/* turboXSolver design system — clean engineering-tool aesthetic (novasolver-inspired, system-depth differentiated) */
:root {
  --bg: #f6f8fa;
  --card: #ffffff;
  --ink: #1a2332;
  --ink-2: #4a586c;
  --ink-3: #8593a8;
  --line: #e2e8f0;
  --brand: #0b5fff;
  --brand-soft: #e8f0ff;
  --green: #18a058;
  --green-soft: #e6f7ee;
  --amber: #d98600;
  --amber-soft: #fdf3e0;
  --red: #d92d20;
  --red-soft: #fdecea;
  --mono: "SFMono-Regular", Consolas, "Liberation Mono", monospace;
  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --radius: 12px;
  --shadow: 0 1px 3px rgba(16, 24, 40, .06), 0 4px 16px rgba(16, 24, 40, .06);
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0; font-family: var(--sans); color: var(--ink);
  background: var(--bg); line-height: 1.6; font-size: 16px;
}
a { color: var(--brand); text-decoration: none; }
a:hover { text-decoration: underline; }

/* ---------- header ---------- */
.site-header {
  position: sticky; top: 0; z-index: 50;
  background: rgba(255,255,255,.92); backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--line);
}
.site-header .wrap {
  max-width: 1080px; margin: 0 auto; padding: 0 20px;
  height: 56px; display: flex; align-items: center; gap: 16px;
  flex-wrap: nowrap;
}
.brand { font-weight: 700; font-size: 18px; letter-spacing: -.02em; color: var(--ink); white-space: nowrap; }
.brand .b1 { color: var(--red); }
.brand .b2 { color: var(--brand); }
.site-nav { display: flex; gap: 16px; margin-left: 8px; }
.site-nav a { color: var(--ink-2); font-size: 14px; font-weight: 500; }
.lang-toggle {
  margin-left: auto; display: inline-flex; border: 1px solid var(--line);
  border-radius: 999px; overflow: hidden; background: var(--card);
}
.lang-toggle button {
  border: 0; background: transparent; padding: 6px 12px; cursor: pointer;
  font-size: 13px; font-weight: 600; color: var(--ink-2); font-family: var(--sans);
}
.lang-toggle button.active { background: var(--ink); color: #fff; }
.unit-toggle {
  display: inline-flex; border: 1px solid var(--line);
  border-radius: 999px; overflow: hidden; background: var(--card);
}
.unit-toggle button {
  border: 0; background: transparent; padding: 6px 14px; cursor: pointer;
  font-size: 13px; font-weight: 600; color: var(--ink-2); font-family: var(--sans);
}
.unit-toggle button.active { background: var(--brand); color: #fff; }

/* ---------- layout ---------- */
.wrap { max-width: 1080px; margin: 0 auto; padding: 0 20px; }
.page-head { padding: 36px 0 8px; }
.page-head h1 { font-size: 30px; letter-spacing: -.02em; margin: 0 0 8px; }
.page-head .sub { color: var(--ink-2); max-width: 760px; margin: 0; }
.breadcrumb { font-size: 13px; color: var(--ink-3); margin-bottom: 12px; }
.breadcrumb a { color: var(--ink-3); }

.tool-grid {
  display: grid; grid-template-columns: 1fr 400px; gap: 24px;
  padding: 20px 0 48px; align-items: start;
}
@media (max-width: 900px) { .tool-grid { grid-template-columns: 1fr; } }

/* compact parameter panel — keep params ≈ chart height so both fit one viewport */
.params { padding: 16px 18px; }
.params h2 { font-size: 14.5px; margin: 14px 0 8px; }
.params h2:first-child { margin-top: 0; }
.params .num-row { display: flex; flex-wrap: wrap; gap: 6px; align-items: flex-end; }
.params .num-field { margin: 3px 0; flex: 1; min-width: 0; }
.params .num-field label {
  font-size: 11.5px; margin-bottom: 2px; line-height: 1.3;
}
.params .num-field input, .params .num-field select {
  padding: 5px 7px; font-size: 12.5px; height: 32px; box-sizing: border-box;
}
.params .slider-row { margin: 8px 0; }
.params .slider-row .lab { font-size: 12.5px; margin-bottom: 2px; }
.params .slider-row .val { font-size: 12.5px; padding: 1px 7px; min-width: 76px; }
.params .slider-row input[type="range"] { height: 22px; }
.params .slider-row .hint { font-size: 11px; }
.params .seg button { padding: 5px 10px; font-size: 12.5px; }

.card {
  background: var(--card); border: 1px solid var(--line);
  border-radius: var(--radius); box-shadow: var(--shadow);
}
.card-pad { padding: 22px; }
.card h2 { font-size: 17px; margin: 0 0 14px; letter-spacing: -.01em; }
.card h2 .en { color: var(--ink-3); font-weight: 500; font-size: 13px; margin-left: 6px; }

/* ---------- inputs ---------- */
.slider-row { margin: 14px 0; }
.slider-row .lab {
  display: flex; justify-content: space-between; align-items: baseline;
  font-size: 14px; font-weight: 600; color: var(--ink-2); margin-bottom: 4px;
}
.slider-row .val {
  font-family: var(--mono); font-size: 14px; color: var(--ink);
  background: var(--bg); border: 1px solid var(--line);
  border-radius: 6px; padding: 2px 8px; min-width: 92px; text-align: right;
}
.slider-row input[type="range"] { width: 100%; accent-color: var(--brand); height: 28px; }
.slider-row .hint { font-size: 12px; color: var(--ink-3); margin-top: 2px; }

