:root {
  --bg: #0b0c0f;
  --text: #f2f4f8;
  --dim: #8b91a0;
  --btn: #f2f4f8;
  --on-btn: #0b0c0f;
  --gap: 18px;
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html,
body {
  height: 100%;
}

body {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 40px 24px;
  overflow: hidden;
  background: var(--bg);
  color: var(--text);
  font-family: "Segoe UI", system-ui, -apple-system, Roboto, Helvetica, Arial, sans-serif;
  -webkit-font-smoothing: antialiased;
}

/* ---------------------------------------------------------------- the wall */

.wall {
  position: fixed;
  inset: -6vh -2vw;
  display: flex;
  gap: var(--gap);
  filter: grayscale(1) contrast(1.05);
  opacity: 0.78;
}

.col {
  flex: 1;
  overflow: hidden;
}

.track {
  display: flex;
  flex-direction: column;
  gap: var(--gap);
  /* The photo list is duplicated in the markup, so shifting by half the track
     (plus half a gap) lands exactly on the copy and the loop is invisible. */
  animation: drift 80s linear infinite;
  will-change: transform;
}

.col:nth-child(2) .track { animation-duration: 104s; animation-direction: reverse; }
.col:nth-child(3) .track { animation-duration: 68s; }
.col:nth-child(4) .track { animation-duration: 92s; animation-direction: reverse; }
.col:nth-child(5) .track { animation-duration: 76s; }

@keyframes drift {
  from { transform: translateY(0); }
  to   { transform: translateY(calc(-50% - var(--gap) / 2)); }
}

.track img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 3 / 4;
  object-fit: cover;
  border-radius: 3px;
}

/* Darkens the wall enough for the logo and button to sit cleanly on top. */
.scrim {
  position: fixed;
  inset: 0;
  background:
    radial-gradient(ellipse 62% 55% at 50% 48%,
      rgba(11, 12, 15, 0.94) 0%,
      rgba(11, 12, 15, 0.8) 45%,
      rgba(11, 12, 15, 0.25) 100%),
    linear-gradient(180deg,
      rgba(11, 12, 15, 0.75) 0%,
      rgba(11, 12, 15, 0.2) 28%,
      rgba(11, 12, 15, 0.2) 72%,
      rgba(11, 12, 15, 0.8) 100%);
}

/* --------------------------------------------------------------- the card */

main {
  position: relative;
  width: 100%;
  max-width: 380px;
  text-align: center;
}

.logo {
  display: block;
  width: 220px;
  max-width: 70%;
  height: auto;
  margin: 0 auto 16px;
  filter: drop-shadow(0 6px 28px rgba(0, 0, 0, 0.6));
}

.tagline {
  margin-bottom: 44px;
  color: var(--dim);
  font-size: 14px;
  letter-spacing: 0.3px;
}

.download {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 14px 28px;
  border-radius: 10px;
  background: var(--btn);
  color: var(--on-btn);
  font-size: 15px;
  font-weight: 600;
  letter-spacing: 0.2px;
  text-decoration: none;
  box-shadow: 0 10px 34px rgba(0, 0, 0, 0.55);
  transition: opacity 0.15s ease;
}

.download:hover {
  opacity: 0.85;
}

.download:focus-visible {
  outline: 2px solid var(--btn);
  outline-offset: 3px;
}

.download svg {
  width: 17px;
  height: 17px;
}

.meta {
  margin-top: 18px;
  color: var(--dim);
  font-size: 12.5px;
  letter-spacing: 0.3px;
}

/* -------------------------------------------------------------- responsive */

@media (max-width: 900px) {
  .col:nth-child(5) { display: none; }
}

@media (max-width: 620px) {
  .col:nth-child(4) { display: none; }
  .wall { opacity: 0.42; }
}

@media (prefers-reduced-motion: reduce) {
  .track { animation: none; }
}