/* FL MATH — aviation math trainer
   "Glass cockpit" theme: chamfered instrument-panel panels, phosphor-green/amber/magenta
   avionics color coding, a faint nav-chart grid instead of a soft gradient blob, and
   Chakra Petch (HUD-style display type) over IBM Plex Sans body text. No dependencies. */

:root {
  --bg: #05070d;
  --bg-2: #0a0f1c;
  --panel: #0d1424;
  --panel-2: #121b30;
  --line: #223350;
  --line-bright: #35507a;
  --text: #eef4ff;
  --muted: #7e93b8;
  --amber: #ffb020;      /* caution / approx */
  --green: #39ff8a;      /* verified / exact / correct */
  --cyan: #2ad4ff;       /* informational / focus */
  --magenta: #ff3fa8;    /* primary / selected / commanded value */
  --red: #ff4d5e;        /* wrong / warning */
  --violet: #b98aff;     /* first-principles tag */
  --teal: #2dd4bf;       /* regulatory tag */
  --shadow: 0 10px 30px rgba(0, 0, 0, 0.45);
  --radius: 10px;
  --mono: "JetBrains Mono", "SF Mono", "Fira Code", ui-monospace, Menlo, Consolas, monospace;
  --sans: "IBM Plex Sans", system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  --display: "Chakra Petch", var(--sans);
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  background-color: var(--bg);
  background-image:
    repeating-linear-gradient(0deg, rgba(140, 175, 230, 0.05) 0px, rgba(140, 175, 230, 0.05) 1px, transparent 1px, transparent 44px),
    repeating-linear-gradient(90deg, rgba(140, 175, 230, 0.05) 0px, rgba(140, 175, 230, 0.05) 1px, transparent 1px, transparent 44px),
    radial-gradient(1100px 700px at 50% -12%, rgba(40, 70, 120, 0.4), transparent 62%);
  background-attachment: fixed;
  color: var(--text);
  font-family: var(--sans);
  -webkit-font-smoothing: antialiased;
  min-height: 100dvh;
}

@keyframes bootFlicker {
  0% { opacity: 0; filter: brightness(2.2) contrast(1.6); }
  6% { opacity: 1; }
  9% { opacity: 0.15; }
  13% { opacity: 1; filter: brightness(1.3) contrast(1.2); }
  100% { opacity: 1; filter: brightness(1) contrast(1); }
}
@keyframes riseIn {
  from { opacity: 0; transform: translateY(8px); }
  to { opacity: 1; transform: translateY(0); }
}
@media (prefers-reduced-motion: reduce) {
  * { animation: none !important; transition: none !important; }
}

#app {
  max-width: 620px;
  margin: 0 auto;
  min-height: 100dvh;
  display: flex;
  flex-direction: column;
  padding: env(safe-area-inset-top) 16px calc(env(safe-area-inset-bottom) + 8px);
  animation: bootFlicker 0.7s ease-out;
}

/* Top bar */
.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px 4px 10px;
  border-bottom: 1px solid var(--line);
}
.brand { display: flex; align-items: center; gap: 10px; }
.brand-mark {
  font-size: 20px;
  color: var(--magenta);
  transform: rotate(-8deg);
  filter: drop-shadow(0 0 8px rgba(255, 63, 168, 0.45));
  display: inline-block;
}
.brand-name { font-family: var(--display); font-weight: 700; letter-spacing: 3px; font-size: 18px; }
.ghost-btn {
  background: var(--panel);
  border: 1px solid var(--line);
  color: var(--cyan);
  border-radius: 8px;
  padding: 9px 11px;
  font-size: 16px;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
}
.ghost-btn:active { transform: scale(0.96); }
.ghost-btn svg { display: block; }

.view { flex: 1; padding: 6px 2px 20px; }

.footer {
  text-align: center;
  color: var(--muted);
  font-size: 11px;
  font-family: var(--mono);
  letter-spacing: 0.3px;
  padding: 8px 0 6px;
  border-top: 1px solid var(--line);
}

/* Headings */
h1.screen-title { font-family: var(--display); font-weight: 600; letter-spacing: 0.3px; font-size: 23px; margin: 8px 2px 2px; }
p.screen-sub { color: var(--muted); margin: 0 2px 18px; font-size: 14px; line-height: 1.5; }
h2.section-h { font-family: var(--display); font-size: 12.5px; font-weight: 600; text-transform: uppercase; letter-spacing: 2px; color: var(--muted); margin: 22px 2px 10px; padding-left: 9px; border-left: 2px solid var(--line-bright); }

