/* ============================================================
   ISE Practice — design tokens
   Dark: near-black indigo ground, violet → cyan accent.
   Light: its own warm-neutral design, not an inversion.
   ============================================================ */
:root {
  --bg: #f6f7fb;
  --bg-glow: radial-gradient(1200px 520px at 50% -8%, #e9e6ff 0%, rgba(246,247,251,0) 70%);
  --surface: #ffffff;
  --surface-2: #f1f2f9;
  --surface-3: #e6e8f4;
  --card-top: #ffffff;
  --card-bottom: #fbfbfe;
  --border: #dde0ee;
  --border-soft: #e9ebf5;
  --ring: rgba(20, 22, 42, .06);
  --text: #14162a;
  --muted: #575d7d;
  --faint: #848aa8;
  --accent: #5b4ae0;
  --accent-soft: #6f5eea;
  --accent-wash: rgba(91, 74, 224, .10);
  --accent-ink: #ffffff;
  --accent-2: #0e9ec4;
  --grad: linear-gradient(135deg, #6455e8 0%, #2aa7d8 100%);
  --good: #0d9c6c;
  --good-wash: rgba(13, 156, 108, .12);
  --warn: #a9700a;
  --warn-wash: rgba(169, 112, 10, .13);
  --bad: #d33b5c;
  --bad-wash: rgba(211, 59, 92, .11);
  --shadow-sm: 0 1px 2px rgba(20, 22, 42, .06), 0 2px 8px rgba(20, 22, 42, .05);
  --shadow: 0 4px 14px rgba(20, 22, 42, .07), 0 14px 34px rgba(20, 22, 42, .07);
  --shadow-lift: 0 8px 20px rgba(20, 22, 42, .10), 0 20px 44px rgba(20, 22, 42, .10);
  --radius: 16px;
  --radius-sm: 11px;
  --radius-xs: 8px;
  --maxw: 1060px;
  --ease: cubic-bezier(.2, .7, .3, 1);
  color-scheme: light;
}
html[data-theme="dark"] {
  --bg: #090b14;
  --bg-glow: radial-gradient(1100px 500px at 50% -10%, #1b1740 0%, rgba(9,11,20,0) 68%);
  --surface: #10131f;
  --surface-2: #171b2b;
  --surface-3: #202537;
  --card-top: #131727;
  --card-bottom: #10131f;
  --border: #272d43;
  --border-soft: #1c2133;
  --ring: rgba(255, 255, 255, .05);
  --text: #e9ecf7;
  --muted: #99a2bd;
  --faint: #6a7390;
  --accent: #7c6cff;
  --accent-soft: #a99bff;
  --accent-wash: rgba(124, 108, 255, .15);
  --accent-ink: #ffffff;
  --accent-2: #4fd8e8;
  --grad: linear-gradient(135deg, #7c6cff 0%, #3fc8e4 100%);
  --good: #3ddc9b;
  --good-wash: rgba(61, 220, 155, .13);
  --warn: #f5b14c;
  --warn-wash: rgba(245, 177, 76, .13);
  --bad: #ff6b81;
  --bad-wash: rgba(255, 107, 129, .12);
  --shadow-sm: 0 1px 2px rgba(0,0,0,.4);
  --shadow: 0 6px 18px rgba(0,0,0,.35), 0 18px 40px rgba(0,0,0,.3);
  --shadow-lift: 0 10px 24px rgba(0,0,0,.45), 0 26px 60px rgba(0,0,0,.4);
  color-scheme: dark;
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  background: var(--bg-glow), var(--bg);
  background-repeat: no-repeat;
  color: var(--text);
  font: 15px/1.6 "Segoe UI", system-ui, -apple-system, "Inter", "Helvetica Neue", Arial, sans-serif;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}
h1, h2, h3 { margin: 0; line-height: 1.22; font-weight: 680; letter-spacing: -.018em; }
p { margin: 0; }
button { font: inherit; color: inherit; }
b, strong { font-weight: 650; }
.num, .hist-score, .bd-score, .ring-pct, .qb-stats b { font-variant-numeric: tabular-nums; }
:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; border-radius: 8px; }
::selection { background: var(--accent-wash); }

/* ============ topbar ============ */
.topbar {
  position: sticky; top: 0; z-index: 40;
  display: flex; align-items: center; justify-content: space-between; gap: 16px;
  padding: 13px 22px;
  background: color-mix(in srgb, var(--bg) 82%, transparent);
  backdrop-filter: saturate(160%) blur(14px);
  border-bottom: 1px solid var(--border-soft);
}
.brand { display: flex; align-items: center; gap: 12px; text-decoration: none; color: inherit; }
.brand-mark {
  display: grid; place-items: center; width: 36px; height: 36px;
  border-radius: 11px; background: var(--grad); color: #fff;
  font-weight: 800; font-size: 13px; letter-spacing: .02em;
  box-shadow: 0 4px 12px var(--accent-wash);
}
.brand-text { display: flex; flex-direction: column; font-weight: 700; font-size: 15px; }
.brand-sub { font-weight: 500; font-size: 10.5px; color: var(--faint); letter-spacing: .09em; text-transform: uppercase; }
.topbar-right { display: flex; align-items: center; gap: 9px; }
.icon-btn {
  width: 36px; height: 36px; border-radius: 11px; cursor: pointer;
  background: var(--surface-2); border: 1px solid var(--border); font-size: 15px;
  transition: background .15s var(--ease), border-color .15s var(--ease);
}
.icon-btn:hover { background: var(--surface-3); border-color: var(--accent); }
.pill {
  padding: 4px 10px; border-radius: 999px; font-size: 10.5px; font-weight: 750; letter-spacing: .07em;
  border: 1px solid var(--border);
}
.pill-admin { background: var(--warn-wash); color: var(--warn); border-color: color-mix(in srgb, var(--warn) 40%, transparent); }

