:root {
  --bg: #f6f7f9; --card: #ffffff; --text: #17202b; --muted: #5b6675; --line: #dde2e8;
  --accent: #1f4e8c; --accent-text: #ffffff; --warn-bg: #fff4e0; --warn-line: #e3a33b;
  --ok-bg: #e7f5ec; --ok-line: #3c9a5f; --err-bg: #fdeceb; --err-line: #cc4b42; --code-bg: #0f1722; --code-text: #e8eef6;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0f141b; --card: #171e28; --text: #e6ebf1; --muted: #9aa5b3; --line: #2a3442;
    --accent: #6ea0e6; --accent-text: #0b1118; --warn-bg: #3a2c12; --warn-line: #c58b2c;
    --ok-bg: #12301f; --ok-line: #3c9a5f; --err-bg: #3a1714; --err-line: #d1625a; --code-bg: #0a0f15; --code-text: #e8eef6;
  }
}
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body { margin: 0; background: var(--bg); color: var(--text); font: 16px/1.55 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif; }
a { color: var(--accent); }
header.top { display: flex; align-items: center; justify-content: space-between; gap: 1rem; padding: 0.9rem 1rem; border-bottom: 1px solid var(--line); background: var(--card); }
header.top .brand { font-weight: 700; font-size: 1.15rem; color: var(--text); text-decoration: none; letter-spacing: 0.01em; }
header.top .brand span { color: var(--accent); }
header.top nav { display: flex; align-items: center; gap: 0.9rem; flex-wrap: wrap; }
header.top nav form { margin: 0; }
main { max-width: 44rem; margin: 2rem auto; padding: 0 1rem; }
.card { background: var(--card); border: 1px solid var(--line); border-radius: 10px; padding: 1.4rem 1.5rem; margin-bottom: 1.25rem; }
h1 { font-size: 1.6rem; line-height: 1.25; margin: 0 0 0.75rem; }
h2 { font-size: 1.15rem; margin: 0 0 0.6rem; }
p { margin: 0 0 0.8rem; }
.muted { color: var(--muted); font-size: 0.93rem; }
label { display: block; font-weight: 600; margin: 0.6rem 0 0.3rem; }
label.check { display: flex; gap: 0.55rem; align-items: flex-start; font-weight: 500; }
label.check input { margin-top: 0.3rem; }
input[type=email], input[type=text], select { width: 100%; font: inherit; padding: 0.6rem 0.7rem; border: 1px solid var(--line); border-radius: 8px; background: var(--bg); color: var(--text); }
input.code { font-family: ui-monospace, SFMono-Regular, Menlo, monospace; font-size: 1.4rem; letter-spacing: 0.2em; max-width: 16rem; }
button { font: inherit; font-weight: 600; padding: 0.6rem 1.1rem; border-radius: 8px; border: 1px solid var(--accent); background: var(--accent); color: var(--accent-text); cursor: pointer; }
button.secondary { background: transparent; color: var(--accent); }
button.link { background: none; border: none; padding: 0; color: var(--accent); font-weight: 500; text-decoration: underline; }
button[disabled] { opacity: 0.55; cursor: not-allowed; }
.actions { display: flex; gap: 0.75rem; flex-wrap: wrap; align-items: center; margin-top: 1rem; }
.actions form { margin: 0; }
pre, code { font-family: ui-monospace, SFMono-Regular, Menlo, monospace; }
pre { background: var(--code-bg); color: var(--code-text); padding: 0.8rem 1rem; border-radius: 8px; overflow-x: auto; font-size: 0.92rem; }
.usercode { font-family: ui-monospace, SFMono-Regular, Menlo, monospace; font-size: 2rem; font-weight: 700; letter-spacing: 0.12em; margin: 0.3rem 0 0.8rem; }
.notice { border-left: 4px solid var(--line); padding: 0.6rem 0.9rem; background: var(--bg); border-radius: 6px; font-size: 0.95rem; }
.alert { border: 1px solid var(--line); border-left-width: 4px; padding: 0.7rem 0.9rem; border-radius: 8px; margin-bottom: 1rem; }
.alert.warn { background: var(--warn-bg); border-color: var(--warn-line); }
.alert.ok { background: var(--ok-bg); border-color: var(--ok-line); }
.alert.err { background: var(--err-bg); border-color: var(--err-line); }
dl.facts { display: grid; grid-template-columns: max-content 1fr; gap: 0.35rem 1rem; margin: 0 0 1rem; }
dl.facts dt { color: var(--muted); }
dl.facts dd { margin: 0; word-break: break-word; }
ul.list { list-style: none; margin: 0; padding: 0; }
ul.list li { border-top: 1px solid var(--line); padding: 0.8rem 0; }
ul.list li:first-child { border-top: none; padding-top: 0; }
footer { max-width: 44rem; margin: 2rem auto 3rem; padding: 0 1rem; color: var(--muted); font-size: 0.88rem; }
@media (max-width: 30rem) { dl.facts { grid-template-columns: 1fr; } h1 { font-size: 1.35rem; } }