/* Stat strip */
.statstrip { display: grid; grid-template-columns: repeat(3, 1fr); gap: 10px; margin: 4px 0 8px; }
.stat {
  background: var(--panel);
  border: 1px solid var(--line);
  border-top: 2px solid var(--cyan);
  clip-path: polygon(0 0, calc(100% - 9px) 0, 100% 9px, 100% 100%, 0 100%);
  padding: 12px 8px;
  text-align: center;
  animation: riseIn 0.4s ease-out both;
}
.statstrip .stat:nth-child(1) { animation-delay: 0.06s; }
.statstrip .stat:nth-child(2) { animation-delay: 0.12s; }
.statstrip .stat:nth-child(3) { animation-delay: 0.18s; }
.stat .num { font-family: var(--mono); font-size: 22px; font-weight: 700; font-variant-numeric: tabular-nums; }
.stat .lbl { color: var(--muted); font-size: 10.5px; text-transform: uppercase; letter-spacing: 1.2px; margin-top: 3px; }
.stat .num.green { color: var(--green); }
.stat .num.amber { color: var(--amber); }

/* Mode cards */
.modes { display: grid; gap: 12px; }
.mode-card {
  display: flex; align-items: center; gap: 14px;
  background: linear-gradient(180deg, var(--panel-2), var(--panel));
  border: 1px solid var(--line);
  clip-path: polygon(0 0, calc(100% - 14px) 0, 100% 14px, 100% 100%, 14px 100%, 0 calc(100% - 14px));
  padding: 16px;
  cursor: pointer;
  text-align: left;
  width: 100%;
  color: var(--text);
  transition: transform 0.06s ease, border-color 0.15s ease, background 0.15s ease;
  animation: riseIn 0.4s ease-out both;
}
.modes .mode-card:nth-child(1) { animation-delay: 0.08s; }
.modes .mode-card:nth-child(2) { animation-delay: 0.16s; }
.modes .mode-card:nth-child(3) { animation-delay: 0.24s; }
.modes .mode-card:nth-child(4) { animation-delay: 0.32s; }
.mode-card:active { transform: scale(0.99); }
.mode-card:hover { border-color: var(--magenta); background: linear-gradient(180deg, var(--panel-2), #16203c); }
.mode-card .emoji {
  font-size: 20px; flex: 0 0 auto;
  width: 44px; height: 44px; display: flex; align-items: center; justify-content: center;
  background: var(--bg-2); border: 1px solid var(--line);
  clip-path: polygon(0 0, calc(100% - 6px) 0, 100% 6px, 100% 100%, 6px 100%, 0 calc(100% - 6px));
  filter: grayscale(0.25) contrast(1.05);
}
.mode-card .mc-title { font-family: var(--display); font-weight: 600; font-size: 15.5px; letter-spacing: 0.3px; }
.mode-card.top-level { padding: 22px; }
.mode-card.top-level .emoji { font-size: 26px; width: 56px; height: 56px; }
.mode-card.top-level .mc-title { font-size: 18px; }
.mode-card .mc-desc { color: var(--muted); font-size: 13px; margin-top: 3px; line-height: 1.4; }
.mode-card-row { display: flex; align-items: stretch; gap: 8px; animation: riseIn 0.4s ease-out both; animation-delay: 0.32s; }
.mode-card-row .mode-card { animation: none; }

/* Account / auth */
.auth-form { display: flex; flex-direction: column; gap: 14px; }
.auth-lbl {
  display: flex; flex-direction: column; gap: 6px;
  font-family: var(--display); font-size: 12px; font-weight: 600;
  letter-spacing: 0.6px; text-transform: uppercase; color: var(--muted);
}
.auth-opt { text-transform: none; letter-spacing: 0; font-weight: 400; }
.auth-form input[type="text"], .auth-form input[type="email"],
.auth-form input[type="password"], .auth-form textarea {
  background: var(--bg-2); border: 1px solid var(--line); border-radius: 6px;
  color: var(--text); font-family: var(--sans); font-size: 16px; padding: 11px 12px;
}
.auth-form input:focus, .auth-form textarea:focus { outline: none; border-color: var(--cyan); }
.auth-ratings { display: grid; grid-template-columns: repeat(auto-fill, minmax(130px, 1fr)); }
.auth-consent { font-size: 13px; color: var(--muted); }
.auth-err { color: var(--red); font-size: 13.5px; min-height: 1em; }
.account-box {
  background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 16px; margin-bottom: 6px;
}
.account-row { display: flex; justify-content: space-between; gap: 12px; margin-bottom: 10px; font-size: 14px; }
.account-lbl { color: var(--muted); font-family: var(--display); font-size: 12px; font-weight: 600; letter-spacing: 0.6px; text-transform: uppercase; }

