Why padding don’t change to the image block using css???

Hi dear forum friends,

As I was trying to apply CSS to one image block to make the padding as "0px", Squarespace does not change after I put the code in. What I put is 

#block-yui_3_17_2_1_1693717952231_38519 .sqs-layout:not(.sqs-editing) .sqs-block+.sqs-row .sqs-block:not(.float):first-child {
    padding-top: 0px !important;
}

the website : https://www.min-zhu.com/

The image I want to change the padding is the yellow image block. Anyone knows what is the issue? Thanks ! 

10 hours ago, Lesum said:

@MinZhu You can try adding this code:

#block-yui_3_17_2_1_1693717952231_38519 {
	padding: 0 !important;
}

@Lesum magic ! why so simple code solves this issue ??? I inspected the code with dev mode and is there a way to learn about coding? Where did you start mate?