.slider {
    max-width: 400px;
    margin: 0 auto;
}

.slider__input {
    width: 100%;
}

.slider__image {
    display: block;
    margin: 20px auto;
    max-width: 100%;
}


#box {
    width: 50px;
    height: 50px;
    background-color: red;
}