:root {
  --bg: #1a141c;
  --surface: #252028;
  --surface-elevated: #2e2833;
  --border: #4a3d4a;
  --text: #f4ebf2;
  --muted: #c4b0bf;
  --accent: #e8b4c8;
  --accent-dim: #d89bb5;
  --accent-glow: rgba(232, 180, 200, 0.14);
  --ok: #9fd9b8;
  --warn: #f5d79a;
  --font-sans: "Source Sans 3", "Segoe UI", system-ui, sans-serif;
  --font-mono: "JetBrains Mono", ui-monospace, monospace;
  --maxw: 44rem;
  --navw: 15.5rem;
  --radius: 0.65rem;
  --radius-lg: 0.9rem;
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: var(--font-sans);
  font-size: clamp(1.02rem, 0.4vw + 1rem, 1.08rem);
  line-height: 1.62;
  color: var(--text);
  background: radial-gradient(130% 90% at 50% -8%, #3a2832 0%, var(--bg) 48%);
  background-attachment: fixed;
}

.skip-link {
  position: absolute;
  left: -9999px;
  top: 0.5rem;
  padding: 0.5rem 1rem;
  background: var(--accent);
  color: #2a1520;
  font-weight: 600;
  z-index: 100;
  border-radius: var(--radius);
}

.skip-link:focus {
  left: 0.5rem;
}

a {
  color: var(--accent);
  text-decoration-thickness: 1px;
  text-underline-offset: 0.15em;
}

a:hover {
  color: var(--accent-dim);
}

.layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
}

@media (min-width: 56rem) {
  .layout {
    grid-template-columns: var(--navw) minmax(0, 1fr);
  }
}

.site-header {
  border-bottom: 1px solid var(--border);
  background: linear-gradient(180deg, var(--surface-elevated) 0%, var(--surface) 100%);
}

@media (min-width: 56rem) {
  .site-header {
    border-bottom: none;
    border-right: 1px solid var(--border);
    min-height: 100vh;
    position: sticky;
    top: 0;
    align-self: start;
  }
}

.brand {
  padding: 1.25rem 1.25rem 0.75rem;
  font-weight: 700;
  font-size: 1.1rem;
  letter-spacing: 0.02em;
}

.brand a {
  color: var(--text);
  text-decoration: none;
}

.brand a:hover {
  color: var(--accent);
}

.nav-primary {
  display: flex;
  flex-direction: column;
  gap: 0.15rem;
  padding: 0 0.75rem 1.25rem;
}

@media (max-width: 55.99rem) {
  .nav-primary {
    flex-flow: row wrap;
    gap: 0.35rem;
    padding-bottom: 1rem;
  }
}

.nav-primary a {
  display: block;
  padding: 0.5rem 0.75rem;
  border-radius: var(--radius);
  color: var(--muted);
  text-decoration: none;
  font-size: 0.95rem;
}

.nav-primary a:hover {
  background: var(--accent-glow);
  color: var(--text);
}

.nav-primary a.is-active {
  background: rgba(232, 180, 200, 0.18);
  color: var(--accent);
  font-weight: 600;
}

.nav-section {
  margin-top: 0.75rem;
  padding: 0.45rem 0.65rem 0.2rem;
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--muted);
}

main {
  padding: 2rem 1.35rem 3.5rem;
  max-width: calc(var(--maxw) + var(--navw));
}

@media (min-width: 56rem) {
  main {
    padding: 2.5rem 2.75rem 4.5rem;
  }
}

.content {
  max-width: var(--maxw);
}

h1 {
  font-size: 1.85rem;
  line-height: 1.2;
  margin: 0 0 0.75rem;
  font-weight: 700;
}

h2 {
  font-size: 1.25rem;
  margin: 2rem 0 0.65rem;
  font-weight: 650;
  color: var(--text);
  border-bottom: 1px solid var(--border);
  padding-bottom: 0.35rem;
}

h3 {
  font-size: 1.05rem;
  margin: 1.25rem 0 0.5rem;
  font-weight: 600;
  color: var(--muted);
}

p,
ul,
ol {
  margin: 0 0 0.85rem;
}

ul,
ol {
  padding-left: 1.35rem;
}

li {
  margin-bottom: 0.35rem;
}

.breadcrumb {
  font-size: 0.88rem;
  color: var(--muted);
  margin-bottom: 1rem;
}

