/* ─── GOOGLE FONTS ─────────────────────────────────────── */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600&family=JetBrains+Mono:wght@400;500&display=swap');

/* ─── DESIGN TOKENS ─────────────────────────────────────── */
:root {
  --bg-base:        #141414;
  --bg-surface:     #1e1e1e;
  --bg-elevated:    #252525;
  --bg-input:       #2a2a2a;
  --border:         #333333;
  --border-focus:   #4a9eff;
  --accent:         #4a9eff;
  --accent-dim:     rgba(74,158,255,0.12);
  --accent-hover:   #6ab4ff;
  --text-primary:   #e8e8e8;
  --text-secondary: #888888;
  --text-muted:     #555555;
  --green:          #5cb85c;
  --green-dim:      rgba(92,184,92,0.12);
  --red:            #d9534f;
  --red-dim:        rgba(217,83,79,0.12);
  --yellow:         #c8a838;
  --yellow-dim:     rgba(200,168,56,0.12);
  --radius-sm:      6px;
  --radius-md:      10px;
  --radius-lg:      14px;
  --shadow-sm:      0 1px 3px rgba(0,0,0,0.4);
  --shadow-md:      0 4px 12px rgba(0,0,0,0.5);
  --font-ui:        'Inter', system-ui, sans-serif;
  --font-mono:      'JetBrains Mono', monospace;
  --navbar-h:       56px;
  --sidebar-w:      220px;
}

[data-theme="light"] {
  --bg-base:        #f2f4f7;
  --bg-surface:     #ffffff;
  --bg-elevated:    #f8f9fb;
  --bg-input:       #ffffff;
  --border:         #e0e3e8;
  --border-focus:   #1a6fce;
  --accent:         #1a6fce;
  --accent-dim:     rgba(26,111,206,0.10);
  --accent-hover:   #145caa;
  --text-primary:   #111827;
  --text-secondary: #5a6374;
  --text-muted:     #9ca3af;
  --green:          #2d7a2d;
  --green-dim:      rgba(45,122,45,0.10);
  --red:            #c0392b;
  --red-dim:        rgba(192,57,43,0.10);
  --yellow:         #8a6a00;
  --yellow-dim:     rgba(138,106,0,0.10);
  --shadow-sm:      0 1px 3px rgba(0,0,0,0.10);
  --shadow-md:      0 4px 12px rgba(0,0,0,0.12);
}

/* ─── RESET & BASE ──────────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { font-family: var(--font-ui); background: var(--bg-base); color: var(--text-primary); scroll-behavior: smooth; }
body { min-height: 100vh; }
a { color: var(--accent); text-decoration: none; }
a:hover { color: var(--accent-hover); }
input, select, textarea, button { font-family: var(--font-ui); }
input[type="number"] { font-family: var(--font-mono); }
input[type="number"]::-webkit-inner-spin-button,
input[type="number"]::-webkit-outer-spin-button { -webkit-appearance: none; }
input[type="number"] { -moz-appearance: textfield; }

/* ─── NAVBAR ────────────────────────────────────────────── */
.navbar {
  position: fixed; top: 0; left: 0; right: 0; z-index: 100;
  height: var(--navbar-h);
  background: var(--bg-surface);
  border-bottom: 1px solid var(--border);
  display: flex; align-items: center; justify-content: space-between;
  padding: 0 20px;
}
.navbar-logo {
  font-family: var(--font-mono);
  font-size: 15px; font-weight: 500;
  letter-spacing: 0.12em;
  color: var(--accent);
  text-decoration: none;
}
.navbar-logo .tld { color: var(--text-muted); font-weight: 400; }
.navbar-logo .sep { color: var(--border); margin: 0 4px; }
.navbar-right { display: flex; align-items: center; gap: 8px; }

/* Theme toggle */
.theme-toggle {
  width: 34px; height: 34px;
  background: transparent;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  cursor: pointer;
  color: var(--text-secondary);
  display: flex; align-items: center; justify-content: center;
  transition: border-color 0.15s, color 0.15s;
}
.theme-toggle:hover { border-color: var(--border-focus); color: var(--text-primary); }
.theme-toggle svg { width: 16px; height: 16px; }
.icon-sun { display: none; }
.icon-moon { display: block; }
[data-theme="light"] .icon-sun { display: block; }
[data-theme="light"] .icon-moon { display: none; }