/* ============ crumbs + layout ============ */
.crumbs {
  max-width: var(--maxw); width: 100%; margin: 0 auto; padding: 16px 22px 0;
  display: flex; flex-wrap: wrap; align-items: center; gap: 4px;
  font-size: 12.5px; color: var(--muted);
}
.crumbs a { color: var(--muted); text-decoration: none; padding: 4px 8px; border-radius: 8px; transition: background .14s var(--ease), color .14s var(--ease); }
.crumbs a:hover { background: var(--surface-2); color: var(--text); }
.crumbs .sep { color: var(--faint); opacity: .6; }
.crumbs .here { color: var(--text); font-weight: 620; padding: 4px 2px; }
.crumbs:empty { padding: 0; }

.app { flex: 1; max-width: var(--maxw); width: 100%; margin: 0 auto; padding: 20px 22px 64px; }
.footer {
  max-width: var(--maxw); width: 100%; margin: 0 auto; padding: 18px 22px 30px;
  display: flex; justify-content: space-between; align-items: center; gap: 12px;
  font-size: 12px; color: var(--faint); border-top: 1px solid var(--border-soft);
}
.linkish { background: none; border: 0; color: var(--faint); cursor: pointer; font-size: 12px; padding: 4px 8px; border-radius: 8px; }
.linkish:hover { color: var(--text); background: var(--surface-2); }

.page-head { margin-bottom: 22px; }
.page-head h1 { font-size: 28px; }
.page-head .sub { color: var(--muted); font-size: 14px; margin-top: 7px; max-width: 62ch; }

/* ============ cards ============ */
.grid { display: grid; gap: 14px; grid-template-columns: repeat(auto-fill, minmax(252px, 1fr)); }
.card {
  display: block; text-align: left; width: 100%; cursor: pointer; position: relative; isolation: isolate;
  background: linear-gradient(180deg, var(--card-top), var(--card-bottom));
  border: 1px solid var(--border); border-radius: var(--radius);
  box-shadow: var(--shadow-sm); padding: 19px; text-decoration: none; color: inherit;
  transition: transform .16s var(--ease), border-color .16s var(--ease), box-shadow .16s var(--ease);
}
.card::before {
  content: ""; position: absolute; inset: 0; border-radius: inherit; z-index: -1;
  background: var(--grad); opacity: 0; transition: opacity .16s var(--ease);
}
.card:hover { transform: translateY(-3px); border-color: color-mix(in srgb, var(--accent) 45%, var(--border)); box-shadow: var(--shadow-lift); }
.card:hover::before { opacity: .05; }
.card-icon { font-size: 23px; line-height: 1; margin-bottom: 13px; }
.card-title { font-size: 17px; font-weight: 660; letter-spacing: -.01em; }
.card-sub { color: var(--muted); font-size: 13px; margin-top: 6px; }
.card-foot { margin-top: 15px; display: flex; align-items: center; justify-content: space-between; gap: 10px; font-size: 12px; color: var(--faint); }
.empty {
  border: 1px dashed var(--border); border-radius: var(--radius); padding: 38px 22px;
  text-align: center; color: var(--muted); background: var(--surface);
}
.empty a { color: var(--accent-soft); }

/* ============ continue strip ============ */
.continue {
  border: 1px solid color-mix(in srgb, var(--accent) 38%, var(--border));
  background: linear-gradient(135deg, var(--accent-wash), transparent 65%), var(--surface);
  border-radius: var(--radius); padding: 16px 18px; margin-bottom: 20px;
  box-shadow: var(--shadow-sm);
}
.continue-head { display: flex; align-items: center; gap: 8px; font-size: 11.5px; font-weight: 700;
  letter-spacing: .08em; text-transform: uppercase; color: var(--accent-soft); margin-bottom: 12px; }
.continue-row {
  display: flex; flex-wrap: wrap; align-items: center; gap: 12px;
  padding: 11px 0; border-top: 1px solid var(--border-soft);
}
.continue-row:first-of-type { border-top: 0; padding-top: 0; }
.continue-main { flex: 1; min-width: 190px; }
.continue-title { font-weight: 640; font-size: 14.5px; }
.continue-meta { color: var(--muted); font-size: 12.5px; margin-top: 3px; }
.mini-progress { height: 4px; border-radius: 999px; background: var(--surface-3); margin-top: 9px; max-width: 320px; overflow: hidden; }
.mini-progress > i { display: block; height: 100%; border-radius: 999px; background: var(--grad); }

/* ============ difficulty meter ============ */
.diff { display: inline-flex; align-items: center; gap: 9px; }
.diff-bars { display: inline-flex; gap: 3px; }
.diff-bars i { width: 16px; height: 6px; border-radius: 3px; background: var(--surface-3); border: 1px solid var(--border); display: block; }
.diff-bars i.on { background: var(--lvl, var(--accent)); border-color: transparent; box-shadow: 0 0 10px color-mix(in srgb, var(--lvl, var(--accent)) 45%, transparent); }
.diff-label { font-size: 12px; color: var(--muted); }
.diff[data-level="1"] { --lvl: #2fd0a0; }
.diff[data-level="2"] { --lvl: #6fd07f; }
.diff[data-level="3"] { --lvl: var(--accent); }
.diff[data-level="4"] { --lvl: #f5b14c; }
.diff[data-level="5"] { --lvl: #ff6b81; }
.diff-lg .diff-bars i { width: 28px; height: 10px; border-radius: 4px; }
.diff-lg .diff-label { font-size: 14px; color: var(--text); font-weight: 620; }

