.ring-portal-background {
  position: fixed;
  inset: 0;
  background: linear-gradient(125deg, #294985 0%, #535790 40%, #76668f 59%, #397f99 80%, #479eaf 100%);
  pointer-events: none;
}

.ring-stage {
  --ring-size: min(720px, 92vw, 88svh);
  position: fixed;
  inset: 0;
  display: grid;
  place-items: center;
  perspective: 1800px;
  perspective-origin: 50% 50%;
  pointer-events: none;
  z-index: 1;
}

.ring-rotor {
  position: relative;
  width: var(--ring-size);
  aspect-ratio: 1;
  transform-style: preserve-3d;
  transform-origin: 50% 97.833333%;
}

.portal-ring {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  overflow: visible;
  fill: none;
  filter: drop-shadow(0 0 5px #95c9df88) drop-shadow(0 0 16px #b393d544);
}

.ring-rail { stroke: #a0b6cc66; stroke-width: 1; }
.ring-trail { stroke-width: 1.6; animation: ring-flow 16s linear infinite; }
@keyframes ring-flow {
  from { stroke-dashoffset: var(--trail-offset); }
  to { stroke-dashoffset: calc(var(--trail-offset) - 100px); }
}

.ring-back {
  position: absolute;
  inset: 2.2%;
  border-radius: 50%;
  background: #000;
  transform: rotateY(180deg) translateZ(1px);
  backface-visibility: hidden;
}

.ring-rotor > .login {
  position: absolute;
  left: 50%;
  top: 50%;
  width: min(420px, 70%);
  transform: translate(-50%, -50%) translateZ(2px);
  backface-visibility: hidden;
  pointer-events: auto;
}

.ring-variant .projects-page { position: relative; z-index: 2; }
.projects-page .back-to-start {
  position: fixed;
  left: clamp(28px, 4vw, 56px);
  bottom: clamp(28px, 4vw, 56px);
  top: auto;
  transform: none;
}
@media (max-width: 600px), (max-height: 560px) {
  .ring-stage { --ring-size: min(96vw, 90svh); }
  .ring-rotor .login { width: 72%; }
  .ring-rotor .login h1 { margin-bottom: 12px; font-size: 22px; }
  .ring-rotor .credential-row { grid-template-columns: minmax(0, 1fr) 95px; gap: 5px; }
  .ring-rotor .credential-next { padding: 0 8px; font-size: 13px; }
  .ring-rotor .login-form { grid-template-rows: 52px 28px 32px; }
  .ring-rotor #login-status { font-size: 10px; }
}
@media (prefers-reduced-motion: reduce) {
  .ring-trail { animation: none; stroke-dashoffset: var(--trail-offset); }

}