:root {
  --bg: #f4f5f7;
  --panel: #ffffff;
  --ink: #111827;
  --muted: #6b7280;
  --line: #d9dee7;
  --soft: #f1f5f9;
  --dark: #1f2937;
  --blue: #255f99;
  --good: #0f766e;
  --bad: #b42318;
  --warn: #8a5a00;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  min-height: 100vh;
  background: var(--bg);
  color: var(--ink);
  font-family: Arial, "Noto Sans SC", "PingFang SC", sans-serif;
}

button, textarea, input { font: inherit; }

.shell {
  width: min(1500px, 100%);
  margin: 0 auto;
  padding: 22px;
}

.top {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 310px;
  gap: 18px;
  margin-bottom: 18px;
  align-items: stretch;
}

.eyebrow {
  margin: 0 0 8px;
  color: var(--blue);
  font-weight: 800;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  font-size: 13px;
}

h1 {
  margin: 0 0 8px;
  font-size: 40px;
  letter-spacing: 0;
}

h2 {
  margin: 0 0 12px;
  font-size: 18px;
}

.sub {
  margin: 0;
  color: var(--muted);
  line-height: 1.5;
}

.page-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 16px;
}

.page-nav a {
  min-height: 36px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0 12px;
  border: 1px solid var(--line);
  border-radius: 7px;
  background: #fff;
  color: var(--ink);
  text-decoration: none;
  font-size: 14px;
  font-weight: 800;
}

.page-nav a:hover {
  background: var(--soft);
}

.score, .questions, .work, .reference {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 8px;
  box-shadow: 0 12px 28px rgba(15, 23, 42, 0.05);
}

.score {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
  padding: 14px;
}

.score div {
  border: 1px solid var(--line);
  border-radius: 7px;
  padding: 10px;
}

.score span {
  display: block;
  color: var(--muted);
  font-size: 13px;
}

.score strong {
  display: block;
  margin-top: 4px;
  font-size: 20px;
}

.score button {
  grid-column: 1 / -1;
}

.grid {
  display: grid;
  grid-template-columns: 310px minmax(0, 1fr) 330px;
  gap: 18px;
  align-items: start;
}

.questions, .reference {
  padding: 14px;
  position: sticky;
  top: 14px;
}

.q-button {
  width: 100%;
  display: grid;
  grid-template-columns: 34px minmax(0, 1fr);
  gap: 10px;
  min-height: 68px;
  border: 0;
  border-radius: 7px;
  background: transparent;
  text-align: left;
  padding: 10px;
  cursor: pointer;
}

.q-button:hover { background: var(--soft); }
.q-button.active { background: var(--dark); color: #fff; }
.q-button.done .num { background: #dff7f3; color: #064e3b; }

.num {
  width: 30px;
  height: 30px;
  display: grid;
  place-items: center;
  border-radius: 999px;
  background: var(--soft);
  font-weight: 800;
}

.q-meta {
  display: block;
  margin-top: 4px;
  color: var(--muted);
  font-size: 12px;
}

.q-button.active .q-meta { color: #d1d5db; }

.chapter-tabs {
  display: grid;
  gap: 6px;
  margin-bottom: 12px;
}

.chapter-tab {
  min-height: 34px;
  padding: 7px 10px;
  text-align: left;
  font-size: 13px;
}

.chapter-tab.active {
  background: var(--dark);
  border-color: var(--dark);
  color: #fff;
}

.chapter-title {
  margin: 6px 0 10px;
  font-size: 15px;
  color: var(--muted);
}

.work {
  padding: 22px;
  min-width: 0;
}

.work-head {
  display: flex;
  gap: 8px;
  margin-bottom: 12px;
}

.pill {
  display: inline-flex;
  align-items: center;
  min-height: 28px;
  border-radius: 999px;
  padding: 4px 10px;
  background: var(--dark);
  color: #fff;
  font-size: 13px;
  font-weight: 800;
}

.pill.muted {
  background: var(--soft);
  color: var(--muted);
}

#qPrompt {
  color: #374151;
  line-height: 1.6;
  margin-bottom: 14px;
}

.code-box {
  width: 100%;
  min-height: 220px;
  resize: vertical;
  border: 1px solid #c7d0dd;
  border-radius: 8px;
  padding: 14px;
  background: #0f172a;
  color: #f8fafc;
  line-height: 1.55;
  font-family: Consolas, "SFMono-Regular", Menlo, monospace;
  font-size: 14px;
}

.short-input {
  width: 100%;
  min-height: 48px;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 10px 12px;
}

.options {
  display: grid;
  gap: 10px;
}

.option {
  min-height: 52px;
  border: 1px solid var(--line);
  border-radius: 7px;
  background: #fff;
  padding: 12px;
  text-align: left;
  cursor: pointer;
}

.option.selected {
  border-color: var(--blue);
  box-shadow: 0 0 0 2px rgba(37, 95, 153, 0.15);
}

.order-list {
  display: grid;
  gap: 10px;
}

.order-card {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 10px;
  align-items: center;
  border: 1px solid var(--line);
  border-radius: 7px;
  background: #fff;
  padding: 12px;
}

.mini-controls {
  display: flex;
  gap: 6px;
}

.mini-controls button {
  width: 32px;
  height: 32px;
  padding: 0;
}

.actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 14px;
}

button {
  min-height: 38px;
  border: 1px solid var(--line);
  border-radius: 7px;
  background: #fff;
  color: var(--ink);
  padding: 8px 12px;
  cursor: pointer;
}

button:hover { background: var(--soft); }

.primary {
  background: var(--dark);
  border-color: var(--dark);
  color: #fff;
}

.feedback {
  margin-top: 14px;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 14px;
  line-height: 1.55;
}

.feedback.good {
  border-color: #99d6cd;
  background: #ecfdf9;
  color: #064e3b;
}

.feedback.bad {
  border-color: #f4b3ad;
  background: #fff1f0;
  color: #7a271a;
}

.feedback.warn {
  border-color: #f2d38a;
  background: #fffbeb;
  color: #6b4200;
}

.reference pre {
  margin: 0 0 14px;
  padding: 12px;
  overflow-x: auto;
  border-radius: 7px;
  background: #111827;
  color: #f8fafc;
  line-height: 1.5;
  font-size: 13px;
}

code {
  font-family: Consolas, "SFMono-Regular", Menlo, monospace;
}

.reference ul {
  margin: 0 0 16px;
  padding-left: 20px;
  color: #374151;
  line-height: 1.55;
}

.chips {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.chips span {
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 5px 9px;
  background: var(--soft);
  font-size: 13px;
}

@media (max-width: 1120px) {
  .top, .grid {
    grid-template-columns: 1fr;
  }
  .questions, .reference {
    position: static;
  }
}