/* ============ set header ============ */
.set-head {
  background: linear-gradient(180deg, var(--card-top), var(--card-bottom));
  border: 1px solid var(--border); border-radius: var(--radius);
  box-shadow: var(--shadow-sm); padding: 24px; margin-bottom: 18px;
}
.set-head h1 { font-size: 25px; }
.set-head .set-meta { display: flex; flex-wrap: wrap; gap: 6px 10px; margin-top: 12px; }
.set-head .set-meta span {
  font-size: 12px; color: var(--muted); background: var(--surface-2);
  border: 1px solid var(--border-soft); border-radius: 999px; padding: 3px 10px;
}
.set-head .set-desc { color: var(--muted); font-size: 14px; margin-top: 12px; max-width: 62ch; }
.set-note {
  margin-top: 16px; padding: 11px 14px; border-radius: var(--radius-sm); font-size: 13px;
  background: var(--accent-wash); border: 1px solid color-mix(in srgb, var(--accent) 26%, transparent);
  color: var(--text);
}
.head-row { display: flex; flex-wrap: wrap; gap: 18px; align-items: flex-start; justify-content: space-between; }

/* ============ panels ============ */
.panel {
  background: linear-gradient(180deg, var(--card-top), var(--card-bottom));
  border: 1px solid var(--border); border-radius: var(--radius);
  box-shadow: var(--shadow-sm); padding: 21px; margin-bottom: 16px;
}
.panel h2 { font-size: 16px; letter-spacing: -.012em; }
.panel .hint { color: var(--muted); font-size: 12.5px; margin-top: 5px; }
.panel-head { display: flex; justify-content: space-between; align-items: baseline; gap: 12px; flex-wrap: wrap; margin-bottom: 15px; }
.step-n {
  display: inline-grid; place-items: center; width: 21px; height: 21px; border-radius: 7px;
  background: var(--accent-wash); color: var(--accent-soft); font-size: 11.5px; font-weight: 750;
  margin-right: 9px; vertical-align: 1px;
}

/* ============ buttons ============ */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  padding: 10px 16px; border-radius: var(--radius-sm); cursor: pointer;
  background: var(--surface-2); border: 1px solid var(--border); font-weight: 620; font-size: 14px;
  text-decoration: none; color: inherit;
  transition: background .14s var(--ease), border-color .14s var(--ease), transform .12s var(--ease), box-shadow .14s var(--ease);
}
.btn:hover { background: var(--surface-3); border-color: color-mix(in srgb, var(--accent) 40%, var(--border)); }
.btn:active { transform: translateY(1px); }
.btn-primary { background: var(--grad); border-color: transparent; color: #fff; box-shadow: 0 4px 14px var(--accent-wash); }
.btn-primary:hover { filter: brightness(1.07); border-color: transparent; }
.btn-lg { padding: 13px 24px; font-size: 15px; border-radius: 13px; }
.btn-sm { padding: 6px 12px; font-size: 12.5px; border-radius: 9px; }
.btn:disabled { opacity: .45; cursor: not-allowed; }
.btn-ghost { background: transparent; }
.btn-row { display: flex; flex-wrap: wrap; gap: 10px; }
@keyframes pulse-ring {
  0% { box-shadow: 0 0 0 0 color-mix(in srgb, var(--accent) 55%, transparent); }
  70% { box-shadow: 0 0 0 9px transparent; }
  100% { box-shadow: 0 0 0 0 transparent; }
}
.btn.pulse { animation: pulse-ring 1s var(--ease) 2; }

/* ============ mode choice ============ */
.choice-row { display: grid; gap: 12px; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); }
.choice-tile {
  text-align: left; cursor: pointer; padding: 17px;
  background: var(--surface-2); border: 1px solid var(--border); border-radius: var(--radius-sm);
  transition: border-color .14s var(--ease), background .14s var(--ease), transform .12s var(--ease);
}
.choice-tile:hover { border-color: color-mix(in srgb, var(--accent) 45%, var(--border)); transform: translateY(-1px); }
.choice-tile[aria-pressed="true"] {
  border-color: var(--accent); background: var(--accent-wash);
  box-shadow: inset 0 0 0 1px var(--accent);
}
.choice-tile .ct-title { font-weight: 660; display: flex; align-items: center; gap: 8px; font-size: 14.5px; }
.choice-tile .ct-desc { color: var(--muted); font-size: 12.5px; margin-top: 7px; line-height: 1.5; }
.tick { color: var(--accent-soft); font-weight: 800; }

/* ============ quick picks ============ */
.quickpicks { display: flex; flex-wrap: wrap; gap: 8px; margin-bottom: 15px; }
.qp {
  display: inline-flex; align-items: center; gap: 7px; cursor: pointer;
  padding: 7px 13px; border-radius: 999px; font-size: 12.5px; font-weight: 600;
  background: var(--surface-2); border: 1px solid var(--border); color: var(--muted);
  transition: background .14s var(--ease), color .14s var(--ease), border-color .14s var(--ease);
}
.qp:hover:not(:disabled) { color: var(--text); border-color: var(--accent); background: var(--accent-wash); }
.qp:disabled { opacity: .4; cursor: not-allowed; }
.qp .qp-n { font-size: 11px; color: var(--faint); font-variant-numeric: tabular-nums; }

