:root { color-scheme: light; --page: #f9f9f7; --surface: #fcfcfb; --ink: #0b0b0b; --ink-2: #52514e; --border: rgba(11,11,11,.10); --accent: #2a78d6; --over: #d03b3b; }
@media (prefers-color-scheme: dark) {
  :root:where(:not([data-theme="light"])) { color-scheme: dark; --page: #0d0d0d; --surface: #1a1a19; --ink: #f0efec; --ink-2: #c3c2b7; --border: rgba(255,255,255,.10); --accent: #3987e5; --over: #f28b82; }
}
:root[data-theme="dark"] { color-scheme: dark; --page: #0d0d0d; --surface: #1a1a19; --ink: #f0efec; --ink-2: #c3c2b7; --border: rgba(255,255,255,.10); --accent: #3987e5; --over: #f28b82; }
* { box-sizing: border-box; }
body { margin: 0; background: var(--page); color: var(--ink); font-family: system-ui, -apple-system, "Segoe UI", "Malgun Gothic", "Apple SD Gothic Neo", "Noto Sans KR", sans-serif; font-size: 15px; line-height: 1.6; }
.simple { max-width: 480px; margin: 0 auto; padding: calc(40px + env(safe-area-inset-top)) 16px 48px; }
.logo { border-radius: 14px; display: block; margin-bottom: 12px; }
h1 { font-size: 22px; margin: 0 0 8px; }
p { color: var(--ink-2); }
.btn { display: block; text-align: center; text-decoration: none; font: inherit; font-weight: 700; font-size: 16px; padding: 13px; border-radius: 12px; border: 0; background: var(--accent); color: #fff; width: 100%; cursor: pointer; }
.btn.ghost { background: transparent; color: var(--ink); border: 1px solid var(--border); }
details { border: 1px solid var(--border); border-radius: 12px; padding: 10px 14px; margin-top: 12px; background: var(--surface); }
summary { font-weight: 600; cursor: pointer; }
ol { padding-left: 20px; color: var(--ink-2); }
form { display: flex; flex-direction: column; gap: 10px; }
input { font: inherit; font-size: 24px; letter-spacing: 6px; text-align: center; padding: 10px; border-radius: 12px; border: 1px solid var(--border); background: var(--surface); color: var(--ink); }
.err { color: var(--over); font-weight: 600; }
.code-box { margin-top: 24px; border: 1px dashed var(--border); border-radius: 12px; padding: 12px 14px; }
.code-box p { font-size: 13px; margin: 0 0 8px; }
.code { font-size: 32px; font-weight: 800; letter-spacing: 8px; text-align: center; }