12.5px;resize:vertical;
}
.flagcomment.hidden{display:none}
.flagbar-actions{display:flex;justify-content:flex-end;gap:8px;margin-top:8px}
.flagbar-actions.hidden{display:none}
.flagsend, .flagcancel{border-radius:8px;padding:6px 12px;font:inherit;font-size:12px;cursor:pointer;border:1px solid var(--line)}
.flagsend{background:var(--warn);border-color:var(--warn);color:#3a2600}
.flagcancel{background:none;color:var(--muted)}

/* ask a question bar */
.askbar{display:flex;gap:8px;padding:12px 16px 16px;border-top:1px solid var(--line)}
.askcapped{font-size:12.5px;color:var(--muted);line-height:1.5}
.askbar.hidden{display:none}
.askinput{
  flex:1;min-width:0;background:var(--panel-2);border:1px solid var(--line);color:var(--ink);
  border-radius:11px;padding:11px 14px;font-size:13.5px;font-family:inherit;
}
.askinput:focus{outline:none;border-color:var(--brand)}
.askinput::placeholder{color:#6b7192}
.askbtn{
  flex:none;width:42px;border-radius:11px;border:none;cursor:pointer;font-size:16px;
  background:linear-gradient(135deg,var(--brand),var(--brand-2));color:#fff;
}
.askbtn:hover{filter:brightness(1.08)}

/* Student's own turns need to read as distinctly different from the coach's
   at a glance, scrolling back — same purple left rule + a near-identical
   card made them indistinguishable. Flat (page background, not a "card"),
   slightly inset, green left rule + name label so it reads as "the student's
   own line" rather than another coach bubble. Coach turns are untouched and
   stay the dominant voice. */
.coach.me{background:var(--bg);border:1px solid var(--line);border-left:3px solid var(--good);margin-left:26px;animation:none}
.coach.me .who{color:var(--good);font-weight:600}
.srctag{font-size:10.5px;color:var(--muted);text-transform:uppercase;letter-spacing:.5px;margin-bottom:5px}

/* hint thumbs */
.thumbs{display:flex;align-items:center;gap:6px;margin-top:10px;font-size:11.5px;color:var(--muted)}
.thumb{cursor:pointer;background:transparent;border:1px solid var(--line);border-radius:8px;padding:3px 8px;font-size:13px;line-height:1}
.thumb:hover{border-color:var(--brand)}
.thumb.picked{border-color:var(--brand);background:var(--panel-2)}

.coach{
  background:var(--coach);border:1px solid var(--line);border-left:3px solid var(--brand);
  border-radius:12px;padding:13px 15px;margin:0 0 12px;font-size:14.5px;line-height:1.55;
  animation:rise .3s ease both;
}
.coach .who{font-size:11px;color:var(--brand-2);font-weight:700;letter-spacing:.4px;text-transform:uppercase;margin-bottom:5px;display:flex;align-items:center;gap:7px}
.coach .who .dot{width:7px;height:7px;border-radius:50%;background:var(--brand);box-shadow:0 0 0 3px rgba(124,108,255,.2)}
.coach.good{border-left-color:var(--good);background:var(--good-bg)}
.coach.good .who{color:var(--good)}
.coach.bad{border-left-color:var(--bad);background:var(--bad-bg)}
.coach.bad .who{color:var(--bad)}
.coach.hint{border-left-color:var(--warn);background:var(--warn-bg)}
.coach.hint .who{color:var(--warn)}
.coach em{color:var(--brand-2);font-style:normal;font-weight:600}
.coach code{background:#0c0e18;padding:1px 6px;border-radius:5px;font-size:13px;color:#e6d6ff;border:1px solid var(--line)}
.hintnum{font-size:11px;color:var(--muted);text-transform:uppercase;letter-spacing:.5px;margin-bottom:4px}

.btn{
  cursor:pointer;font-family:inherit;font-size:14px;font-weight:600;width:100%;
  border-radius:11px;padding:12px 16px;border:1px solid var(--line);
  background:var(--panel-2);color:var(--ink);transition:transform .1s,background .15s;
}
.btn:hover{transform:translateY(-1px)}
.btn.primary{background:linear-gradient(135deg,var(--brand),var(--brand-2));border:none;color:#fff;box-shadow:0 6px 18px rgba(124,108,255,.4)}
.btn.warn{background:var(--warn-bg);border-color:rgba(255,176,32,.35);color:var(--warn)}
.btn.ghost{background:transparent;color:var(--muted);font-weight:500;font-size:12.5px;padding:8px}
.btn.ghost:hover{color:var(--ink)}

.field{width:100%;background:var(--panel-2);border:1px solid var(--line);color:var(--ink);border-radius:12px;padding:13px 15px;font-size:14.5px;font-family:inherit;resize:vertical;min-height:80px}
.field:focus{outline:none;border-color:var(--brand)}

/* playbook */
.pbitem{display:flex;gap:12px;padding:14px;border:1px solid var(--line);border-radius:13px;background:var(--panel-2);margin:10px 0;animation:rise .35s ease both}
.pbitem .ic{font-size:20px;flex:none}
.pbitem h4{margin:0 0 4px;font-size:14px}
.pbitem p{margin:0;font-size:13px;color:var(--muted);line-height:1.5}
.donehead{text-align:center;padding:6px 4px 10px}
.donehead .big{font-size:36px}
.donehead h2{margin:6px 0 4px;font-size:18px}
.donehead p{color:var(--muted);font-size:13px;margin:0;line-height:1.5}

.typing{display:inline-flex;gap:4px;align-items:center}
.typing span{width:6px;height:6px;border-radius:50%;background:var(--brand-2);opacity:.5;animation:blink 1.2s infinite}
.typing span:nth-child(2){animation-delay:.2s}
.typing span:nth-child(3){animation-delay:.4s}
@keyframes blink{0%,60%,100%{opacity:.3}30%{opacity:1}}
@media (prefers-reduced-motion: reduce){
  .typing span{animation:none;opacity:.7}
}
@keyframes rise{from{opacity:0;transform:translateY(6px)}to{opacity:1;transform:translateY(0)}}
.hidden{display:none}

/* narrower desktops: shrink the side columns so the question keeps room */
@media (max-width:1120px){
  :root{--nav-w:212px;--guide-w:344px}
}

/* ---------- phones: stack (out of the three-column scope) ---------- */
@media (max-width:720px){
  body{overflow:auto}
  .app,.app.nav-collapsed{grid-template-columns:1fr;height:auto}
  .resizer{display:none}
  .stage{overflow:visible}
  .stage-body{overflow:visible;padding:22px 16px 40px}
  .nav{flex-direction:row;flex-wrap:wrap;align-items:center;border-right:none;border-bottom:1px solid var(--line)}
  .navsec{padding:6px}
  .navlist{flex-direction:row;flex-wrap:wrap}
  /* The problem list must not be able to bury the question. Unbounded, 43
     questions rendered ~2,800px of list ABOVE the stage on a phone — the
     student never reached the thing she tapped. Cap it and let it scroll
     inside itself, so the question is always within a screen of the top
     however large the bank grows. */
  .navsec-problems .navlist{max-height:38vh;overflow-y:auto;-webkit-overflow-scrolling:touch}
  .navspacer,.navfoot{display:none}
  .guide{border-left:none;border-top:1px solid var(--line)}
  .guide-stream{max-height:60vh}
}