:root {
  --bg: #0f1512;
  --panel: #18211c;
  --panel-2: #202c25;
  --text: #f3f7f4;
  --muted: #afbeb4;
  --accent: #8ed06c;
  --accent-2: #c9f2ae;
  --border: #33443a;
  --danger: #ffb4a8;
  --shadow: 0 18px 50px rgba(0, 0, 0, .28);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  color: var(--text);
  background:
    radial-gradient(circle at 15% 0%, rgba(142, 208, 108, .12), transparent 32rem),
    var(--bg);
  line-height: 1.6;
}
a { color: var(--accent-2); }
a:hover { color: white; }
button, input, select { font: inherit; }
button { cursor: pointer; }

.site-header {
  border-bottom: 1px solid var(--border);
  background: rgba(15, 21, 18, .92);
  backdrop-filter: blur(12px);
  position: sticky;
  top: 0;
  z-index: 20;
}
.header-inner, .container {
  width: min(1100px, calc(100% - 32px));
  margin: 0 auto;
}
.header-inner {
  min-height: 68px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}
.brand {
  text-decoration: none;
  color: white;
  font-weight: 850;
  letter-spacing: -.03em;
  font-size: 1.15rem;
}
.brand span { color: var(--accent); }
nav { display: flex; gap: 18px; flex-wrap: wrap; }
nav a { text-decoration: none; color: var(--muted); font-size: .95rem; }
nav a:hover { color: white; }

main { padding: 58px 0 80px; }
.hero { max-width: 780px; margin-bottom: 34px; }
.eyebrow {
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: .14em;
  font-weight: 800;
  font-size: .78rem;
}
h1, h2, h3 { line-height: 1.15; letter-spacing: -.035em; }
h1 { font-size: clamp(2.3rem, 6vw, 4.7rem); margin: 10px 0 18px; }
h2 { font-size: clamp(1.65rem, 3vw, 2.5rem); margin-top: 46px; }
h3 { font-size: 1.2rem; }
.lede { color: var(--muted); font-size: 1.14rem; max-width: 68ch; }

.tool-shell {
  background: linear-gradient(180deg, var(--panel-2), var(--panel));
  border: 1px solid var(--border);
  border-radius: 20px;
  padding: clamp(20px, 4vw, 34px);
  box-shadow: var(--shadow);
}
.grid { display: grid; gap: 18px; }
.grid.two { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid.three { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.field label { display: block; font-weight: 750; margin-bottom: 7px; }
.field small { display: block; color: var(--muted); margin-top: 6px; }
input, select {
  width: 100%;
  background: #0d1310;
  color: white;
  border: 1px solid #42554a;
  border-radius: 11px;
  padding: 13px 14px;
  outline: none;
}
input:focus, select:focus { border-color: var(--accent); box-shadow: 0 0 0 3px rgba(142, 208, 108, .14); }
.actions { display: flex; gap: 10px; flex-wrap: wrap; margin-top: 20px; }
.btn {
  border: 1px solid var(--border);
  border-radius: 11px;
  padding: 11px 15px;
  color: white;
  background: #26342c;
  font-weight: 760;
}
.btn.primary { background: var(--accent); border-color: var(--accent); color: #10200f; }
.btn:hover { filter: brightness(1.08); }
.result-grid { display: grid; grid-template-columns: repeat(3, minmax(0,1fr)); gap: 12px; margin-top: 24px; }
.result-card { background: #0d1310; border: 1px solid var(--border); border-radius: 14px; padding: 17px; }
.result-label { color: var(--muted); font-size: .85rem; }
.result-value { font-size: 1.45rem; font-weight: 850; margin-top: 4px; word-break: break-word; }
.notice { background: rgba(142, 208, 108, .09); border-left: 3px solid var(--accent); padding: 13px 15px; color: var(--muted); margin-top: 20px; }
.error { color: var(--danger); min-height: 1.4em; margin-top: 10px; }

.cards { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 18px; }
.card { background: var(--panel); border: 1px solid var(--border); border-radius: 17px; padding: 23px; text-decoration: none; color: inherit; }
.card:hover { transform: translateY(-2px); border-color: #5e7a67; }
.card p { color: var(--muted); }
.card .arrow { color: var(--accent); font-weight: 800; }
.content { max-width: 780px; }
.content p, .content li { color: #d4ddd7; }
.content code { background: #0d1310; padding: 2px 6px; border-radius: 5px; }
.formula { background: #0d1310; border: 1px solid var(--border); border-radius: 12px; padding: 16px; overflow-x: auto; }
.breadcrumbs { color: var(--muted); font-size: .9rem; margin-bottom: 20px; }
.breadcrumbs a { color: var(--muted); }
.home-intro { margin: 64px auto 0; text-align: center; }
.home-intro .lede, .home-intro p { margin-left: auto; margin-right: auto; }
.faq { margin-top: 46px; }
.faq details { background: var(--panel); border: 1px solid var(--border); border-radius: 12px; margin: 10px 0; padding: 0 16px; }
.faq summary { cursor: pointer; color: var(--text); font-weight: 760; padding: 15px 0; }
.faq details p { margin-top: 0; padding-bottom: 15px; }

.site-footer { border-top: 1px solid var(--border); padding: 28px 0 40px; color: var(--muted); font-size: .9rem; }
.footer-inner { display: flex; justify-content: space-between; align-items: flex-start; gap: 22px; flex-wrap: wrap; }
.footer-note { display: block; margin-top: 5px; }
.footer-links { gap: 16px; }
.footer-links a { color: var(--muted); text-decoration: none; }
.footer-links a:hover { color: white; }

@media (max-width: 760px) {
  .header-inner { align-items: flex-start; flex-direction: column; padding: 14px 0; }
  nav { gap: 12px; }
  main { padding-top: 36px; }
  .grid.two, .grid.three, .result-grid, .cards { grid-template-columns: 1fr; }
  h1 { font-size: 2.65rem; }
  .home-intro { margin-top: 46px; }
}