/* ============ chapter picker ============ */
.chapters { display: flex; flex-direction: column; gap: 9px; }
.chapter { border: 1px solid var(--border); border-radius: var(--radius-sm); background: var(--surface-2); overflow: hidden; transition: border-color .14s var(--ease); }
.chapter:hover { border-color: color-mix(in srgb, var(--accent) 30%, var(--border)); }
.chapter-row { display: flex; align-items: center; gap: 13px; padding: 14px 15px; cursor: pointer; }
.chapter-row:hover { background: var(--surface-3); }
.chapter-main { flex: 1; min-width: 0; }
.chapter-title { font-weight: 630; font-size: 14.5px; }
.chapter-title .range { color: var(--faint); font-weight: 400; }
.chapter-blurb { color: var(--muted); font-size: 12.5px; margin-top: 3px; }
.count-chip {
  font-size: 11.5px; color: var(--muted); background: var(--surface); border: 1px solid var(--border);
  padding: 3px 10px; border-radius: 999px; white-space: nowrap; font-variant-numeric: tabular-nums;
}
.count-chip.full { color: var(--accent-soft); border-color: color-mix(in srgb, var(--accent) 35%, transparent); background: var(--accent-wash); }
.disclose { background: none; border: 0; cursor: pointer; color: var(--faint); padding: 5px 7px; font-size: 11.5px; border-radius: 8px; }
.disclose:hover { color: var(--text); background: var(--surface); }
.topics { display: none; padding: 5px 15px 13px 48px; flex-direction: column; gap: 2px; border-top: 1px solid var(--border-soft); }
.chapter.open .topics { display: flex; }
.topic-row { display: flex; align-items: center; gap: 11px; padding: 8px 9px; border-radius: 9px; cursor: pointer; font-size: 13px; }
.topic-row:hover { background: var(--surface-3); }
.topic-row .t-name { flex: 1; min-width: 0; }
.cb {
  width: 19px; height: 19px; border-radius: 6px; border: 1.5px solid var(--faint);
  display: grid; place-items: center; flex: none; font-size: 12px; color: transparent; background: transparent;
  transition: background .13s var(--ease), border-color .13s var(--ease);
}
.cb.on { background: var(--accent); border-color: var(--accent); color: #fff; }
.cb.some { border-color: var(--accent); color: var(--accent-soft); }
.selection-bar {
  display: flex; flex-wrap: wrap; gap: 12px; align-items: center; justify-content: space-between;
  margin-top: 17px; padding-top: 16px; border-top: 1px solid var(--border-soft);
}
.sel-count { font-size: 13.5px; color: var(--muted); }
.sel-count b { font-size: 19px; color: var(--text); font-variant-numeric: tabular-nums; }

/* ============ options ============ */
.opts { display: flex; flex-direction: column; gap: 2px; }
.opt-row { display: flex; align-items: center; gap: 14px; padding: 10px 9px; border-radius: 10px; cursor: pointer; }
.opt-row:hover { background: var(--surface-2); }
.opt-row .o-name { flex: 1; font-size: 14px; }
.opt-row .o-desc { color: var(--muted); font-size: 12.5px; margin-top: 2px; }
.switch { width: 40px; height: 22px; border-radius: 999px; background: var(--surface-3); border: 1px solid var(--border); position: relative; flex: none; transition: background .16s var(--ease), border-color .16s var(--ease); }
.switch::after { content: ""; position: absolute; top: 2px; left: 2px; width: 16px; height: 16px; border-radius: 50%; background: var(--faint); transition: transform .16s var(--ease), background .16s var(--ease); }
.switch.on { background: var(--accent-wash); border-color: var(--accent); }
.switch.on::after { transform: translateX(18px); background: var(--accent); }
.num-input { width: 82px; padding: 8px 11px; border-radius: 9px; background: var(--surface-2); border: 1px solid var(--border); color: var(--text); font-variant-numeric: tabular-nums; }

/* ============ progress panel ============ */
.stat-grid { display: grid; gap: 12px; grid-template-columns: repeat(auto-fit, minmax(116px, 1fr)); margin-bottom: 18px; }
.stat {
  background: var(--surface-2); border: 1px solid var(--border-soft);
  border-radius: var(--radius-sm); padding: 13px 14px;
}
.stat .s-label { font-size: 10.5px; letter-spacing: .07em; text-transform: uppercase; color: var(--faint); }
.stat .s-value { font-size: 22px; font-weight: 700; margin-top: 4px; font-variant-numeric: tabular-nums; letter-spacing: -.02em; }
.stat .s-sub { font-size: 11.5px; color: var(--muted); margin-top: 2px; }
.trend { display: flex; align-items: flex-end; gap: 10px; height: 104px; padding: 4px 0; margin-top: 4px; }
.trend-bar { flex: 0 0 42px; display: flex; flex-direction: column; justify-content: flex-end; height: 100%; }
.trend-bar .tb-val { font-size: 10.5px; color: var(--faint); text-align: center; margin-bottom: 5px; font-variant-numeric: tabular-nums; }
.trend-bar > i {
  display: block; width: 100%; border-radius: 6px 6px 3px 3px;
  background: linear-gradient(180deg, var(--good), color-mix(in srgb, var(--good) 45%, transparent));
  transition: filter .14s var(--ease);
}
.trend-bar:hover > i { filter: brightness(1.15); }
.trend-bar:hover .tb-val { color: var(--text); }
.trend-bar.low > i { background: linear-gradient(180deg, var(--bad), color-mix(in srgb, var(--bad) 45%, transparent)); }
.trend-bar.mid > i { background: linear-gradient(180deg, var(--warn), color-mix(in srgb, var(--warn) 45%, transparent)); }
.trend-axis { display: flex; justify-content: space-between; font-size: 10.5px; color: var(--faint); margin-top: 7px; }
.delta-pill {
  display: inline-flex; align-items: center; gap: 4px; padding: 3px 10px; border-radius: 999px;
  font-size: 12px; font-weight: 680; border: 1px solid var(--border);
}
.delta-pill.up { color: var(--good); background: var(--good-wash); border-color: color-mix(in srgb, var(--good) 35%, transparent); }
.delta-pill.down { color: var(--bad); background: var(--bad-wash); border-color: color-mix(in srgb, var(--bad) 35%, transparent); }
.delta-pill.flat { color: var(--muted); background: var(--surface-2); }

