:root {
  --bg: #0a0e17;
  --bg-soft: #0d1322;
  --card: #111a2e;
  --card-hover: #14203a;
  --border: #1e2b47;
  --border-strong: #2b3d63;
  --text: #e2e8f0;
  --muted: #8b9bb4;
  --accent: #22d3ee;
  --accent-soft: rgba(34, 211, 238, 0.12);
  --violet: #a78bfa;
  --danger: #f87171;
  --danger-soft: rgba(248, 113, 113, 0.1);
  --ok: #34d399;
  --mono: ui-monospace, "Cascadia Code", "JetBrains Mono", Consolas, "Courier New", monospace;
  --sans: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: var(--sans);
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  background-image:
    radial-gradient(ellipse 80% 50% at 20% -10%, rgba(34, 211, 238, 0.07), transparent),
    radial-gradient(ellipse 60% 40% at 90% 0%, rgba(167, 139, 250, 0.06), transparent),
    linear-gradient(rgba(139, 155, 180, 0.04) 1px, transparent 1px),
    linear-gradient(90deg, rgba(139, 155, 180, 0.04) 1px, transparent 1px);
  background-size: auto, auto, 40px 40px, 40px 40px;
}

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

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

.topbar {
  border-bottom: 1px solid var(--border);
  background: rgba(10, 14, 23, 0.8);
  backdrop-filter: blur(8px);
  position: sticky;
  top: 0;
  z-index: 10;
}
.topbar-inner {
  display: flex; align-items: center; gap: 16px;
  height: 58px; max-width: 1100px; margin: 0 auto; padding: 0 24px;
}
.brand {
  font-family: var(--mono); font-weight: 700; font-size: 17px;
  color: var(--text); letter-spacing: 0.5px; display: flex; align-items: center; gap: 10px;
}
.brand:hover { text-decoration: none; }
.brand .chip-dot {
  width: 10px; height: 10px; border-radius: 2px;
  background: linear-gradient(135deg, var(--accent), var(--violet));
  box-shadow: 0 0 10px rgba(34, 211, 238, 0.6);
}
.topnav { margin-left: auto; display: flex; gap: 20px; font-size: 14px; }
.topnav a { color: var(--muted); }
.topnav a:hover { color: var(--text); text-decoration: none; }

.hero { padding: 72px 0 32px; }
.hero h1 {
  font-size: 40px; margin: 0 0 14px; letter-spacing: -0.5px;
  font-family: var(--mono);
}
.hero h1 .grad {
  background: linear-gradient(90deg, var(--accent), var(--violet));
  -webkit-background-clip: text; background-clip: text; color: transparent;
}
.hero p { color: var(--muted); font-size: 16px; max-width: 640px; line-height: 1.7; margin: 0; }

.section-title {
  font-family: var(--mono); font-size: 13px; text-transform: uppercase;
  letter-spacing: 2px; color: var(--muted); margin: 40px 0 18px;
  display: flex; align-items: center; gap: 12px;
}
.section-title::after { content: ""; flex: 1; height: 1px; background: var(--border); }

.tools-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(300px, 1fr)); gap: 18px; padding-bottom: 40px; }

.tool-card {
  display: block; background: var(--card); border: 1px solid var(--border);
  border-radius: 12px; padding: 22px; color: var(--text);
  transition: border-color 0.2s, transform 0.2s, box-shadow 0.2s;
}
a.tool-card:hover {
  text-decoration: none; border-color: var(--accent);
  transform: translateY(-2px);
  box-shadow: 0 8px 30px rgba(34, 211, 238, 0.12);
}
.tool-card.disabled { opacity: 0.55; cursor: default; }
.tool-icon {
  width: 42px; height: 42px; border-radius: 10px;
  background: var(--accent-soft); border: 1px solid var(--border-strong);
  display: flex; align-items: center; justify-content: center; margin-bottom: 14px;
}
.tool-icon svg { width: 22px; height: 22px; stroke: var(--accent); fill: none; stroke-width: 1.6; }
.tool-card h3 { margin: 0 0 8px; font-size: 17px; }
.tool-card p { margin: 0; color: var(--muted); font-size: 13.5px; line-height: 1.6; }
.tool-tag {
  display: inline-block; margin-top: 12px; font-family: var(--mono); font-size: 11px;
  color: var(--accent); border: 1px solid var(--border-strong); border-radius: 999px;
  padding: 3px 10px; background: var(--accent-soft);
}

footer.site-footer {
  border-top: 1px solid var(--border); color: var(--muted); font-size: 13px;
  padding: 26px 0 40px; margin-top: 40px;
}

