/* ══════════════════════════════════════════════
  星空科技 · 自行车工具 · 统一设计系统 v1
  Stellar Tech · Bike Tools · Design System
  ══════════════════════════════════════════════ */

:root {
  --bg: #0a0f1a;
  --surface: rgba(10,20,40,.7);
  --surface-hover: rgba(10,20,40,.9);
  --border: rgba(79,209,255,.1);
  --border-hover: rgba(79,209,255,.25);
  --primary: #4fd1ff;
  --primary-dim: rgba(79,209,255,.12);
  --accent: #ff9800;
  --accent-dim: rgba(255,152,0,.12);
  --green: #4caf50;
  --green-dim: rgba(76,175,80,.12);
  --red: #e04040;
  --red-dim: rgba(224,64,64,.1);
  --gold: #ffd700;
  --text: #e0e0e0;
  --text-heading: #c0d8ff;
  --text-sub: #8a9fc0;
  --text-dim: #6a8aaa;
  --radius-sm: 8px;
  --radius: 12px;
  --radius-lg: 16px;
  --radius-xl: 20px;
  --shadow-sm: 0 2px 8px rgba(0,0,0,.2);
  --shadow: 0 4px 16px rgba(0,0,0,.3);
  --shadow-glow: 0 0 20px rgba(79,209,255,.1);
}

*{margin:0;padding:0;box-sizing:border-box}

html,body{
  font-family: -apple-system, BlinkMacSystemFont, 'PingFang SC', 'Microsoft YaHei', 'Helvetica Neue', sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
}

body{
  display:flex;flex-direction:column;align-items:center;
  padding:40px 20px 60px;
  min-height:100vh;
  overflow-y:scroll;scrollbar-gutter:stable;
}

/* ── Container ── */
.container{
  max-width:900px;width:100%;
}

/* ── Header ── */
.tool-header{
  text-align:center;
  padding:10px 0 20px;
}
.tool-header h1{
  font-size:26px;font-weight:800;
  background:linear-gradient(135deg,var(--primary),#a0c4ff);
  -webkit-background-clip:text;-webkit-text-fill-color:transparent;
  background-clip:text;
  margin-bottom:6px;
}
.tool-header .subtitle{
  font-size:13px;color:var(--text-sub);
}

/* ── Card ── */
.card{
  background:var(--surface);
  border:1px solid var(--border);
  border-radius:var(--radius-lg);
  padding:20px 24px;
  margin-bottom:16px;
  backdrop-filter:blur(12px);
  -webkit-backdrop-filter:blur(12px);
  transition:border-color .2s,box-shadow .2s;
}
.card:hover{border-color:var(--border-hover);box-shadow:var(--shadow-glow)}
.card-title{
  font-size:16px;font-weight:700;color:var(--text-heading);
  margin-bottom:12px;
  display:flex;align-items:center;gap:8px;
}
.card-desc{font-size:12px;color:var(--text-sub);margin-bottom:14px;line-height:1.6}

/* ── Form Fields ── */
.field{margin-bottom:12px}
.field label{
  display:block;font-size:12px;color:var(--text-sub);
  font-weight:600;margin-bottom:5px;
}
.field input,.field select,.field textarea{
  width:100%;padding:10px 14px;
  background:rgba(0,0,0,.3);
  border:1px solid var(--border);
  border-radius:var(--radius);
  color:var(--text);font-size:14px;
  font-family:inherit;outline:none;
  transition:border-color .2s,box-shadow .2s;
}
.field input:focus,.field select:focus,.field textarea:focus{
  border-color:var(--primary);
  box-shadow:0 0 0 3px var(--primary-dim);
}
.field .unit{
  position:absolute;right:12px;top:50%;transform:translateY(-50%);
  color:var(--text-dim);font-size:12px;pointer-events:none;
}
.field-row{
  display:flex;gap:12px;flex-wrap:wrap;
}
.field-row .field{flex:1;min-width:120px}

/* ── Buttons ── */
.btn{
  display:inline-flex;align-items:center;justify-content:center;
  gap:6px;padding:10px 20px;border-radius:var(--radius);
  font-size:14px;font-weight:600;font-family:inherit;
  cursor:pointer;border:none;transition:all .2s;
  white-space:nowrap;text-decoration:none;
}
.btn-primary{
  background:linear-gradient(135deg,var(--primary),#2b9fd4);
  color:#000;
}
.btn-primary:hover{box-shadow:0 4px 16px rgba(79,209,255,.3);transform:translateY(-1px)}
.btn-primary:active{transform:translateY(0)}
.btn-secondary{
  background:var(--primary-dim);color:var(--primary);
  border:1px solid var(--border);
}
.btn-secondary:hover{background:rgba(79,209,255,.2)}
.btn-accent{
  background:var(--accent-dim);color:var(--accent);
  border:1px solid rgba(255,152,0,.2);
}
.btn-ghost{
  background:transparent;color:var(--text-sub);
  border:1px solid transparent;
}
.btn-ghost:hover{color:var(--text);border-color:var(--border)}
.btn-sm{padding:6px 14px;font-size:12px;border-radius:var(--radius-sm)}
.btn-lg{padding:12px 28px;font-size:16px}
.btn-block{width:100%}

