This...

Come and look at the code; communicate at any time:

HTML:

    <p>
        <ul>
            <li></li>
            <li></li>
            <li></li>
            <li></li>
            <li></li>
            <li></li>
            <li></li>
            <li></li>
            <li></li>
            <li></li>
            <li></li>
            <li></li>
        </ul>
    </p>
    
    
    

CSS:

    p{
        width: 996px;
        height: 120px;
        overflow-x:auto;
        overflow-y:hidden;  
    }
    ul{
        width: 1990px;
    }
    li{
        width: 220px;
        height: 300px;
        margin: 10px;
        float: left;
        background: red;
    }

ul li writes and then li float, display block

In the same building, put another p on the outer layer, and set the overflow-x of the outer p: auto