csslearn/styles/style.css

body {
    display: grid;
    height: 100vh;
    place-items: center;
}

a {
    font-family: 'Courier New', Courier, monospace;
    font-size: 27px;
    font-weight: 700;
}

/* sliding effect */
.slidinglink  {
    line-height: 1.5;
    box-shadow: inset 0 0 0 0 #3282dd;
    color: #3282dd;
    padding: 0 .25rem;
    margin: 0 -.25rem;
    transition: color .3s ease-in-out, box-shadow .3s ease-in-out;
    text-decoration: none;
}

.slidinglink:hover  {
    color: rgb(255, 255, 255);
    box-shadow: inset 200px 0 0 0 #3282dd;
    text-decoration: none;
}

/*swappin effect*/

.swappinlink {
    overflow: hidden;
    position: relative;
    display: inline-block;
}
  
.swappinlink::before,
.swappinlink::after {
    content: '';
    position: absolute;
    width: 100%;
    left: 0;
}

.swappinlink::before {
    background-color: #54b3d6;
    height: 2px;
    bottom: 0;
    transform-origin: 100% 50%;
    transform: scaleX(0);
    transition: transform .3s cubic-bezier(0.76, 0, 0.24, 1);
}
.swappinlink::after {
    content: attr(data-replace);
    height: 100%;
    top: 0;
    transform-origin: 100% 50%;
    transform: translate3d(200%, 0, 0);
    transition: transform .3s cubic-bezier(0.76, 0, 0.24, 1);
    color: #54b3d6;
}

.swappinlink:hover::before {
    transform-origin: 0% 50%;
    transform: scaleX(1);
}
.swappinlink:hover::after {
    transform: translate3d(0, 0, 0);
}

.swappinlink span {
    display: inline-block;
    transition: transform .3s cubic-bezier(0.76, 0, 0.24, 1);
}

.swappinlink:hover span {
    transform: translate3d(-200%, 0, 0);
}

/**/
.growinglink {
    text-decoration: none;
    position: relative;
}

.growinglink::before {
    content: '';
    background-color: hsla(196, 61%, 58%, .75);
    position: absolute;
    left: 0;
    bottom: 3px;
    width: 100%;
    height: 4px;
    z-index: -1;
    transition: all .3s ease-in-out;
}

.growinglink:hover::before {
    bottom: 0;
    height: 100%;
}

/* r2l color swapping link */
.colorswapping {
    background-image: linear-gradient(
        to right,
        #54b3d6,
        #54b3d6 50%,
        #000 50%
    );
    background-size: 200% 100%;
    background-clip: text;
    background-position: -100%;
    display: inline-block;
    padding: 5px 0;
    position: relative;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    transition: all 0.3s ease-in-out;
}

.colorswapping:before {
    content: '';
    background: #54b3d6;
    display: block;
    position: absolute;
    bottom: 0px;
    left: 0;
    width: 0;
    height: 2px;
    transition: all 0.3s ease-in-out;
}

.colorswapping:hover {
    background-position: 0;
}

.colorswapping:hover::before {
    width: 100%;
}

/* the rainbow link */


.rainbowlink {
    color: inherit;
    text-decoration: none;
}

.rainbowlink {
    background:
        linear-gradient(
            to right,
            rgba(100, 200, 200, 1),
            rgba(100, 200, 200, 1)
        ),
        linear-gradient(
            to right,
            rgba(255, 0, 0, 1),
            rgba(255, 0, 180, 1),
            rgba(0, 100, 200, 1)
    );
    background-size: 100% 3px, 0 3px;
    background-position: 100% 100%, 0 100%;
    background-repeat: no-repeat;
    transition: background-size 400ms;                              
}
  
.rainbowlink:hover {
    background-size: 0 3px, 100% 3px;
}

/* passing underline */
.passinglink {
    position: relative;
}

.passinglink::before {
    content: '';
    position: absolute;
    width: 100%;
    height: 4px;
    border-radius: 4px;
    background-color: aqua;
    bottom: 0;
    left: 0;
    transform-origin: right;
    transform: scaleX(0);
    transition: transform .3s ease-in-out;
}

.passinglink:hover::before {
    transform-origin: left;
    transform: scaleX(1);
}