CSS Sliding Underline

css-sliding-underline-animation.css

/* TOP TO BOTTOM */
.sliding-u-t-b {
    text-decoration: none;
    display: inline-block;
    border-bottom: 0px solid transparent;  
    width: 210px;
    transition: 0.5s ease;
    height: 25px;
}
.sliding-u-t-b:hover {
    border-bottom: 3px solid blue;
}

/* TOP TO BOTTOM */
.sliding-u-t-b {
display: inline-block;
}
.sliding-u-t-b:after {
content: '';
display: block;
height: 0;
width: 100%;
background: transparent;
transition: height .5s ease, background-color .5s ease;
}
.sliding-u-t-b:hover:after {
height: 3px;
background: blue;
}
/* BOTTOM TO TOP */
.sliding-u-b-t {
	display: inline-block;
	position: relative;
}
.sliding-u-b-t:after {
	content: '';
	position: absolute;
	bottom: 0;
	left: 0;
	height: 0px;
	width: 100%;
	background: transparent;
	-webkit-transition: all ease 0.5s;
	-moz-transition: all ease 0.5s;
	transition: all ease 0.5s;
}
.sliding-u-b-t:hover:after {
	height: 3px;
	background: blue;
}

.sliding-u-l-r {
    text-decoration: none;
    display: inline-block;
    border-bottom: 3px solid transparent;    
    width: 0px;
    transition: 0.5s ease;
    white-space: nowrap;
    height: 25px;
}
.sliding-u-l-r:hover {
    border-bottom: 3px solid blue;
    width: 200px;
}

/* LEFT TO RIGHT */
.sliding-u-l-r {
display: inline-block;
}
.sliding-u-l-r:after {
content: '';
display: block;
height: 3px;
width: 0;
background: transparent;
transition: width .5s ease, background-color .5s ease;
}
.sliding-u-l-r:hover:after {
width: 100%;
background: blue;
}

.sliding-u-r-l {
    display: inline-block;
    position: relative;
    padding-bottom: 3px;
}

.sliding-u-r-l:after {
    content: '';
    display: block;
    position: absolute;
    right: 0;
    bottom: 0;
    height: 3px;
    width: 0;
    background: transparent;
    transition: width .5s ease, background-color .5s ease;
}

.sliding-u-r-l:hover:after {
    width: 100%;
    background: blue;
}

.sliding-middle-out {
	display: inline-block;
	position: relative;
	padding-bottom: 3px;
}
.sliding-middle-out:after {
	content: '';
	display: block;
	margin: auto;
	height: 3px;
	width: 0px;
	background: transparent;
	transition: width .5s ease, background-color .5s ease;
}
.sliding-middle-out:hover:after {
	width: 100%;
	background: blue;
}

.sliding-u-l-r-l {
    display: inline-block;
    position: relative;
    padding-bottom: 3px;
}
.sliding-u-l-r-l:before {
    content: '';
    display: block;
    position: absolute;
    left: 0;
    bottom: 0;
    height: 3px;
    width: 0;
    transition: width 0s ease, background .5s ease;
}
.sliding-u-l-r-l:after {
    content: '';
    display: block;
    position: absolute;
    right: 0;
    bottom: 0;
    height: 3px;
    width: 0;
    background: blue;
    transition: width .5s ease;
}
.sliding-u-l-r-l:hover:before {
    width: 100%;
    background: blue;
    transition: width .5s ease;
}
.sliding-u-l-r-l:hover:after {
    width: 100%;
    background: transparent;
    transition: all 0s ease;
}

.sliding-u-l-r-l-inverse {
    display: inline-block;
    position: relative;
    padding-bottom: 3px;
}
.sliding-u-l-r-l-inverse:before {
    content: '';
    display: block;
    position: absolute;
    left: 0;
    bottom: 0;
    height: 3px;
    width: 100%;
    transition: width 0s ease;
}
.sliding-u-l-r-l-inverse:after {
    content: '';
    display: block;
    position: absolute;
    right: 0;
    bottom: 0;
    height: 3px;
    width: 100%;
    background: blue;
    transition: width .5s ease;
}
.sliding-u-l-r-l-inverse:hover:before {
    width: 0%;
    background: blue;
    transition: width .5s ease;
}
.sliding-u-l-r-l-inverse:hover:after {
    width: 0%;
    background: transparent;
    transition: width 0s ease;
}