/* Hamburger */
.hamburger {
  display: none;
  width: 34px; height: 34px;
  background: transparent;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  cursor: pointer;
  color: var(--text-secondary);
  flex-direction: column; align-items: center; justify-content: center; gap: 4px;
}
.hamburger span { display: block; width: 16px; height: 2px; background: currentColor; border-radius: 2px; }

/* ─── LAYOUT ────────────────────────────────────────────── */
.layout {
  display: flex;
  padding-top: var(--navbar-h);
  min-height: 100vh;
}

/* ─── SIDEBAR ───────────────────────────────────────────── */
.sidebar {
  width: var(--sidebar-w);
  flex-shrink: 0;
  position: fixed;
  top: var(--navbar-h);
  left: 0;
  bottom: 0;
  background: var(--bg-surface);
  border-right: 1px solid var(--border);
  overflow-y: auto;
  padding: 16px 0 24px;
  scrollbar-width: thin;
  scrollbar-color: var(--border) transparent;
}
.sidebar::-webkit-scrollbar { width: 4px; }
.sidebar::-webkit-scrollbar-track { background: transparent; }
.sidebar::-webkit-scrollbar-thumb { background: var(--border); border-radius: 4px; }
.sidebar-all {
  display: block;
  padding: 7px 16px;
  font-size: 13px; font-weight: 500;
  color: var(--text-secondary);
  border-left: 3px solid transparent;
  transition: color 0.12s, background 0.12s;
}
.sidebar-all:hover { color: var(--text-primary); background: var(--accent-dim); }
.sidebar-all.active { color: var(--accent); background: var(--accent-dim); border-left-color: var(--accent); }
.sidebar-divider { height: 1px; background: var(--border); margin: 10px 0; }
.sidebar-cat {
  padding: 6px 16px 4px;
  font-size: 11px; font-weight: 500;
  color: var(--text-muted);
  letter-spacing: 0.08em;
  text-transform: uppercase;
}
.sidebar-link {
  display: block;
  padding: 7px 16px;
  font-size: 13px;
  color: var(--text-secondary);
  border-left: 3px solid transparent;
  transition: color 0.12s, background 0.12s;
  white-space: nowrap; overflow: hidden; text-overflow: ellipsis;
}
.sidebar-link:hover { color: var(--text-primary); background: var(--accent-dim); }
.sidebar-link.active { color: var(--accent); background: var(--accent-dim); border-left-color: var(--accent); }

/* ─── MAIN CONTENT ──────────────────────────────────────── */
.content {
  flex: 1;
  margin-left: var(--sidebar-w);
  padding: 32px 32px 64px;
  max-width: calc(1120px + var(--sidebar-w));
  min-width: 0;
}
.content-inner { max-width: 1120px; }

/* ─── MOBILE DRAWER ─────────────────────────────────────── */
.drawer-overlay {
  display: none;
  position: fixed; inset: 0; z-index: 200;
  background: rgba(0,0,0,0.6);
}
.drawer-overlay.open { display: block; }
.drawer {
  position: fixed;
  top: 0; left: 0; bottom: 0;
  width: 260px;
  background: var(--bg-surface);
  border-right: 1px solid var(--border);
  overflow-y: auto;
  padding: 16px 0 32px;
  transform: translateX(-100%);
  transition: transform 0.2s ease;
  z-index: 201;
}
.drawer-overlay.open .drawer { transform: translateX(0); }
.drawer-close {
  display: flex; align-items: center; justify-content: space-between;
  padding: 8px 16px 16px;
  border-bottom: 1px solid var(--border);
  margin-bottom: 8px;
}
.drawer-close-btn {
  background: transparent; border: none; cursor: pointer;
  color: var(--text-secondary); font-size: 20px; line-height: 1;
}

/* ─── FOOTER ────────────────────────────────────────────── */
.site-footer {
  background: var(--bg-surface);
  border-top: 1px solid var(--border);
  padding: 20px 32px;
  font-size: 13px;
  color: var(--text-muted);
  display: flex; align-items: center; justify-content: space-between;
  flex-wrap: wrap; gap: 12px;
  margin-left: var(--sidebar-w);
}
.footer-links { display: flex; gap: 20px; flex-wrap: wrap; }
.footer-links a { color: var(--text-muted); }
.footer-links a:hover { color: var(--text-secondary); }