.breadcrumb a {
  color: var(--muted);
}

.breadcrumb a:hover {
  color: var(--accent);
}

.map-interactive-links {
  line-height: 1.55;
  margin: 0.35rem 0 1.1rem;
}

.callout {
  border: 1px solid var(--border);
  border-left: 4px solid var(--accent);
  background: var(--surface-elevated);
  padding: 1rem 1.15rem;
  border-radius: 0 var(--radius-lg) var(--radius-lg) 0;
  margin: 1.1rem 0;
  box-shadow: 0 6px 32px rgba(0, 0, 0, 0.14);
}

.callout-warn {
  border-left-color: var(--warn);
}

.callout-ok {
  border-left-color: var(--ok);
}

.callout-title {
  font-weight: 650;
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--muted);
  margin-bottom: 0.35rem;
}

.muted {
  color: var(--muted);
  font-size: 0.95rem;
}

.hwmatrix {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.92rem;
  margin: 0.75rem 0 1.25rem;
}

.hwmatrix th,
.hwmatrix td {
  border: 1px solid var(--border);
  padding: 0.5rem 0.65rem;
  text-align: left;
  vertical-align: top;
}

.hwmatrix th {
  background: var(--surface);
  color: var(--muted);
  font-weight: 600;
}

.site-footer {
  margin-top: 2.5rem;
  padding-top: 1.25rem;
  border-top: 1px solid var(--border);
  font-size: 0.88rem;
  color: var(--muted);
}

.katex-display {
  overflow-x: auto;
  overflow-y: hidden;
  padding: 0.35rem 0;
}

code {
  font-family: var(--font-mono);
  font-size: 0.88em;
  background: var(--surface-elevated);
  padding: 0.12em 0.35em;
  border-radius: var(--radius);
  border: 1px solid var(--border);
}

/* --- Practice bank UI --- */

.practice-mount {
  margin: 0.5rem 0 1.5rem;
}

.practice-loading,
.practice-error {
  padding: 0.75rem 0;
}

.practice-error {
  color: #f0b4b4;
}

.practice-card {
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  background: var(--surface-elevated);
  padding: 1.15rem 1.25rem 1.25rem;
  margin-bottom: 1.25rem;
  box-shadow: 0 8px 36px rgba(0, 0, 0, 0.12);
}

.practice-type {
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--muted);
  margin: 0 0 0.65rem;
}

.practice-prompt {
  margin-bottom: 0.85rem;
}

.practice-prompt p:last-child {
  margin-bottom: 0;
}

.practice-label {
  display: block;
  font-size: 0.88rem;
  font-weight: 600;
  color: var(--muted);
  margin-bottom: 0.35rem;
}

.practice-input {
  width: 100%;
  min-height: 3.2rem;
  padding: 0.65rem 0.75rem;
  font-family: var(--font-sans);
  font-size: 1rem;
  line-height: 1.45;
  color: var(--text);
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  resize: vertical;
}

.practice-input:focus {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
  border-color: var(--accent-dim);
}

.practice-btn-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  align-items: center;
  margin-top: 0.65rem;
}

.practice-btn {
  cursor: pointer;
  font-family: var(--font-sans);
  font-size: 0.95rem;
  font-weight: 600;
  padding: 0.45rem 1rem;
  border-radius: var(--radius);
  border: 1px solid var(--accent-dim);
  background: linear-gradient(180deg, #f5dfe8 0%, #e8b4c8 100%);
  color: #2a1520;
}

.practice-btn:hover {
  filter: brightness(1.06);
}

.practice-btn:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

.practice-feedback {
  min-height: 1.35em;
  margin: 0.5rem 0 0;
  font-size: 0.95rem;
}

.practice-feedback.is-correct {
  color: var(--ok);
  font-weight: 600;
}

.practice-feedback.is-wrong {
  color: #fca5a5;
}

.practice-feedback.is-muted {
  color: var(--muted);
}

details.practice-solution {
  margin-top: 0.85rem;
  border-top: 1px solid var(--border);
  padding-top: 0.75rem;
}

details.practice-solution > summary {
  cursor: pointer;
  font-weight: 600;
  color: var(--accent);
  list-style-position: outside;
}

details.practice-solution > summary:hover {
  color: var(--accent-dim);
}

.practice-solution-inner {
  margin-top: 0.65rem;
  padding: 0.75rem 0.85rem;
  background: var(--surface);
  border-radius: var(--radius);
  border: 1px solid var(--border);
}

