/* ────────────────────────────────────────────────────────────────
   Pairwise testing tool — visual identity
   Palette: paper (bg) / surface (cards) / ink + ink-soft (text) /
   line (hairlines) / action (teal, primary) / verified (green,
   coverage only) / error (red, validation only).
   Type: system sans for UI chrome, monospace for the actual test
   data (parameter values, counts, matrix) so the tool's own subject
   matter — literal values being combined — reads visually distinct
   from interface labels.
   ──────────────────────────────────────────────────────────────── */

:root {
  --paper: #eef1f6;
  --surface: #ffffff;
  --ink: #131b29;
  --ink-soft: #57667a;
  --line: #d7dee8;
  --action: #0e6b6b;
  --action-ink: #ffffff;
  --verified: #21874b;
  --verified-bg: #e7f5ec;
  --error: #b3261e;
  --error-bg: #fbeceb;
  --radius: 10px;

  --font-ui: system-ui, "Segoe UI", -apple-system, sans-serif;
  --font-display: system-ui, "Segoe UI Semibold", -apple-system, sans-serif;
  --font-mono: ui-monospace, "Cascadia Code", "SF Mono", "JetBrains Mono", Consolas, monospace;
}

@media (prefers-color-scheme: dark) {
  :root {
    --paper: #10151d;
    --surface: #1a2230;
    --ink: #e8edf4;
    --ink-soft: #93a1b5;
    --line: #2b3648;
    --action: #3ec9c0;
    --action-ink: #06211f;
    --verified: #59d68a;
    --verified-bg: #163826;
    --error: #ff8a80;
    --error-bg: #3a1d1c;
  }
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  background: var(--paper);
  background-image:
    linear-gradient(var(--line) 1px, transparent 1px),
    linear-gradient(90deg, var(--line) 1px, transparent 1px);
  background-size: 28px 28px;
  background-attachment: fixed;
  color: var(--ink);
  font-family: var(--font-ui);
  line-height: 1.45;
}

.page {
  max-width: 920px;
  margin: 0 auto;
  padding: 48px 24px 96px;
}

.page-header {
  margin-bottom: 36px;
}

.eyebrow {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--action);
  margin: 0 0 10px;
}

h1 {
  font-family: var(--font-display);
  font-size: clamp(1.5rem, 2.4vw + 1rem, 2.1rem);
  letter-spacing: -0.01em;
  margin: 0 0 10px;
  color: var(--ink);
}

.lede {
  margin: 0;
  max-width: 62ch;
  color: var(--ink-soft);
}

.parameters {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  align-items: start;
  gap: 20px;
  margin-bottom: 16px;
}

.parameter-card {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 18px 20px 20px;
}

.parameter-card__head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  margin-bottom: 6px;
}

.parameter-card__head .field-label {
  margin-bottom: 0;
}

.btn--remove-parameter {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 26px;
  height: 26px;
  flex: 0 0 auto;
  background: transparent;
  border: 1px solid var(--line);
  color: var(--ink-soft);
}

.btn--remove-parameter:hover:not(:disabled) {
  background: var(--error-bg);
  color: var(--error);
}

.btn--remove-parameter:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}

.file-actions {
  display: flex;
  justify-content: center;
  gap: 12px;
  margin-bottom: 20px;
}

.file-actions input[type="file"] {
  display: none;
}

.add-parameter-row {
  display: flex;
  justify-content: center;
  margin-bottom: 24px;
}

.btn--secondary {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: var(--surface);
  border: 1px solid var(--line);
  color: var(--action);
  font-weight: 600;
  font-size: 0.9rem;
  padding: 9px 16px;
  border-radius: 999px;
}

.btn--secondary:hover {
  background: var(--verified-bg);
}

.field-label {
  display: block;
  font-weight: 600;
  font-size: 0.92rem;
  margin-bottom: 6px;
  color: var(--ink);
}

.field-label--sub {
  margin-top: 16px;
  font-weight: 500;
  color: var(--ink-soft);
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

input[type="text"] {
  width: 100%;
  font: inherit;
  font-family: var(--font-mono);
  font-size: 0.95rem;
  padding: 9px 11px;
  border: 1px solid var(--line);
  border-radius: 7px;
  background: var(--surface);
  color: var(--ink);
}

input[type="text"]:focus-visible {
  outline: 2px solid var(--action);
  outline-offset: 1px;
}

.value-add {
  display: flex;
  gap: 8px;
  margin-top: 6px;
}

.value-add input {
  flex: 1;
}

.btn {
  font: inherit;
  border: none;
  border-radius: 7px;
  cursor: pointer;
  transition: background-color 120ms ease, transform 60ms ease;
}

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

.btn--add {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 38px;
  flex: 0 0 auto;
  background: var(--paper);
  border: 1px solid var(--line);
  color: var(--action);
}