/* ─── TOOL PAGE HEADER ──────────────────────────────────── */
.tool-eyebrow {
  font-size: 11px; font-weight: 500;
  color: var(--text-muted);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-bottom: 8px;
}
.tool-title {
  font-size: 24px; font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 8px;
}
.tool-desc {
  font-size: 14px; color: var(--text-secondary);
  line-height: 1.6; margin-bottom: 24px;
  max-width: 640px;
}
.tool-divider { height: 1px; background: var(--border); margin-bottom: 28px; }

/* ─── TOOL AREA ─────────────────────────────────────────── */
.tool-area { margin-bottom: 40px; }

/* ─── RELATED TOOLS ─────────────────────────────────────── */
.related-title {
  font-size: 14px; font-weight: 600;
  color: var(--text-secondary);
  margin-bottom: 12px;
  text-transform: uppercase; letter-spacing: 0.06em; font-size: 11px;
}
.related-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 10px; margin-bottom: 40px;
}
.related-card {
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 12px 14px;
  display: flex; align-items: center; justify-content: space-between;
  color: var(--text-secondary);
  font-size: 13px;
  transition: border-color 0.15s, color 0.15s, box-shadow 0.15s;
}
.related-card:hover { border-color: var(--accent); color: var(--text-primary); box-shadow: var(--shadow-sm); }
.related-card-icon { font-size: 16px; margin-right: 8px; }
.related-card-arrow { color: var(--accent); font-size: 12px; }

/* ─── FAQ ───────────────────────────────────────────────── */
.faq-title {
  font-size: 11px; font-weight: 500;
  color: var(--text-muted);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-bottom: 12px;
}
.faq-item {
  border-bottom: 1px solid var(--border);
}
.faq-item summary {
  padding: 13px 0;
  cursor: pointer;
  font-size: 14px; font-weight: 500;
  color: var(--text-primary);
  list-style: none;
  display: flex; align-items: center; justify-content: space-between;
  gap: 12px;
  user-select: none;
}
.faq-item summary::-webkit-details-marker { display: none; }
.faq-item summary::after {
  content: '+';
  color: var(--text-muted);
  font-size: 18px; font-weight: 300;
  flex-shrink: 0;
}
.faq-item[open] summary { color: var(--accent); }
.faq-item[open] summary::after { content: '−'; color: var(--accent); }
.faq-answer {
  padding: 4px 0 14px 12px;
  font-size: 13px; color: var(--text-secondary);
  line-height: 1.7;
  border-left: 2px solid var(--accent-dim);
}

/* ─── HOMEPAGE HERO ─────────────────────────────────────── */
.hero { padding: 8px 0 32px; }
.hero h1 {
  font-size: 28px; font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 10px; line-height: 1.3;
}
.hero p {
  font-size: 15px; color: var(--text-secondary);
  line-height: 1.6; max-width: 580px;
}
.cat-label {
  font-size: 11px; font-weight: 500;
  color: var(--text-muted);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin: 28px 0 12px;
}
.cat-label:first-of-type { margin-top: 16px; }

/* ─── TOOL CARD (homepage grid) ─────────────────────────── */
.tools-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 12px;
  margin-bottom: 8px;
}
.tool-card {
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 16px;
  display: flex; flex-direction: column; gap: 8px;
  transition: border-color 0.15s, box-shadow 0.15s, transform 0.15s;
  cursor: pointer;
}
.tool-card:hover {
  border-color: var(--accent);
  box-shadow: var(--shadow-md);
  transform: translateY(-2px);
}
.tool-card-top { display: flex; align-items: center; gap: 10px; }
.tool-card-icon { font-size: 22px; }
.tool-card-title { font-size: 15px; font-weight: 600; color: var(--text-primary); }
.tool-card-desc {
  font-size: 13px; color: var(--text-secondary);
  line-height: 1.55;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}
.tool-card-footer {
  margin-top: auto;
  font-size: 12px; color: var(--accent);
  font-weight: 500;
}