/* ---------- tool page ---------- */
.tool-header { padding: 40px 0 8px; }
.tool-header h1 { font-family: var(--mono); font-size: 28px; margin: 0 0 10px; }
.tool-header p { color: var(--muted); margin: 0; line-height: 1.7; max-width: 720px; }
.back-link { font-size: 13px; font-family: var(--mono); color: var(--muted); }
.back-link:hover { color: var(--accent); text-decoration: none; }

.panel {
  background: var(--card); border: 1px solid var(--border); border-radius: 12px;
  padding: 22px; margin: 22px 0;
}
.panel h2 {
  font-family: var(--mono); font-size: 15px; margin: 0 0 4px;
  display: flex; align-items: center; gap: 10px;
}
.step-num {
  display: inline-flex; align-items: center; justify-content: center;
  width: 22px; height: 22px; border-radius: 6px; font-size: 12px;
  background: var(--accent-soft); color: var(--accent); border: 1px solid var(--border-strong);
}
.panel .hint { color: var(--muted); font-size: 13px; margin: 4px 0 0; line-height: 1.6; }

.sig-cols { display: grid; grid-template-columns: 1fr 1fr; gap: 24px; margin-top: 16px; }
@media (max-width: 720px) { .sig-cols { grid-template-columns: 1fr; } }
.sig-col h3 { font-size: 13px; font-family: var(--mono); color: var(--muted); margin: 0 0 10px; text-transform: uppercase; letter-spacing: 1px; }
.sig-row { display: flex; gap: 8px; margin-bottom: 8px; align-items: center; }
.sig-row input {
  flex: 1; background: var(--bg-soft); border: 1px solid var(--border);
  color: var(--text); border-radius: 8px; padding: 8px 12px;
  font-family: var(--mono); font-size: 14px; outline: none;
}
.sig-row input:focus { border-color: var(--accent); }
.sig-row input.invalid { border-color: var(--danger); }
.btn-mini {
  background: var(--bg-soft); border: 1px solid var(--border); color: var(--muted);
  border-radius: 8px; width: 34px; height: 34px; font-size: 16px; cursor: pointer;
  display: inline-flex; align-items: center; justify-content: center; flex: none;
}
.btn-mini:hover { color: var(--text); border-color: var(--border-strong); }
.btn-mini.remove:hover { color: var(--danger); border-color: var(--danger); }
.btn-add {
  background: transparent; border: 1px dashed var(--border-strong); color: var(--muted);
  border-radius: 8px; padding: 7px 14px; font-size: 13px; cursor: pointer; font-family: var(--mono);
}
.btn-add:hover { color: var(--accent); border-color: var(--accent); }

.gate-chips { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 16px; }
.gate-chip { position: relative; }
.gate-chip input { position: absolute; opacity: 0; pointer-events: none; }
.gate-chip label {
  display: inline-block; padding: 8px 16px; border-radius: 999px; cursor: pointer;
  border: 1px solid var(--border-strong); background: var(--bg-soft);
  font-family: var(--mono); font-size: 13px; color: var(--muted);
  transition: all 0.15s; user-select: none;
}
.gate-chip input:checked + label {
  color: var(--accent); border-color: var(--accent); background: var(--accent-soft);
  box-shadow: 0 0 12px rgba(34, 211, 238, 0.15);
}
.chipbar { display: flex; gap: 10px; flex-wrap: wrap; margin-top: 14px; }
.link-btn {
  background: none; border: none; color: var(--muted); font-size: 12.5px;
  cursor: pointer; font-family: var(--mono); padding: 4px 6px;
}
.link-btn:hover { color: var(--accent); }

