:root {
  --bg: #1a1f2b;
  --panel: #232a3a;
  --panel-alt: #2b3448;
  --border: #374260;
  --accent: #3fb6ea;
  --accent-dark: #2c8fc0;
  --text: #e8ecf5;
  --subtext: #8b96af;
  --row-stripe: #242c3c;
  --error: #e05561;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: "Segoe UI", "Segoe UI Semibold", system-ui, -apple-system, Arial, sans-serif;
  font-size: 14px;
}

.container {
  max-width: 900px;
  margin: 0 auto;
  padding: 24px 20px 48px;
}

header {
  padding: 4px 0 18px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
}

header a.brand {
  display: flex;
  align-items: center;
  gap: 20px;
  text-decoration: none;
  color: inherit;
}

header h1 {
  margin: 0 0 4px;
  font-size: 22px;
  font-weight: 600;
}

header p {
  margin: 0;
  color: var(--subtext);
}

header .logo {
  height: 60px;
  width: auto;
  flex: 0 0 auto;
}

nav.toc {
  display: flex;
  flex-wrap: wrap;
  gap: 4px 6px;
  padding: 0 0 18px;
  font-size: 12px;
}

nav.toc a {
  color: var(--subtext);
  text-decoration: none;
  padding: 5px 10px;
  border-radius: 14px;
  border: 1px solid var(--border);
  white-space: nowrap;
}

nav.toc a:hover {
  color: var(--text);
  border-color: var(--accent);
}

nav.toc a.active {
  color: var(--text);
  background: var(--panel-alt);
  border-color: var(--accent);
}

.card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 16px 18px;
  margin-bottom: 18px;
}

.card h2 {
  margin: 0 0 14px;
  font-size: 13px;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--accent);
  font-weight: 600;
}

details.card summary {
  margin: -16px -18px 0;
  padding: 16px 18px;
  cursor: pointer;
  font-size: 13px;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--accent);
  font-weight: 600;
  list-style: none;
}

details.card summary::-webkit-details-marker { display: none; }

details.card summary::before {
  content: "▸ ";
  display: inline-block;
  transition: transform .15s;
}

details.card[open] summary::before { transform: rotate(90deg); }

details.card[open] summary { margin-bottom: 14px; }

details.card .body-pad { padding-top: 2px; }

h3.sub-heading {
  font-size: 13px;
  color: var(--text);
  margin: 18px 0 8px;
}

h3.sub-heading:first-child { margin-top: 0; }

p.explain, li.explain {
  color: var(--text);
  line-height: 1.55;
}

ul.explain-list { margin: 6px 0 14px; padding-left: 20px; }

code.inline {
  background: var(--panel-alt);
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 1px 5px;
  font-family: Consolas, monospace;
  font-size: 12px;
  color: var(--accent);
}

label {
  display: block;
  font-size: 12px;
  color: var(--subtext);
  margin-bottom: 6px;
}

input[type="text"], select, textarea {
  width: 100%;
  background: var(--panel-alt);
  border: 1px solid var(--border);
  color: var(--text);
  border-radius: 6px;
  padding: 9px 10px;
  font-size: 14px;
  font-family: inherit;
  outline: none;
}

textarea {
  font-family: Consolas, monospace;
  font-size: 13px;
  min-height: 90px;
  resize: vertical;
}

input[type="text"]:focus, select:focus, textarea:focus {
  border-color: var(--accent);
}

select {
  appearance: none;
  -webkit-appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='10' height='6'%3E%3Cpath d='M0 0l5 6 5-6z' fill='%233fb6ea'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 12px center;
  padding-right: 30px;
}

.row {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  align-items: end;
  margin-bottom: 14px;
}

.row:last-child { margin-bottom: 0; }

.field {
  flex: 1 1 220px;
  min-width: 180px;
}

button {
  background: var(--accent);
  color: #0b1320;
  border: none;
  border-radius: 6px;
  padding: 10px 18px;
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
  white-space: nowrap;
}

button:hover {
  background: var(--accent-dark);
}

.toolbar {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 12px;
}

.btn-sm {
  background: var(--panel-alt);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 7px 12px;
  font-size: 12px;
  font-weight: 600;
  cursor: pointer;
  white-space: nowrap;
}

.btn-sm:hover {
  border-color: var(--accent);
  color: var(--accent);
  background: var(--panel-alt);
}