/* ─── SHARED CALCULATOR STYLES ──────────────────────────── */
.toolbar {
  display: flex; align-items: center; gap: 12px;
  margin-bottom: 18px; flex-wrap: wrap;
}
.toolbar label { font-size: 13px; color: var(--text-secondary); }
select, input[type=number] {
  background: var(--bg-input);
  border: 1px solid var(--border);
  color: var(--text-primary);
  border-radius: var(--radius-sm);
  font-size: 13px;
}
select { padding: 5px 8px; height: 32px; cursor: pointer; }
input[type=number] { padding: 4px 6px; height: 28px; width: 100%; }
input[type=number]:focus, select:focus { outline: none; border-color: var(--border-focus); }
input[type=checkbox] { width: auto; accent-color: var(--accent); cursor: pointer; }

.mode-toggle {
  display: flex;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: 8px; overflow: hidden;
}
.mode-btn {
  padding: 6px 16px; font-size: 13px;
  cursor: pointer; border: none;
  background: transparent; color: var(--text-muted);
  transition: background 0.15s, color 0.15s;
}
.mode-btn:hover { color: var(--text-primary); }
.mode-btn.active-fwd { background: var(--green-dim); color: var(--green); }
.mode-btn.active-rev { background: var(--red-dim); color: var(--red); }

.clamp-row {
  display: flex; align-items: center; gap: 6px;
  cursor: pointer; font-size: 13px; color: var(--text-secondary);
}

/* ─── SCALE CALCULATOR SPECIFICS ────────────────────────── */
#chain-outer { width: 100%; }
.chain-row { display: flex; align-items: center; flex-wrap: nowrap; }
.block {
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 12px; width: 172px; flex-shrink: 0;
}
.blk-title {
  font-size: 11px; font-weight: 500;
  color: var(--accent);
  text-align: center; margin-bottom: 10px;
  letter-spacing: 0.07em; text-transform: uppercase;
}
.sides { display: grid; grid-template-columns: 1fr 1fr; gap: 8px; }
.side-lbl { font-size: 11px; color: var(--text-muted); text-align: center; margin-bottom: 5px; font-weight: 500; }
.fr { margin-bottom: 5px; }
.fr span { display: block; font-size: 11px; color: var(--text-muted); margin-bottom: 2px; }
.conn {
  display: flex; flex-direction: column;
  align-items: center; justify-content: center;
  padding: 0 6px; min-width: 64px; flex-shrink: 0;
}
.cv {
  font-size: 12px; font-weight: 500;
  color: #c8d8f0;
  background: #1f2d40; border: 1px solid #3a5070;
  border-radius: var(--radius-sm);
  padding: 3px 7px; margin-bottom: 3px;
  text-align: center; white-space: nowrap;
  font-family: var(--font-mono);
}
[data-theme="light"] .cv {
  color: #1a3a6a; background: #e8f0fa; border-color: #b0c8e8;
}
.arr { font-size: 16px; color: var(--text-muted); line-height: 1; }
.arr.rev { color: var(--red); opacity: 0.7; }
.inp-lbl { font-size: 11px; color: var(--text-muted); margin-bottom: 3px; text-align: center; }
.turn-svg { display: block; width: 100%; height: 34px; }
.result-box {
  border-radius: var(--radius-md);
  padding: 12px 20px;
  display: flex; align-items: baseline; gap: 12px;
  flex-wrap: wrap; margin-top: 16px;
}
.result-box.fwd { background: var(--green-dim); border: 1px solid rgba(92,184,92,0.25); }
.result-box.rev { background: var(--red-dim); border: 1px solid rgba(217,83,79,0.25); }
.res-lbl-fwd { font-size: 13px; color: var(--green); }
.res-val-fwd { font-size: 28px; font-weight: 500; color: var(--green); font-family: var(--font-mono); }
.res-lbl-rev { font-size: 13px; color: var(--red); }
.res-val-rev { font-size: 28px; font-weight: 500; color: var(--red); font-family: var(--font-mono); }
.cbadge {
  font-size: 11px; padding: 2px 8px; border-radius: var(--radius-sm);
  background: var(--yellow-dim); color: var(--yellow);
  border: 1px solid rgba(200,168,56,0.3);
}
.errtxt { font-size: 12px; color: var(--red); }