.num-row { display: flex; gap: 10px; flex-wrap: wrap; align-items: flex-end; }
.num-field { flex: 1; min-width: 0; margin: 4px 0; }
.num-field label { display: block; font-size: 12.5px; font-weight: 600; color: var(--ink-2); margin-bottom: 3px; line-height: 1.3; }
.num-field input, .num-field select {
  width: 100%; padding: 7px 9px; font-size: 13.5px; font-family: var(--mono);
  border: 1px solid var(--line); border-radius: 8px; background: #fff; color: var(--ink);
  box-sizing: border-box; height: 36px;
}
.num-field input:focus, .num-field select:focus { outline: 2px solid var(--brand-soft); border-color: var(--brand); }
.seg { display: inline-flex; border: 1px solid var(--line); border-radius: 8px; overflow: hidden; }
.seg button { border: 0; background: #fff; padding: 7px 12px; font-size: 13px; cursor: pointer; color: var(--ink-2); font-family: var(--sans); }
.seg button.active { background: var(--brand); color: #fff; }

/* ---------- outputs ---------- */
.result-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(150px, 1fr)); gap: 12px; margin: 6px 0 0; }
.result-box {
  background: var(--bg); border: 1px solid var(--line); border-radius: 10px; padding: 12px 14px;
}
.result-box .k { font-size: 12px; color: var(--ink-2); font-weight: 600; }
.result-box .v { font-family: var(--mono); font-size: 20px; font-weight: 600; margin-top: 2px; }
.result-box .u { font-size: 12px; color: var(--ink-3); font-family: var(--mono); }

.verdict {
  display: flex; gap: 12px; align-items: flex-start;
  border-radius: 10px; padding: 14px 16px; margin-top: 14px;
  font-size: 14px; border: 1px solid transparent;
}
.verdict .dot { width: 12px; height: 12px; border-radius: 50%; margin-top: 5px; flex: none; }
.verdict.green { background: var(--green-soft); border-color: #bbe5cd; }
.verdict.green .dot { background: var(--green); }
.verdict.amber { background: var(--amber-soft); border-color: #f0dcae; }
.verdict.amber .dot { background: var(--amber); }
.verdict.red { background: var(--red-soft); border-color: #f5c6c1; }
.verdict.red .dot { background: var(--red); }
.verdict b { display: block; margin-bottom: 2px; }

/* ---------- canvas ---------- */
.canvas-wrap { position: relative; background: #fff; border: 1px solid var(--line); border-radius: var(--radius); box-shadow: var(--shadow); padding: 10px; }
canvas.plot { width: 100%; display: block; border-radius: 8px; touch-action: none; }
.canvas-legend { display: flex; flex-wrap: wrap; gap: 14px; font-size: 12px; color: var(--ink-2); padding: 8px 6px 2px; }
.canvas-legend .sw { display: inline-block; width: 14px; height: 3px; border-radius: 2px; margin-right: 5px; vertical-align: middle; }

/* ---------- content sections ---------- */
.content { max-width: 860px; margin: 0 auto; padding: 0 0 64px; }
.content h2 { font-size: 22px; letter-spacing: -.01em; margin: 40px 0 12px; }
.content h3 { font-size: 17px; margin: 26px 0 8px; }
.content p, .content li { color: var(--ink-2); }
.content .formula-box {
  background: var(--card); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 18px 22px; margin: 14px 0; overflow-x: auto; box-shadow: var(--shadow);
}
.content table { border-collapse: collapse; width: 100%; margin: 14px 0; font-size: 14px; }
.content th, .content td { border: 1px solid var(--line); padding: 8px 10px; text-align: left; }
.content th { background: var(--bg); font-weight: 600; }
.ref-list { font-size: 13px; color: var(--ink-3); }
.ref-list li { margin: 4px 0; }
.cite-box {
  background: var(--brand-soft); border: 1px solid #c7dbff; border-radius: 10px;
  padding: 14px 18px; font-size: 13px; color: var(--ink-2); margin: 20px 0;
}
.cite-box code { font-family: var(--mono); background: #fff; padding: 2px 6px; border-radius: 5px; border: 1px solid var(--line); }

/* ---------- home ---------- */
.hero { padding: 56px 0 28px; }
.hero h1 { font-size: 38px; letter-spacing: -.03em; margin: 0 0 12px; }
.hero p { font-size: 17px; color: var(--ink-2); max-width: 720px; margin: 0; }
.tool-cards { display: grid; grid-template-columns: repeat(auto-fill, minmax(300px, 1fr)); gap: 16px; padding: 24px 0 56px; }
.tool-card {
  display: block; background: var(--card); border: 1px solid var(--line);
  border-radius: var(--radius); padding: 20px; box-shadow: var(--shadow);
  color: var(--ink); transition: transform .12s ease, box-shadow .12s ease;
}
.tool-card:hover { text-decoration: none; transform: translateY(-2px); box-shadow: 0 4px 12px rgba(16,24,40,.1), 0 8px 28px rgba(16,24,40,.1); }
.tool-card h3 { margin: 0 0 6px; font-size: 16px; }
.tool-card p { margin: 0; font-size: 13.5px; color: var(--ink-2); }
.tool-card .tag {
  display: inline-block; font-size: 11px; font-weight: 700; letter-spacing: .04em;
  padding: 2px 8px; border-radius: 999px; margin-bottom: 10px;
}
.tag.live { background: var(--green-soft); color: var(--green); }
.tag.soon { background: var(--bg); color: var(--ink-3); }
.tool-card.soon { opacity: .65; pointer-events: none; }

/* ---------- footer ---------- */
.site-footer { border-top: 1px solid var(--line); background: #fff; margin-top: 40px; }
.site-footer .wrap { padding: 28px 20px; font-size: 13px; color: var(--ink-3); display: flex; gap: 24px; flex-wrap: wrap; }
.site-footer a { color: var(--ink-2); }