/* Signup nudge banner (dismissible) */
.nudge {
  display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: 10px;
  background: var(--panel); border: 1px solid rgba(42, 212, 255, 0.35); border-radius: var(--radius);
  padding: 13px 15px; margin: 14px 0 4px; animation: riseIn 0.4s ease-out both;
}
.nudge-txt { font-size: 13.5px; color: var(--text); line-height: 1.45; flex: 1 1 260px; }
.nudge-btns { display: flex; align-items: center; gap: 8px; }
.nudge .btn { width: auto; margin: 0; padding: 9px 14px; font-size: 13px; }
.nudge-x {
  background: none; border: 1px solid var(--line); border-radius: 5px; color: var(--muted);
  width: 32px; height: 32px; cursor: pointer; font-size: 13px;
}
.nudge-x:hover { color: var(--red); border-color: var(--red); }

/* Review Due (spaced repetition) — badge shows the live due count */
.due-badge {
  display: inline-block; margin-left: 8px; padding: 2px 8px; vertical-align: middle;
  font-family: var(--display); font-size: 11px; font-weight: 700; letter-spacing: 0.5px;
  text-transform: uppercase; color: var(--muted);
  background: var(--bg-2); border: 1px solid var(--line); border-radius: 4px;
}
#reviewDueCard.has-due .due-badge { color: var(--amber); border-color: rgba(255, 176, 32, 0.5); }
.settings-btn {
  flex: 0 0 auto; width: 48px;
  background: var(--panel-2); border: 1px solid var(--line); color: var(--muted);
  font-size: 18px; cursor: pointer;
  clip-path: polygon(0 0, calc(100% - 10px) 0, 100% 10px, 100% 100%, 10px 100%, 0 calc(100% - 10px));
  transition: border-color 0.15s ease, color 0.15s ease;
}
.settings-btn:hover { border-color: var(--magenta); color: var(--magenta); }
.settings-btn:active { transform: scale(0.94); }
.prog .settings-btn { width: auto; padding: 2px 8px; font-size: 14px; margin-right: 8px; }

/* Chips (filters) */
.chips { display: flex; flex-wrap: wrap; gap: 8px; }
.chip {
  background: var(--panel);
  border: 1px solid var(--line);
  color: var(--muted);
  border-radius: 5px;
  padding: 8px 13px;
  font-family: var(--display);
  font-size: 12.5px;
  font-weight: 500;
  letter-spacing: 0.2px;
  cursor: pointer;
  user-select: none;
  transition: background 0.1s ease, color 0.1s ease, border-color 0.1s ease;
}
.chip.on { background: var(--magenta); color: #1a0210; border-color: var(--magenta); font-weight: 700; }

/* Question card */
.qcard {
  background: linear-gradient(180deg, var(--panel-2), var(--panel));
  border: 1px solid var(--line);
  clip-path: polygon(0 0, calc(100% - 20px) 0, 100% 20px, 100% 100%, 20px 100%, 0 calc(100% - 20px));
  padding: 22px 20px;
  box-shadow: var(--shadow);
}
.qmeta { display: flex; flex-wrap: wrap; gap: 7px; align-items: center; margin-bottom: 14px; }
.badge {
  font-family: var(--mono);
  font-size: 10.5px; font-weight: 700; letter-spacing: 0.4px; text-transform: uppercase;
  padding: 4px 8px 4px 7px; border-radius: 3px;
  border: 1px solid var(--line); border-left-width: 3px;
  background: var(--bg-2);
  color: var(--muted);
}
.badge.cat-tag { color: var(--cyan); border-left-color: var(--cyan); }
.badge.cat-tag.tag-mm { color: var(--green); border-left-color: var(--green); }
.badge.cat-tag.tag-fp { color: var(--violet); border-left-color: var(--violet); }
.badge.cat-tag.tag-reg { color: var(--teal); border-left-color: var(--teal); }
.badge.aircraft-tag { color: var(--text); border-left-color: var(--line-bright); background: var(--panel-2); }
.badge.reg-tag { color: var(--muted); border-left-color: var(--muted); font-style: italic; text-transform: none; }
.badge.subj-tag { color: var(--amber); border-left-color: var(--amber); text-transform: none; }
.badge.cl-tag { color: var(--magenta); border-left-color: var(--magenta); text-transform: none; font-size: 10.5px; }
.badge.auth-tag { color: var(--green); border-left-color: var(--green); font-weight: 700; }
.card-diagram { margin: 14px 0; padding: 10px; background: var(--panel-2); border: 1px solid var(--line); border-radius: 6px; }
.card-diagram .diagram-svg { width: 100%; height: auto; display: block; }
.badge.cat  { color: var(--muted); border-left-color: var(--line-bright); }
.badge.exact  { color: var(--green); border-left-color: var(--green); }
.badge.approx { color: var(--amber); border-left-color: var(--amber); }
.badge.prov-verified { color: var(--green); border-left-color: var(--green); }
.badge.prov-standard { color: var(--amber); border-left-color: var(--amber); }
.badge.prov-source   { color: var(--cyan); border-left-color: var(--cyan); }