/* ─── 4-20mA CALCULATOR ─────────────────────────────────── */
.calc-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(180px, 1fr)); gap: 12px; margin-bottom: 16px; }
.field-group { display: flex; flex-direction: column; gap: 5px; }
.field-label { font-size: 12px; color: var(--text-secondary); font-weight: 500; }
.field-unit { font-size: 11px; color: var(--text-muted); }
.result-card {
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 16px 20px;
  display: flex; align-items: baseline; gap: 12px;
  flex-wrap: wrap; margin-bottom: 16px;
}
.result-big { font-size: 32px; font-weight: 500; font-family: var(--font-mono); color: var(--text-primary); }
.result-unit { font-size: 14px; color: var(--text-secondary); }
.badge {
  font-size: 11px; padding: 3px 10px;
  border-radius: var(--radius-sm); font-weight: 500;
}
.badge-green { background: var(--green-dim); color: var(--green); border: 1px solid rgba(92,184,92,0.3); }
.badge-yellow { background: var(--yellow-dim); color: var(--yellow); border: 1px solid rgba(200,168,56,0.3); }
.badge-red { background: var(--red-dim); color: var(--red); border: 1px solid rgba(217,83,79,0.3); }
.badge-blue { background: var(--accent-dim); color: var(--accent); border: 1px solid rgba(74,158,255,0.3); }
.span-bar-wrap { margin-bottom: 16px; }
.span-bar-labels { display: flex; justify-content: space-between; font-size: 11px; color: var(--text-muted); margin-bottom: 4px; }
.span-bar-track {
  height: 8px; border-radius: 4px;
  background: var(--bg-elevated); border: 1px solid var(--border);
  position: relative; overflow: visible;
}
.span-bar-fill {
  height: 100%; border-radius: 4px;
  background: linear-gradient(90deg, var(--accent-dim), var(--accent));
  transition: width 0.2s;
}
.span-bar-marker {
  position: absolute; top: -4px; width: 3px; height: 16px;
  background: var(--accent); border-radius: 2px;
  transform: translateX(-50%);
  transition: left 0.2s;
}
.live-zero-note { font-size: 12px; color: var(--text-muted); margin-top: 6px; }

/* ─── RTD CALCULATOR ────────────────────────────────────── */
.sensor-toggle { display: flex; gap: 8px; margin-bottom: 16px; }
.sensor-btn {
  padding: 7px 18px; border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  background: transparent; color: var(--text-secondary);
  cursor: pointer; font-size: 13px; font-weight: 500;
  transition: all 0.15s;
}
.sensor-btn.active { background: var(--accent-dim); border-color: var(--accent); color: var(--accent); }
.collapsible-section { margin-bottom: 16px; }
.collapsible-section summary {
  font-size: 13px; font-weight: 500; color: var(--text-secondary);
  cursor: pointer; padding: 8px 0; list-style: none;
  display: flex; align-items: center; gap: 6px;
}
.collapsible-section summary::-webkit-details-marker { display: none; }
.collapsible-section summary::before { content: '▶'; font-size: 9px; }
.collapsible-section[open] summary::before { content: '▼'; }
.collapsible-content { padding: 10px 0 4px 12px; }
.radio-group { display: flex; gap: 16px; flex-wrap: wrap; }
.radio-label { display: flex; align-items: center; gap: 6px; font-size: 13px; color: var(--text-secondary); cursor: pointer; }
.tol-class-group { display: flex; gap: 8px; flex-wrap: wrap; margin-top: 8px; }
.tol-btn {
  padding: 5px 14px; border-radius: var(--radius-sm);
  border: 1px solid var(--border); background: transparent;
  color: var(--text-secondary); cursor: pointer; font-size: 12px;
  transition: all 0.15s;
}
.tol-btn.active { background: var(--accent-dim); border-color: var(--accent); color: var(--accent); }
.ref-table { width: 100%; border-collapse: collapse; font-size: 12px; margin-top: 8px; }
.ref-table th { text-align: left; padding: 6px 8px; color: var(--text-muted); border-bottom: 1px solid var(--border); font-weight: 500; }
.ref-table td { padding: 6px 8px; color: var(--text-secondary); border-bottom: 1px solid var(--border); font-family: var(--font-mono); }
.ref-table tr:last-child td { border-bottom: none; }

