/* ═══════════════════════════════════
   EE·LAB APP STYLES
   提取自 index.html <style> 块
═══════════════════════════════════ */

:root {
  --bg: #0a0c0f;
  --surface: #111318;
  --surface2: #181c23;
  --border: #1e2530;
  --border2: #2a3340;
  --amber: #f5a623;
  --amber2: #ffbe4d;
  --green: #39d353;
  --cyan: #26c6da;
  --red: #f44336;
  --blue: #4fc3f7;
  --text: #c8d0dc;
  --text2: #6b7d8f;
  --text3: #3d4f61;
  --mono: 'Share Tech Mono', monospace;
  --sans: 'Noto Sans SC', sans-serif;
  --radius: 6px;
  --glow: 0 0 20px rgba(245,166,35,0.15);
}
* { box-sizing: border-box; margin: 0; padding: 0; }
body {
  background: var(--bg);
  color: var(--text);
  font-family: var(--sans);
  min-height: 100vh;
  overflow-x: hidden;
}
/* Grid noise background */
body::before {
  content: '';
  position: fixed;
  inset: 0;
  background-image: 
    linear-gradient(var(--border) 1px, transparent 1px),
    linear-gradient(90deg, var(--border) 1px, transparent 1px);
  background-size: 40px 40px;
  opacity: 0.3;
  pointer-events: none;
  z-index: 0;
}

/* ── HEADER ── */
header {
  position: sticky; top: 0; z-index: 100;
  background: rgba(10,12,15,0.95);
  border-bottom: 1px solid var(--border2);
  backdrop-filter: blur(12px);
  padding: 0 24px;
  display: flex; align-items: center; gap: 16px;
  height: 56px;
}
.logo {
  font-family: var(--mono);
  font-size: 18px;
  color: var(--amber);
  letter-spacing: 2px;
  text-shadow: 0 0 20px rgba(245,166,35,0.5);
  flex-shrink: 0;
}
.logo span { color: var(--text2); font-size: 12px; margin-left: 8px; letter-spacing: 1px; }
.search-wrap {
  flex: 1; max-width: 400px; position: relative;
}
.search-wrap input {
  width: 100%; background: var(--surface2);
  border: 1px solid var(--border2);
  border-radius: var(--radius);
  color: var(--text); font-family: var(--sans);
  font-size: 13px; padding: 7px 12px 7px 36px;
  outline: none; transition: border-color .2s;
}
.search-wrap input:focus { border-color: var(--amber); }
.search-wrap::before {
  content: '⌕'; position: absolute; left: 11px; top: 50%;
  transform: translateY(-50%); color: var(--text2); font-size: 16px;
  pointer-events: none;
}
.circuit-link {
  margin-left: auto;
  font-family: var(--mono); font-size: 12px;
  color: var(--cyan); text-decoration: none;
  border: 1px solid rgba(38,198,218,0.3);
  padding: 5px 12px; border-radius: var(--radius);
  transition: all .2s; letter-spacing: 1px;
  flex-shrink: 0;
}
.circuit-link:hover { background: rgba(38,198,218,0.1); border-color: var(--cyan); }

/* ── SIDEBAR TOGGLE BUTTON ── */
.sb-toggle {
  display: flex; align-items: center; justify-content: center;
  width: 32px; height: 32px;
  background: transparent;
  border: 1px solid var(--border2);
  border-radius: var(--radius);
  color: var(--text2);
  cursor: pointer;
  flex-shrink: 0;
  transition: all .15s;
  font-size: 17px;
  line-height: 1;
  padding: 0;
}
.sb-toggle:hover {
  background: var(--surface2);
  color: var(--amber);
  border-color: rgba(245,166,35,0.4);
}
.sb-toggle.active {
  color: var(--amber);
  border-color: rgba(245,166,35,0.4);
  background: rgba(245,166,35,0.06);
}

/* ── LAYOUT ── */
.layout { display: flex; min-height: calc(100vh - 56px); position: relative; z-index: 1; }

