<style>
    #details-element{
        padding: 1rem;
        border: 1px solid;
        margin: 1rem;
        border-radius: 0.4rem;
        cursor: pointer;
    }

    #details-element[open] {
        border-color: lightgreen !important;
    }
</style>
<details id="details-element">
    <summary>Show more details</summary>
    <p>Lorem ipsum dolor sit amet consectetur adipisicing elit. Commodi tempore rerum possimus. Ipsum temporibus consequuntur saepe aliquid quis deserunt quisquam a odit voluptatum eveniet?</p>
</details>