:root {
  color-scheme: dark;
  --bg: #0b0e14;
  --card: #161b24;
  --text: #f4f8f7;
  --muted: #a7b4be;
  --line: rgba(236, 246, 242, 0.14);
  --accent: #3ddcb8;
  --danger: #e25b4a;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: "Segoe UI", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.55;
}

header, main, footer {
  width: min(760px, calc(100% - 32px));
  margin-inline: auto;
}

header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
  padding: 22px 0;
}

.brand {
  color: var(--text);
  font-weight: 700;
  text-decoration: none;
  font-size: 20px;
}

nav {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
}

nav a, footer a {
  color: var(--muted);
  text-decoration: none;
}

nav a:hover, footer a:hover { color: var(--accent); }

main {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 18px;
  padding: 28px 22px 32px;
}

h1 { font-size: 32px; line-height: 1.15; margin: 0 0 8px; }
h2 { font-size: 18px; margin: 28px 0 8px; }
p, li { color: var(--muted); }
ul { padding-left: 18px; }

form { display: grid; gap: 12px; margin-top: 18px; }
label { display: grid; gap: 6px; color: var(--text); font-size: 14px; }
input {
  min-height: 46px;
  border-radius: 12px;
  border: 1px solid var(--line);
  background: #0b0e14;
  color: var(--text);
  padding: 0 12px;
  font: inherit;
}
button {
  min-height: 48px;
  border: 0;
  border-radius: 12px;
  background: var(--danger);
  color: white;
  font: inherit;
  font-weight: 700;
}
#result { min-height: 1.4em; }
footer { padding: 22px 0 36px; color: var(--muted); font-size: 14px; }