.error-msg {
  color: var(--error);
  font-size: 13px;
  margin-top: 10px;
  display: none;
}

.error-msg.show {
  display: block;
}

table {
  width: 100%;
  border-collapse: collapse;
}

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

th, td {
  text-align: left;
  padding: 8px 12px;
  font-size: 13px;
  border-bottom: 1px solid var(--border);
  white-space: nowrap;
}

th {
  color: var(--subtext);
  background: var(--panel-alt);
  font-weight: 600;
  text-transform: uppercase;
  font-size: 11px;
  letter-spacing: 0.03em;
}

.kv-table td:first-child {
  color: var(--subtext);
  width: 38%;
}

.kv-table td:nth-child(2) {
  font-variant-numeric: tabular-nums;
}

.kv-table td:last-child {
  width: 30px;
  text-align: right;
}

.ref-table td, .ref-table th { white-space: normal; }

.copy-btn {
  background: none;
  border: none;
  color: var(--subtext);
  cursor: pointer;
  font-size: 15px;
  line-height: 1;
  padding: 3px 5px;
  border-radius: 4px;
}

.copy-btn:hover {
  color: var(--accent);
  background: var(--panel-alt);
}

tbody tr:nth-child(odd) { background: var(--row-stripe); }
tbody tr:nth-child(even) { background: var(--panel-alt); }

.split-controls {
  display: flex;
  flex-wrap: wrap;
  gap: 20px;
  align-items: center;
  margin-bottom: 14px;
}

.split-option {
  display: flex;
  align-items: center;
  gap: 8px;
}

.split-option input[type="radio"] {
  accent-color: var(--accent);
  width: 15px;
  height: 15px;
}

.split-option input[type="text"] {
  width: 70px;
}

.split-scroll {
  max-height: 420px;
  overflow-y: auto;
  overflow-x: auto;
  border: 1px solid var(--border);
  border-radius: 6px;
}

.split-scroll table { min-width: 640px; }
.split-scroll thead th { position: sticky; top: 0; z-index: 1; }

.visualizer {
  display: none;
  height: 26px;
  border-radius: 6px;
  overflow: hidden;
  border: 1px solid var(--border);
  margin-bottom: 14px;
}

.visualizer .seg {
  flex: 1;
  border-right: 1px solid var(--bg);
  background: var(--accent);
}

.visualizer .seg:last-child { border-right: none; }
.visualizer .seg:nth-child(even) { background: var(--accent-dark); }

.subtext {
  color: var(--subtext);
  font-size: 12px;
  margin-top: 8px;
}

.subtext:first-child { margin-top: 0; margin-bottom: 12px; }

.toast {
  position: fixed;
  bottom: 22px;
  left: 50%;
  transform: translateX(-50%) translateY(16px);
  background: var(--accent);
  color: #0b1320;
  padding: 8px 16px;
  border-radius: 6px;
  font-size: 13px;
  font-weight: 600;
  opacity: 0;
  transition: opacity .18s ease, transform .18s ease;
  pointer-events: none;
  z-index: 999;
}

.toast.show {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}

footer {
  text-align: center;
  color: var(--subtext);
  font-size: 12px;
  padding-top: 8px;
}

footer code.inline { font-size: 11px; }

/* -------------------------------------------------------------- hub page */
.tool-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  gap: 14px;
  margin-bottom: 18px;
}

.tool-card {
  display: block;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 16px 18px;
  text-decoration: none;
  color: var(--text);
  transition: border-color .15s;
}

.tool-card:hover {
  border-color: var(--accent);
}

.tool-card h3 {
  margin: 0 0 6px;
  font-size: 15px;
  color: var(--accent);
}

.tool-card p {
  margin: 0;
  color: var(--subtext);
  font-size: 12.5px;
  line-height: 1.5;
}

.preview-banner {
  background: var(--panel-alt);
  border: 1px dashed var(--accent);
  border-radius: 8px;
  padding: 10px 14px;
  font-size: 12.5px;
  color: var(--subtext);
  margin-bottom: 18px;
}

.preview-banner strong { color: var(--accent); }

.back-link {
  display: inline-block;
  margin-bottom: 14px;
  font-size: 12px;
  color: var(--subtext);
  text-decoration: none;
}

.back-link:hover { color: var(--accent); }