<style>
body { overflow: hidden; }

summary.fixed {
    position: fixed;
    left: 50px;
    top: 150px;
}

summary.relative {
    position: relative;
    left: 150px;
    top: 150px;
}

summary.absolute {
    position: absolute;
    left: 250px;
    top: 150px;
}

</style>

<body>
    <details>
        <summary class="fixed">fixed</summary>
        <input>
    </details>
    <details>
        <summary class="relative">relative</summary>
        <input>
    </details>
    <details>
        <summary class="absolute">absolute</summary>
        <input>
    </details>
</body>