:root {
  --bg: #0f1419;
  --fg: #e7ecf1;
  --muted: #8b98a5;
  --accent: #1d9bf0;
  --card: #1a2332;
  --danger: #f4212e;
}
* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  background: var(--bg);
  color: var(--fg);
  line-height: 1.5;
  min-height: 100vh;
}
a { color: var(--accent); }
.container { max-width: 720px; margin: 0 auto; padding: 2rem 1.25rem; }
.narrow { max-width: 420px; margin: 0 auto; padding: 2rem 1.25rem; }
.hero {
  max-width: 640px;
  margin: 0 auto;
  padding: 4rem 1.5rem;
}
.hero h1 { font-size: clamp(1.75rem, 4vw, 2.25rem); margin-bottom: 0.5rem; }
.lead { color: var(--muted); font-size: 1.05rem; }
.actions { display: flex; flex-wrap: wrap; gap: 0.75rem; margin-top: 1.5rem; }
.btn {
  display: inline-block;
  padding: 0.55rem 1rem;
  border-radius: 999px;
  text-decoration: none;
  border: 1px solid var(--muted);
  color: var(--fg);
}
.btn.primary { background: var(--accent); border-color: var(--accent); color: #fff; }
.stack label { display: flex; flex-direction: column; gap: 0.35rem; margin-bottom: 1rem; }
.stack input {
  padding: 0.5rem 0.65rem;
  border-radius: 8px;
  border: 1px solid #38444d;
  background: var(--card);
  color: var(--fg);
}
.flash-list { list-style: none; margin: 0; padding: 0.75rem 1rem; }
.flash { padding: 0.5rem 0.75rem; margin-bottom: 0.35rem; border-radius: 8px; }
.flash-error { background: rgba(244, 33, 46, 0.15); color: #ff7a7a; }
.flash-success { background: rgba(0, 186, 124, 0.15); color: #6ee7b7; }

.wide-container { max-width: 900px; margin: 0 auto; padding: 2rem 1.25rem; }
.stack textarea {
  padding: 0.5rem 0.65rem;
  border-radius: 8px;
  border: 1px solid #38444d;
  background: var(--card);
  color: var(--fg);
  min-height: 10rem;
  font-family: inherit;
  resize: vertical;
}
.stack textarea.mono { font-size: 0.9rem; line-height: 1.45; }
.muted-note { color: var(--muted); font-size: 0.9rem; margin-top: -0.5rem; }
.results { margin-top: 2rem; display: none; }
.results.visible { display: block; }
.card {
  background: var(--card);
  border: 1px solid #38444d;
  border-radius: 12px;
  padding: 1rem 1.25rem;
  margin-bottom: 1rem;
}
.card h2 { font-size: 1.1rem; margin: 0 0 0.75rem; }
.score-row { display: flex; align-items: center; gap: 1rem; flex-wrap: wrap; }
.score-pill {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--accent);
}
.tutor-box {
  white-space: pre-wrap;
  line-height: 1.55;
}
.checklist { list-style: none; padding: 0; margin: 0; }
.checklist li {
  padding: 0.35rem 0;
  border-bottom: 1px solid #2f3b47;
  display: flex;
  gap: 0.5rem;
  align-items: flex-start;
}
.checklist li:last-child { border-bottom: none; }
.badge { font-size: 0.75rem; padding: 0.15rem 0.45rem; border-radius: 6px; }
.badge.ok { background: rgba(0, 186, 124, 0.2); color: #6ee7b7; }
.badge.fail { background: rgba(244, 33, 46, 0.15); color: #ff7a7a; }
.matrix-table { width: 100%; border-collapse: collapse; font-size: 0.9rem; }
.matrix-table th, .matrix-table td {
  border: 1px solid #38444d;
  padding: 0.45rem 0.6rem;
  text-align: left;
}
.matrix-table th { background: #141c28; }
.err-list { color: #ff9a9a; margin: 0; padding-left: 1.2rem; }
.status-msg { margin-top: 0.75rem; color: var(--muted); font-size: 0.9rem; }
.status-msg.error { color: #ff7a7a; }
button.btn { cursor: pointer; font: inherit; }
button.btn:disabled { opacity: 0.5; cursor: not-allowed; }