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

:root {
  --bg:        #0d1117;
  --bg2:       #161b22;
  --bg3:       #21262d;
  --border:    #30363d;
  --text:      #e6edf3;
  --text2:     #8b949e;
  --accent:    #58a6ff;
  --accent2:   #3fb950;
  --warn:      #f0883e;
  --ok:        #3fb950;
  --radius:    8px;
  --font:      'Courier New', 'Menlo', monospace;
}

/* ===== Light Theme ===== */
html.light-theme,
html.light-theme body {
  --bg:        #f6f8fa;
  --bg2:       #ffffff;
  --bg3:       #eaeef2;
  --border:    #d0d7de;
  --text:      #1f2328;
  --text2:     #57606a;
  --accent:    #0969da;
  --accent2:   #1a7f37;
  --warn:      #bc4c00;
  --ok:        #1a7f37;
}

html { font-size: 16px; }
body {
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  line-height: 1.6;
  min-height: 100vh;
}

/* ===== Header ===== */
header {
  background: var(--bg2);
  border-bottom: 1px solid var(--border);
  padding: 1rem 1.5rem;
  display: flex;
  align-items: center;
  gap: 1rem;
  position: sticky;
  top: 0;
  z-index: 100;
}
header .callsign {
  font-family: var(--font);
  font-size: 1.3rem;
  font-weight: bold;
  color: var(--accent);
  letter-spacing: 2px;
}
header .title {
  font-size: 1rem;
  color: var(--text2);
  flex: 1;
}
.theme-toggle {
  background: var(--bg3);
  border: 1px solid var(--border);
  border-radius: 20px;
  color: var(--text2);
  cursor: pointer;
  font-size: 1.1rem;
  width: 36px;
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background 0.2s, border-color 0.2s;
  flex-shrink: 0;
}
.theme-toggle:hover {
  background: var(--border);
  color: var(--text);
}

/* ===== Tab Navigation ===== */
.tab-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 2px;
  background: var(--bg2);
  border-bottom: 1px solid var(--border);
  padding: 0.5rem 1rem 0;
  position: sticky;
  top: 60px;
  z-index: 90;
}
.tab-btn {
  background: none;
  border: none;
  color: var(--text2);
  padding: 0.5rem 1rem;
  cursor: pointer;
  font-size: 0.85rem;
  border-bottom: 2px solid transparent;
  white-space: nowrap;
  transition: color 0.15s, border-color 0.15s;
}
.tab-btn:hover { color: var(--text); }
.tab-btn.active {
  color: var(--accent);
  border-bottom-color: var(--accent);
}

/* ===== Main Content ===== */
main { max-width: 900px; margin: 0 auto; padding: 1.5rem 1rem 3rem; }

.tab-panel { display: none; }
.tab-panel.active { display: block; }

/* ===== Section / Card ===== */
.card {
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.5rem;
  margin-bottom: 1.5rem;
}
.card h2 {
  font-size: 1.1rem;
  color: var(--accent);
  margin-bottom: 1rem;
  padding-bottom: 0.5rem;
  border-bottom: 1px solid var(--border);
}
.card h3 {
  font-size: 0.95rem;
  color: var(--text);
  margin: 1rem 0 0.5rem;
}

/* ===== Form Row ===== */
.form-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.5rem;
  margin-bottom: 0.75rem;
}
.form-row label {
  min-width: 180px;
  color: var(--text2);
  font-size: 0.9rem;
}
.form-row input[type="number"],
.form-row select {
  background: var(--bg3);
  border: 1px solid var(--border);
  border-radius: 4px;
  color: var(--text);
  padding: 0.4rem 0.6rem;
  font-size: 0.9rem;
  width: 130px;
  outline: none;
  transition: border-color 0.15s;
}
.form-row input[type="number"]:focus,
.form-row select:focus {
  border-color: var(--accent);
}
.form-row input[readonly] {
  opacity: 0.6;
  cursor: not-allowed;
}
.form-row .unit {
  color: var(--text2);
  font-size: 0.85rem;
  min-width: 30px;
}

