<style>

    @keyframes checked-anim {
    50% {
        width: 3000px;
        height: 3000px;
    }
    100% {
        width: 100%;
        height: 100%;
        border-radius: 0;
    }
}
@keyframes not-checked-anim {
    0% {
        width: 3000px;
        height: 3000px;
    }
}
li, a {
    margin: 75px auto -55px;
    color: #03A9F4;
    font: 14pt "Roboto", sans-serif;
    font-weight: 700;
    line-height: 1.8;
    text-decoration: none;
    text-transform: none;
    list-style: none;
    outline: 0;
    display: none;
}
li {
    width: 230px;
    text-indent: 56px;}
a:focus {
    display: block;
    color: #333;
    background-color: #eee;
    transition: all .5s;
}

html, body {
    margin: 0;
    padding: 0;
    background-color: #03A9F4;
    font-family: 'Roboto', sans-serif;
    overflow: hidden;
}

#trigger, #burger, #burger:before, #burger:after {
    position: absolute;
    top: 25px;
    right: 25px;
    background: #03A9F4;
    width: 30px;
    height: 5px;
    transition: .2s ease;
    cursor: pointer;
    z-index: 1;
}
#trigger {
    height: 25px;
    background: none;
}
#burger:before {
    content: " ";
    top: 10px;
    left: 0;
}
#burger:after {
    content: " ";
    top: 20px;
    left: 0;
}
#menu-toggle:checked + #trigger + #burger {
    top: 35px;
    transform: rotate(180deg);
    transition: transform .2s ease;
}

#menu-toggle:checked + #trigger + #burger:before {
    width: 20px;
    top: -2px;
    left: 18px;
    transform: rotate(45deg) translateX(-5px);
    transition: transform .2s ease;
}
#menu-toggle:checked + #trigger + #burger:after {
    width: 20px;
    top: 2px;
    left: 18px;
    transform: rotate(-45deg) translateX(-5px);
    transition: transform .2s ease;
}
#menu-top-nav {
    position: absolute;
    right:0;
    margin: 0; padding: 0;
    width: 90px;
    height: 90px;
    background-color: #fff;
    border-bottom-left-radius: 100%;
    box-shadow: 0 2px 5px rgba(0,0,0,0.26);
    animation: not-checked-anim .2s both;
    transition: .2s;
}
#menu-toggle:checked + #trigger + #burger + #menu-top-nav {
    animation: checked-anim 1s ease both;
}
#menu-toggle:checked + #trigger ~ #menu-top-nav > li, a {
    display: block;
}
[type="checkbox"]:not(:checked), [type="checkbox"]:checked {
    display: none;
}

</style>


<input type="checkbox" id="menu-toggle"/>
  <label id="trigger" for="menu-toggle"></label>
  <label id="burger" for="menu-toggle"></label>
  <ul id="menu-top-nav">
    <li><a href="#">Home</a></li>
    <li><a href="#">About</a></li>
    <li><a href="#">Portfolio</a></li>
    <li><a href="#">Contact</a></li>
  </ul>