.qname { font-family: var(--display); font-size: 12.5px; font-weight: 600; color: var(--muted); margin-bottom: 7px; text-transform: uppercase; letter-spacing: 1.4px; }
.qprompt { font-size: 19px; line-height: 1.45; margin: 4px 0 18px; }

.answer-row { display: flex; gap: 10px; align-items: stretch; }
.answer-row input {
  flex: 1;
  background: var(--bg-2);
  border: 1.5px solid var(--line);
  border-radius: 7px;
  color: var(--text);
  font-family: var(--mono);
  font-size: 22px;
  padding: 14px 16px;
  min-width: 0;
}
.answer-row input:focus { outline: none; border-color: var(--cyan); box-shadow: 0 0 0 3px rgba(42,212,255,0.15); }
.unit-tag {
  display: flex; align-items: center; padding: 0 14px;
  background: var(--bg-2); border: 1.5px solid var(--line); border-radius: 7px;
  color: var(--muted); font-family: var(--mono); font-size: 15px; white-space: nowrap;
}

/* Buttons */
.btn {
  width: 100%; border: none; border-radius: 7px; padding: 16px;
  font-family: var(--display); font-size: 15.5px; font-weight: 600;
  text-transform: uppercase; letter-spacing: 1px;
  cursor: pointer; margin-top: 14px;
  transition: filter 0.08s ease;
}
.btn:active { transform: scale(0.99); filter: brightness(1.15); }
.btn.primary { background: var(--magenta); color: #1a0210; }
.btn.secondary { background: var(--panel-2); color: var(--text); border: 1px solid var(--line); }
.btn.ghost { background: transparent; color: var(--muted); border: 1px solid var(--line); }
.btn-row { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; }

/* Feedback */
.feedback { margin-top: 16px; border-radius: 8px; padding: 14px 16px; border: 1px solid; }
.feedback.correct { background: rgba(57,255,138,0.08); border-color: rgba(57,255,138,0.4); }
.feedback.wrong { background: rgba(255,77,94,0.08); border-color: rgba(255,77,94,0.4); }
.feedback .verdict { font-family: var(--display); font-weight: 700; font-size: 16px; letter-spacing: 0.3px; margin-bottom: 6px; }
.feedback.correct .verdict { color: var(--green); }
.feedback.wrong .verdict { color: var(--red); }
.feedback .exactline { font-family: var(--mono); font-size: 15px; margin: 4px 0 10px; }
.feedback .solution { font-size: 14px; line-height: 1.55; color: var(--text); }
.feedback .note {
  margin-top: 10px; font-size: 12.5px; color: var(--muted);
  border-top: 1px dashed var(--line); padding-top: 8px;
}

/* Aviator's Take — practical "why this rule / how a pilot reasons through it" callout,
   distinct from the math Methods block. Regulatory items only. */
.aviator-note {
  margin-top: 12px; padding: 12px 14px;
  background: rgba(45,212,191,0.07); border: 1px solid rgba(45,212,191,0.35); border-left-width: 3px;
  border-radius: 6px;
}
.aviator-tag {
  font-family: var(--display); font-size: 11px; font-weight: 700; text-transform: uppercase;
  letter-spacing: 0.6px; color: var(--teal); margin-bottom: 6px;
}
.aviator-body { font-size: 13.5px; line-height: 1.6; color: var(--text); }