/* ── Result Display ── */
.result-card{
  background:var(--surface);
  border:1px solid rgba(79,209,255,.15);
  border-radius:var(--radius-lg);
  padding:20px 24px;
  margin-top:16px;
  text-align:center;
}
.result-value{
  font-size:42px;font-weight:900;
  background:linear-gradient(135deg,var(--primary),#a0c4ff);
  -webkit-background-clip:text;-webkit-text-fill-color:transparent;
  background-clip:text;
  line-height:1.2;
}
.result-label{font-size:12px;color:var(--text-sub);margin-top:4px}
.result-grid{
  display:grid;grid-template-columns:repeat(auto-fit,minmax(140px,1fr));
  gap:12px;margin-top:12px;
}
.result-item{
  background:rgba(0,0,0,.2);
  border-radius:var(--radius);
  padding:14px 12px;text-align:center;
}
.result-item .val{font-size:24px;font-weight:800;color:var(--text-heading)}
.result-item .lbl{font-size:11px;color:var(--text-dim);margin-top:2px}

/* ── Gauge/Meter ── */
.gauge-ring{
  position:relative;width:120px;height:120px;margin:0 auto;
}
.gauge-ring svg{transform:rotate(-90deg)}
.gauge-ring .gauge-bg{fill:none;stroke:rgba(79,209,255,.08);stroke-width:8}
.gauge-ring .gauge-fill{fill:none;stroke:var(--primary);stroke-width:8;stroke-linecap:round;transition:stroke-dashoffset .8s}
.gauge-ring .gauge-text{
  position:absolute;inset:0;display:flex;
  flex-direction:column;align-items:center;justify-content:center;
}
.gauge-ring .gauge-val{font-size:28px;font-weight:900;color:var(--text-heading)}
.gauge-ring .gauge-unit{font-size:11px;color:var(--text-dim)}

/* ── Tabs ── */
.tabs{display:flex;gap:4px;margin-bottom:16px;flex-wrap:wrap}
.tab{
  padding:8px 18px;border-radius:20px;
  font-size:13px;font-weight:600;cursor:pointer;
  border:1px solid var(--border);
  background:transparent;color:var(--text-sub);
  transition:all .2s;font-family:inherit;
}
.tab.active,.tab:hover{
  background:var(--primary-dim);color:var(--primary);
  border-color:rgba(79,209,255,.3);
}

/* ── Table ── */
.data-table{
  width:100%;border-collapse:collapse;font-size:13px;
}
.data-table th{
  text-align:left;padding:10px 12px;
  color:var(--text-dim);font-weight:600;
  border-bottom:1px solid var(--border);font-size:11px;
  text-transform:uppercase;letter-spacing:.5px;
}
.data-table td{
  padding:10px 12px;border-bottom:1px solid rgba(79,209,255,.04);
  color:var(--text);
}
.data-table tr:hover td{background:rgba(79,209,255,.03)}

/* ── Badges ── */
.badge{
  display:inline-block;padding:2px 8px;border-radius:6px;
  font-size:10px;font-weight:700;letter-spacing:.3px;
}
.badge-primary{background:var(--primary-dim);color:var(--primary)}
.badge-accent{background:var(--accent-dim);color:var(--accent)}
.badge-green{background:var(--green-dim);color:var(--green)}

/* ── Tips & Warnings ── */
.tips-box{
  background:rgba(79,209,255,.04);
  border:1px solid rgba(79,209,255,.08);
  border-radius:var(--radius);
  padding:14px 18px;margin-top:14px;
}
.tips-box .tip{
  font-size:12px;color:var(--text-sub);
  padding:4px 0;line-height:1.6;
}
.warn-box{
  background:rgba(255,152,0,.06);
  border:1px solid rgba(255,152,0,.15);
  border-radius:var(--radius);
  padding:12px 16px;margin-top:12px;
  color:var(--accent);font-size:12px;
}

/* ── Back link ── */
.back-link{
  display:inline-flex;align-items:center;gap:4px;
  color:var(--text-dim);text-decoration:none;
  font-size:12px;margin-bottom:12px;transition:color .2s;
}
.back-link:hover{color:var(--primary)}

/* ── Mobile ── */
@media(max-width:768px){
  body{padding:20px 12px 40px}
  .tool-header h1{font-size:22px}
  .card{padding:16px 18px}
  .result-value{font-size:34px}
  .result-grid{grid-template-columns:repeat(2,1fr)}
  .field-row{flex-direction:column}
  .field-row .field{min-width:0}
}

@media(max-width:480px){
  body{padding:14px 10px 30px}
  .tool-header h1{font-size:20px}
  .card{padding:14px 14px}
  .result-value{font-size:28px}
  .result-grid{grid-template-columns:1fr 1fr}
  .tabs{gap:2px}
  .tab{padding:6px 12px;font-size:11px}
}