:root {
  --bg: #0f1115;
  --fg: #e8e8ea;
  --muted: #9aa0a6;
  --accent: #e5484d;
  --card: #1a1d24;
  --border: #262a33;
}
* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  background: var(--bg);
  color: var(--fg);
  line-height: 1.5;
}

/* Header (only rendered when logged in) */
.topbar {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.75rem 1rem;
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  background: var(--bg);
}
.brand { font-weight: 700; }
.identity { margin-left: auto; color: var(--muted); font-size: 0.9rem; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }

/* Burger (CSS-only <details>) */
.burger { position: relative; }
.burger summary { list-style: none; cursor: pointer; font-size: 1.25rem; padding: 0.25rem 0.5rem; }
.burger summary::-webkit-details-marker { display: none; }
.burger nav {
  position: absolute;
  right: 0;
  top: 2.25rem;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 0.5rem;
  display: flex;
  flex-direction: column;
  min-width: 10rem;
  overflow: hidden;
  z-index: 10;
}
.burger nav a { padding: 0.75rem 1rem; color: var(--fg); text-decoration: none; }
.burger nav a:hover { background: #232732; }

/* Content — mobile-first, capped for desktop */
.content { max-width: 40rem; margin: 0 auto; padding: 1.5rem 1rem; }
h1 { font-size: 1.5rem; margin-top: 0; }

.btn, button {
  display: inline-block;
  background: var(--accent);
  color: #fff;
  border: none;
  padding: 0.7rem 1.1rem;
  border-radius: 0.5rem;
  font-size: 1rem;
  text-decoration: none;
  cursor: pointer;
}

.invite-form { display: flex; flex-direction: column; gap: 1rem; margin-top: 1rem; }
.invite-form label { display: flex; flex-direction: column; gap: 0.35rem; }
.invite-form label.checkbox { flex-direction: row; align-items: center; gap: 0.5rem; }
.invite-form input[type=text],
.enroll-url {
  width: 100%;
  padding: 0.6rem;
  border-radius: 0.4rem;
  border: 1px solid #333a46;
  background: var(--card);
  color: var(--fg);
  font-size: 1rem;
}
.result { background: var(--card); border: 1px solid #2b3b2b; padding: 1rem; border-radius: 0.5rem; margin-bottom: 1rem; }
.error { color: var(--accent); }

@media (min-width: 640px) {
  .content { padding: 2rem 1rem; }
}