style.css

*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body{
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    background: #27282c;
    gap: 200px;
    flex-direction: column;
}

a{
    position: relative;
    background: #fff;
    color: #fff;
    text-decoration: none;
    text-transform: uppercase;
    font-size: 1.5em;
    letter-spacing: 0.1em;
    font-weight: 400;
    padding: 10px 30px;
    transition: 0.5s;
}

a:hover{
    color: var(--clo);
    background: var(--clo);
    letter-spacing: 0.25em;
    box-shadow: 0 0 35px var(--clo);
}

a:before{
    content: '';
    position: absolute;
    inset: 2px;
    background: #27282c;
}

a span{
    position: relative;
    z-index: 1;
}

a i{
    position: absolute;
    inset: 0;
    display: block;
}

a i::before{
    content: '';
    position: absolute;
    top: 0;
    left: 80%;
    width: 10px;
    height: 4px;
    background-color: #27282c;
    transform: translateX(-50%) skewX(325deg);
    transition: 0.5s;
}

a:hover i::before{
    width: 20px;
    left: 20%;
}

a i::after{
    content: '';
    position: absolute;
    bottom: 0;
    left: 20%;
    width: 10px;
    height: 4px;
    background-color: #27282c;
    transform: translateX(-50%) skewX(325deg);
    transition: 0.5s;
}

a:hover i::after{
    width: 20px;
    left: 80%;
}

a i.box::before{
    height: 7px;
    top: -3.5px;
    border: 2px solid var(--clo);
}

a i.box::after{
    top: -3.5px;
    height: 7px;
    border: 2px solid var(--clo);
}

#btn{
    background: none;
    border: none;
    padding: 15px 40px;
    color: #fff;
    position: relative;
    display: inline-block;
    font-size: 25px;
    cursor: pointer;
    text-transform: uppercase;
    transition: all 0.2s ease-in-out;
}

#btn::before,
#btn::after{
    content: '';
    position: absolute;
    width: 40px;
    height: 25px;
    border: 1px solid #7fffd4;
    transform: skew(-30deg);
    transition: all 0.4s ease-in-out;
}

#btn::before{
    bottom: 0;
    left: 0;
    border-width: 0 0 3px 3px;
}

#btn::after{
    top: 0;
    right: 0;
    border-width: 3px 3px 0 0;
}

#btn:hover{
    color: #222;
}

#btn:hover::before,
#btn:hover::after{
    background: #7fffd4;
    width: 99%;
    height: 99%;
    z-index: -1;
    transform: scale(.8,.8) skew(-30deg);
}