You can actually combine both.
eg:
<!DOCTYPE html><html lang="en"><head><meta charset="UTF-8"><title>Title</title><style> .grid-1 { height: 60px; width: 200px; overflow: auto; } .grid-2 { height: 60px; width: 900px; overflow: auto; } /* here */ .nav { min-width: fit-content; max-width: 100%; position: sticky; top: 0; background: #da1039; } .rows { min-width: fit-content; max-width: 100%; display: flex; flex-direction: column; flex-wrap: nowrap; background: #00b89c; } .row { display: flex; flex-direction: row; flex-wrap: nowrap; justify-content: space-evenly; } .rowitem { border: 1px solid; min-width: 20px; }</style></head><body><div class="grid-1"><div class="nav"><div class="row"><div class="rowitem">HHH</div><div class="rowitem">HHH</div><div class="rowitem">HHH</div><div class="rowitem">HHH</div><div class="rowitem">HHH</div><div class="rowitem">HHH</div><div class="rowitem">HHH</div><div class="rowitem">HHH</div><div class="rowitem">HHH</div><div class="rowitem">HHH</div><div class="rowitem">HHH</div><div class="rowitem">HHH</div><div class="rowitem">HHH</div><div class="rowitem">HHH</div><div class="rowitem">HHH</div></div></div><div class="rows"><div class="row"><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div></div><div class="row"><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div></div><div class="row"><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div></div><div class="row"><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div></div><div class="row"><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div></div><div class="row"><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div></div><div class="row"><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div></div><div class="row"><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div></div><div class="row"><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div></div><div class="row"><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div></div></div></div></div><div style="height: 20px"></div><div class="grid-2"><div class="nav"><div class="row"><div class="rowitem">HHH</div><div class="rowitem">HHH</div><div class="rowitem">HHH</div></div></div><div class="rows"><div class="row"><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div></div><div class="row"><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div></div><div class="row"><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div></div><div class="row"><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div></div><div class="row"><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div></div><div class="row"><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div></div><div class="row"><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div></div><div class="row"><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div></div><div class="row"><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div></div><div class="row"><div class="rowitem">AAA</div><div class="rowitem">AAA</div><div class="rowitem">AAA</div></div></div></div></body></html>