If you are using the new layout designer, you can use the following CSS. Add the class "hide-header" to both tables and the class "top-table" to the top table and "bottom-table" to the bottom table.

/** Hides all table columns **/
.hide-header thead {
  display: none;
}
/** Removes gap between table elements **/
.hide-header table {
  margin-top: 0px;
  margin-bottom: 0px;
}
/** Removes minor spacing between table form fields **/
.line.ng-star-inserted:has(.hide-header) {
    margin: 0px;
    margin-top: -3px;
}
/** Hides table form field name area **/
.hide-header .section-title {
  display: none;
}
/** Removes top table's bottom padding **/
.top-table {
  padding-bottom: 0px;
}
/** Removes bottom table's top padding **/
.bottom-table {
  padding-top: 0px;
}