hexo-theme-shoka/source/css/_common/outline/header/menu.styl

// Menu
// --------------------------------------------------
#nav .menu {
  padding: .625rem 0;
  margin: 0;
  width: 100%;

  .item {
    display: inline-block;
    position: relative;

    padding: 0 .625rem;
    letter-spacing: .0625rem;

    +mobile() {
      display: none;
    }

    .ic {
      margin-right: .5rem;
    }

    a {
      display: block;
      font-size: $font-size-medium;

      @extend $hover-underline;
    }

    &.active:not(.dropdown), &:not(.dropdown):hover {
      a::before {
        width: 70%;
      }
    }
  }

  .submenu {
    display: none;
    position: absolute;
    margin-top: .5rem;
    padding: 0;
    width: max-content;
    background-color: var(--grey-9-a5);
    box-shadow: 0 .3125rem 1.25rem -.25rem var(--grey-9-a1);
    border-radius: .625rem 0;
    @extend .slide-up-in;

    &::before {
      position: absolute;
      top: -1.25rem;
      left: 0;
      width: 100%;
      height: 2.5rem;
      content: '';
    }

    &:hover {
      display: block;
    }

    .item {
      display: block;

      &:first-child{
        border-radius: .625rem 0 0 0;
      }

      &:last-child{
        border-radius: 0 0 .625rem 0
      }

      a {
        display: inline-block;
        padding: .3rem .7rem;
        width: 100%;
        text-shadow: none;
        &::before {
          content: none;
        }
      }

      &:hover a {
        transform: translateX(.3rem);
      }

      &:hover, &.active {
        @extend $color-btn;
        a {
          opacity: 1;
        }
      }
    }
  }

  .item.dropdown {
    >a::after {
      content: "";
      display: inline-block;
      margin-left: .3em;
      vertical-align: middle;
      border-top: .3em solid;
      border-right: .3em solid transparent;
      border-bottom: 0;
      border-left: .3em solid transparent;
    }
    &:hover {
      .submenu {
        display: block;
      }
    }
  }
}