quelle porte ?

<style>
    a {
        text-align: center;
        align-content: center;

        width: 100px;
        height: 100px;
        position: absolute;
    }

    #bonne-porte {
        left: 300px;
        top: 200px;
        background-color: green;
    }

    #mauvaise-porte {
        left: 500px;
        top: 200px;
        background-color: red;
    }

</style>

<a id="bonne-porte" href="4b.html">la bonne porte</a>

<a id="mauvaise-porte" href="4m.html">la mauvaise porte</a>