/* Deliberately plain and self-contained: this page is the first thing a pupil
   sees and it must render before anything else on the server is reachable. No
   web fonts, no framework, no JavaScript at all. */

:root {
  color-scheme: light dark;
  --bg: #0f1420;
  --card: #18202f;
  --ink: #f2f5fa;
  --muted: #a6b2c6;
  --line: rgba(255, 255, 255, 0.14);
  --accent: #d9a441;
  --accent-ink: #1a1408;
  --error-bg: #3a1a1c;
  --error-ink: #ffc9cd;
  --error-line: #a3383f;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 1.5rem;
  background: var(--bg);
  color: var(--ink);
  font: 16px/1.55 system-ui, -apple-system, "Segoe UI", Roboto, Arial, sans-serif;
}

.card {
  width: 100%;
  max-width: 24rem;
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 14px;
  padding: 2rem 1.75rem;
  box-shadow: 0 18px 50px -18px rgba(0, 0, 0, 0.8);
}

h1 { margin: 0 0 0.35rem; font-size: 1.5rem; }

.sub { margin: 0 0 1.4rem; color: var(--muted); }

.form { display: grid; gap: 0.4rem; }

label { font-weight: 600; font-size: 0.9rem; }

input {
  width: 100%;
  padding: 0.7rem 0.8rem;
  margin-bottom: 0.7rem;
  font-size: 1rem;
  color: var(--ink);
  background: rgba(0, 0, 0, 0.28);
  border: 1px solid var(--line);
  border-radius: 8px;
}

input:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 1px;
}

button {
  margin-top: 0.3rem;
  padding: 0.75rem 1rem;
  font-size: 1rem;
  font-weight: 700;
  color: var(--accent-ink);
  background: var(--accent);
  border: 0;
  border-radius: 8px;
  cursor: pointer;
}

button:hover { filter: brightness(1.07); }

.error {
  margin: 0 0 1rem;
  padding: 0.7rem 0.85rem;
  background: var(--error-bg);
  color: var(--error-ink);
  border: 1px solid var(--error-line);
  border-radius: 8px;
  font-size: 0.92rem;
}

.help {
  margin: 1.4rem 0 0;
  font-size: 0.85rem;
  color: var(--muted);
}

.help a { color: var(--accent); }

@media (prefers-color-scheme: light) {
  :root {
    --bg: #eef1f6;
    --card: #ffffff;
    --ink: #16202f;
    --muted: #5a6880;
    --line: rgba(0, 0, 0, 0.16);
    --error-bg: #fdecee;
    --error-ink: #8c2b33;
    --error-line: #e3a3a9;
  }
  input { background: #f7f9fc; }
  .card { box-shadow: 0 14px 40px -20px rgba(0, 0, 0, 0.4); }
}