/* ── Reset & base ── */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  --blue: #2563eb;
  --blue-dark: #1d4ed8;
  --blue-light: #eff6ff;
  --green: #16a34a;
  --green-bg: #f0fdf4;
  --green-bd: #bbf7d0;
  --red: #dc2626;
  --red-bg: #fef2f2;
  --red-bd: #fecaca;
  --gray-50: #f9fafb;
  --gray-100: #f3f4f6;
  --gray-200: #e5e7eb;
  --gray-400: #9ca3af;
  --gray-600: #4b5563;
  --gray-700: #374151;
  --gray-900: #111827;
  --radius: 8px;
  --radius-lg: 12px;
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.08), 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
  --font: "Segoe UI", system-ui, -apple-system, sans-serif;
  --mono: "Fira Code", "Cascadia Code", "Consolas", monospace;
}

body {
  font-family: var(--font);
  background: var(--gray-50);
  color: var(--gray-900);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* ── Header ── */
header {
  display: inline-block;
  width: 100%;
  background: white;
  border-bottom: 1px solid var(--gray-200);
  margin: 0 auto;
  padding: 1.25rem 2rem;
  box-shadow: var(--shadow-sm);
}

h1 {
  font-size: 1.5rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--gray-900);
}

.tagline {
  font-size: 0.8125rem;
  color: var(--gray-600);
  margin-top: 2px;
}

/* ── Main ── */
main {
  max-width: 860px;
  margin: 0 auto;
  padding: 2rem 2rem 3rem;
  width: 100%;
  flex: 1;
}

/* ── Input section ── */
.input-section {
  background: white;
  border: 1px solid var(--gray-200);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  box-shadow: var(--shadow-sm);
  margin-bottom: 1.5rem;
}

.input-label {
  display: block;
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--gray-600);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 0.6rem;
}

.input-row {
  display: flex;
  gap: 0.5rem;
}

input[type="text"] {
  flex: 1;
  padding: 0.625rem 0.875rem;
  font-size: 1rem;
  font-family: var(--mono);
  border: 1.5px solid var(--gray-200);
  border-radius: var(--radius);
  background: var(--gray-50);
  color: var(--gray-900);
  outline: none;
  transition:
    border-color 0.15s,
    box-shadow 0.15s,
    background 0.15s;
}

input[type="text"]:hover {
  border-color: var(--gray-400);
}

input[type="text"]:focus {
  border-color: var(--blue);
  background: white;
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.12);
}

button#check-btn {
  padding: 0.625rem 1.375rem;
  font-size: 0.9375rem;
  font-weight: 600;
  font-family: var(--font);
  color: white;
  background: var(--blue);
  border: none;
  border-radius: var(--radius);
  cursor: pointer;
  transition:
    background 0.15s,
    transform 0.1s;
  white-space: nowrap;
}

button#check-btn:hover {
  background: var(--blue-dark);
}
button#check-btn:active {
  transform: scale(0.97);
}
button#check-btn:focus-visible {
  outline: none;
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.35);
}

.hint {
  font-size: 0.78rem;
  color: var(--gray-400);
  margin-top: 0.6rem;
  line-height: 1.6;
}

.hint code {
  font-family: var(--mono);
  background: var(--gray-100);
  padding: 1px 5px;
  border-radius: 4px;
  font-size: 0.76rem;
  color: var(--gray-700);
}

/* ── Empty state ── */
.empty-state {
  text-align: center;
  padding: 4rem 2rem;
  color: var(--gray-400);
}

.empty-icon {
  font-size: 3rem;
  line-height: 1;
  margin-bottom: 1rem;
  color: var(--gray-200);
}

.empty-title {
  font-size: 1.0625rem;
  font-weight: 600;
  color: var(--gray-600);
  margin-bottom: 0.4rem;
}

.empty-desc {
  font-size: 0.875rem;
  color: var(--gray-400);
  max-width: 380px;
  margin: 0 auto;
  line-height: 1.6;
}

.empty-desc strong {
  color: var(--gray-600);
  font-weight: 600;
}

/* ── Summary banner ── */
.summary-banner {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.875rem 1.125rem;
  border-radius: var(--radius);
  font-size: 0.9375rem;
  font-weight: 500;
  margin-bottom: 1.25rem;
  border: 1px solid transparent;
}

