blockscout/apps/explorer_web/assets/css/components/_menu.scss

/* ---------------------------------------------------
    SIDEBAR STYLE
----------------------------------------------------- */
#sidebar {
    min-width: 200px;
    background: $gray-200;
    position: sticky;
    top: 0px;

    @media (max-width: 768px) {
      transition: all 0.6s cubic-bezier(0.945, 0.020, 0.270, 0.665);
      transform-origin: bottom left;
    }
}

#sidebar .active {

  @media (max-width: 768px) {
    margin-left: -200px;
    transform: rotateY(100deg);
    }
  }

#sidebar .sidebar-header {
  background-color: $primary;
  color: $gray-800;
  height: 66px;
  padding: 12px 12px 17px;
  text-align: center;
  box-shadow:0 2px 2px 0 rgba(38,50,56,.16), 0 0 2px 0 rgba(38,50,56,.12);

}

#sidebar .menu-items {
  list-style: none;
  padding: 0.5em 0;
  margin: 0;

  div {
    color: $gray-800;
    padding: 24px 2px 24px 18px;
    font-size: 13px;
    font-weight: normal;
    background-repeat: no-repeat;
    background-position: left 20px center;
    transition: all 0.15s linear;
    cursor: pointer;

    img {
      width: 35px;
      height: 100%;
      margin-right: 5px;
    }

    &:hover {
     background-color: rgba(0, 0, 0, 0.1);
    }

    &:focus {
     outline: none;
    }
  }

}


#sidebar ul li.active > a, a[aria-expanded="true"] {

}

#sidebar li {
  list-style-type: none;
  padding-left: 5px;
  line-height: 25px;
}
a[data-toggle="collapse"] {
    position: relative;
}

#pageSubmenu {
  margin-bottom: 5px;
}

.sidebar-footer {
  font-size: 11px;
  padding: 20px;
  position: absolute;
  bottom: 0;
  color: $gray-500;

}
/* ---------------------------------------------------
    CONTENT STYLE
----------------------------------------------------- */
#sidebarCollapse {
  display: none;
}


/* ---------------------------------------------------
    MEDIAQUERIES
----------------------------------------------------- */
@media (max-width: 768px) {
    #sidebar {
        margin-left: -200px;
        transform: rotateY(90deg);
        height: 100vh;
        position: fixed;


    }
    #sidebar.active {
        margin-left: 0;
        transform: none;

        ~ #content {
          position: absolute;
          right: -200px;
        }
    }

    #sidebar .menu-items div {
      padding-top: 11px;
    }

    #sidebarCollapse {
      display: block;
      width: 45px;
      height: 65px;
      background-image: none;
      border-color: transparent !important;
      box-shadow: 0 2px 2px 0 rgba(38,50,56,.16), 0 0 2px 0 rgba(38,50,56,.12);
    }

    #sidebarCollapse span {
        width: 80%;
        height: 2px;
        margin: 0 auto;
        display: block;
        background: $black;
        transition: all 0.8s;
    }


    #sidebarCollapse span:first-of-type,
    #sidebarCollapse span:nth-of-type(2),
    #sidebarCollapse span:last-of-type {
        transform: none;
        opacity: 1;
        margin: 7px auto;
    }
    #sidebarCollapse.active span {
        transform: none;
        opacity: 1;
        margin: 0 auto;
    }
    #sidebarCollapse.active span:first-of-type {
        transform: rotate(45deg) translate(2px, 2px);
    }
    #sidebarCollapse.active span:nth-of-type(2) {
        opacity: 0;
    }
    #sidebarCollapse.active span:last-of-type {
        transform: rotate(-45deg) translate(1px, -1px);
    }
}