web-backset.cn/apps/server/view/page/home/index.scss

.select-menu {
  --background: #242836;
  --text: #fff;
  --icon: #fff;
  --icon-active: #3f4656;
  --list: #1c212e;
  --list-text: rgba(255, 255, 255, 0.2);
  --list-text-hover: rgba(255, 255, 255, 0.5);
  position: relative;
  z-index: 1;
  font-weight: 500;
  font-size: 14px;
  line-height: 25px;
  select,
  .button {
    font-family: inherit;
    margin: 0;
    border: 0;
    text-align: left;
    text-transform: none;
    -webkit-appearance: none;
  }
  select {
    pointer-events: none;
    user-select: none;
    opacity: 0;
    padding: 8px 36px 8px 12px;
    visibility: hidden;
    font-weight: 500;
    font-size: 14px;
    line-height: 25px;
  }
  ul {
    margin: 0;
    padding: 0;
    list-style: none;
    position: absolute;
    left: 0;
    top: 0;
    right: 0;
    transform: translateY(var(--t));
    transition: opacity 0.3s ease,
      transform 0.4s cubic-bezier(0.2, 0.9, 0.4, 1.1);
    li {
      padding: 8px 36px 8px 12px;
      cursor: pointer;
    }
  }
  & > ul {
    background: var(--list);
    color: var(--list-text);
    border-radius: 6px;
    li {
      transition: color 0.3s ease;
      &:hover {
        color: var(--list-text-hover);
      }
    }
  }
  .button {
    position: absolute;
    left: 0;
    top: 0;
    right: 0;
    bottom: 0;
    padding: 0;
    z-index: 1;
    width: 100%;
    display: block;
    overflow: hidden;
    border-radius: 6px;
    color: var(--text);
    background: var(--background);
    em {
      --r: 45deg;
      display: block;
      position: absolute;
      right: 12px;
      top: 0;
      width: 7px;
      height: 7px;
      margin-top: 13px;
      -webkit-backface-visibility: hidden;
      &:before,
      &:after {
        --o: 0.4;
        content: '';
        width: 7px;
        height: 7px;
        opacity: var(--o);
        display: block;
        position: relative;
        transition: opacity 0.2s ease;
        transform: rotate(var(--r)) scale(0.75);
      }
      &:before {
        border-left: 2px solid var(--icon);
        border-top: 2px solid var(--icon);
        top: 1px;
      }
      &:after {
        border-right: 2px solid var(--icon);
        border-bottom: 2px solid var(--icon);
        bottom: 1px;
      }
    }
  }
  &:not(.open) {
    & > ul {
      opacity: 0;
      pointer-events: none;
    }
  }
  &.open {
    &.tilt-up {
      animation: tilt-up 0.4s linear forwards;
      .button {
        em {
          &:before {
            --o: 1;
          }
        }
      }
    }
    &.tilt-down {
      animation: tilt-down 0.4s linear forwards;
      .button {
        em {
          &:after {
            --o: 1;
          }
        }
      }
    }
  }
}

@keyframes tilt-up {
  40%,
  60% {
    transform: perspective(500px) rotateX(8deg);
  }
}

@keyframes tilt-down {
  40%,
  60% {
    transform: perspective(500px) rotateX(-8deg);
  }
}

html {
  box-sizing: border-box;
  -webkit-font-smoothing: antialiased;
}

* {
  box-sizing: inherit;
  &:before,
  &:after {
    box-sizing: inherit;
  }
}

// Center & dribbble
body {
  min-height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  font-family: 'Roboto', Arial;
  background: #fff;
  .dribbble {
    position: fixed;
    display: block;
    right: 20px;
    bottom: 20px;
    img {
      display: block;
      height: 28px;
    }
  }
}