:root {
  --bg: #0b1220;
  --card: #111827;
  --border: #1f2937;
  --text: #e5e7eb;
  --muted: #9ca3af;
  --accent: #3b82f6;
  --accent2: #a78bfa;
  --err: #f87171;
  --radius: 12px;
  font-family: "Segoe UI", system-ui, -apple-system, sans-serif;
}
html.theme-light {
  --bg: #f1f5f9;
  --card: #ffffff;
  --border: #e2e8f0;
  --text: #0f172a;
  --muted: #64748b;
  --accent: #2563eb;
  --accent2: #7c3aed;
  --err: #dc2626;
}
html.theme-light body {
  background: radial-gradient(1200px 600px at 20% -10%, #bfdbfe55, transparent), var(--bg);
}
html.theme-light header {
  background: linear-gradient(180deg, #e2e8f0, var(--bg));
}
html.theme-light input,
html.theme-light select,
html.theme-light textarea {
  background: #ffffff;
  color: var(--text);
}
html.theme-light .out {
  background: #f8fafc;
  border-color: #cbd5e1;
}
html.theme-light .out.error {
  border-color: #fecaca;
}
html.theme-light .formula {
  background: #f8fafc;
  color: #334155;
}
* { box-sizing: border-box; }
body {
  margin: 0;
  background: radial-gradient(1200px 600px at 20% -10%, #1e3a8a22, transparent), var(--bg);
  color: var(--text);
  line-height: 1.55;
}
header {
  padding: 1.25rem 1.25rem 0.5rem;
  border-bottom: 1px solid var(--border);
  background: linear-gradient(180deg, #0f172a, var(--bg));
}
header .header-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  margin-bottom: 0.35rem;
}
header .header-top h1 {
  margin: 0;
  flex: 1;
  min-width: 0;
  font-size: 1.35rem;
  letter-spacing: 0.02em;
}
.header-site {
  flex-shrink: 0;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 2.5rem;
  height: 2.5rem;
  border-radius: 10px;
  color: var(--accent);
  border: 1px solid var(--border);
  background: #0b1020;
  text-decoration: none;
}
.header-site:hover,
.header-site:focus-visible {
  background: #1e293b;
  outline: none;
}
html.theme-light .header-site {
  background: #f8fafc;
}
html.theme-light .header-site:hover,
html.theme-light .header-site:focus-visible {
  background: #e2e8f0;
}
.header-site svg {
  display: block;
}
h1 { font-size: 1.35rem; margin: 0 0 0.35rem; letter-spacing: 0.02em; }
.sub { color: var(--muted); font-size: 0.95rem; max-width: 70ch; }
a { color: var(--accent); }
main { max-width: 1100px; margin: 0 auto; padding: 1rem 1.25rem 3rem; }
.panel { margin-bottom: 2rem; }
.panel.hidden { display: none; }
.grid2 { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; }
@media (max-width: 820px) { .grid2 { grid-template-columns: 1fr; } }
.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1rem 1.1rem;
}
h2 { font-size: 1.05rem; margin: 0 0 0.75rem; color: #f9fafb; }
h3 { font-size: 0.95rem; margin: 1rem 0 0.5rem; color: var(--accent2); }
label { display: block; font-size: 0.8rem; color: var(--muted); margin: 0.35rem 0 0.2rem; }
input, select, textarea {
  width: 100%;
  padding: 0.5rem 0.6rem;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: #0b1020;
  color: var(--text);
}
textarea { min-height: 4.5rem; font-family: ui-monospace, monospace; }
.row { display: flex; gap: 0.5rem; flex-wrap: wrap; align-items: flex-end; margin-top: 0.5rem; }
.row > div { flex: 1; min-width: 140px; }
button.primary {
  border: none;
  background: linear-gradient(135deg, #2563eb, #7c3aed);
  color: #fff;
  padding: 0.55rem 1rem;
  border-radius: 10px;
  cursor: pointer;
  font-weight: 600;
}
.out {
  margin-top: 0.75rem;
  padding: 0.65rem 0.75rem;
  border-radius: 8px;
  background: #0b1020;
  border: 1px dashed #334155;
  min-height: 2.75rem;
  font-size: 0.9rem;
}
.out.error { border-color: #7f1d1d; color: var(--err); }
code, .mono { font-family: ui-monospace, "Cascadia Code", monospace; font-size: 0.88em; }
.formula {
  background: #0b1020;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 0.65rem 0.75rem;
  margin: 0.35rem 0 0.75rem;
  color: #d1d5db;
  font-size: 0.88rem;
}
ul.compact { margin: 0.25rem 0 0.75rem 1.1rem; padding: 0; }
ul.compact li { margin: 0.2rem 0; }
.muted { color: var(--muted); font-size: 0.85rem; }
footer { text-align: center; color: var(--muted); font-size: 0.8rem; padding: 2rem 1rem; }
