:root {
  --c-primary: #1f3a5f;
  --c-primary-dark: #142a44;
  --c-accent: #c00000;
  --c-ok: #137333;
  --c-warn: #a06800;
  --c-bg: #f5f7fa;
  --c-card: #ffffff;
  --c-border: #d8dde5;
  --c-text: #1a2533;
  --c-muted: #5b6b7e;
  --shadow: 0 1px 3px rgba(0,0,0,0.06), 0 1px 2px rgba(0,0,0,0.04);
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', system-ui, sans-serif;
  background: var(--c-bg);
  color: var(--c-text);
  line-height: 1.5;
}

header {
  background: linear-gradient(135deg, var(--c-primary) 0%, var(--c-primary-dark) 100%);
  color: white;
  padding: 24px 32px;
}

header h1 {
  margin: 0;
  font-size: 24px;
  font-weight: 600;
}

.subtitle {
  margin: 4px 0 0;
  font-size: 13px;
  opacity: 0.85;
}

main {
  max-width: 1100px;
  margin: 24px auto;
  padding: 0 24px;
}

.tabs {
  display: flex;
  gap: 4px;
  border-bottom: 1px solid var(--c-border);
  margin-bottom: 16px;
  flex-wrap: wrap;
}

.tab {
  background: none;
  border: none;
  padding: 12px 20px;
  cursor: pointer;
  color: var(--c-muted);
  font-size: 14px;
  font-weight: 500;
  border-bottom: 2px solid transparent;
  margin-bottom: -1px;
}

.tab:hover { color: var(--c-text); }
.tab.active { color: var(--c-primary); border-bottom-color: var(--c-primary); }

.panel {
  display: none;
  background: var(--c-card);
  border: 1px solid var(--c-border);
  border-radius: 8px;
  padding: 24px;
  box-shadow: var(--shadow);
}

.panel.active { display: block; }

.panel h2 {
  margin: 0 0 16px;
  font-size: 18px;
  color: var(--c-primary);
}

.panel h3 {
  margin: 24px 0 8px;
  font-size: 15px;
  color: var(--c-primary);
}

.hint {
  font-size: 13px;
  color: var(--c-muted);
  margin-bottom: 16px;
}

.demo-bar {
  background: linear-gradient(135deg, #f4f7fb 0%, #e8eef7 100%);
  border: 1px solid #d6dfec;
  border-radius: 8px;
  padding: 14px 16px;
  margin-bottom: 18px;
}

.demo-bar select {
  width: 100%;
  font-weight: 500;
}

.demo-bar .hint { margin: 6px 0 0; }
.demo-bar optgroup { font-weight: 600; color: var(--c-primary); }

.grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 16px;
  margin-bottom: 20px;
}

label {
  display: flex;
  flex-direction: column;
  font-size: 13px;
  font-weight: 500;
  color: var(--c-text);
  gap: 6px;
}

label.full { grid-column: 1 / -1; }

input, select, textarea {
  font: inherit;
  padding: 9px 12px;
  border: 1px solid var(--c-border);
  border-radius: 6px;
  background: white;
  color: var(--c-text);
  width: 100%;
}

input:focus, select:focus, textarea:focus {
  outline: 2px solid rgba(31,58,95,0.25);
  border-color: var(--c-primary);
}

textarea {
  width: 100%;
  font-family: 'Consolas', 'Monaco', monospace;
  font-size: 13px;
  resize: vertical;
}

.actions {
  display: flex;
  gap: 8px;
  align-items: center;
  flex-wrap: wrap;
}

button.primary {
  background: var(--c-primary);
  color: white;
  border: none;
  padding: 10px 20px;
  border-radius: 6px;
  font-weight: 500;
  cursor: pointer;
  font-size: 14px;
}

button.primary:hover { background: var(--c-primary-dark); }
button.primary:disabled { background: #99a3b0; cursor: not-allowed; }

button.ghost {
  background: white;
  color: var(--c-primary);
  border: 1px solid var(--c-border);
  padding: 10px 20px;
  border-radius: 6px;
  font-weight: 500;
  cursor: pointer;
  font-size: 14px;
}

button.ghost:hover:not(:disabled) { background: var(--c-bg); }
button.ghost:disabled { color: #99a3b0; cursor: not-allowed; }

