HTMLify

* {
    box-sizing: border-box;
}

html,
body {
    height: 100%;
}

body {
    display: grid;
    font-family: Avenir;
    -webkit-text-size-adjust: 100%;
    -webkit-font-smoothing: antialiased;
    overflow: hidden;
    background-color: #151515;
}

.input_control {
    position: relative;
    margin: auto;
    width: 100%;
    max-width: 280px;
    height: 53px;
}

.input_control .elastic_border {
    position: absolute;
    left: 0;
    bottom: 0;
    height: 18px;
    fill: none;
}

.input_control .elastic_border path {
    stroke: #fff;
    stroke-width: 2;
}

.input_control .elastic_border path d {
    transition: all 0.2s ease;
}

.input_control .check {
    position: absolute;
    top: 20px;
    right: 20px;
    fill: none;
    transform: translate(0, 9px) scale(0);
    transition: all 0.3s cubic-bezier(0.5, 0.9, 0.25, 1.3);
    transition-delay: 0.15s;
}

.input_control .check path {
    stroke: rgb(65, 148, 243);
    stroke-width: 2;
}

.input_control input {
    appearance: none;
    width: 100%;
    border: 0;
    font-family: inherit;
    padding: 0;
    height: 48px;
    font-size: 16px;
    font-weight: 500;
    background: none;
    border-radius: 0;
    color: #fff;
    transition: all 0.15s ease;
}

.input_control input:focus {
    outline: none;
}

.input_control input:focus+.elastic_border path {
    stroke: rgb(65, 148, 243);
}

.input_control input:valid+.elastic_border path {
    animation: elasticInput 0.8s ease forwards;
}

.input_control input:valid+.elastic_border+.check {
    transform: translate(0, 0) scale(1);
}

::placeholder {
    color: #fff;
}

@keyframes elasticInput {
    33% {
        d: path("M0,12 L226,12 C220,12 220.666667,12 228,12 C239,12 245,1 253,1 C261,1 268,12 278,12 C284.666667,12 285.333333,12 280,12"
            );
    }

    66% {
        d: path("M0,12 L226,12 C220,12 220.666667,12 228,12 C239,12 245,17 253,17 C261,17 268,12 278,12 C284.666667,12 285.333333,12 280,12"
            );
    }
}