/* ── SIDEBAR ── */
.sidebar {
  width: 220px; flex-shrink: 0;
  background: var(--surface);
  border-right: 1px solid var(--border);
  padding: 16px 0;
  position: sticky; top: 56px; height: calc(100vh - 56px);
  overflow-y: auto;
  transition: width .25s ease, padding .25s ease, border-color .25s ease;
}
.sidebar.collapsed {
  width: 0;
  padding: 0;
  border-right: none;
  overflow: hidden;
}
.sidebar::-webkit-scrollbar { width: 4px; }
.sidebar::-webkit-scrollbar-track { background: transparent; }
.sidebar::-webkit-scrollbar-thumb { background: var(--border2); border-radius: 2px; }
.cat-label {
  font-family: var(--mono); font-size: 10px; letter-spacing: 2px;
  color: var(--text3); text-transform: uppercase;
  padding: 12px 16px 6px;
}
.nav-item {
  display: flex; align-items: center; gap: 10px;
  padding: 8px 16px; cursor: pointer;
  font-size: 13px; color: var(--text2);
  transition: all .15s; border-left: 2px solid transparent;
  user-select: none;
}
.nav-item:hover { color: var(--text); background: var(--surface2); }
.nav-item.active {
  color: var(--amber); border-left-color: var(--amber);
  background: rgba(245,166,35,0.06);
}
.nav-icon { font-size: 16px; flex-shrink: 0; }

/* ── CONTENT ── */
.content { flex: 1; padding: 24px; overflow-y: auto; }
.tool-panel { display: none; animation: fadeIn .2s ease; }
.tool-panel.active { display: block; }
@keyframes fadeIn { from { opacity: 0; transform: translateY(8px); } to { opacity: 1; transform: translateY(0); } }

.tool-header { margin-bottom: 20px; }
.tool-header h2 { font-size: 22px; font-weight: 500; color: var(--text); }
.tool-header p { font-size: 13px; color: var(--text2); margin-top: 4px; line-height: 1.6; }

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 20px;
  margin-bottom: 16px;
}
.card h3 {
  font-size: 13px; font-family: var(--mono); letter-spacing: 1px;
  color: var(--amber); margin-bottom: 16px; text-transform: uppercase;
}

/* Form elements */
.form-row { display: flex; gap: 12px; flex-wrap: wrap; margin-bottom: 12px; align-items: flex-end; }
.form-group { display: flex; flex-direction: column; gap: 5px; flex: 1; min-width: 120px; }
.form-group label { font-size: 12px; color: var(--text2); font-family: var(--mono); }
input[type=number], input[type=text], select {
  background: var(--surface2); border: 1px solid var(--border2);
  border-radius: var(--radius); color: var(--text);
  font-family: var(--mono); font-size: 14px;
  padding: 8px 10px; outline: none; transition: border-color .2s; width: 100%;
}
input[type=number]:focus, input[type=text]:focus, select:focus { border-color: var(--amber); }
select option { background: var(--surface2); }

/* Result display */
.result-box {
  background: var(--bg);
  border: 1px solid var(--border2);
  border-left: 3px solid var(--amber);
  border-radius: var(--radius);
  padding: 12px 16px;
  margin-top: 12px;
  font-family: var(--mono);
}
.result-box .label { font-size: 11px; color: var(--text2); margin-bottom: 4px; }
.result-box .value { font-size: 20px; color: var(--amber2); }
.result-box .value.green { color: var(--green); }
.result-box .value.cyan { color: var(--cyan); }
.result-box .value.blue { color: var(--blue); }
.result-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(160px,1fr)); gap: 10px; margin-top: 12px; }
.result-item {
  background: var(--bg); border: 1px solid var(--border2);
  border-radius: var(--radius); padding: 10px 12px;
  font-family: var(--mono);
}
.result-item .ri-label { font-size: 11px; color: var(--text2); }
.result-item .ri-val { font-size: 16px; color: var(--amber2); margin-top: 2px; }