/* ─── OHM'S LAW ─────────────────────────────────────────── */
.ohm-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 12px; margin-bottom: 16px; }
.ohm-field { background: var(--bg-elevated); border: 1px solid var(--border); border-radius: var(--radius-md); padding: 14px; }
.ohm-field.computed { background: var(--accent-dim); border-color: rgba(74,158,255,0.3); }
.ohm-field-label { font-size: 12px; font-weight: 600; color: var(--text-muted); letter-spacing: 0.05em; margin-bottom: 8px; text-transform: uppercase; }
.ohm-input-row { display: flex; gap: 6px; align-items: center; }
.ohm-input-row input { flex: 1; }
.ohm-input-row select { width: 64px; flex-shrink: 0; }
.formula-display {
  background: var(--bg-elevated); border: 1px solid var(--border);
  border-radius: var(--radius-md); padding: 12px 16px;
  font-family: var(--font-mono); font-size: 13px;
  color: var(--text-secondary); margin-bottom: 16px;
  min-height: 42px;
}

/* ─── VOLTAGE DROP ──────────────────────────────────────── */
.vd-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(160px, 1fr)); gap: 12px; margin-bottom: 16px; }
.vd-result-card {
  background: var(--bg-elevated); border: 1px solid var(--border);
  border-radius: var(--radius-md); padding: 14px 16px;
  display: flex; flex-direction: column; gap: 4px;
}
.vd-result-label { font-size: 11px; color: var(--text-muted); font-weight: 500; text-transform: uppercase; letter-spacing: 0.05em; }
.vd-result-value { font-size: 22px; font-weight: 500; font-family: var(--font-mono); color: var(--text-primary); }
.vd-result-sub { font-size: 12px; color: var(--text-muted); }
.vd-results-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 10px; margin-bottom: 16px; }
.pass-bar {
  height: 6px; border-radius: 3px;
  background: var(--bg-elevated); border: 1px solid var(--border);
  margin-bottom: 16px; position: relative; overflow: hidden;
}
.pass-bar-fill { height: 100%; border-radius: 3px; transition: width 0.3s, background 0.3s; }

/* ─── WIRE GAUGE ────────────────────────────────────────── */
.wg-conv-row { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; margin-bottom: 16px; }
.amp-table { width: 100%; border-collapse: collapse; font-size: 13px; margin-top: 12px; }
.amp-table th { padding: 8px 10px; background: var(--bg-elevated); color: var(--text-muted); font-size: 11px; text-transform: uppercase; letter-spacing: 0.05em; border: 1px solid var(--border); font-weight: 500; }
.amp-table td { padding: 8px 10px; border: 1px solid var(--border); color: var(--text-secondary); font-family: var(--font-mono); text-align: center; }
.amp-table tr.highlighted td { background: var(--accent-dim); color: var(--text-primary); }

/* ─── UNIT CONVERTERS ───────────────────────────────────── */
.conv-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(180px, 1fr)); gap: 10px; margin-bottom: 16px; }
.conv-field { display: flex; flex-direction: column; gap: 4px; }
.conv-field label { font-size: 12px; color: var(--text-muted); font-weight: 500; }
.conv-field input {
  background: var(--bg-input); border: 1px solid var(--border);
  color: var(--text-primary); border-radius: var(--radius-sm);
  padding: 6px 8px; font-size: 14px; font-family: var(--font-mono);
  width: 100%; transition: border-color 0.15s;
}
.conv-field input:focus { outline: none; border-color: var(--border-focus); }
.conv-field input.active { border-color: var(--border-focus); }
.quick-ref {
  background: var(--bg-elevated); border: 1px solid var(--border);
  border-radius: var(--radius-md); padding: 14px 16px;
  font-size: 12px; color: var(--text-secondary); line-height: 1.8;
}
.quick-ref strong { color: var(--text-primary); }

