CSS输入框动效

<div class="input-box">
    <input type="text" required />
    <span>your name</span>
</div>

.input-box {
        position: relative;
        width: 200px;
        input {
            width: 100%;
            padding: 10px;
            border: 1px solid plum;
            border-radius: 5px;
            font-size: 1em;
            outline: none;
            &:valid~span,
            &:focus~span {
                color: aqua;
                transform: translateX(10px) translateY(-12px);
                padding: 0 10px;
                background-color: #fff;
            }
        }
        span {
            position: absolute;
            left: 0;
            top: 0;
            padding: 10px;
            font-size: 1em;
            pointer-events: none;
            columns: #ccc;
            transition: all 0.5s;
        }
}