(Squarespace) Summary Block with Fullwidth item on top

[tuanphan]

#1. You need to use Summary Block Grid Layout.

#2. Next, find Summary Block ID.

In my example, it is: #block-yui_3_17_2_1_1738493272859_6666

#3. Use this code to Custom CSS box.
If code doesn’t work, you can comment below, message or email me.

#block-yui_3_17_2_1_1738493272859_6666 .summary-item:first-child {
    width: 100% !important;
}