/* ─── TEMP CONVERTER ────────────────────────────────────── */
.temp-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 12px; margin-bottom: 20px; }
.temp-card {
  background: var(--bg-elevated); border: 1px solid var(--border);
  border-radius: var(--radius-md); padding: 16px;
  display: flex; flex-direction: column; align-items: center; gap: 8px;
}
.temp-symbol { font-family: var(--font-mono); font-size: 28px; font-weight: 500; color: var(--accent); }
.temp-card input {
  width: 100%; text-align: center;
  background: var(--bg-input); border: 1px solid var(--border);
  color: var(--text-primary); border-radius: var(--radius-sm);
  padding: 6px 4px; font-size: 15px; font-family: var(--font-mono);
  transition: border-color 0.15s;
}
.temp-card input:focus { outline: none; border-color: var(--border-focus); }
.landmark-table { width: 100%; border-collapse: collapse; font-size: 13px; }
.landmark-table th { padding: 8px; background: var(--bg-elevated); color: var(--text-muted); font-size: 11px; text-transform: uppercase; border: 1px solid var(--border); font-weight: 500; }
.landmark-table td { padding: 8px; border: 1px solid var(--border); color: var(--text-secondary); font-family: var(--font-mono); text-align: center; }
.landmark-table tr { cursor: pointer; transition: background 0.12s; }
.landmark-table tr:hover td { background: var(--accent-dim); color: var(--text-primary); }
.landmark-table td:first-child { font-family: var(--font-ui); text-align: left; }

/* ─── TORQUE CONVERTER ──────────────────────────────────── */
.ptr-section { margin-top: 24px; padding-top: 20px; border-top: 1px solid var(--border); }
.ptr-title { font-size: 13px; font-weight: 600; color: var(--text-secondary); margin-bottom: 12px; text-transform: uppercase; letter-spacing: 0.06em; font-size: 11px; }
.ptr-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px; }
.ptr-formula { font-family: var(--font-mono); font-size: 12px; color: var(--text-muted); margin-top: 10px; }

/* ─── FLOW RATE ─────────────────────────────────────────── */
.section-divider { border: none; border-top: 1px solid var(--border); margin: 24px 0; }
.section-heading { font-size: 13px; font-weight: 600; color: var(--text-secondary); text-transform: uppercase; letter-spacing: 0.06em; font-size: 11px; margin-bottom: 12px; }
.pipe-results { display: grid; grid-template-columns: repeat(auto-fit, minmax(140px, 1fr)); gap: 10px; margin-top: 12px; }
.pipe-result-card {
  background: var(--bg-elevated); border: 1px solid var(--border);
  border-radius: var(--radius-md); padding: 12px;
}
.pipe-result-label { font-size: 11px; color: var(--text-muted); font-weight: 500; text-transform: uppercase; letter-spacing: 0.05em; margin-bottom: 4px; }
.pipe-result-val { font-size: 18px; font-weight: 500; font-family: var(--font-mono); color: var(--text-primary); }
.pipe-result-unit { font-size: 11px; color: var(--text-muted); }

/* ─── STATIC PAGES ──────────────────────────────────────── */
.static-page { max-width: 680px; }
.static-page h1 { font-size: 24px; font-weight: 600; margin-bottom: 20px; }
.static-page h2 { font-size: 16px; font-weight: 600; color: var(--text-secondary); margin: 24px 0 8px; }
.static-page p { font-size: 14px; color: var(--text-secondary); line-height: 1.75; margin-bottom: 12px; }
.static-page a { color: var(--accent); }
.static-page ul { padding-left: 20px; margin-bottom: 12px; }
.static-page li { font-size: 14px; color: var(--text-secondary); line-height: 1.75; }

/* ─── RESPONSIVE ────────────────────────────────────────── */
@media (max-width: 768px) {
  .sidebar { display: none; }
  .content { margin-left: 0; padding: 20px 16px 48px; }
  .site-footer { margin-left: 0; }
  .hamburger { display: flex; }
  .related-grid { grid-template-columns: 1fr; }
  .temp-grid { grid-template-columns: repeat(2, 1fr); }
  .ohm-grid { grid-template-columns: 1fr; }
  .vd-results-grid { grid-template-columns: 1fr 1fr; }
  .wg-conv-row { grid-template-columns: 1fr; }
  .ptr-grid { grid-template-columns: 1fr; }
}
@media (max-width: 480px) {
  .tools-grid { grid-template-columns: 1fr; }
  .temp-grid { grid-template-columns: repeat(2, 1fr); }
  .vd-results-grid { grid-template-columns: 1fr; }
}

/* ─── SECTION UTILITY ───────────────────────────────────── */
.mt8 { margin-top: 8px; }
.mt12 { margin-top: 12px; }
.mt16 { margin-top: 16px; }
.mb8 { margin-bottom: 8px; }
.mb12 { margin-bottom: 12px; }
.flex-row { display: flex; align-items: center; gap: 8px; flex-wrap: wrap; }
.text-muted { color: var(--text-muted); font-size: 12px; }