.summary-banner.pass {
  background: var(--green-bg);
  border-color: var(--green-bd);
  color: var(--green);
}

.summary-banner.fail {
  background: var(--red-bg);
  border-color: var(--red-bd);
  color: var(--red);
}

.summary-icon {
  font-size: 1.2rem;
}

/* ── Tabs ── */
.tabs {
  display: flex;
  gap: 0.25rem;
  border-bottom: 1.5px solid var(--gray-200);
  margin-bottom: 1rem;
}

.tab {
  padding: 0.5rem 1rem 0.6rem;
  font-size: 0.875rem;
  font-weight: 500;
  font-family: var(--font);
  color: var(--gray-600);
  background: none;
  border: none;
  border-bottom: 2px solid transparent;
  margin-bottom: -1.5px;
  cursor: pointer;
  border-radius: var(--radius) var(--radius) 0 0;
  transition:
    color 0.15s,
    background 0.15s;
  display: flex;
  align-items: center;
  gap: 0.4rem;
}

.tab:hover {
  color: var(--gray-900);
  background: var(--gray-100);
}

.tab.active {
  color: var(--blue);
  border-bottom-color: var(--blue);
  font-weight: 600;
}

.tab:focus-visible {
  outline: none;
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.25);
}

.tab-badge {
  font-size: 0.7rem;
  font-weight: 700;
  padding: 1px 6px;
  border-radius: 20px;
  background: var(--gray-200);
  color: var(--gray-600);
  min-width: 1.5rem;
  text-align: center;
}

.tab.active .tab-badge {
  background: var(--blue-light);
  color: var(--blue);
}

/* ── Tables ── */
table {
  border-collapse: collapse;
  width: 100%;
  background: white;
  border: 1px solid var(--gray-200);
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  font-size: 0.875rem;
}

thead {
  background: var(--gray-50);
}

th {
  padding: 0.625rem 1rem;
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--gray-600);
  border-bottom: 1.5px solid var(--gray-200);
  text-align: center;
}

th:first-child {
  text-align: left;
}

td {
  padding: 0.5rem 1rem;
  border-bottom: 1px solid var(--gray-100);
  text-align: center;
  color: var(--gray-700);
  font-variant-numeric: tabular-nums;
}

td:first-child {
  text-align: left;
  color: var(--gray-400);
  font-size: 0.78rem;
}
td:nth-child(2) {
  font-family: var(--mono);
  font-size: 0.8rem;
  color: var(--gray-900);
}
td:nth-child(3),
td:nth-child(4) {
  font-family: var(--mono);
  font-size: 0.8rem;
  color: var(--gray-600);
}

tbody tr:last-child td {
  border-bottom: none;
}
tbody tr:hover {
  background: var(--gray-50);
}

/* Pass/Fail cell */
.pass-cell {
  color: var(--green);
  font-weight: 600;
  font-size: 0.8rem;
}
.fail-cell {
  color: var(--red);
  font-weight: 600;
  font-size: 0.8rem;
}

/* Error cell */
.error-cell {
  color: var(--gray-400);
  font-style: italic;
  font-size: 0.78rem;
}

/* ── Footer ── */
footer {
  text-align: center;
  padding: 1.25rem;
  font-size: 0.78rem;
  color: var(--gray-400);
  border-top: 1px solid var(--gray-200);
  background: white;
}

/* ── Responsive ── */
@media (max-width: 600px) {
  main {
    padding: 1.25rem 1rem 2rem;
  }
  header {
    padding: 1rem;
  }
  .header-inner {
    gap: 0.75rem;
  }
  .logo-mark {
    font-size: 2rem;
  }
  h1 {
    font-size: 1.25rem;
  }
  .input-row {
    flex-direction: column;
  }
  button#check-btn {
    width: 100%;
  }
  td,
  th {
    padding: 0.5rem 0.625rem;
  }
  td:nth-child(2),
  td:nth-child(3),
  td:nth-child(4) {
    font-size: 0.72rem;
  }
}

/* ── Animations ── */
@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(6px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.results-section {
  animation: fadeIn 0.2s ease;
}

@media (prefers-reduced-motion: reduce) {
  .results-section {
    animation: none;
  }
}