/* Flashcard */
.flashcard {
  background: linear-gradient(180deg, var(--panel-2), var(--panel));
  border: 1px solid var(--line);
  clip-path: polygon(0 0, calc(100% - 20px) 0, 100% 20px, 100% 100%, 20px 100%, 0 calc(100% - 20px));
  padding: 26px 20px; box-shadow: var(--shadow); min-height: 220px;
  display: flex; flex-direction: column; justify-content: center;
}
.flashcard .fc-front { font-size: 20px; line-height: 1.4; }
.flashcard .fc-back { font-size: 16px; line-height: 1.6; color: var(--text); margin-top: 16px; border-top: 1px solid var(--line); padding-top: 16px; white-space: pre-line; }
.flashcard .fc-hint { color: var(--muted); font-size: 12px; margin-top: 14px; }

/* Column rendering for multi-line flashcard/qbox answers — shape picked in stepListHTML():
 * ol.step-list = numbered steps, ul.step-list.marker-list = mnemonic-letter column,
 * ul.step-list.bullet-list = plain bullets for unordered/parallel facts. */
.step-list { list-style: none; counter-reset: step; margin: 0; padding: 0; }
.step-list li { position: relative; padding-left: 30px; margin-bottom: 9px; }
.step-list li:last-child { margin-bottom: 0; }
ol.step-list li { counter-increment: step; }
ol.step-list li::before {
  content: counter(step) "."; position: absolute; left: 0; top: 0;
  color: var(--cyan); font-weight: 700; font-family: var(--mono); font-size: 0.95em;
}
.step-list.bullet-list li::before {
  content: "•"; position: absolute; left: 6px; top: 0; color: var(--cyan); font-weight: 700;
}
.step-list.marker-list .step-marker {
  position: absolute; left: 0; top: 0; min-width: 22px;
  color: var(--cyan); font-weight: 700; font-family: var(--mono); font-size: 0.95em;
}
/* Trailing exception/caveat, split off from the main list by a blank line in the source —
 * rendered as its own block instead of a bogus extra numbered/bulleted entry. */
.step-note {
  margin-top: 12px; padding-top: 10px; border-top: 1px dashed var(--line);
  color: var(--muted); font-size: 0.92em;
}
.step-note .step-list { margin-top: 4px; }

/* Progress line */
.prog { display: flex; align-items: center; justify-content: space-between; margin: 2px 2px 14px; color: var(--muted); font-size: 12.5px; font-family: var(--mono); }
.prog .streak { color: var(--amber); font-family: var(--mono); }
.prog .sc-right { color: var(--green); font-weight: 700; }
.prog .sc-wrong { color: var(--red); font-weight: 700; }

.back-link { background: none; border: none; color: var(--muted); font-family: var(--display); font-size: 13.5px; letter-spacing: 0.3px; padding: 6px 2px; cursor: pointer; margin-bottom: 6px; }

/* Per-type hide / restore (drill sessions) */
.excl-row { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 14px; padding-top: 12px; border-top: 1px dashed var(--line); }
.excl-btn { background: transparent; color: var(--muted); border: 1px solid var(--line); border-radius: 5px; padding: 6px 12px; font-size: 12px; cursor: pointer; }
.excl-btn:hover { color: var(--text); border-color: var(--muted); }
.excl-btn:active { transform: scale(0.97); }
.excl-note { color: var(--muted); font-size: 12px; font-style: italic; }
.hidden-strip { display: flex; flex-wrap: wrap; align-items: center; gap: 6px; margin: 0 2px 12px; font-size: 12px; }
.hidden-label { color: var(--muted); }
.hidden-chip { background: rgba(255,77,94,0.08); color: var(--red); border: 1px solid rgba(255,77,94,0.35); border-radius: 5px; padding: 4px 10px; font-size: 12px; cursor: pointer; }
.hidden-chip:hover { background: rgba(255,77,94,0.16); }
.hidden-chip:active { transform: scale(0.97); }

.legend { font-size: 12px; color: var(--muted); line-height: 1.8; margin-top: 8px; }
.legend .dot { display: inline-block; width: 8px; height: 8px; border-radius: 50%; margin-right: 6px; vertical-align: middle; }
.dot.g { background: var(--green); box-shadow: 0 0 6px rgba(57,255,138,0.7); }
.dot.a { background: var(--amber); box-shadow: 0 0 6px rgba(255,176,32,0.7); }
.dot.b { background: var(--cyan); box-shadow: 0 0 6px rgba(42,212,255,0.7); }

