:root {
  color-scheme: dark;
  --page-bg: #09090b;
  --card-bg: #18181b;
  --line: #3f3f46;
  --text: #f4f4f5;
  --muted: #a1a1aa;
}
* { box-sizing: border-box; }
body {
  min-height: 100vh;
  margin: 0;
  background: linear-gradient(180deg, #18181b 0%, var(--page-bg) 100%);
  color: var(--text);
  font-family: Arial, sans-serif;
}
.auth-shell { max-width: 1100px; min-height: 100vh; margin: 0 auto; padding: 32px 20px 60px; }
.auth-card {
  max-width: 520px;
  margin: 80px auto 0;
  padding: 30px;
  border: 1px solid var(--line);
  border-radius: 20px;
  background: #18181bf5;
  box-shadow: 0 18px 40px #0007;
}
.auth-mark { display: grid; place-items: center; width: 40px; height: 40px; margin-bottom: 20px; border-radius: 11px; background: linear-gradient(135deg, #3b82f6, #7c3aed); font-weight: 800; }
.auth-kicker { margin: 0 0 8px; color: #c4b5fd; font-size: .83rem; font-weight: 800; letter-spacing: .11em; text-transform: uppercase; }
h1 { margin: 0 0 9px; font-size: 2rem; letter-spacing: -.03em; }
.auth-intro { margin: 0 0 26px; color: var(--muted); line-height: 1.5; }
.auth-form { display: grid; gap: 10px; }
label { font-weight: 700; }
input, button { font: inherit; min-height: 45px; border-radius: 12px; }
input:not([type="hidden"]) { width: 100%; margin-bottom: 9px; padding: 10px 12px; border: 1px solid #52525b; background: #111113; color: var(--text); }
input:focus-visible, button:focus-visible { outline: 2px solid #a78bfa; outline-offset: 2px; }
button { padding: 10px 16px; border: 1px solid #52525b; background: #3f3f46; color: white; cursor: pointer; font-weight: 700; }
button:hover { background: #52525b; }
.auth-error { padding: 12px 14px; border: 1px solid #b91c1c; border-radius: 12px; background: #450a0a; color: #fecaca; line-height: 1.4; }
.challenge-code { margin: 23px 0; padding: 18px; border: 2px solid #a78bfa; border-radius: 15px; text-align: center; color: #ddd6fe; font-size: clamp(2rem, 8vw, 3.2rem); font-weight: 800; letter-spacing: .08em; }
.auth-status { min-height: 24px; color: var(--muted); }
.cancel-form { margin-top: 10px; }
.cancel-form button { width: 100%; background: transparent; }
@media (max-width: 620px) { .auth-card { margin-top: 36px; padding: 24px; } }