* {
  margin: 0;
  padding: 0;
  font: inherit;
}

.grid {
  display: grid;
}

body {
  min-height: 100vh;
  background: #f2f3f9;
}

main {
  place-self: center;
  overflow: hidden;
  max-width: 56.25em;
  box-shadow: -16px 16px 23px currentcolor;
  background: #fff;
  color: #b9b7bb;
  font: 1em/1.25 ubuntu, trebuchet ms, sans-serif;
}

article {
  --not-sel: min(1, max(var(--k) - var(--i), var(--i) - var(--k)));
  --sel: calc(1 - var(--not-sel));
  --sgn-sel: calc(2*var(--sel) - 1);
  --pad: min(1.5em, 5vw);
  grid-area: 1/1;
  grid-auto-flow: column;
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 24em), 1fr));
  z-index: var(--sel);
  padding: var(--pad);
  transition: z-index 0s 1s;
}

a {
  font-size: 0.875em;
  text-decoration: none;
  color: #000;
}
a:focus {
  outline: none;
}
a:hover, a:focus {
  color: mediumvioletred;
}

.c--ini {
  grid-column: 1;
}

.c--fin {
  grid-column-end: -1;
}

.fade {
  transform: translatey(calc(var(--not-sel)*2rem));
  opacity: var(--sel);
  transition: transform 1s ease-out calc(var(--sel)*1s), opacity 1s ease-in calc(var(--sel)*1s);
}

h3 {
  font-size: clamp(1.25em, 8vw, 2.5em);
  font-weight: 900;
  place-self: end center;
  padding: 0 0 1em;
  color: #2c2a2e;
}

p {
  padding: 0 5vw;
  color: #989898;
  font-size: 0.875em;
}

.nav {
  place-self: start center;
  margin: 0.5em 0 2em;
  border: solid 1px #e0dee0;
  padding: 1em min(2.5em, 5vw);
  border-radius: 4em;
  font-weight: 700;
  text-align: center;
}

section {
  grid-row-end: span 3;
  clip-path: inset(calc(-1*var(--pad)) 0);
}

.slice {
  --p: calc(var(--j)/var(--m));
  --s: calc((1 + var(--j))/var(--m)*100%);
  --mask:
  	linear-gradient(90deg,
  		transparent calc(var(--p)*100% - 1px),
  		red calc(var(--p)*100%) var(--s),
  		transparent calc(var(--s) + 1px));
  grid-area: 1/1;
  height: 50vmin;
  transform: translatey(calc(var(--not-sel)*(-100% - var(--pad) - 1px)));
  background: var(--img) 50%/cover;
  -webkit-mask: var(--mask);
  mask: var(--mask);
  transition: transform 1s ease-out calc((var(--sel) + var(--p))*1s);
}

.det {
  grid-auto-flow: column;
  grid-gap: 0.5em;
  place-content: end start;
  place-self: end start;
  position: relative;
  z-index: 2;
  padding: 0 1em;
  height: 0;
  line-height: 2;
  white-space: nowrap;
}
.det::before {
  position: absolute;
  z-index: -1;
  bottom: 0;
  height: 2em;
  width: 100%;
  background: #fff;
  content: "";
}
.det::after {
  content: "➔";
}