:root {
  color-scheme: dark;
  --overlay: rgba(4, 5, 12, 0.55);
  --island-bg: rgba(10, 12, 26, 0.62);
  --island-border: rgba(255, 255, 255, 0.2);
  --button-bg: rgba(255, 255, 255, 0.15);
  --button-bg-hover: rgba(255, 255, 255, 0.25);
  --text: #f7f8ff;
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  width: 100%;
  min-height: 100%;
  font-family: "Inter", "Segoe UI", sans-serif;
  color: var(--text);
}

body {
  position: relative;
  min-height: 100vh;
  overflow: hidden;
}

.background-slideshow,
.bg-layer,
.bg-overlay {
  position: fixed;
  inset: 0;
}

.background-slideshow {
  z-index: -2;
}

.bg-layer {
  background-size: cover;
  background-position: center;
  transform-origin: center;
  transform: translate3d(0, 0, 0) scale(1.08);
  transition: opacity 1.4s ease-in-out;
  will-change: opacity, transform;
  animation: bg-pan 6.5s linear forwards;
}

.bg-layer-a {
  opacity: 1;
}

.bg-layer-b {
  opacity: 0;
}

.bg-overlay {
  z-index: 1;
  background: radial-gradient(circle at 50% 50%, transparent 0%, rgba(2, 3, 10, 0.3) 55%),
    var(--overlay);
}

.portal {
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: 1.25rem;
}

.island {
  width: min(420px, 100%);
  text-align: center;
  padding: 2rem 1.5rem;
  border-radius: 18px;
  border: 1px solid var(--island-border);
  background: var(--island-bg);
  backdrop-filter: blur(10px);
  box-shadow: 0 16px 48px rgba(0, 0, 0, 0.35);
}

h1 {
  margin-top: 0;
  margin-bottom: 0.75rem;
  font-size: clamp(1.8rem, 4vw, 2.2rem);
}

p {
  margin-top: 0;
  margin-bottom: 1.6rem;
  line-height: 1.5;
}

.link-list {
  margin: 0;
  padding: 0;
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.portal-button {
  display: block;
  border-radius: 10px;
  border: 1px solid rgba(255, 255, 255, 0.28);
  background: var(--button-bg);
  color: var(--text);
  text-decoration: none;
  font-weight: 600;
  padding: 0.8rem 1rem;
  transition: transform 0.2s ease, background-color 0.2s ease;
}

.portal-button:hover,
.portal-button:focus-visible {
  background: var(--button-bg-hover);
  transform: translateY(-1px);
}

.portal-button:focus-visible {
  outline: 2px solid rgba(255, 255, 255, 0.7);
  outline-offset: 2px;
}

@media (prefers-reduced-motion: reduce) {
  .bg-layer,
  .portal-button {
    transition: none;
    animation: none;
    transform: none;
  }
}

@keyframes bg-pan {
  0% {
    transform: translate3d(var(--pan-start-x, 0), var(--pan-start-y, 0), 0)
      scale(var(--pan-start-scale, 1.08));
  }

  100% {
    transform: translate3d(var(--pan-end-x, 0), var(--pan-end-y, 0), 0)
      scale(var(--pan-end-scale, 1.14));
  }
}