/* Structured solution breakdown */
.solbox { margin: 6px 0 2px; }
.solrow { display: grid; grid-template-columns: minmax(96px, auto) 1fr; gap: 12px; padding: 7px 0; border-bottom: 1px dashed var(--line); }
.solrow:last-child { border-bottom: none; }
.sollabel { font-family: var(--display); font-size: 10.5px; text-transform: uppercase; letter-spacing: 0.6px; color: var(--muted); align-self: start; padding-top: 2px; }
.solrow.rot .sollabel { color: var(--amber); }
.solrow.exact .sollabel { color: var(--green); }
.solrow.tip .sollabel { color: var(--cyan); }
.solval { font-family: var(--mono); font-size: 14px; line-height: 1.5; word-break: break-word; }
.solrow.tip .solval { font-family: var(--sans); color: var(--text); }

/* Codified methods, grouped & sorted by provenance */
.methods { margin: 6px 0 2px; }
.mgroup { margin-bottom: 14px; }
.mgroup:last-child { margin-bottom: 0; }
.mglabel { font-family: var(--display); font-size: 10.5px; text-transform: uppercase; letter-spacing: 0.8px; font-weight: 700; margin-bottom: 7px; display: flex; align-items: center; gap: 8px; }
.mglabel::before { content: ""; width: 3px; height: 13px; background: currentColor; }
.mgroup.aviation .mglabel { color: var(--amber); }
.mgroup.math .mglabel { color: var(--cyan); }
.mgroup.exact .mglabel { color: var(--green); }
.method { border-left: 2px solid var(--line); padding: 2px 0 2px 12px; margin-bottom: 8px; }
.method:last-child { margin-bottom: 0; }
.mgroup.aviation .method { border-color: rgba(255,176,32,0.45); }
.mgroup.math .method { border-color: rgba(42,212,255,0.45); }
.mgroup.exact .method { border-color: rgba(57,255,138,0.45); }
.mname { font-size: 12px; font-weight: 700; color: var(--text); margin-bottom: 2px; }
.msteps { font-size: 13.5px; line-height: 1.55; color: var(--muted); }
.msteps.steplist { margin: 2px 0 0; padding-left: 20px; }
.msteps.steplist li { margin-bottom: 6px; padding-left: 2px; }
.msteps.steplist li:last-child { margin-bottom: 0; }
.msteps.steplist li::marker { color: var(--muted); font-weight: 700; }

/* "I don't know" revealed feedback */
.feedback.revealed { background: rgba(42,212,255,0.07); border-color: rgba(42,212,255,0.4); }
.feedback.revealed .verdict { color: var(--cyan); }
.btn.ghost { margin-top: 10px; }

/* Small filter chips (list view) */
.chip.sm { padding: 6px 12px; font-size: 11.5px; }

/* Question Bank list */
.qlist { display: grid; gap: 10px; margin-top: 14px; }
.qbox {
  background: var(--panel); border: 1px solid var(--line);
  clip-path: polygon(0 0, calc(100% - 12px) 0, 100% 12px, 100% 100%, 12px 100%, 0 calc(100% - 12px));
  padding: 12px 14px; transition: opacity 0.15s ease;
  animation: riseIn 0.3s ease-out both;
}
.qbox.off { opacity: 0.5; }
.qbox-head { display: flex; align-items: center; justify-content: space-between; gap: 10px; margin-bottom: 10px; }
.qbox-name { font-family: var(--display); font-weight: 600; font-size: 15px; line-height: 1.3; }
.qbox-desc { font-size: 12.5px; color: var(--muted); line-height: 1.5; margin-top: 10px; }
.qbox-q { font-size: 14px; line-height: 1.5; margin: 12px 0 10px; color: var(--text); }
.qbox-a { font-size: 13.5px; line-height: 1.6; margin-bottom: 6px; color: var(--text); border-left: 2px solid rgba(57,255,138,0.45); padding-left: 12px; white-space: pre-line; }
.qbox-note { font-size: 12px; color: var(--muted); line-height: 1.5; margin-top: 12px; border-top: 1px dashed var(--line); padding-top: 8px; }