.result {
  margin-top: 20px;
  padding: 16px;
  border-radius: 8px;
  border: 1px solid var(--c-border);
  background: #fafbfc;
}

.result.hidden { display: none; }

.result.ok { border-color: #c8e6c9; background: #f1f8f4; }
.result.fail { border-color: #ffcdd2; background: #fdf3f3; }

.result h3 {
  margin: 0 0 8px;
  font-size: 16px;
}

.result.ok h3 { color: var(--c-ok); }
.result.fail h3 { color: var(--c-accent); }

.checks {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 8px;
  margin: 12px 0;
}

.check {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 12px;
  background: white;
  border: 1px solid var(--c-border);
  border-radius: 6px;
  font-size: 13px;
}

.check .icon { font-weight: bold; font-size: 16px; }
.check.pass .icon { color: var(--c-ok); }
.check.fail .icon { color: var(--c-accent); }
.check.info .icon { color: var(--c-muted); }

.diff {
  font-family: 'Consolas', monospace;
  font-size: 14px;
  background: white;
  padding: 12px;
  border-radius: 6px;
  border: 1px solid var(--c-border);
  margin: 8px 0;
  overflow-x: auto;
}

.diff .row { display: flex; gap: 16px; align-items: center; padding: 2px 0; }
.diff .label { width: 110px; color: var(--c-muted); font-family: inherit; font-size: 12px; }
.diff .pos { font-family: inherit; letter-spacing: 4px; }
.diff .pos .bad { background: #ffe5e5; color: var(--c-accent); padding: 0 2px; border-radius: 2px; }
.diff .pos .good { color: var(--c-ok); }

pre, code {
  font-family: 'Consolas', 'Monaco', monospace;
  font-size: 13px;
}

pre {
  background: #f6f8fa;
  border: 1px solid var(--c-border);
  border-radius: 6px;
  padding: 12px;
  overflow-x: auto;
}

.summary {
  margin-top: 16px;
  padding: 12px 16px;
  background: white;
  border: 1px solid var(--c-border);
  border-radius: 6px;
  display: flex;
  gap: 24px;
  flex-wrap: wrap;
}

.summary.hidden { display: none; }
.summary .stat { font-size: 13px; }
.summary .stat strong { font-size: 18px; display: block; color: var(--c-primary); }

table {
  width: 100%;
  border-collapse: collapse;
  margin-top: 12px;
  font-size: 12px;
}

th, td {
  text-align: left;
  padding: 8px 10px;
  border-bottom: 1px solid var(--c-border);
}

th {
  background: #f6f8fa;
  font-weight: 600;
  color: var(--c-primary);
  position: sticky;
  top: 0;
}

td.mono { font-family: 'Consolas', monospace; }

tr.fail-row { background: #fdf3f3; }
tr.fail-row td { color: var(--c-accent); }

footer {
  text-align: center;
  padding: 16px;
  color: var(--c-muted);
  font-size: 12px;
}

.badge {
  display: inline-block;
  padding: 2px 8px;
  border-radius: 12px;
  font-size: 11px;
  font-weight: 600;
}

.badge.ok { background: #d4edda; color: var(--c-ok); }
.badge.fail { background: #f8d7da; color: var(--c-accent); }
.badge.warn { background: #fff3cd; color: var(--c-warn); }

@media (max-width: 600px) {
  .grid { grid-template-columns: 1fr; }
  header { padding: 16px 20px; }
  main { padding: 0 12px; }
  .panel { padding: 16px; }
}