/* Button */
.btn {
  background: rgba(245,166,35,0.12);
  border: 1px solid rgba(245,166,35,0.4);
  color: var(--amber); font-family: var(--mono);
  font-size: 13px; letter-spacing: 1px;
  padding: 8px 20px; border-radius: var(--radius);
  cursor: pointer; transition: all .2s; flex-shrink: 0;
}
.btn:hover { background: rgba(245,166,35,0.2); border-color: var(--amber); box-shadow: var(--glow); }
.btn-sm { padding: 5px 12px; font-size: 12px; }

/* Resistor color code */
.band-row { display: flex; gap: 8px; flex-wrap: wrap; margin-bottom: 12px; }
.band-sel { display: flex; flex-direction: column; gap: 4px; }
.band-sel label { font-size: 11px; color: var(--text2); font-family: var(--mono); text-align: center; }
.band-sel select { width: 90px; padding: 6px 4px; font-size: 12px; text-align: center; }
.color-preview {
  display: flex; gap: 4px; margin-top: 8px;
  height: 28px; border-radius: 4px; overflow: hidden;
}
.color-strip { flex: 1; }

/* Table */
.data-table { width: 100%; border-collapse: collapse; font-family: var(--mono); font-size: 13px; }
.data-table th { background: var(--surface2); color: var(--amber); font-weight: 400; padding: 8px 12px; text-align: left; border-bottom: 1px solid var(--border2); }
.data-table td { padding: 7px 12px; border-bottom: 1px solid var(--border); color: var(--text2); }
.data-table tr:hover td { background: var(--surface2); color: var(--text); }

/* PWM visualizer */
.pwm-vis { margin-top: 12px; }
.pwm-canvas { width: 100%; height: 80px; background: var(--bg); border: 1px solid var(--border2); border-radius: var(--radius); display: block; }

/* Color ring display */
.resistor-body {
  display: flex; align-items: center; justify-content: center;
  margin: 12px 0; gap: 0;
}
.r-end { width: 30px; height: 20px; background: #8B7355; border-radius: 10px 0 0 10px; }
.r-end.right { border-radius: 0 10px 10px 0; }
.r-body { display: flex; height: 28px; flex: 1; max-width: 240px; overflow: hidden; }
.r-band { flex: 1; }
.r-lead { width: 40px; height: 2px; background: var(--border2); align-self: center; }

/* Search highlight */
.nav-item.hidden { display: none; }
.cat-group.hidden { display: none; }

/* ── FAVOURITES ── */
.fav-star {
  margin-left: auto; flex-shrink: 0;
  background: none; border: none; cursor: pointer;
  font-size: 13px; padding: 0 2px;
  color: var(--text3); opacity: .45;
  transition: opacity .15s, color .15s;
  line-height: 1;
}
.nav-item:hover .fav-star { opacity: 1; }
.fav-star.active { opacity: 1 !important; color: #f5a623; }
.fav-section {
  border-bottom: 1px solid var(--border);
  padding-bottom: 4px; margin-bottom: 4px;
}
.fav-section-hd {
  display: flex; align-items: center; gap: 8px;
  padding: 10px 16px 4px; cursor: pointer;
  font-family: var(--mono); font-size: 11px; letter-spacing: 1.5px;
  color: var(--text3); text-transform: uppercase; user-select: none;
}
.fav-section-hd:hover { color: var(--text2); }
.fav-empty { font-size: 12px; color: var(--text3); padding: 6px 16px 10px; font-style: italic; }
.home-quick { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 8px; }
.home-quick-empty { font-size: 12px; color: var(--text3); font-style: italic; }
.home-quick-item {
  display: flex; align-items: center; gap: 6px;
  padding: 6px 12px; border-radius: 6px;
  background: var(--surface); border: 1px solid var(--border);
  font-size: 12px; color: var(--text2); cursor: pointer;
  transition: all .15s;
}
.home-quick-item:hover { border-color: var(--amber); color: var(--text); }

/* Responsive */
@media (max-width: 768px) {
  .sidebar { width: 56px; }
  .ni-label { display: none; }
  .cat-header span:not(.cat-icon) { display: none; }
  .content { padding: 16px; }
}

