/* Estilos compartidos por las tres versiones de la portada (es, en, pt). */
:root {
  --bg: #f6f7f9;
  --surface: #ffffff;
  --text: #1d2330;
  --muted: #5b6475;
  --line: #e3e6eb;
  --brand: #1565c0;
  --brand-dark: #0d47a1;
  --accent: #e8f1fc;
  --radius: 14px;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #12151b;
    --surface: #1b2029;
    --text: #e8ebf0;
    --muted: #a3abba;
    --line: #2c3340;
    --brand: #64a8f0;
    --brand-dark: #8cbff5;
    --accent: #1f2a3a;
  }
}
* { box-sizing: border-box; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 16px/1.6 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
}
a { color: var(--brand); }
.wrap { max-width: 980px; margin: 0 auto; padding: 0 16px; }

header.top {
  background: var(--surface);
  border-bottom: 1px solid var(--line);
}
header.top .wrap {
  display: flex; align-items: center; justify-content: space-between;
  gap: 12px; padding-top: 12px; padding-bottom: 12px; flex-wrap: wrap;
}
.logo { display: flex; align-items: center; gap: 10px; font-weight: 700; color: var(--text); text-decoration: none; }
.logo img { width: 36px; height: 36px; flex: none; }
.right { display: flex; align-items: center; gap: 18px; flex-wrap: wrap; }
nav a { margin-left: 16px; color: var(--muted); text-decoration: none; font-size: 15px; }
nav a:hover { color: var(--brand); }

.lang { display: flex; border: 1px solid var(--line); border-radius: 8px; overflow: hidden; font-size: 13px; }
.lang a { padding: 4px 9px; color: var(--muted); text-decoration: none; font-weight: 600; }
.lang a + a { border-left: 1px solid var(--line); }
.lang a:hover { color: var(--brand); }
.lang a[aria-current="page"] { background: var(--brand); color: #fff; }
@media (prefers-color-scheme: dark) { .lang a[aria-current="page"] { color: #0b1220; } }

.hero { padding: 56px 0 40px; }
.hero-title { display: flex; align-items: center; gap: 18px; margin-bottom: 14px; }
.hero-title img { width: 72px; height: 72px; flex: none; }
.hero h1 { font-size: clamp(28px, 5vw, 44px); line-height: 1.15; margin: 0; }
.hero p { font-size: 18px; color: var(--muted); max-width: 640px; margin: 0 0 26px; }
.cta { display: flex; gap: 12px; flex-wrap: wrap; }
.btn {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 12px 20px; border-radius: 10px; font-weight: 600; text-decoration: none;
}
.btn.primary { background: var(--brand); color: #fff; }
.btn.primary:hover { background: var(--brand-dark); }
.btn.ghost { border: 1px solid var(--line); background: var(--surface); color: var(--text); }
.btn.ghost:hover { border-color: var(--brand); }
@media (prefers-color-scheme: dark) { .btn.primary { color: #0b1220; } }

section { padding: 36px 0; }
h2 { font-size: 26px; margin: 0 0 8px; }
.lead { color: var(--muted); margin: 0 0 24px; }

.grid { display: grid; gap: 16px; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); }
.card {
  background: var(--surface); border: 1px solid var(--line);
  border-radius: var(--radius); padding: 20px;
}
.card h3 { margin: 0 0 6px; font-size: 17px; }
.card p { margin: 0; color: var(--muted); font-size: 15px; }

article.guide {
  background: var(--surface); border: 1px solid var(--line);
  border-radius: var(--radius); padding: 24px; margin-bottom: 18px;
}
article.guide h3 { margin-top: 0; font-size: 20px; }
.formula {
  background: var(--accent); border-radius: 10px; padding: 12px 16px;
  font-family: ui-monospace, Consolas, monospace; font-size: 15px; overflow-x: auto;
}
.table-scroll { overflow-x: auto; }
table { border-collapse: collapse; width: 100%; font-size: 15px; margin: 8px 0; }
th, td { text-align: left; padding: 8px 10px; border-bottom: 1px solid var(--line); white-space: nowrap; }
th { color: var(--muted); font-weight: 600; }
td.num, th.num { text-align: right; }

details { background: var(--surface); border: 1px solid var(--line); border-radius: 10px; padding: 14px 18px; margin-bottom: 10px; }
summary { cursor: pointer; font-weight: 600; }
details p { color: var(--muted); margin: 10px 0 0; }

footer { border-top: 1px solid var(--line); padding: 28px 0 40px; color: var(--muted); font-size: 14px; }
footer .wrap { display: flex; justify-content: space-between; gap: 12px; flex-wrap: wrap; }
footer a { color: var(--muted); }

@media (max-width: 640px) {
  .right { width: 100%; justify-content: space-between; }
  nav a { margin: 0 14px 0 0; }
  .hero-title img { width: 56px; height: 56px; }
}