:root {
  --navy: #07305d;
  --gold: #eaa159;
  --gold-soft: #f0bb86;
  --white: #ffffff;
  --fire: #ff4444;
  --fire-hot: #ff2222;
  --font-display: Sora, system-ui, sans-serif;
  --font-body: Inter, system-ui, sans-serif;
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  min-height: 100%;
}

body {
  min-height: 100vh;
  overflow: hidden;
  background: var(--navy);
  color: var(--white);
  font-family: var(--font-body);
  font-weight: 400;
  line-height: 1.6;
}

h1,
h2,
h3 {
  font-family: var(--font-display);
  font-weight: 600;
  letter-spacing: -0.03em;
  line-height: 1.15;
}

.stage {
  position: relative;
  z-index: 10;
  min-height: 100vh;
  display: grid;
  place-items: center;
  align-content: center;
  justify-items: center;
  gap: 1.25rem;
  padding: 2rem;
  text-align: center;
  opacity: 0;
  transition: opacity 0.7s ease 0.15s;
}

.logo {
  display: grid;
  justify-items: center;
  gap: 0.85rem;
}

.logo-mark {
  display: block;
  width: min(11.5rem, 42vw);
  height: auto;
  opacity: 0;
  transition: opacity 0.45s ease;
}

body.is-ready .logo-mark {
  opacity: 1;
}

.logo-word {
  font-family: var(--font-body);
  font-weight: 700;
  font-size: clamp(2.15rem, 7vw, 3.35rem);
  letter-spacing: -0.04em;
  line-height: 1;
  color: var(--white);
}

h1 {
  margin: 0;
  font-size: clamp(1.75rem, 4vw, 2.5rem);
}

.stage p {
  margin: 0;
  max-width: 32rem;
  color: color-mix(in srgb, var(--white) 78%, var(--navy));
  font-size: 1.05rem;
}

.neural-container {
  position: fixed;
  inset: 0;
  z-index: 1;
  pointer-events: none;
  opacity: 0;
  transition: opacity 0.9s ease;
}

.neural-container.is-visible {
  opacity: 1;
}

.neuron {
  position: absolute;
  width: 14px;
  height: 14px;
  border: 2px solid var(--gold);
  border-radius: 50%;
  background: transparent;
  box-sizing: border-box;
  transition: border-color 0.25s ease, box-shadow 0.25s ease, opacity 0.7s ease, transform 0.7s ease;
}

.neuron-core {
  position: absolute;
  top: 50%;
  left: 50%;
  width: 4px;
  height: 4px;
  border-radius: 50%;
  background: transparent;
  transform: translate(-50%, -50%);
}

.neuron.is-firing {
  border-color: var(--fire);
  box-shadow: 0 0 12px color-mix(in srgb, var(--fire) 70%, transparent);
}

.neuron.is-firing .neuron-core {
  background: var(--fire-hot);
  box-shadow:
    0 0 10px var(--fire),
    0 0 18px var(--fire),
    0 0 28px var(--fire);
  animation: core-fire 0.6s ease-in-out;
}

.connection {
  position: absolute;
  height: 1.5px;
  background: var(--gold);
  opacity: 0.4;
  border-radius: 1px;
  transform-origin: 0 0;
  z-index: 0;
}

.connection.is-active {
  opacity: 1;
  height: 2px;
  background: linear-gradient(90deg, #ff6666, var(--fire), #ff6666);
  box-shadow: 0 0 8px color-mix(in srgb, var(--fire) 60%, transparent);
  animation: neural-flow 0.75s ease-in-out;
}

.neural-container.is-converging .neuron.is-keeper {
  z-index: 2;
  transition:
    left 1.15s cubic-bezier(0.22, 1, 0.36, 1),
    top 1.15s cubic-bezier(0.22, 1, 0.36, 1),
    opacity 0.4s ease;
}

.neuron.is-exiting,
.connection.is-exiting {
  opacity: 0;
}

.neuron.is-exiting {
  transform: scale(0.35);
}

.neural-container.is-done {
  opacity: 0;
  transition: opacity 0.4s ease;
}

body.is-ready .stage {
  opacity: 1;
}

body.is-intro .stage {
  pointer-events: none;
}

@keyframes core-fire {
  0% {
    transform: translate(-50%, -50%) scale(1);
    background: var(--fire-hot);
  }
  18% {
    transform: translate(-50%, -50%) scale(2.1);
    background: var(--white);
    box-shadow: 0 0 22px var(--white);
  }
  100% {
    transform: translate(-50%, -50%) scale(1.25);
    background: var(--fire);
  }
}

@keyframes neural-flow {
  0% {
    filter: brightness(1);
  }
  15% {
    filter: brightness(1.8);
  }
  100% {
    filter: brightness(1.15);
  }
}

@media (prefers-reduced-motion: reduce) {
  .neural-container,
  .stage,
  body.is-ready .neural-container {
    transition: none;
  }

  .neuron.is-firing .neuron-core,
  .connection.is-active {
    animation: none;
  }
}