/* ============ quiz runner ============ */
.quiz-bar {
  position: sticky; top: 62px; z-index: 30; margin: -20px -22px 20px; padding: 13px 22px;
  background: color-mix(in srgb, var(--bg) 88%, transparent); backdrop-filter: saturate(160%) blur(14px);
  border-bottom: 1px solid var(--border-soft);
}
.qb-top { display: flex; align-items: center; justify-content: space-between; gap: 14px; flex-wrap: wrap; }
.qb-title { font-weight: 640; font-size: 13.5px; }
.qb-title .qb-mode { color: var(--faint); font-weight: 400; }
.qb-stats { display: flex; gap: 15px; align-items: center; font-size: 12.5px; color: var(--muted); }
.qb-stats b { color: var(--text); font-weight: 640; }
.progress { height: 6px; border-radius: 999px; background: var(--surface-3); margin-top: 11px; overflow: hidden; }
.progress > i { display: block; height: 100%; background: var(--grad); border-radius: 999px; transition: width .28s var(--ease); }

.q-card {
  background: linear-gradient(180deg, var(--card-top), var(--card-bottom));
  border: 1px solid var(--border); border-radius: var(--radius); box-shadow: var(--shadow); padding: 26px;
}
.q-meta { display: flex; flex-wrap: wrap; gap: 8px; align-items: center; font-size: 11.5px; color: var(--faint); margin-bottom: 16px; }
.q-tag { background: var(--surface-2); border: 1px solid var(--border-soft); border-radius: 999px; padding: 3px 11px; }
.q-num { font-weight: 750; color: var(--accent-soft); background: var(--accent-wash); border-radius: 999px; padding: 3px 11px; font-variant-numeric: tabular-nums; }
.q-seen { margin-left: auto; }
.q-prompt { font-size: 19px; line-height: 1.48; font-weight: 620; margin-bottom: 22px; letter-spacing: -.012em; }

.answers { display: flex; flex-direction: column; gap: 10px; }
.answer {
  display: flex; align-items: center; gap: 14px; text-align: left; width: 100%; cursor: pointer;
  padding: 15px 17px; border-radius: var(--radius-sm);
  background: var(--surface-2); border: 1px solid var(--border);
  transition: border-color .13s var(--ease), background .13s var(--ease), transform .1s var(--ease);
}
.answer:hover:not(:disabled) { border-color: color-mix(in srgb, var(--accent) 50%, var(--border)); background: var(--surface-3); }
.answer:active:not(:disabled) { transform: scale(.995); }
/* keycap */
.answer .key {
  flex: none; width: 30px; height: 30px; border-radius: 9px; display: grid; place-items: center;
  background: var(--surface); border: 1px solid var(--border); border-bottom-width: 2.5px;
  font-size: 12.5px; font-weight: 750; color: var(--muted);
  font-family: ui-monospace, "Cascadia Mono", Consolas, monospace;
  transition: background .13s var(--ease), color .13s var(--ease), border-color .13s var(--ease);
}
.answer .txt { flex: 1; min-width: 0; line-height: 1.45; }
.answer[aria-pressed="true"] { border-color: var(--accent); background: var(--accent-wash); }
.answer[aria-pressed="true"] .key { background: var(--accent); border-color: var(--accent); color: #fff; }
.answer.correct { border-color: var(--good); background: var(--good-wash); }
.answer.correct .key { background: var(--good); border-color: var(--good); color: #04231a; }
.answer.wrong { border-color: var(--bad); background: var(--bad-wash); }
.answer.wrong .key { background: var(--bad); border-color: var(--bad); color: #2b0710; }
.answer .mark { flex: none; font-weight: 700; font-size: 12.5px; white-space: nowrap; }
.answer.correct .mark { color: var(--good); }
.answer.wrong .mark { color: var(--bad); }
.answer:disabled { cursor: default; opacity: 1; }
@keyframes key-hit {
  0% { box-shadow: 0 0 0 0 color-mix(in srgb, var(--accent) 60%, transparent); }
  100% { box-shadow: 0 0 0 10px transparent; }
}
.answer.key-hit { animation: key-hit .42s var(--ease); }
.answer.key-hit .key { transform: translateY(1.5px); border-bottom-width: 1px; }

.short-input {
  width: 100%; min-height: 104px; resize: vertical; padding: 14px 16px; border-radius: var(--radius-sm);
  background: var(--surface-2); border: 1px solid var(--border); color: var(--text); font: inherit; line-height: 1.5;
}
.short-input:focus { border-color: var(--accent); outline: none; box-shadow: 0 0 0 3px var(--accent-wash); }
.short-input:disabled { opacity: .85; }

.verdict {
  margin-top: 20px; padding: 15px 17px; border-radius: var(--radius-sm);
  border: 1px solid var(--border); border-left-width: 4px; background: var(--surface-2);
}
.verdict.is-correct { border-color: color-mix(in srgb, var(--good) 40%, transparent); border-left-color: var(--good); background: var(--good-wash); }
.verdict.is-wrong { border-color: color-mix(in srgb, var(--bad) 40%, transparent); border-left-color: var(--bad); background: var(--bad-wash); }
.verdict .v-head { font-weight: 720; display: flex; align-items: center; gap: 8px; font-size: 14px; }
.verdict.is-correct .v-head { color: var(--good); }
.verdict.is-wrong .v-head { color: var(--bad); }
.verdict .v-body { margin-top: 9px; font-size: 13.5px; color: var(--muted); line-height: 1.55; }
.verdict .v-body b { color: var(--text); }
.self-grade { display: flex; gap: 8px; margin-top: 13px; flex-wrap: wrap; align-items: center; }
.self-grade .sg-label { font-size: 12.5px; color: var(--muted); margin-right: 2px; }

.q-actions { display: flex; justify-content: space-between; align-items: center; gap: 12px; margin-top: 24px; flex-wrap: wrap; }
.q-actions-left { display: flex; gap: 8px; flex-wrap: wrap; }
.flag-btn.on { border-color: var(--warn); color: var(--warn); background: var(--warn-wash); }
.kbd-hint {
  display: flex; flex-wrap: wrap; justify-content: center; gap: 6px 16px;
  font-size: 11.5px; color: var(--faint); margin-top: 18px; padding-top: 16px; border-top: 1px solid var(--border-soft);
}
.kbd-hint span { display: inline-flex; align-items: center; gap: 5px; }
kbd {
  background: var(--surface-2); border: 1px solid var(--border); border-bottom-width: 2px;
  border-radius: 6px; padding: 2px 7px; font-size: 10.5px; font-weight: 650; color: var(--muted);
  font-family: ui-monospace, "Cascadia Mono", Consolas, monospace;
}

