:root {
  --bg: #f6f7fb;
  --card: #ffffff;
  --ink: #1d2433;
  --muted: #6b7280;
  --line: #e5e7eb;
  --brand: #2f5bea;
  --brand-ink: #ffffff;
  --ok: #15803d;
  --ok-bg: #dcfce7;
  --bad: #b91c1c;
  --bad-bg: #fee2e2;
  --warn: #92400e;
  --warn-bg: #fef3c7;
  --info-bg: #dbeafe;
  --radius: 12px;
  --shadow: 0 1px 2px rgba(16, 24, 40, 0.06), 0 1px 3px rgba(16, 24, 40, 0.1);
  --hp: #2f5bea;
  --mfp: #0f766e;
}
* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  font-size: 16px; line-height: 1.5; color: var(--ink); background: var(--bg);
  min-height: 100vh; display: flex; flex-direction: column;
}
main.wrap { flex: 1; }
.wrap { max-width: 980px; margin: 0 auto; padding: 0 16px; width: 100%; }
a { color: var(--brand); text-decoration: none; }
a:hover { text-decoration: underline; }
h1 { font-size: 1.6rem; margin: 0 0 12px; }
h2 { font-size: 1.25rem; margin: 20px 0 8px; }
h3 { font-size: 1.05rem; margin: 16px 0 6px; }
p { margin: 0 0 10px; }
.muted { color: var(--muted); }
.small { font-size: 0.875rem; }
.tiny { font-size: 0.78rem; }
.right { text-align: right; }
.center { text-align: center; }
.mono { font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; }

/* top bar */
.topbar { background: var(--card); border-bottom: 1px solid var(--line); position: sticky; top: 0; z-index: 10; }
.topbar .wrap { display: flex; align-items: center; gap: 18px; height: 54px; }
.brand { font-weight: 700; font-size: 1.15rem; color: var(--ink); }
.nav { display: flex; gap: 4px; flex: 1; overflow-x: auto; }
.nav a { padding: 6px 10px; border-radius: 8px; color: var(--ink); white-space: nowrap; }
.nav a.active, .nav a:hover { background: var(--bg); text-decoration: none; }
.logout { display: flex; align-items: center; gap: 10px; margin: 0; }
.who { color: var(--muted); font-size: 0.9rem; }
button.link { background: none; border: 0; color: var(--brand); cursor: pointer; padding: 0; font: inherit; }
.foot { border-top: 1px solid var(--line); color: var(--muted); font-size: 0.8rem; padding: 12px 0; margin-top: 30px; }

/* cards */
.card { background: var(--card); border: 1px solid var(--line); border-radius: var(--radius); padding: 20px; margin: 18px 0; box-shadow: var(--shadow); }
.card.narrow { max-width: 420px; margin: 40px auto; }
.card.tight { padding: 12px 16px; }
.grid { display: grid; gap: 14px; }
.grid.two { grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); }
.grid.three { grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); }
.row { display: flex; gap: 12px; align-items: center; flex-wrap: wrap; }
.row.between { justify-content: space-between; }
.stack > * + * { margin-top: 10px; }

/* forms */
.form label { display: block; margin-bottom: 12px; font-weight: 500; }
.form input[type=text], .form input[type=email], .form input[type=password], .form input[type=number],
.form input[type=date], .form input[type=url], .form select, .form textarea,
input.answer, textarea.answer, select.answer {
  display: block; width: 100%; padding: 9px 11px; margin-top: 4px; border: 1px solid #cbd5e1;
  border-radius: 8px; font: inherit; background: #fff;
}
.form textarea, textarea.answer { min-height: 90px; }
.inline { display: inline-flex; gap: 8px; align-items: center; }
.btn { display: inline-block; padding: 9px 16px; border-radius: 8px; border: 1px solid #cbd5e1; background: #fff; color: var(--ink); font: inherit; cursor: pointer; text-decoration: none; }
.btn:hover { background: var(--bg); text-decoration: none; }
.btn.primary { background: var(--brand); color: var(--brand-ink); border-color: var(--brand); }
.btn.primary:hover { filter: brightness(1.05); }
.btn.ghost { background: transparent; }
.btn.danger { color: var(--bad); border-color: var(--bad); }
.btn.small { padding: 5px 10px; font-size: 0.875rem; }
.btn.block { display: block; width: 100%; text-align: center; }
.btn[disabled] { opacity: 0.5; cursor: not-allowed; }

/* flashes / badges */
.flash { padding: 10px 14px; border-radius: 8px; margin: 12px 0; }
.flash.error, .flash.bad { background: var(--bad-bg); color: var(--bad); }
.flash.ok { background: var(--ok-bg); color: var(--ok); }
.flash.warn { background: var(--warn-bg); color: var(--warn); }
.flash.info { background: var(--info-bg); color: #1e3a8a; }
.badge { display: inline-block; padding: 2px 8px; border-radius: 999px; font-size: 0.75rem; font-weight: 600; background: var(--line); color: var(--ink); vertical-align: middle; }
.badge.hp { background: #dbe4ff; color: var(--hp); }
.badge.mfp { background: #ccfbf1; color: var(--mfp); }
.badge.ok { background: var(--ok-bg); color: var(--ok); }
.badge.bad { background: var(--bad-bg); color: var(--bad); }
.badge.warn { background: var(--warn-bg); color: var(--warn); }
.badge.muted { background: var(--line); color: var(--muted); }

