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

body {
  margin: 0;
  padding: 16px;
  font-family: var(--font-sans, system-ui, -apple-system, sans-serif);
  color: var(--color-text-primary);
  background: var(--color-background-primary);
  line-height: 1.45;
}

.page {
  display: flex;
  flex-direction: column;
  gap: 14px;
  max-width: 1180px;
  margin: 0 auto;
}

.page-header {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.header-top {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
}

.back-link {
  color: var(--color-text-info);
  text-decoration: none;
  font-size: 13px;
  font-weight: 600;
}

.back-link:hover {
  text-decoration: underline;
}

.level-tag {
  font-size: 12px;
  font-weight: 600;
  padding: 2px 8px;
  border-radius: var(--border-radius-sm, 4px);
  background: var(--color-background-secondary);
  color: var(--color-text-secondary);
  border: 1px solid var(--color-border-primary);
}

h1 {
  font-size: 20px;
  margin: 0;
  font-weight: 700;
}

.subtitle {
  margin: 0;
  font-size: 13.5px;
  color: var(--color-text-secondary);
}

.top-controls {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.unit-row, .btn-group, .special-bar, .k-presets {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 6px;
}

.unit-row {
  justify-content: space-between;
}

.bar-label {
  font-size: 12.5px;
  font-weight: 600;
  color: var(--color-text-secondary);
  margin-right: 2px;
}

.btn-chip, .btn-mini {
  font-family: inherit;
  font-size: 12.5px;
  font-weight: 500;
  padding: 5px 10px;
  border-radius: var(--border-radius-sm, 6px);
  border: 1px solid var(--color-border-primary);
  background: var(--color-background-secondary);
  color: var(--color-text-primary);
  cursor: pointer;
}

.btn-mini {
  font-size: 12px;
  padding: 4px 8px;
}

.btn-chip.active, .btn-mini.active {
  background: var(--color-background-info);
  color: var(--color-text-info);
  border-color: var(--color-text-info);
  font-weight: 600;
}

.canvas-card, .info-card {
  border: 1px solid var(--color-border-primary);
  border-radius: var(--border-radius-md, 8px);
  background: var(--color-background-secondary);
  padding: 12px;
  display: flex;
  flex-direction: column;
  gap: 10px;
  min-width: 0;
}

.slider-bar {
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  gap: 10px;
  font-size: 13px;
  font-weight: 600;
}

.slider-bar input[type="range"] {
  width: 100%;
  margin: 0;
}

.slider-bar output {
  font-family: var(--font-mono, monospace);
  color: var(--color-text-info);
  min-width: 48px;
  text-align: right;
}

.canvas-wrap {
  width: 100%;
  border: 1px solid var(--color-border-primary);
  border-radius: var(--border-radius-sm, 6px);
  background: var(--color-background-primary);
  overflow: hidden;
}

#uc-canvas {
  display: block;
  width: 100%;
  height: auto;
  touch-action: none;
  cursor: pointer;
}

.layer-toggles {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  font-size: 12.5px;
}

.chk-label {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  cursor: pointer;
}

.swatch {
  display: inline-block;
  width: 10px;
  height: 10px;
  border-radius: 50%;
}

.sw-sin { background: var(--traycer-chart-2, #d97706); }
.sw-cos { background: var(--traycer-chart-1, #2563eb); }
.sw-tan { background: var(--traycer-chart-4, #9333ea); }
.sw-solve { background: var(--traycer-chart-3, #16a34a); }

.bottom-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 440px), 1fr));
  gap: 14px;
  align-items: start;
}

.card-head {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 6px;
}

.card-head h2 {
  font-size: 15px;
  margin: 0;
  font-weight: 700;
}

.subhead {
  font-size: 13px;
  margin: 2px 0 0;
  font-weight: 700;
}

.status-pill {
  font-size: 12px;
  font-weight: 700;
  padding: 2px 8px;
  border-radius: var(--border-radius-sm, 4px);
  background: var(--color-background-info);
  color: var(--color-text-info);
}

.concept-note {
  margin: 0;
  font-size: 12.5px;
  color: var(--color-text-secondary);
}

.formula-block {
  background: var(--color-background-primary);
  border: 1px solid var(--color-border-primary);
  border-radius: var(--border-radius-sm, 6px);
  padding: 10px;
  font-family: var(--font-mono, monospace);
  font-size: 12.5px;
  display: flex;
  flex-direction: column;
  gap: 6px;
  overflow-x: auto;
}

.math-line {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 6px;
}

.math-label {
  font-family: var(--font-sans, sans-serif);
  font-size: 12px;
  font-weight: 600;
  color: var(--color-text-secondary);
  min-width: 112px;
}

.math-ans {
  font-weight: 700;
  color: var(--color-text-info);
}

.math-divider {
  border: 0;
  border-top: 1px dashed var(--color-border-primary);
  margin: 2px 0;
}

.k-controls {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.table-wrap {
  overflow-x: auto;
}

.exact-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 12px;
  background: var(--color-background-primary);
  border: 1px solid var(--color-border-primary);
}

.exact-table th, .exact-table td {
  padding: 6px 8px;
  border-bottom: 1px solid var(--color-border-primary);
  text-align: left;
  font-family: var(--font-mono, monospace);
}

.exact-table th {
  font-family: var(--font-sans, sans-serif);
  font-weight: 700;
  background: var(--color-background-secondary);
}

.exact-table tbody tr {
  cursor: pointer;
}

.exact-table tbody tr:hover {
  background: var(--color-background-secondary);
}

.exact-table tbody tr.active-row {
  background: var(--color-background-info);
  color: var(--color-text-info);
  font-weight: 700;
}