/* ===== Result Table ===== */
.result-box {
  background: var(--bg3);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1rem;
  margin-top: 1rem;
}
.result-box h3 {
  font-size: 0.85rem;
  color: var(--text2);
  text-transform: uppercase;
  letter-spacing: 1px;
  margin-bottom: 0.5rem;
}
table.result-table {
  width: 100%;
  border-collapse: collapse;
  font-family: var(--font);
  font-size: 0.9rem;
}
table.result-table td {
  padding: 0.35rem 0.5rem;
  border-bottom: 1px solid var(--border);
}
table.result-table td:first-child { color: var(--text2); width: 55%; }
table.result-table td:last-child { color: var(--text); text-align: right; }
table.result-table tr:last-child td { border-bottom: none; }
table.result-table strong { color: var(--accent2); }

/* ===== Mode Toggle ===== */
.mode-group {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
  margin-bottom: 1rem;
}
.mode-group select {
  background: var(--bg3);
  border: 1px solid var(--border);
  border-radius: 4px;
  color: var(--accent);
  padding: 0.4rem 0.8rem;
  font-size: 0.9rem;
  cursor: pointer;
}

/* ===== Diagram SVG ===== */
.diagram-svg {
  width: 100%;
  max-width: 400px;
  height: auto;
  display: block;
  margin: 0.75rem auto 1rem;
  background: var(--bg3);
  border-radius: 6px;
  padding: 6px;
}
.diagram-svg.narrow { max-width: 220px; }
.desc-text {
  color: var(--text2);
  font-size: 0.875rem;
  line-height: 1.7;
  margin-bottom: 1rem;
  padding: 0.6rem 0.75rem;
  background: var(--bg3);
  border-left: 3px solid var(--border);
  border-radius: 0 4px 4px 0;
}

/* ===== Warning / OK boxes ===== */
.warn-box {
  background: rgba(240,136,62,0.1);
  border: 1px solid var(--warn);
  border-radius: var(--radius);
  padding: 0.75rem 1rem;
  color: var(--warn);
  font-size: 0.9rem;
  line-height: 1.8;
}
.ok-box {
  background: rgba(63,185,80,0.1);
  border: 1px solid var(--ok);
  border-radius: var(--radius);
  padding: 0.75rem 1rem;
  color: var(--ok);
  font-size: 0.9rem;
}

/* ===== Random Wire Table ===== */
.rw-tables {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
  margin-top: 1rem;
}
@media (max-width: 600px) {
  .rw-tables { grid-template-columns: 1fr; }
}
.rw-tables table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.85rem;
}
.rw-tables th {
  background: var(--bg3);
  color: var(--text2);
  padding: 0.4rem 0.6rem;
  text-align: left;
  font-weight: normal;
  font-size: 0.8rem;
  border-bottom: 1px solid var(--border);
}
.rw-tables td {
  padding: 0.35rem 0.6rem;
  border-bottom: 1px solid var(--border);
  font-family: var(--font);
}

/* ===== Divider ===== */
.sub-divider {
  border: none;
  border-top: 1px solid var(--border);
  margin: 1.5rem 0;
}

/* ===== Footer ===== */
footer {
  text-align: center;
  color: var(--text2);
  font-size: 0.8rem;
  padding: 2rem 1rem;
  border-top: 1px solid var(--border);
}

/* ===== Responsive ===== */
@media (max-width: 600px) {
  header { padding: 0.75rem 1rem; }
  .tab-nav { padding: 0.25rem 0.5rem 0; top: 52px; }
  .tab-btn { font-size: 0.78rem; padding: 0.4rem 0.7rem; }
  main { padding: 1rem 0.75rem 3rem; }
  .card { padding: 1rem; }
  .form-row label { min-width: 140px; font-size: 0.85rem; }
  .form-row input[type="number"],
  .form-row select { width: 110px; }
}