/* ============ navigator ============ */
.nav-grid { display: flex; flex-wrap: wrap; gap: 6px; max-height: 220px; overflow-y: auto; padding: 3px; }
.nav-cell {
  width: 35px; height: 32px; border-radius: 9px; cursor: pointer; font-size: 12px; font-weight: 650;
  background: var(--surface-2); border: 1px solid var(--border); color: var(--muted); position: relative;
  font-variant-numeric: tabular-nums; transition: transform .1s var(--ease), border-color .12s var(--ease);
}
.nav-cell:hover { border-color: var(--accent); color: var(--text); transform: translateY(-1px); }
.nav-cell.answered { background: var(--surface-3); color: var(--text); border-color: var(--faint); }
.nav-cell.correct { background: var(--good-wash); border-color: var(--good); color: var(--text); }
.nav-cell.wrong { background: var(--bad-wash); border-color: var(--bad); color: var(--text); }
.nav-cell.current { box-shadow: 0 0 0 2px var(--accent); border-color: var(--accent); color: var(--text); }
.nav-cell.flagged::after { content: ""; position: absolute; top: -2px; right: -2px; width: 8px; height: 8px; border-radius: 50%; background: var(--warn); }
.legend { display: flex; flex-wrap: wrap; gap: 12px; font-size: 11.5px; color: var(--faint); margin-top: 13px; }
.legend span { display: inline-flex; align-items: center; gap: 6px; }
.legend i { width: 11px; height: 11px; border-radius: 4px; border: 1px solid var(--border); display: block; }

/* ============ results ============ */
.score-wrap { display: flex; flex-wrap: wrap; gap: 28px; align-items: center; }
.ring {
  --pct: 0; width: 140px; height: 140px; flex: none; border-radius: 50%; display: grid; place-items: center;
  background: conic-gradient(var(--ring-color, var(--accent)) calc(var(--pct) * 1%), var(--surface-3) 0);
  box-shadow: 0 0 32px color-mix(in srgb, var(--ring-color, var(--accent)) 22%, transparent);
}
.ring-inner { width: 112px; height: 112px; border-radius: 50%; background: var(--surface); display: grid; place-items: center; text-align: center; }
.ring-pct { font-size: 30px; font-weight: 760; letter-spacing: -.03em; }
.ring-sub { font-size: 11.5px; color: var(--muted); }
.score-facts { display: flex; flex-wrap: wrap; gap: 12px 28px; }
.fact .fact-label { font-size: 10.5px; color: var(--faint); text-transform: uppercase; letter-spacing: .07em; }
.fact .fact-value { font-size: 20px; font-weight: 700; margin-top: 3px; font-variant-numeric: tabular-nums; letter-spacing: -.02em; }

.bd-row { display: flex; align-items: center; gap: 14px; padding: 10px 0; border-bottom: 1px solid var(--border-soft); }
.bd-row:last-child { border-bottom: 0; }
.bd-name { flex: 1.4; min-width: 0; font-size: 13.5px; }
.bd-name small { display: block; color: var(--faint); font-size: 11.5px; }
.bd-bar { flex: 1; height: 9px; border-radius: 999px; background: var(--surface-3); overflow: hidden; }
.bd-bar > i { display: block; height: 100%; border-radius: 999px; background: linear-gradient(90deg, color-mix(in srgb, var(--good) 70%, transparent), var(--good)); transition: width .3s var(--ease); }
.bd-bar > i.mid { background: linear-gradient(90deg, color-mix(in srgb, var(--warn) 70%, transparent), var(--warn)); }
.bd-bar > i.low { background: linear-gradient(90deg, color-mix(in srgb, var(--bad) 70%, transparent), var(--bad)); }
.bd-score { width: 96px; text-align: right; font-size: 12.5px; color: var(--muted); }
.bd-score b { color: var(--text); }
.sub-rows { padding-left: 15px; border-left: 2px solid var(--border-soft); margin: 2px 0 10px; }

.filters { display: flex; gap: 6px; flex-wrap: wrap; }
.chip {
  padding: 6px 13px; border-radius: 999px; cursor: pointer; font-size: 12.5px;
  background: var(--surface-2); border: 1px solid var(--border); color: var(--muted);
  transition: background .13s var(--ease), color .13s var(--ease);
}
.chip:hover { color: var(--text); }
.chip[aria-pressed="true"] { background: var(--grad); border-color: transparent; color: #fff; font-weight: 640; }

.review { display: flex; flex-direction: column; gap: 10px; }
.rev { border: 1px solid var(--border); border-left-width: 4px; border-radius: var(--radius-sm); background: var(--surface-2); padding: 15px 17px; }
.rev.ok { border-left-color: var(--good); }
.rev.no { border-left-color: var(--bad); }
.rev.skip { border-left-color: var(--faint); }
.rev-head { display: flex; gap: 9px; align-items: center; flex-wrap: wrap; font-size: 11.5px; color: var(--faint); }
.rev-badge { background: var(--bad-wash); color: var(--bad); border: 1px solid color-mix(in srgb, var(--bad) 30%, transparent); border-radius: 999px; padding: 2px 9px; font-weight: 650; }
.rev-q { font-weight: 620; margin: 9px 0 11px; font-size: 14.5px; color: var(--text); line-height: 1.45; }
.rev-line { font-size: 13px; display: flex; gap: 10px; padding: 3px 0; }
.rev-line .lbl { color: var(--faint); min-width: 96px; flex: none; }
.rev-line.yours-wrong .val { color: var(--bad); }
.rev-line.correct .val { color: var(--good); }