/* tables */
table.data { width: 100%; border-collapse: collapse; font-size: 0.93rem; }
table.data th, table.data td { padding: 8px 10px; border-bottom: 1px solid var(--line); text-align: left; vertical-align: top; }
table.data th { font-weight: 600; color: var(--muted); font-size: 0.8rem; text-transform: uppercase; letter-spacing: 0.02em; }
table.data tr:hover td { background: #fafbff; }
.scroll-x { overflow-x: auto; }

/* progress bars */
.bar { height: 10px; background: var(--line); border-radius: 999px; overflow: hidden; }
.bar > span { display: block; height: 100%; background: var(--brand); border-radius: 999px; }
.bar.mfp > span { background: var(--mfp); }
.bar.ok > span { background: var(--ok); }
.bar.warn > span { background: #d97706; }
.bar.bad > span { background: var(--bad); }
.stat { display: flex; flex-direction: column; }
.stat .v { font-size: 1.5rem; font-weight: 700; }
.stat .l { color: var(--muted); font-size: 0.8rem; }

/* plan list */
.plan-item { display: flex; align-items: center; gap: 12px; padding: 10px 12px; border: 1px solid var(--line); border-radius: 10px; background: #fff; }
.plan-item.done { opacity: 0.6; }
.plan-item.current { border-color: var(--brand); box-shadow: 0 0 0 2px #dbe4ff; }
.plan-item .num { width: 26px; height: 26px; border-radius: 50%; background: var(--bg); display: inline-flex; align-items: center; justify-content: center; font-size: 0.8rem; font-weight: 600; }
.plan-item .title { flex: 1; }
.block-head { display: flex; justify-content: space-between; align-items: baseline; margin: 16px 0 6px; }
.block-head h3 { margin: 0; }

/* problem */
.problem .stem { font-size: 1.05rem; }
.problem .passage { background: #fafafa; border: 1px solid var(--line); border-radius: 8px; padding: 12px 14px; max-height: 420px; overflow: auto; margin-bottom: 12px; }
.problem img.figure { max-width: 100%; height: auto; border: 1px solid var(--line); border-radius: 8px; margin: 8px 0; }
.options { list-style: none; padding: 0; margin: 12px 0; }
.options li { margin: 6px 0; }
.options label { display: flex; gap: 10px; align-items: flex-start; padding: 10px 12px; border: 1px solid var(--line); border-radius: 8px; cursor: pointer; }
.options label:hover { background: #fafbff; }
.options input { margin-top: 5px; }
.options label.correct { border-color: var(--ok); background: var(--ok-bg); }
.options label.wrong { border-color: var(--bad); background: var(--bad-bg); }
.feedback { border-radius: 10px; padding: 14px 16px; margin-top: 14px; }
.feedback.ok { background: var(--ok-bg); }
.feedback.bad { background: var(--bad-bg); }
.feedback.info { background: var(--info-bg); }
.solution { background: #fff; border: 1px solid var(--line); border-radius: 8px; padding: 12px 14px; margin-top: 10px; }
.timer { font-variant-numeric: tabular-nums; font-weight: 700; }
.timer.low { color: var(--bad); }
.self-report { display: flex; gap: 8px; margin: 10px 0; flex-wrap: wrap; }
.self-report label { border: 1px solid var(--line); border-radius: 999px; padding: 4px 10px; font-size: 0.85rem; cursor: pointer; }
.self-report input { margin-right: 4px; }
.katex-preview { min-height: 28px; padding: 6px 0; color: var(--muted); }
.kbd { font-family: ui-monospace, monospace; background: var(--bg); padding: 1px 5px; border-radius: 4px; border: 1px solid var(--line); font-size: 0.85em; }

/* review editor */
.split { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
@media (max-width: 860px) { .split { grid-template-columns: 1fr; } }
.page-image { position: relative; border: 1px solid var(--line); border-radius: 8px; overflow: hidden; background: #fff; }
.page-image img { display: block; width: 100%; height: auto; user-select: none; -webkit-user-drag: none; }
.page-image .crop { position: absolute; border: 2px dashed var(--brand); background: rgba(47, 91, 234, 0.12); pointer-events: none; }
.tabs { display: flex; gap: 6px; border-bottom: 1px solid var(--line); margin: 12px 0; }
.tabs a { padding: 8px 12px; border-radius: 8px 8px 0 0; color: var(--ink); }
.tabs a.active { background: var(--card); border: 1px solid var(--line); border-bottom-color: var(--card); margin-bottom: -1px; }
.htmx-indicator { display: none; }
.htmx-request .htmx-indicator, .htmx-request.htmx-indicator { display: inline; }
.sparkline { display: flex; gap: 3px; align-items: flex-end; height: 40px; }
.sparkline span { flex: 1; background: var(--brand); border-radius: 2px 2px 0 0; min-height: 2px; }
.sparkline span.zero { background: var(--line); }
details summary { cursor: pointer; font-weight: 500; }
.hero { display: flex; justify-content: space-between; align-items: flex-end; flex-wrap: wrap; gap: 12px; }