:root {
  color-scheme: light;
  --bg: #f6f4ef;
  --surface: #fffdf8;
  --ink: #1c1915;
  --muted: #5e584f;
  --line: #e4ddd2;
  --accent: #1f4d3a;
  --accent-ink: #f7fbf8;
  --warn: #8a4b12;
  --warn-bg: #fff4e8;
  --ok: #1d6b45;
  --ok-bg: #e8f6ee;
  --bad-bg: #fdecea;
  --shadow: none;
  font-family: "Iowan Old Style", Palatino, "Palatino Linotype", Georgia, serif;
}

* { box-sizing: border-box; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
}
button, input, textarea { font: inherit; color: inherit; }
button { cursor: pointer; }
.sr {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
}

.top {
  display: grid;
  grid-template-columns: minmax(220px, 1fr) auto minmax(220px, 320px);
  gap: 20px;
  align-items: end;
  padding: 28px 32px 12px;
}
.eyebrow {
  margin: 0;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  font-family: ui-sans-serif, system-ui, sans-serif;
  font-size: 12px;
  color: var(--muted);
}
h1, h2, h3 { font-weight: 600; letter-spacing: -0.02em; }
h1 { margin: 2px 0 0; font-size: 32px; }
.stats {
  display: flex;
  gap: 18px;
  font-family: ui-sans-serif, system-ui, sans-serif;
}
.stat strong { display: block; font-size: 22px; }
.stat span { color: var(--muted); font-size: 12px; }
.search input {
  width: 100%;
  border: 1px solid var(--line);
  background: var(--surface);
  border-radius: 8px;
  padding: 10px 12px;
  font-family: ui-sans-serif, system-ui, sans-serif;
}

.modes, .domains, .concept-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}
.modes { padding: 8px 32px 0; }
.chip, .choice, .nav-btn, .text-btn {
  border: 1px solid var(--line);
  background: var(--surface);
  border-radius: 999px;
  padding: 7px 12px;
  font-family: ui-sans-serif, system-ui, sans-serif;
  font-size: 14px;
}
.chip.active, .choice.selected {
  background: var(--accent);
  color: var(--accent-ink);
  border-color: var(--accent);
}
.choice.good { background: var(--ok-bg); border-color: var(--ok); color: var(--ink); }
.choice.bad { background: var(--bad-bg); border-color: #a33b32; color: var(--ink); }
.choice { display: block; width: 100%; text-align: left; border-radius: 10px; margin: 8px 0; padding: 12px 14px; }
.choice:disabled { cursor: default; }

.notice {
  margin: 16px 32px 0;
  padding: 12px 14px;
  background: var(--warn-bg);
  color: var(--warn);
  border-radius: 10px;
  font-family: ui-sans-serif, system-ui, sans-serif;
  font-size: 14px;
}
.layout {
  display: grid;
  grid-template-columns: 280px minmax(0, 1fr);
  gap: 24px;
  padding: 20px 32px 40px;
}
aside {
  position: sticky;
  top: 16px;
  align-self: start;
  display: flex;
  flex-direction: column;
  gap: 8px;
  max-height: calc(100vh - 32px);
  overflow: auto;
}
.topic {
  text-align: left;
  border: 0;
  border-left: 2px solid transparent;
  background: transparent;
  border-radius: 0;
  padding: 8px 10px;
  font-family: ui-sans-serif, system-ui, sans-serif;
  font-size: 14px;
}
.topic.active { border-left-color: var(--accent); background: #efeae2; }
.topic small { display: block; color: var(--muted); }
main {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 14px;
  padding: 28px;
  min-height: 70vh;
}
.idea { font-size: 20px; margin-top: 0; }
ul { padding-left: 18px; }
li { margin: 8px 0; line-height: 1.45; }
.traps {
  background: #f3efe7;
  border-radius: 12px;
  padding: 14px 16px;
  margin-top: 22px;
}
.traps h3 { margin: 0 0 8px; font-size: 16px; }
.toolbar { display: flex; gap: 8px; align-items: center; margin: 18px 0; flex-wrap: wrap; }
.check {
  display: flex;
  gap: 10px;
  align-items: flex-start;
  margin: 10px 0;
  font-family: ui-sans-serif, system-ui, sans-serif;
}
textarea, .lab-note {
  width: 100%;
  min-height: 120px;
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 12px;
  background: #fff;
  resize: vertical;
}
.explain {
  margin-top: 12px;
  padding: 12px 14px;
  border-radius: 10px;
  background: var(--ok-bg);
  font-family: ui-sans-serif, system-ui, sans-serif;
}
.explain.miss { background: var(--warn-bg); }
table { width: 100%; border-collapse: collapse; font-family: ui-sans-serif, system-ui, sans-serif; font-size: 14px; }
th, td { text-align: left; padding: 10px 8px; border-bottom: 1px solid var(--line); vertical-align: top; }
.lab { border-top: 1px solid var(--line); padding: 18px 0; }
.result { width: 100%; text-align: left; }
footer {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  padding: 0 32px 28px;
  color: var(--muted);
  font-family: ui-sans-serif, system-ui, sans-serif;
  font-size: 13px;
}
.footer-actions {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: flex-end;
  gap: 8px;
}
.footer-actions button { border-radius: 8px; white-space: nowrap; }
#offline { color: var(--ok); }

.toc {
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 14px 18px;
  margin: 18px 0 8px;
  font-family: ui-sans-serif, system-ui, sans-serif;
  font-size: 14px;
}
.toc ol { margin: 8px 0 0; padding-left: 20px; columns: 2; column-gap: 28px; }
.toc li { margin: 4px 0; break-inside: avoid; }
.toc a { color: var(--accent); text-decoration: none; }
.toc a:hover { text-decoration: underline; }
.deep-section { padding-top: 22px; margin-top: 22px; border-top: 1px solid var(--line); scroll-margin-top: 16px; }
.deep-section > h3 { font-size: 22px; margin: 0 0 10px; }
.deep-section p { line-height: 1.65; font-size: 17px; }
.deep-section li { font-size: 16.5px; }
.steps li { margin: 10px 0; }
code {
  font-family: ui-monospace, "SF Mono", Menlo, monospace;
  font-size: 0.86em;
  background: #efeae2;
  padding: 1px 5px;
  border-radius: 4px;
}
figure.code { margin: 16px 0; border: 1px solid #2b2924; border-radius: 10px; overflow: hidden; }
figure.code figcaption {
  background: #2b2924;
  color: #d9d3c7;
  font-family: ui-sans-serif, system-ui, sans-serif;
  font-size: 12px;
  padding: 6px 12px;
}
figure.code pre { margin: 0; padding: 14px 16px; background: #1d1c19; color: #f1ece2; overflow-x: auto; line-height: 1.5; }
figure.code code { background: transparent; padding: 0; font-size: 13.5px; color: inherit; }
.table-wrap { overflow-x: auto; margin: 14px 0; }
.hint { color: var(--muted); font-family: ui-sans-serif, system-ui, sans-serif; font-size: 14px; }
details.qa {
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 12px 14px;
  margin: 10px 0;
  background: #fff;
}
details.qa summary { cursor: pointer; font-weight: 600; line-height: 1.45; }
details.qa div { margin-top: 10px; line-height: 1.6; color: #2c2822; }

@media (max-width: 900px) {
  .toc ol { columns: 1; }
  .top, .layout { grid-template-columns: 1fr; }
  .top, .modes, .notice, .layout, footer { padding-left: 16px; padding-right: 16px; }
  aside { position: static; max-height: none; }
  footer { flex-direction: column; }
}