/* =============================================================
   AUTH SCREEN
   ============================================================= */
#auth-screen {
  position: fixed; inset: 0; z-index: 200;
  background: var(--bg);
  display: flex; flex-direction: column;
  align-items: center; justify-content: center;
  padding: var(--s-8) var(--s-6);
}
#auth-screen.hidden { display: none; }

/* Flip-Container: Login <-> Register drehen sich um die vertikale Achse. */
.auth-flip-stage {
  width: 100%; max-width: 360px;
  perspective: 1400px;
}
.auth-flip {
  position: relative;
  transform-style: preserve-3d;
  transition: transform 620ms var(--ease-spring);
  will-change: transform;
}
.auth-flip.flipped { transform: rotateY(180deg); }
.auth-face {
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
  width: 100%;
}
.auth-face-back {
  position: absolute; top: 0; left: 0; right: 0;
  transform: rotateY(180deg);
}
@media (prefers-reduced-motion: reduce) {
  .auth-flip { transition: none; }
}
.auth-logo {
  font-family: var(--font-display);
  font-size: 48px; letter-spacing: 0.05em;
  color: var(--primary); margin-bottom: var(--s-2);
}
.auth-tagline {
  font-family: var(--font-display);
  font-size: var(--fs-micro); color: var(--muted); margin-bottom: 48px;
  text-align: center; letter-spacing: var(--tracking-wider); text-transform: uppercase;
}
.auth-card {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--r-lg); padding: 28px var(--s-6);
  width: 100%; max-width: 360px;
}
.auth-title {
  font-family: var(--font-display);
  font-size: 18px; margin-bottom: var(--s-5);
}
.auth-input {
  width: 100%; padding: 14px var(--s-4);
  background: var(--surface2); border: 1px solid var(--border);
  border-radius: var(--r-md); color: var(--text); font-size: var(--fs-body);
  font-family: var(--font-body);
  margin-bottom: var(--s-4); outline: none;
  transition: border-color var(--dur-fast) var(--ease), background var(--dur-fast) var(--ease);
}
.auth-input::placeholder { color: var(--muted-deep); }
.auth-input:focus { border-color: var(--primary); background: var(--surface3); }
.auth-btn {
  width: 100%; padding: 15px;
  border-radius: var(--r-md);
  font-family: var(--font-display);
  font-size: 13px; letter-spacing: var(--tracking-wide); text-transform: uppercase;
  margin-bottom: var(--s-2);
  transition: background var(--dur-fast) var(--ease), transform var(--dur-fast) var(--ease), border-color var(--dur-fast) var(--ease);
  display: inline-flex; align-items: center; justify-content: center;
}
.auth-btn:active { transform: translateY(1px); }
.auth-btn[disabled], .auth-btn.is-disabled {
  opacity: 0.4; cursor: not-allowed; pointer-events: none;
}
.auth-btn-primary { background: var(--primary); color: #fff; }
.auth-btn-ghost {
  background: var(--surface2); border: 1px solid var(--border);
  color: var(--muted);
}
.auth-btn-ghost:hover { border-color: var(--border-strong); color: var(--text); }
.auth-btn-cancel { color: var(--danger); }
.auth-btn-cancel:hover { color: var(--danger); border-color: var(--danger); }
.auth-error {
  font-size: 12px; color: var(--danger); margin-top: var(--s-2);
  text-align: center; min-height: 16px;
}
/* Hinweis, wenn die Registrierung deaktiviert ist (Admin-Setting). */
.auth-disabled-hint {
  font-size: 13px; color: var(--muted);
  text-align: center; line-height: 1.5;
  padding: var(--s-3); margin-top: var(--s-2);
  background: var(--surface2); border: 1px solid var(--border);
  border-radius: var(--r-md);
}
.auth-disabled-hint a { color: var(--primary); font-weight: 600; }
.auth-disabled-hint a:hover { color: var(--accent); }
.auth-switch {
  font-size: 12px; color: var(--muted); text-align: center;
  margin-top: var(--s-4);
}
.auth-switch button {
  font-family: var(--font-display);
  color: var(--primary); padding: 0 2px;
  letter-spacing: 0.02em;
}
.passkey-icon { font-size: 1.3em; margin-right: 6px; }