/* ============ history ============ */
.hist { display: flex; flex-direction: column; gap: 4px; }
.hist-row { display: flex; gap: 12px; align-items: center; font-size: 13px; padding: 8px 0; border-bottom: 1px solid var(--border-soft); }
.hist-row:last-child { border-bottom: 0; }
.hist-when { color: var(--muted); flex: 1; min-width: 0; }
.hist-mode { font-size: 11.5px; color: var(--faint); }
.hist-score { font-weight: 650; }
.score-pill { padding: 3px 10px; border-radius: 999px; font-size: 11.5px; font-weight: 660; border: 1px solid var(--border); font-variant-numeric: tabular-nums; }
.score-pill.good { color: var(--good); border-color: color-mix(in srgb, var(--good) 38%, transparent); background: var(--good-wash); }
.score-pill.mid { color: var(--warn); border-color: color-mix(in srgb, var(--warn) 38%, transparent); background: var(--warn-wash); }
.score-pill.low { color: var(--bad); border-color: color-mix(in srgb, var(--bad) 38%, transparent); background: var(--bad-wash); }

/* ============ admin ============ */
.admin-panel { border-color: color-mix(in srgb, var(--warn) 38%, var(--border)); }
.admin-panel h2 { color: var(--warn); }
.field { display: flex; flex-direction: column; gap: 7px; margin-bottom: 15px; }
.field label { font-size: 11.5px; color: var(--muted); font-weight: 640; letter-spacing: .02em; }
.field input[type="text"], .field textarea {
  width: 100%; padding: 11px 13px; border-radius: var(--radius-sm);
  background: var(--surface-2); border: 1px solid var(--border); color: var(--text); font: inherit;
}
.field input:focus, .field textarea:focus { border-color: var(--accent); outline: none; box-shadow: 0 0 0 3px var(--accent-wash); }
.field textarea { min-height: 64px; resize: vertical; }
.level-picker { display: grid; gap: 8px; grid-template-columns: repeat(auto-fit, minmax(136px, 1fr)); }
.level-tile { cursor: pointer; text-align: left; padding: 12px 14px; border-radius: var(--radius-sm); background: var(--surface-2); border: 1px solid var(--border); transition: border-color .13s var(--ease), background .13s var(--ease); }
.level-tile:hover { border-color: var(--faint); }
.level-tile[aria-pressed="true"] { border-color: var(--lv); box-shadow: inset 0 0 0 1px var(--lv); background: color-mix(in srgb, var(--lv) 13%, var(--surface-2)); }
.level-tile .lv-num { font-size: 10.5px; font-weight: 750; color: var(--lv); letter-spacing: .07em; }
.level-tile .lv-label { font-weight: 640; font-size: 13.5px; margin-top: 4px; }
.level-tile .lv-blurb { color: var(--muted); font-size: 11.5px; margin-top: 5px; line-height: 1.42; }
.level-tile[data-lv="1"] { --lv: #2fd0a0; } .level-tile[data-lv="2"] { --lv: #6fd07f; }
.level-tile[data-lv="3"] { --lv: var(--accent); } .level-tile[data-lv="4"] { --lv: #f5b14c; }
.level-tile[data-lv="5"] { --lv: #ff6b81; }

/* ============ modal ============ */
.modal-back { position: fixed; inset: 0; z-index: 90; background: rgba(4, 6, 14, .66); display: grid; place-items: center; padding: 22px; backdrop-filter: blur(4px); }
.modal {
  width: 100%; max-width: 470px; background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); box-shadow: var(--shadow-lift); padding: 24px;
  animation: pop .18s var(--ease);
}
@keyframes pop { from { transform: translateY(8px) scale(.98); opacity: 0; } to { transform: none; opacity: 1; } }
.modal h3 { font-size: 17px; margin-bottom: 9px; }
.modal p { color: var(--muted); font-size: 13.5px; line-height: 1.55; }
.modal input[type="password"], .modal textarea {
  width: 100%; margin-top: 15px; padding: 11px 13px; border-radius: var(--radius-sm);
  background: var(--surface-2); border: 1px solid var(--border); color: var(--text); font: inherit;
}
.modal input:focus, .modal textarea:focus { border-color: var(--accent); outline: none; box-shadow: 0 0 0 3px var(--accent-wash); }
.modal textarea { min-height: 156px; font-family: ui-monospace, Consolas, monospace; font-size: 12px; }
.modal-actions { display: flex; justify-content: flex-end; gap: 8px; margin-top: 18px; }
.modal .err { color: var(--bad); font-size: 12.5px; margin-top: 9px; }
.modal code { background: var(--surface-2); border-radius: 5px; padding: 1px 5px; font-size: 12px; }

/* ============ responsive ============ */
@media (max-width: 700px) {
  .app { padding: 16px 15px 48px; }
  .crumbs { padding: 13px 15px 0; font-size: 12px; }
  .topbar { padding: 11px 15px; }
  .quiz-bar { margin: -16px -15px 16px; padding: 11px 15px; top: 58px; }
  .q-card, .panel, .set-head { padding: 17px; }
  .q-prompt { font-size: 17px; }
  .page-head h1 { font-size: 23px; }
  .grid { grid-template-columns: 1fr; }
  .bd-score { width: 78px; font-size: 12px; }
  .ring { width: 116px; height: 116px; } .ring-inner { width: 92px; height: 92px; }
  .ring-pct { font-size: 26px; }
  .kbd-hint { display: none; }
  .answer { padding: 13px 14px; gap: 12px; }
  .topics { padding-left: 30px; }
}
@media (prefers-reduced-motion: reduce) { *, *::before, *::after { animation: none !important; transition: none !important; } }

