Remove Template Design Feature

.square {
    display: none;
}

To add or override CSS: use the “Additional CSS” option in the customizer. https://ww.wp.xz.cn/support/article/appearance-customize-screen/

Learn to use the Chrome Developer Tools or Firefox Developer Tools to help you see and test changes to your CSS.

Clear the cache I don’t see that CSS added at all.

Right above it in the custom CSS, you have this line that does not belong in CSS. Delete it: wp_get_attachment_image()