CSS menu button animation

    //Change class through click event in vue
    <div 
        class="burger" 
        style="float: right;"
        :class="{'transform':rightTopBtn}"
        @click.stop="rightTopBtn=!rightTopBtn"
    >
        <div></div>
        <div></div>
        <div></div>
    </div>

  <!--Button container START-->
    .burger {
        cursor: pointer;
        display: inline-block;
        margin: 7px 6px 0 0;
        outline: none;
    }
    <!--Button containerEND-->
    <!--The three horizontal lines are rotated by rotate3d START-->
    .burger div {
        width: 30px;
        height: 4px;
        margin-bottom: 6px;
        background-color: rgb(51, 51, 51);
        transform: rotate3d(0, 0, 0, 0);
    }
    <!--Three horizontal lines END-->
    .burger.transform div {
        background-color: transparent;
    }
    .burger.transform div:first-of-type {
        top: 10px;
        transform: rotate3d(0, 0, 1, 45deg)
    }
    .burger.transform div:last-of-type {
        bottom: 10px;
        transform: rotate3d(0, 0, 1, -45deg)
    }
    <!--The effect of the first and third horizontal lines after clicking START-->
    .burger.transform div:first-of-type, .burger.transform div:last-of-type {
        transition: transform .4s .3s ease, background-color 250ms ease-in;
        background: #00c1de;
    }
    <!--The effect of the first and third horizontal lines after clickingEND-->
    <!--Resume animation after canceling click START-->
    .burger div:first-of-type, .burger div:last-of-type {
        transition: transform .3s ease .0s, background-color 0ms ease-out;
        position: relative;
    }
    <!--Resume animation after canceling clickEND-->