/* ============ solutions ============ */
.solution { margin-top: 12px; border-top: 1px dashed var(--border); padding-top: 12px; display: flex; flex-direction: column; gap: 9px; }
.sol-line { display: flex; gap: 10px; font-size: 13px; line-height: 1.5; color: var(--muted); }
.sol-line .sol-k {
  flex: none; min-width: 104px; font-weight: 650; font-size: 11.5px; letter-spacing: .02em;
  text-transform: uppercase; padding-top: 2px;
}
.sol-line.sol-yes .sol-k { color: var(--good); }
.sol-line.sol-no .sol-k { color: var(--bad); }
.slide-chip {
  align-self: flex-start; font-size: 11.5px; color: var(--accent-soft);
  background: var(--accent-wash); border: 1px solid color-mix(in srgb, var(--accent) 28%, transparent);
  border-radius: 999px; padding: 3px 11px;
}

/* ============ drill banner ============ */
.drill-bar {
  display: flex; flex-wrap: wrap; gap: 12px; align-items: flex-start; justify-content: space-between;
  margin-top: 17px; padding: 14px 15px; border-radius: var(--radius-sm);
  background: var(--accent-wash); border: 1px solid color-mix(in srgb, var(--accent) 40%, transparent);
}
.drill-bar.empty { background: var(--warn-wash); border-color: color-mix(in srgb, var(--warn) 40%, transparent); }
.drill-main { min-width: 0; flex: 1; }
.drill-title { font-weight: 640; font-size: 14.5px; }
.drill-title b { font-variant-numeric: tabular-nums; }
.drill-list { margin-top: 8px; }
.drill-list summary { cursor: pointer; font-size: 12.5px; color: var(--accent-soft); }
.drill-list ul { list-style: none; margin: 10px 0 0; padding: 0; max-height: 240px; overflow-y: auto; display: flex; flex-direction: column; gap: 2px; }
.drill-list li { display: flex; gap: 10px; align-items: baseline; font-size: 12.5px; padding: 5px 8px; border-radius: 7px; background: var(--surface); }
.dq-n { font-weight: 700; font-variant-numeric: tabular-nums; color: var(--accent-soft); flex: none; min-width: 46px; }
.dq-t { color: var(--muted); flex: 1; min-width: 0; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.dq-w { color: var(--faint); font-size: 11.5px; flex: none; }
.pick-rule { margin-top: 8px; }

/* ============ flagged panel ============ */
.flag-list { display: flex; flex-direction: column; gap: 6px; }
.flag-row { border: 1px solid var(--border); border-radius: var(--radius-sm); background: var(--surface-2); }
.flag-row summary { display: flex; gap: 10px; align-items: baseline; padding: 11px 13px; cursor: pointer; font-size: 13.5px; }
.flag-row summary::-webkit-details-marker { display: none; }
.flag-row[open] { border-color: color-mix(in srgb, var(--warn) 40%, var(--border)); }
.fl-prompt { flex: 1; min-width: 0; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.fl-body { padding: 0 13px 13px 13px; display: flex; flex-direction: column; gap: 10px; align-items: flex-start; }

/* ============ attempt log rows as links ============ */
a.hist-row { text-decoration: none; color: inherit; padding: 10px 8px; border-radius: 9px; }
a.hist-row:hover { background: var(--surface-2); }
.hist-go { color: var(--faint); font-size: 16px; }
.readonly-bar {
  display: flex; flex-wrap: wrap; gap: 12px; align-items: center; justify-content: space-between;
  padding: 12px 16px; margin-bottom: 16px; border-radius: var(--radius-sm); font-size: 13px;
  background: var(--surface-2); border: 1px solid var(--border); color: var(--muted);
}

/* ============ solutions browser ============ */
.study-list { display: flex; flex-direction: column; gap: 8px; }
.study-q { border: 1px solid var(--border); border-radius: var(--radius-sm); background: var(--surface); }
.study-q summary { display: flex; gap: 10px; align-items: baseline; padding: 13px 15px; cursor: pointer; font-size: 14px; }
.study-q summary::-webkit-details-marker { display: none; }
.study-q[open] { border-color: color-mix(in srgb, var(--accent) 40%, var(--border)); box-shadow: var(--shadow-sm); }
.study-body { padding: 0 15px 15px; display: flex; flex-direction: column; gap: 9px; align-items: flex-start; }
.study-opt { display: flex; gap: 12px; width: 100%; padding: 11px 13px; border-radius: var(--radius-sm); border: 1px solid var(--border); background: var(--surface-2); }
.study-opt.yes { border-color: color-mix(in srgb, var(--good) 45%, transparent); background: var(--good-wash); }
.study-opt .key { flex: none; width: 26px; height: 26px; border-radius: 8px; display: grid; place-items: center;
  background: var(--surface); border: 1px solid var(--border); font-size: 12px; font-weight: 700; color: var(--muted);
  font-family: ui-monospace, Consolas, monospace; }
.study-opt.yes .key { background: var(--good); border-color: var(--good); color: #04231a; }
.so-text { font-size: 13.5px; }
.so-why { font-size: 12.5px; color: var(--muted); margin-top: 5px; line-height: 1.5; }
.qb-drill { color: var(--accent-soft); font-weight: 600; }

@media (max-width: 700px) {
  .sol-line { flex-direction: column; gap: 3px; }
  .sol-line .sol-k { min-width: 0; }
  .drill-bar { flex-direction: column; }
  .dq-t { white-space: normal; }
}

/* expandable rows need to look expandable */
.study-q summary::before, .flag-row summary::before, .drill-list summary::before {
  content: "▸"; color: var(--faint); flex: none; font-size: 11px; line-height: 1.6;
}
.study-q[open] summary::before, .flag-row[open] summary::before, .drill-list[open] summary::before { content: "▾"; }
.drill-list summary { display: flex; align-items: center; gap: 6px; }