/* ── CATEGORY COLLAPSIBLE ── */
.cat-group > .cat-items { overflow: hidden; }
.cat-group:not(.open) > .cat-items { display: none; }
.cat-header {
  display: flex; align-items: center; gap: 8px;
  padding: 10px 16px 6px; cursor: pointer;
  font-family: var(--mono); font-size: 11px; letter-spacing: 1.5px;
  color: var(--text3); text-transform: uppercase;
  user-select: none;
}
.cat-header:hover { color: var(--text2); }
.cat-icon { font-size: 14px; }
.cat-name { flex: 1; }
.cat-arrow { font-size: 9px; transition: transform .2s; color: var(--text3); }
.cat-group.open .cat-arrow { transform: rotate(90deg); }
.ni-icon { font-size: 14px; flex-shrink: 0; min-width: 20px; text-align: center; }
.ni-label { font-size: 13px; }
.sidebar-home { display: flex; align-items: center; gap: 10px; padding: 10px 16px 12px; border-bottom: 1px solid var(--border); margin-bottom: 6px; cursor: pointer; }
.home-count { margin-left: auto; font-family: var(--mono); font-size: 11px; color: var(--text3); }

/* ── TOOL PANEL STYLES ── */
.tool-breadcrumb { font-family: var(--mono); font-size: 11px; color: var(--text3); margin-bottom: 6px; letter-spacing: 1px; }
.tool-breadcrumb span { color: var(--text2); }
.tool-title { font-size: 22px; font-weight: 500; color: var(--text); margin-bottom: 4px; }
.tool-desc { font-size: 13px; color: var(--text2); line-height: 1.6; }
.formula-bar { font-family: var(--mono); font-size: 12px; color: var(--cyan); background: rgba(38,198,218,0.06); border: 1px solid rgba(38,198,218,0.15); border-radius: var(--radius); padding: 6px 12px; margin-top: 8px; margin-bottom: 4px; }
.card-title { font-size: 13px; font-family: var(--mono); letter-spacing: 1px; color: var(--amber); margin-bottom: 16px; text-transform: uppercase; }

/* ── RESULT COMPONENTS ── */
.result-panel { background: var(--bg); border: 1px solid var(--border2); border-left: 3px solid var(--amber); border-radius: var(--radius); padding: 14px 18px; margin-top: 12px; }
.result-panel.green { border-left-color: var(--green); }
.result-panel.red   { border-left-color: var(--red);   }
.result-panel.cyan  { border-left-color: var(--cyan);  }
.result-label { font-family: var(--mono); font-size: 11px; color: var(--text2); margin-bottom: 6px; }
.result-value { font-family: var(--mono); font-size: 24px; color: var(--amber2); }
.result-value.green { color: var(--green); }
.result-value.red   { color: var(--red); }
.result-value.cyan  { color: var(--cyan); }
.result-value.amber { color: var(--amber2); }
.result-unit { font-size: 14px; color: var(--text2); margin-left: 6px; }
.result-note { font-size: 12px; color: var(--text2); margin-top: 6px; }
.result-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(160px,1fr)); gap: 10px; margin-top: 12px; }
.rg-item  { background: var(--bg); border: 1px solid var(--border2); border-radius: var(--radius); padding: 10px 12px; font-family: var(--mono); }
.rg-label { font-size: 11px; color: var(--text2); margin-bottom: 4px; }
.rg-value { font-size: 16px; color: var(--amber2); }
.rg-value.amber { color: var(--amber2); }
.rg-value.green { color: var(--green); }
.rg-value.red   { color: var(--red); }
.rg-value.cyan  { color: var(--cyan); }
.rg-unit { font-size: 12px; color: var(--text2); margin-left: 4px; }

