Клиентская оптимизация – как правильно выполнить css-анимацию для свойства box-shadow:
/* All HTML you need is <div class="box"></div> */
/* Create a simple white box, and add the shadow for the initial state */
.box {
position: relative;
display: inline-block;
width: 100px;
height: 100px;
border-radius: 5px;
background-color: #fff;
box-shadow: 0 1px 2px rgba(0,0,0,0.15);
transition: all 0.3s ease-in-out;
}
/* Create the hidden pseudo-element */
/* include the shadow for the end state */
.box:after {
content: '';
position: absolute;
width: 100%;
height: 100%;
opacity: 0;
border-radius: 5px;
box-shadow: 0 5px 15px rgba(0,0,0,0.3);
transition: opacity 0.3s ease-in-out;
}