.tt-wrap { overflow: auto; max-height: 480px; border: 1px solid var(--border); border-radius: 10px; margin-top: 16px; }
table.tt { border-collapse: collapse; width: 100%; font-family: var(--mono); font-size: 13.5px; }
table.tt th, table.tt td { padding: 7px 14px; text-align: center; border-bottom: 1px solid var(--border); }
table.tt thead th {
  position: sticky; top: 0; background: var(--bg-soft); color: var(--accent);
  font-weight: 600; letter-spacing: 0.5px; z-index: 1;
}
table.tt thead th.in-col { color: var(--text); }
table.tt thead th.out-col { color: var(--violet); }
table.tt tbody tr:nth-child(even) { background: rgba(139, 155, 180, 0.03); }
table.tt td.in-bit { color: var(--muted); }
table.tt td.out-cell { padding: 3px 8px; }
table.tt td.out-cell input {
  width: 44px; text-align: center; background: transparent; border: 1px solid transparent;
  border-radius: 6px; color: var(--violet); font-family: var(--mono); font-size: 14px; padding: 4px 0;
  outline: none;
}
table.tt td.out-cell input:hover { border-color: var(--border); }
table.tt td.out-cell input:focus { border-color: var(--violet); background: var(--bg-soft); }
table.tt td.out-cell input.invalid { border-color: var(--danger); color: var(--danger); }
.tt-meta { color: var(--muted); font-size: 12.5px; font-family: var(--mono); margin-top: 10px; }

.btn-primary {
  background: linear-gradient(135deg, var(--accent), #0891b2);
  color: #06202a; font-weight: 700; font-family: var(--mono); font-size: 15px;
  border: none; border-radius: 10px; padding: 13px 34px; cursor: pointer;
  letter-spacing: 0.5px;
}
.btn-primary:hover { filter: brightness(1.12); }
.btn-primary:disabled { opacity: 0.4; cursor: not-allowed; }
.generate-bar { display: flex; align-items: center; gap: 16px; margin: 26px 0 10px; flex-wrap: wrap; }

.error-box {
  background: var(--danger-soft); border: 1px solid rgba(248, 113, 113, 0.4);
  border-radius: 10px; padding: 16px 18px; margin: 18px 0; color: #fecaca;
}
.error-box strong { color: var(--danger); font-family: var(--mono); display: block; margin-bottom: 6px; }
.error-box code { font-family: var(--mono); background: rgba(0,0,0,0.3); padding: 1px 6px; border-radius: 4px; font-size: 12.5px; }

.result-out { margin: 14px 0; }
.result-out .expr-name { font-family: var(--mono); font-weight: 700; color: var(--violet); font-size: 15px; }
.expr-html { font-family: var(--mono); font-size: 16px; margin: 8px 0 4px; letter-spacing: 0.5px; }
.expr-html .ovl { text-decoration: overline; }
.expr-ascii { font-family: var(--mono); font-size: 12.5px; color: var(--muted); margin: 2px 0 0; }
.stat-chips { display: flex; flex-wrap: wrap; gap: 8px; margin: 12px 0 4px; }
.stat-chip {
  font-family: var(--mono); font-size: 12px; color: var(--text);
  border: 1px solid var(--border-strong); background: var(--bg-soft);
  border-radius: 999px; padding: 4px 12px;
}
.stat-chip.total { color: var(--ok); border-color: rgba(52, 211, 153, 0.4); }
.stat-chip.map { color: var(--accent); }

.circuit-box {
  border: 1px solid var(--border); border-radius: 10px; background: var(--bg-soft);
  overflow: auto; margin-top: 14px;
}
.circuit-box svg { display: block; min-width: 100%; }
.circuit-toolbar { display: flex; gap: 12px; align-items: center; margin-top: 10px; }
.empty-note { color: var(--muted); font-size: 14px; padding: 8px 0; }

hr.sep { border: none; border-top: 1px solid var(--border); margin: 26px 0; }

.hidden { display: none !important; }

.expr-row {
  display: grid; grid-template-columns: auto auto 1fr; gap: 4px 12px;
  align-items: baseline; padding: 12px 0; border-bottom: 1px dashed var(--border);
}
.expr-row:last-child { border-bottom: none; }
.expr-name { font-family: var(--mono); font-weight: 700; color: var(--violet); font-size: 15px; }
.expr-eq { font-family: var(--mono); color: var(--muted); }
.expr-html { grid-column: 3; }
.expr-ascii { grid-column: 3; }
.expr-path {
  grid-column: 3; font-family: var(--mono); font-size: 11.5px; color: var(--accent);
  opacity: 0.85; margin-top: 2px;
}
.expr-path::before { content: "mapping: "; color: var(--muted); }

.error-title { color: var(--danger); font-family: var(--mono); font-weight: 700; margin-bottom: 6px; }
.error-msg { font-family: var(--mono); font-size: 13px; margin-bottom: 6px; }
.error-reasons { margin: 8px 0 0; padding-left: 20px; }
.error-reasons li { font-family: var(--mono); font-size: 12.5px; color: #fca5a5; margin: 3px 0; }
.error-reasons li:last-child { color: var(--muted); }