Background color on instagram block

Site URL: https://freeplayforkids.com/jrhome

Hello, 

How can I add a background color to an instagram block? 

I have tried the following code by placing it into custom css: 

#collection-601df060dbf6cd75be418f10 {
instagram-block {
   background-color: #ff5757;
 }
}

Add to Design > Custom CSS

/* Instagram color */
div#block-yui_3_17_2_1_1546551430935_8316 {
    background: green;
}