Fix FSE Group Block Layout Property Overriding Custom CSS
TL;DR
WordPress FSE Group blocks with layout property automatically generate is-layout-* CSS classes that have higher specificity than custom CSS, causing size settings to be ignored. Solution: 1) Use "layout":{"type":"default"} in block annotation to avoid extra layout classes; 2) Use !important in CSS to force override; 3) Key: Add padding: 0 !important to clear the Group block's default padding.