actuel-inactuel/assets/css/src/header.css

#main-header {
  position: fixed;
  z-index: 1;
  top: 0;
  left: 0;
  box-sizing: border-box;
  width: 100vw;
  height: calc(var(--unit--vertical) * 5);
  padding: var(--unit--vertical) var(--unit--horizontal);
  transition: height 0.2s ease-in-out;
}
#logo {
  position: relative;
}

#main-header.open #actuel {
  color: var(--color-background);
}
#logo #actuel {
  color: var(--color-primary--transparent);
  position: relative;
  z-index: 1;
}
#logo #inactuel {
  position: absolute;
  z-index: 0;
  color: var(--color-secondary);
  bottom: -48%;
  transition: bottom 0.2s ease-in-out;
}
#main-header.minimized #logo #inactuel {
  bottom: 0%;
}

.page-cover {
  box-sizing: border-box;
  height: 100svh;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  padding-top: 25svh;
  padding-bottom: calc(5 * var(--unit--vertical));
}

@media screen and (min-width: 640px) {
  #main-header {
    display: flex;
    justify-content: center;
  }
  #logo {
    width: 37vw;
  }
  #logo * {
    font-size: 11vw;
  }

  #main-header.minimized {
    height: calc(var(--unit--vertical) * 4.3);
  }

  .page-cover {
    padding: calc(10 * var(--unit--vertical)) 0;
  }
}