A div sets the width 15%, adding: the inherit, set by the before, width, but the actual width exceeds the width of the div
< div class= "aside-left" >
< / div >
< style type= "text/css" >
.aside-left{
width: 15%;
float: left;
background-color:blue;
}
.aside-left::before{
content: "";
width: inherit;
position: absolute;
top: 0;
bottom: 0;
z-index: -1;
background-color: inherit;
border: inherit;
}
</style>
.aside-left285.59:before288