.calc-links { display: grid; grid-template-columns: repeat(auto-fill, minmax(200px, 1fr)); gap: 0.5rem 1rem; margin-top: 0.75rem; }
.calc-links a { text-decoration: none; }
.calc-links a:hover { text-decoration: underline; }
.about-page {
  min-height: 100vh;
  margin: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 2rem 1.25rem;
}
.about-page .about-inner {
  text-align: center;
  max-width: 28rem;
}
.about-page .about-logo {
  display: block;
  width: 128px;
  height: auto;
  margin: 0 auto 1rem;
  border-radius: 22px;
  box-shadow: 0 12px 40px #00000044;
}
html.theme-light .about-page .about-logo {
  box-shadow: 0 12px 28px #1e293b22;
}
.about-page .about-line1 {
  margin: 0 0 0.65rem;
  font-size: 1.5rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  color: var(--text);
}
.about-page .about-line2 {
  margin: 0;
  font-size: 1rem;
  color: var(--muted);
  line-height: 1.5;
}

/* --- App/web shell: top nav + centered calculator (index.html) --- */
.skip-link {
  position: absolute;
  left: -9999px;
  top: auto;
  width: 1px;
  height: 1px;
  overflow: hidden;
}
.skip-link:focus {
  left: 1rem;
  top: 1rem;
  width: auto;
  height: auto;
  padding: 0.35rem 0.6rem;
  z-index: 100;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 8px;
  color: var(--text);
}
body.site-layout {
  margin: 0;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}
body.site-layout > .site-header {
  flex-shrink: 0;
}
.site-header {
  padding: 0;
  border-bottom: 1px solid var(--border);
  background: linear-gradient(180deg, #0f172a, var(--bg));
}
html.theme-light .site-header {
  background: linear-gradient(180deg, #e2e8f0, var(--bg));
}
.site-topnav {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0.65rem 1rem;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 0.65rem 1rem;
}
.nav-brand {
  font-weight: 700;
  font-size: 1.1rem;
  letter-spacing: 0.04em;
  color: var(--text);
  text-decoration: none;
}
.nav-brand:hover,
.nav-brand:focus-visible {
  color: var(--accent);
}
.nav-primary {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.35rem;
}
.nav-pill {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.4rem 0.75rem;
  border-radius: 999px;
  font-size: 0.88rem;
  font-weight: 600;
  color: var(--text);
  text-decoration: none;
  border: 1px solid transparent;
  background: transparent;
}
.nav-pill:hover,
.nav-pill:focus-visible {
  border-color: var(--border);
  background: #0b1020;
  outline: none;
}
html.theme-light .nav-pill:hover,
html.theme-light .nav-pill:focus-visible {
  background: #f8fafc;
}
.nav-pill.nav-quiet {
  font-weight: 500;
  color: var(--muted);
}
.nav-pill.nav-quiet:hover,
.nav-pill.nav-quiet:focus-visible {
  color: var(--text);
}
details.nav-more {
  position: relative;
}
details.nav-more > summary {
  list-style: none;
  cursor: pointer;
}
details.nav-more > summary::-webkit-details-marker {
  display: none;
}
.nav-more-trigger::after {
  content: "▾";
  margin-left: 0.25rem;
  font-size: 0.75em;
  color: var(--muted);
}
.nav-pop {
  position: absolute;
  top: calc(100% + 0.35rem);
  right: 0;
  z-index: 50;
  min-width: 220px;
  max-height: min(70vh, 420px);
  overflow-y: auto;
  padding: 0.35rem;
  border-radius: 12px;
  border: 1px solid var(--border);
  background: var(--card);
  box-shadow: 0 12px 40px #00000055;
}
.nav-pop a {
  display: block;
  padding: 0.45rem 0.65rem;
  border-radius: 8px;
  color: var(--text);
  text-decoration: none;
  font-size: 0.88rem;
}
.nav-pop a:hover,
.nav-pop a:focus-visible {
  background: #0b1020;
  outline: none;
}
html.theme-light .nav-pop a:hover,
html.theme-light .nav-pop a:focus-visible {
  background: #f1f5f9;
}
.site-main {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 1rem 1rem 2rem;
  max-width: none;
  margin: 0;
}
.site-main iframe#calc-frame {
  width: min(720px, 100%);
  height: min(88vh, 920px);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--card);
  box-shadow: 0 18px 50px #00000044;
}
body.in-iframe header {
  display: none;
}
body.in-iframe main {
  padding-top: 0.75rem;
}