HTMLify

body {
    margin: 5% auto 0 auto;
    width: 90%;
    max-width: 1125px;
    background-color: #151515;
}

input,
span,
label {
    font-family: "Ubuntu", sans-serif;
    display: block;
    margin: 10px;
    padding: 5px;
    border: none;
}

input:focus {
    outline: 0;
}

input.input__control {
    font-size: 2.5rem;
    font-weight: 300;
    border-radius: 2px;
    margin: 0;
    border: none;
    width: 80%;
    background-color: transparent;
    color: #fff;
    transition: padding-top 0.2s ease, margin-top 0.2s ease;
    overflow-x: hidden;
}

input.input__control+label {
    display: block;
    position: relative;
    white-space: nowrap;
    padding: 0;
    margin: 0;
    width: 10%;
    border-top: 1px solid #388bff;
    transition: width 0.4s ease;
    height: 0;
}

input.input__control:focus+label {
    width: 80%;
}

input.input__control:focus,
input.input__control:valid {
    padding-top: 35px;
}

input.input__control:focus+label>span,
input.input__control:valid+label>span {
    top: -100px;
    font-size: 1.4rem;
    color: #fff;
}

input.input__control:valid+label {
    border-color: #00cb00;
}

input.input__control+label>span {
    font-weight: 300;
    margin: 0;
    position: absolute;
    color: #8f8f8f;
    font-size: 3rem;
    top: -66px;
    left: 0px;
    z-index: -1;
    transition: top 0.2s ease, font-size 0.2s ease, color 0.2s ease;
}

@keyframes appear {
    100% {
        opacity: 1;
    }
}