/* ── ALERTS ── */
.alert { padding: 10px 14px; border-radius: var(--radius); font-size: 13px; line-height: 1.5; }
.alert-success { background: rgba(57,211,83,0.08);  border: 1px solid rgba(57,211,83,0.25);  color: var(--green); }
.alert-error   { background: rgba(244,67,54,0.08);  border: 1px solid rgba(244,67,54,0.25);  color: var(--red);   }
.alert-warn    { background: rgba(245,166,35,0.08); border: 1px solid rgba(245,166,35,0.25); color: var(--amber); }
.alert-info    { background: rgba(38,198,218,0.06); border: 1px solid rgba(38,198,218,0.2);  color: var(--cyan);  }
.mt-8  { margin-top: 8px; }
.mt-12 { margin-top: 12px; }

/* ── TABLE UTILITIES ── */
.table-wrap { overflow-x: auto; }
.hi     { color: var(--amber); font-family: var(--mono); }
.center { text-align: center; }
.green  { color: var(--green); }
.red    { color: var(--red);   }
.amber  { color: var(--amber); }
.color-swatch { display: inline-block; width: 12px; height: 12px; border-radius: 2px; margin-right: 5px; vertical-align: middle; }

/* ── FORM UTILITIES ── */
.form-group.wide { flex: 2; }
.input-unit { display: flex; gap: 6px; }
.input-unit input  { flex: 1; }
.input-unit select { flex-shrink: 0; width: 80px; }
.waveform-canvas { width:100%; height:90px; background:var(--bg); border:1px solid var(--border2); border-radius:var(--radius); display:block; margin-top:12px; }
.card-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px,1fr)); gap: 16px; }
.btn-primary { background: rgba(245,166,35,0.2); border-color: var(--amber); }

/* ── HOME PAGE ── */
.home-hero { margin-bottom: 32px; }
.hero-eyebrow { font-family: var(--mono); font-size: 12px; color: var(--text3); letter-spacing: 2px; margin-bottom: 8px; }
.hero-title { font-size: 32px; font-weight: 700; color: var(--amber); letter-spacing: 2px; margin-bottom: 12px; text-shadow: 0 0 30px rgba(245,166,35,0.3); }
.hero-desc { font-size: 14px; color: var(--text2); line-height: 1.7; max-width: 640px; }
.hero-stats { display: flex; gap: 32px; margin-top: 20px; }
.hero-stat-val { font-family: var(--mono); font-size: 28px; color: var(--amber2); }
.hero-stat-lbl { font-size: 12px; color: var(--text3); margin-top: 2px; }
.section-label { font-family: var(--mono); font-size: 11px; letter-spacing: 2px; color: var(--text3); text-transform: uppercase; margin: 24px 0 12px; border-left: 2px solid var(--amber); padding-left: 10px; }
.tool-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(160px,1fr)); gap: 10px; }
.tool-card { background: var(--surface); border: 1px solid var(--border); border-radius: 8px; padding: 14px; cursor: pointer; transition: all .15s; }
.tool-card:hover { border-color: var(--amber); background: var(--surface2); transform: translateY(-2px); }
.tc-icon { font-size: 20px; margin-bottom: 8px; }
.tc-name { font-size: 13px; color: var(--text); font-weight: 500; margin-bottom: 4px; }
.tc-cat  { font-size: 11px; color: var(--text3); font-family: var(--mono); }

/* ── MOBILE RESPONSIVE IMPROVEMENTS ── */
@media (max-width: 480px) {
  header { padding: 0 12px; gap: 8px; }
  .logo span { display: none; }
  .search-wrap { max-width: 100%; }
  .content { padding: 12px; }
  .card { padding: 14px; }
  .hero-title { font-size: 24px; }
  .hero-stats { gap: 16px; flex-wrap: wrap; }
  .result-grid { grid-template-columns: repeat(auto-fill, minmax(130px,1fr)); }
}

/* ── SCROLLBAR ── */
::-webkit-scrollbar { width: 6px; height: 6px; }
::-webkit-scrollbar-track { background: var(--bg); }
::-webkit-scrollbar-thumb { background: var(--border2); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: var(--text3); }

/* ── FOCUS VISIBLE ── */
:focus-visible { outline: 2px solid var(--amber); outline-offset: 2px; }
button:focus-visible, input:focus-visible, select:focus-visible { outline: 2px solid var(--amber); outline-offset: 2px; }