:root {
  --bg: #0b1220;
  --fg: #e8eef7;
  --muted: #9aacbf;
  --accent: #2dd4bf;
  --btn: #1e3a5f;
  --line: #334155;
}
* { box-sizing: border-box; }
/* Author .btn { display } must not override HTML hidden. */
[hidden] { display: none !important; }
body {
  margin: 0;
  min-height: 100vh;
  font-family: "Segoe UI", system-ui, sans-serif;
  color: var(--fg);
  background:
    radial-gradient(1200px 600px at 10% -10%, #134e4a 0%, transparent 55%),
    radial-gradient(900px 500px at 100% 0%, #1e3a5f 0%, transparent 50%),
    var(--bg);
}
a { color: var(--accent); }
.top {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
  padding: 1rem 1.5rem;
  border-bottom: 1px solid var(--line);
}
.top .brand { font-weight: 700; font-size: 1.25rem; text-decoration: none; color: var(--accent); }
.top nav { display: flex; flex-wrap: wrap; gap: 0.75rem; align-items: center; }
.top nav a:not(.btn) { color: var(--muted); text-decoration: none; }
.hero, .block { max-width: 42rem; margin: 0 auto; padding: 3rem 1.5rem; }
.hero { padding-top: 12vh; }
.hero-brand { font-size: 2rem; font-weight: 700; margin: 0 0 1rem; color: var(--accent); }
h1 { font-size: clamp(1.6rem, 4vw, 2.25rem); line-height: 1.2; margin: 0 0 0.75rem; }
h2 { font-size: 1.35rem; margin: 0 0 0.75rem; }
.lead { color: var(--muted); margin: 0 0 1.5rem; line-height: 1.55; }
.cta { display: flex; flex-wrap: wrap; gap: 0.75rem; }
.btn {
  display: inline-block;
  padding: 0.65rem 1.1rem;
  border-radius: 0.4rem;
  text-decoration: none;
  color: var(--fg);
  background: var(--btn);
  border: 1px solid var(--line);
  cursor: pointer;
  font: inherit;
}
.btn.primary {
  background: var(--accent);
  color: #042f2e;
  border-color: transparent;
  font-weight: 600;
}
.features { margin: 0; padding-left: 1.1rem; color: var(--muted); line-height: 1.7; }
.features strong { color: var(--fg); }
.foot {
  max-width: 42rem;
  margin: 2rem auto 0;
  padding: 1.5rem;
  border-top: 1px solid var(--line);
  color: var(--muted);
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
  justify-content: space-between;
}
.shell { max-width: 28rem; margin: 0 auto; padding: 12vh 1.5rem 3rem; }
.brand { font-size: 1.5rem; font-weight: 700; color: var(--accent); margin: 0 0 1rem; }
.err { color: #fca5a5; min-height: 1.25rem; }
.field { display: grid; gap: 0.35rem; margin-bottom: 0.85rem; }
.field label { color: var(--muted); font-size: 0.9rem; }
.field input {
  padding: 0.65rem 0.75rem;
  border-radius: 0.4rem;
  border: 1px solid var(--line);
  background: #0f172a;
  color: var(--fg);
}