.practice-solution-inner p:last-child {
  margin-bottom: 0;
}

.look-back {
  margin-top: 0.35rem;
  margin-bottom: 1rem;
}

.look-back p {
  margin: 0;
}

.practice-type-panel {
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  background: var(--surface);
  padding: 1rem 1.1rem 1.1rem;
  margin-bottom: 1rem;
}

.practice-type-heading {
  margin: 0 0 0.35rem;
  font-size: 1.05rem;
}

.practice-variant-meta {
  margin: 0 0 0.75rem;
  font-size: 0.88rem;
}

.practice-type-slot {
  min-height: 0.5rem;
}

.practice-type-actions {
  margin-top: 0.75rem;
}

.practice-actions {
  margin-top: 0.65rem;
}

.practice-btn-secondary {
  border-color: var(--border);
  background: linear-gradient(180deg, var(--surface-elevated) 0%, var(--surface) 100%);
  color: var(--text);
}

.practice-btn-secondary:hover {
  filter: brightness(1.08);
}

.practice-input-wrap,
.quiz-input-wrap {
  width: 100%;
}

.practice-math-field,
.quiz-math-field {
  display: block;
  width: 100%;
  min-height: 3rem;
  padding: 0.35rem 0.5rem;
  font-size: 1.05rem;
  color: var(--text);
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
}

.practice-math-field:focus-within,
.quiz-math-field:focus-within {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
  border-color: var(--accent-dim);
}

/* --- Quiz UI --- */

.quiz-mount {
  margin: 0.5rem 0 1.5rem;
}

.quiz-root {
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  background: var(--surface-elevated);
  padding: 1rem 1.15rem 1.2rem;
  box-shadow: 0 8px 36px rgba(0, 0, 0, 0.12);
}

.quiz-header {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: 0.5rem 1rem;
  margin-bottom: 0.65rem;
}

.quiz-progress {
  font-size: 0.88rem;
  color: var(--muted);
}

.quiz-stage {
  margin: 0.5rem 0 0.75rem;
}

.quiz-card {
  padding: 0.15rem 0 0.35rem;
}

.quiz-source {
  font-size: 0.82rem;
  margin: 0 0 0.5rem;
}

.quiz-prompt {
  margin-bottom: 0.85rem;
}

.quiz-prompt p:last-child {
  margin-bottom: 0;
}

.quiz-textarea {
  width: 100%;
  min-height: 3.2rem;
  padding: 0.65rem 0.75rem;
  font-family: var(--font-sans);
  font-size: 1rem;
  line-height: 1.45;
  color: var(--text);
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  resize: vertical;
}

.quiz-textarea:focus {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
  border-color: var(--accent-dim);
}

.quiz-btn-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  align-items: center;
  margin-top: 0.75rem;
}

.quiz-score {
  margin: 0.5rem 0 0;
  font-size: 0.95rem;
}

.quiz-review {
  margin-top: 1rem;
  padding-top: 0.75rem;
  border-top: 1px solid var(--border);
}

.quiz-review details {
  margin-bottom: 0.5rem;
}

.quiz-review summary {
  cursor: pointer;
  font-weight: 600;
  color: var(--accent);
}

@media print {
  .site-header,
  .site-footer,
  .skip-link,
  .practice-btn-row,
  .practice-type-actions,
  .quiz-btn-row {
    display: none !important;
  }

  body {
    background: #fff;
    color: #111;
  }

  .layout {
    display: block;
  }

  .content {
    max-width: none;
  }

  .practice-math-field,
  .quiz-math-field,
  .practice-input,
  .quiz-textarea {
    border: 1px solid #ccc;
    background: #fff;
    color: #111;
  }

  details.practice-solution,
  .quiz-review details {
    border: none;
  }

  details.practice-solution[open] > summary,
  .quiz-review details[open] > summary {
    list-style: none;
  }

  .hwmatrix th,
  .hwmatrix td {
    border-color: #ccc;
  }

  .callout {
    border: 1px solid #ccc;
    box-shadow: none;
    background: #fafafa;
  }

}