world-game/test_anim/style.css

* { margin: 0; padding: 0; box-sizing: border-box; }
body {
  min-height: 100vh;
}
.gallery-animation {
  --gap: 20px;
  --half-gap: calc(var(--gap) / 2);
  --vertical-wrapper-width: 900px;
  --shadow-diffusion: 5px;
  --gallery-animation-width: 40vw;
  --max-portion : 0.7;
  position: fixed;
  top: 0;
  left: 0;
  width: var(--gallery-animation-width);
  height: 100vh;
    overflow: hidden;
}

.gallery-animation__wrapper {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  display: flex;
  background-color: green;
}

.gallery-animation__track {
  display: flex;
  animation-timing-function: linear;
  animation-iteration-count: infinite;
}

.gallery-animation__image {
  object-fit: cover;
  flex-shrink: 0;
  filter: drop-shadow(0px 0px var(--shadow-diffusion) rgb(0, 0, 0));
}

/* ==========================================================================
   MODE VERTICAL
   ========================================================================== */

.gallery-animation--vertical .gallery-animation__wrapper{
  width: var(--vertical-wrapper-width);
  flex-direction: row;
  justify-content: center;
  padding: 0 var(--gap);
  left: 50%;
  transform: translateX(-50%);
}

.gallery-animation--vertical .gallery-animation__column {
  width: min(100%, calc(var(--gallery-animation-width) * var(--max-portion)));
  display: flex;
  flex-direction: column;
  align-items: stretch;
  overflow: hidden;
}

.gallery-animation--vertical .gallery-animation__track {
  flex-direction: column;
  align-items: stretch;
  width: 100%;
  padding-inline: var(--half-gap);
}

.gallery-animation--vertical .gallery-animation__image {
  width: 100%;
  height: auto;
  /* height: calc(100vh * var(--max-portion)); */ /*  */
  object-fit: contain;
  margin-block: var(--half-gap);
}

/* Animations verticales */
.gallery-animation--vertical .gallery-animation__column:nth-child(odd) .gallery-animation__track {
  animation: scrollDown var(--animation-duration) linear infinite;
}

.gallery-animation--vertical .gallery-animation__column:nth-child(even) .gallery-animation__track {
  animation: scrollUp var(--animation-duration) linear infinite;
}


@keyframes scrollDown {
  from { transform: translateY(0); }
  to { transform: translateY(-50%); }
}

@keyframes scrollUp {
  from { transform: translateY(-50%); }
  to { transform: translateY(0); }
}

/* ==========================================================================
   MODE HORIZONTAL
   ========================================================================== */

.gallery-animation--horizontal .gallery-animation__wrapper {
  flex-direction: column;
  padding: var(--half-gap) 0;
  height: auto;
}

.gallery-animation--horizontal .gallery-animation__column {
  --gallery-animation__wrapper-inner-height: calc(100vh - var(--half-gap) * 2) ;
  height: clamp(calc(var(--gallery-animation__wrapper-inner-height) / 5), calc(var(--gallery-animation-width) / 2), calc(var(--gallery-animation__wrapper-inner-height) / 3));
  display: flex;
  flex-direction: row;
  align-items: stretch;
  overflow: hidden;
}

.gallery-animation--horizontal .gallery-animation__track {
  flex-direction: row;
  align-items: stretch;
  height: 100%;
  padding-block: var(--half-gap);
}

.gallery-animation--horizontal .gallery-animation__image {
  height: 100%; 
  width: auto;
  object-fit: contain;
  margin-inline: var(--half-gap);
}

/* Animations horizontales */
.gallery-animation--horizontal .gallery-animation__column:nth-child(odd) .gallery-animation__track {
  animation: scrollRight var(--animation-duration) linear infinite;
}

.gallery-animation--horizontal .gallery-animation__column:nth-child(even) .gallery-animation__track {
  animation: scrollLeft var(--animation-duration) linear infinite;
}


@keyframes scrollRight {
  from { transform: translateX(-50%); }
  to { transform: translateX(0); }
}

@keyframes scrollLeft {
  from { transform: translateX(0); }
  to { transform: translateX(-50%); }
}

/* ==========================================================================
   REDUCED MOTION
   ========================================================================== */

@media (prefers-reduced-motion: reduce) {
  .gallery-animation__track {
    animation: none !important;
  }
}