.btn--add:hover {
  background: var(--verified-bg);
}

.btn--add:active {
  transform: scale(0.94);
}

.value-list {
  list-style: none;
  margin: 12px 0 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.value-chip {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 5px 6px 5px 12px;
  font-family: var(--font-mono);
  font-size: 0.88rem;
}

.chip-remove {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 20px;
  height: 20px;
  border-radius: 999px;
  border: none;
  background: transparent;
  color: var(--ink-soft);
  cursor: pointer;
  padding: 0;
}

.chip-remove:hover {
  background: var(--error-bg);
  color: var(--error);
}

.chip-remove:focus-visible {
  outline: 2px solid var(--action);
  outline-offset: 1px;
}

.pair-coverage-heading--rules {
  margin-top: 8px;
}

.rules {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  align-items: start;
  gap: 20px;
  margin-bottom: 16px;
}

.rule-card {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 18px 20px 20px;
}

.rule-card__head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  margin-bottom: 6px;
}

.rule-card__head .field-label {
  margin-bottom: 0;
}

.rule-pairs {
  list-style: none;
  margin: 12px 0 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.rule-pair-item {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 5px 6px 5px 12px;
  font-family: var(--font-mono);
  font-size: 0.88rem;
}

.rule-add-pair {
  display: flex;
  gap: 8px;
  margin-top: 12px;
}

.rule-add-pair select {
  flex: 1;
  font: inherit;
  font-family: var(--font-mono);
  font-size: 0.88rem;
  padding: 8px 10px;
  border: 1px solid var(--line);
  border-radius: 7px;
  background: var(--surface);
  color: var(--ink);
}

.add-rule-row {
  display: flex;
  justify-content: center;
  margin-bottom: 24px;
}

.applied-rules {
  list-style: none;
  margin: 0 0 24px;
  padding: 0;
  display: grid;
  gap: 8px;
}

.applied-rule-item {
  padding: 8px 12px;
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: 8px;
  font-family: var(--font-mono);
  font-size: 0.85rem;
}

.field-error {
  color: var(--error);
  background: var(--error-bg);
  border-radius: 6px;
  padding: 6px 10px;
  font-size: 0.85rem;
  margin: 8px 0 0;
}

.field-error--center {
  max-width: 920px;
  text-align: center;
  margin: 12px auto 0;
}

.start-row {
  display: flex;
  justify-content: center;
  margin: 28px 0 40px;
}

.btn--primary {
  background: var(--action);
  color: var(--action-ink);
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 1rem;
  padding: 13px 30px;
  border-radius: 999px;
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.08);
}

.btn--primary:hover:not(:disabled) {
  filter: brightness(1.08);
}

.btn--primary:disabled {
  background: var(--line);
  color: var(--ink-soft);
  cursor: not-allowed;
}

.results {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 22px 24px 26px;
}

.results-summary {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 14px;
  margin-bottom: 18px;
  font-family: var(--font-display);
}

.results-total strong {
  font-family: var(--font-mono);
  color: var(--action);
}

.badge-covered {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: var(--verified-bg);
  color: var(--verified);
  font-family: var(--font-ui);
  font-weight: 600;
  font-size: 0.85rem;
  padding: 5px 12px;
  border-radius: 999px;
}

.table-scroll {
  max-height: 420px;
  overflow: auto;
  border: 1px solid var(--line);
  border-radius: 8px;
  margin: 0 0 24px;
}

.combination-table,
.value-pair-table {
  width: 100%;
  border-collapse: collapse;
  font-family: var(--font-mono);
  font-size: 0.85rem;
}

.combination-table thead th,
.value-pair-table thead th {
  position: sticky;
  top: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font-ui);
  font-weight: 600;
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  text-align: left;
  padding: 8px 14px;
  border-bottom: 1px solid var(--line);
  white-space: nowrap;
}

.combination-table tbody td,
.value-pair-table tbody td {
  padding: 8px 14px;
  border-bottom: 1px solid var(--line);
  color: var(--ink);
  white-space: nowrap;
}

.combination-table tbody tr:last-child td,
.value-pair-table tbody tr:last-child td {
  border-bottom: none;
}

.combination-item__number {
  color: var(--ink-soft);
}

.pair-coverage-heading {
  font-family: var(--font-display);
  font-size: 1rem;
  margin: 0 0 12px;
  color: var(--ink);
}

.pair-coverage {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 8px;
}

.pair-coverage-item {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 10px;
  padding: 8px 12px;
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: 8px;
  font-size: 0.85rem;
}

.pair-coverage-item__names {
  font-weight: 600;
  color: var(--ink);
}

.pair-coverage-item__cases {
  font-family: var(--font-mono);
  color: var(--ink-soft);
}

@media (prefers-reduced-motion: no-preference) {
  .results:not([hidden]) {
    animation: reveal 220ms ease-out;
  }
}

@keyframes reveal {
  from {
    opacity: 0;
    transform: translateY(4px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}