/* Sub-organization headers — group the flat list by the item's fine-grained `cat` field so
 * browsing the whole bank isn't one undifferentiated wall of cards. Plain dividers, not
 * interactive/sortable. */
.qgroup-header {
  font-family: var(--display); font-size: 13px; font-weight: 700; text-transform: uppercase;
  letter-spacing: 1.5px; color: var(--cyan); margin: 26px 2px 8px; padding-bottom: 6px;
  border-bottom: 1px solid var(--line);
}
.qlist .qgroup-header:first-child { margin-top: 4px; }

/* Collapsed-by-default card: only the name + question show until expanded, via native
 * <details> (free open/close behavior, no JS needed). */
.qbox-disclosure > summary { list-style: none; cursor: pointer; }
.qbox-disclosure > summary::-webkit-details-marker { display: none; }
.qbox-summary { display: flex; align-items: baseline; gap: 10px; }
.qbox-summary .chevron { flex: 0 0 auto; color: var(--muted); font-size: 12px; transition: transform 0.15s ease; margin-top: 2px; }
.qbox-disclosure[open] > summary .chevron { transform: rotate(90deg); }
.qbox-summary-text { display: flex; flex-direction: column; gap: 3px; min-width: 0; }
.qbox-q-preview { font-size: 13.5px; color: var(--muted); line-height: 1.4; }
.qbox-disclosure[open] .qbox-q-preview { color: var(--text); }
.qbox-full { margin-top: 12px; padding-top: 12px; border-top: 1px dashed var(--line); }
.qbox-actions-row { display: flex; justify-content: flex-end; gap: 6px; margin-bottom: 10px; }

/* Methods / Notation / Worked view switching */
.qbox .view-methods, .qbox .view-notation, .qbox .view-worked,
.viewwrap .view-methods, .viewwrap .view-notation, .viewwrap .view-worked { display: none; }
.qbox[data-view="methods"] .view-methods, .viewwrap[data-view="methods"] .view-methods { display: block; }
.qbox[data-view="notation"] .view-notation, .viewwrap[data-view="notation"] .view-notation { display: block; }
.qbox[data-view="worked"] .view-worked, .viewwrap[data-view="worked"] .view-worked { display: block; }
.view-tabs { display: inline-flex; gap: 3px; margin: 12px 0 6px; background: var(--bg-2); border: 1px solid var(--line); border-radius: 6px; padding: 3px; }
.vtab { background: transparent; border: none; color: var(--muted); border-radius: 4px; padding: 5px 12px; font-family: var(--display); font-size: 11.5px; font-weight: 600; letter-spacing: 0.3px; cursor: pointer; }
.vtab.on { background: var(--magenta); color: #1a0210; }
.vtab:active { transform: scale(0.97); }

/* Fully-worked view */
.worked { margin: 6px 0 4px; }
.wblock { font-size: 13px; line-height: 1.55; margin-bottom: 6px; }
.wtag { display: inline-block; font-family: var(--display); font-size: 10px; font-weight: 700; text-transform: uppercase; letter-spacing: 0.6px; color: var(--cyan); border: 1px solid rgba(42,212,255,0.4); border-radius: 4px; padding: 1px 6px; margin-right: 7px; }
.wgiven { font-family: var(--mono); }
.wsteps { margin: 10px 0 4px; }
.wstep { display: flex; gap: 12px; padding: 12px 14px; border-radius: 8px; border: 1px solid var(--line); margin: 8px 0; background: var(--panel); }
.wstep.alt { background: var(--panel-2); }
.wstep-num { flex: 0 0 auto; width: 26px; height: 26px; border-radius: 4px; background: var(--bg-2); border: 1px solid var(--cyan); color: var(--cyan); font-family: var(--mono); font-weight: 800; font-size: 13px; display: flex; align-items: center; justify-content: center; margin-top: 1px; }
.wstep-body { flex: 1 1 auto; min-width: 0; }
.wstep-t { font-family: var(--display); font-size: 12px; font-weight: 600; color: var(--text); text-transform: uppercase; letter-spacing: 0.5px; margin-bottom: 7px; }
.weq { font-family: var(--mono); font-size: 13.5px; line-height: 1.5; background: var(--bg-2); border: 1px solid var(--line); border-radius: 6px; padding: 8px 10px; overflow-x: auto; }
.wtip { font-size: 12.5px; line-height: 1.5; color: var(--green); margin-top: 7px; }
.wtip b { color: var(--text); }
.wanswer { font-family: var(--mono); font-size: 15px; font-weight: 700; text-align: center; margin-top: 14px; padding: 11px; border: 2px solid var(--green); border-radius: 6px; color: var(--text); }

