pgadmin4/web/pgadmin/static/css/aci_tree.overrides.css

.aciTree .aciTreeText {
    font-family: 'Open Sans';
    font-size: 12px;
}

/* Hover over an element */
.aciTree .aciTreeLine.aciTreeHover .aciTreeItem  {
    background-color: #e7f2ff;
    border-color: #84acdd;
}

/* Selected element and in focus*/
.aciTree.aciTreeFocus .aciTreeFocus > .aciTreeLine .aciTreeItem {
    background-color: #e7f2ff;
}

/* Selected element but not in focus */
.aciTree .aciTreeSelected > .aciTreeLine .aciTreeItem {
    background-color: #e7f2ff;
    border-color: #84acdd;
}