/* carried-value highlights (same colour links a step's result to the next step's input) */
.carry { border-radius: 3px; padding: 0 3px; font-weight: 800; }
.carry-0 { background: rgba(255,176,32,0.22); color: var(--amber); }
.carry-1 { background: rgba(42,212,255,0.22); color: var(--cyan); }
.carry-2 { background: rgba(57,255,138,0.22); color: var(--green); }
.carry-3 { background: rgba(255,77,94,0.20); color: var(--red); }
.wcarry-note { font-size: 11px; color: var(--muted); font-style: italic; margin: 4px 0 2px; }

.notation { display: flex; flex-direction: column; gap: 16px; align-items: flex-start; margin: 12px 0 4px; }
.nstep { display: inline-flex; flex-direction: column; align-items: stretch; }
.nrow { display: flex; align-items: center; justify-content: center; gap: 7px; font-family: var(--mono); font-size: 15px; color: var(--text); }
.nfrac { display: inline-flex; flex-direction: column; text-align: center; }
.ntop { padding: 0 8px 1px; }
.nbot { padding: 1px 8px 0; border-top: 1.5px solid var(--text); }
.neq { white-space: nowrap; }
.nbrace { height: 6px; border: 1.5px solid var(--muted); border-top: none; border-radius: 0 0 8px 8px; margin-top: 3px; }
.nlabel { text-align: center; font-family: var(--sans); font-size: 11px; color: var(--muted); margin-top: 4px; line-height: 1.3; }
.nunit { color: var(--muted); font-size: 0.82em; margin-left: 1px; }
.qbox .qmeta { margin-bottom: 0; }

/* Question Bank: per-card category editor */
.cat-editor { margin: 10px 0; }
.cat-editor summary { cursor: pointer; font-family: var(--display); font-size: 12px; color: var(--muted); font-weight: 600; letter-spacing: 0.2px; list-style: none; }
.cat-editor summary::-webkit-details-marker { display: none; }
.cat-editor summary:hover { color: var(--text); }
.cat-editor-panel { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 8px; padding: 10px 12px; background: var(--bg-2); border: 1px solid var(--line); border-radius: 6px; }
.cat-opt { display: inline-flex; align-items: center; gap: 6px; font-size: 12.5px; color: var(--text); cursor: pointer; }
.cat-opt input { accent-color: var(--magenta); }
.studyall-cats { margin: 4px 0 20px; padding: 16px; }
.studyall-cats .cat-opt { font-size: 15px; gap: 9px; }
.studyall-cats .cat-opt input { width: 16px; height: 16px; }

.bank-toggle { border-radius: 5px; padding: 7px 13px; font-family: var(--display); font-size: 11.5px; font-weight: 600; letter-spacing: 0.2px; cursor: pointer; border: 1px solid; white-space: nowrap; }
.bank-toggle:active { transform: scale(0.96); }
.bank-toggle.on { background: rgba(57,255,138,0.15); color: var(--green); border-color: rgba(57,255,138,0.5); }
.bank-toggle.off { background: transparent; color: var(--muted); border-color: var(--line); }
.bank-badge { color: var(--cyan); font-family: var(--mono); }
.qbox-actions { display: flex; align-items: center; gap: 6px; flex: 0 0 auto; }
.flag-toggle { background: transparent; border: 1px solid var(--line); color: var(--muted); border-radius: 5px; padding: 5px 9px; font-size: 13px; line-height: 1; cursor: pointer; }
.flag-toggle:active { transform: scale(0.94); }
.flag-toggle.on { background: rgba(255,77,94,0.15); color: var(--red); border-color: rgba(255,77,94,0.55); }
.qbox.flagged { border-color: rgba(255,77,94,0.5); }
.btn-drill { width: 100%; margin-top: 12px; background: var(--panel-2); color: var(--magenta); border: 1px solid rgba(255,63,168,0.5); border-radius: 6px; padding: 11px; font-family: var(--display); font-size: 13px; font-weight: 600; letter-spacing: 0.3px; cursor: pointer; }
.btn-drill:hover { border-color: var(--magenta); }
.btn-drill:active { transform: scale(0.99); }

@media (min-width: 560px) { .qprompt { font-size: 21px; } }