Summary: Change color for only one

Site URL: https://wisteria-violin-nbre.squarespace.com/config/design/custom-css

All across my website I have one color as my summary background, but for my subscription page I need to match it to the other color on the page. Is there a special code so that it changes it on that one specific block? I don't want the color to change on my other pages. I tried using this code to match the background but It doesn't seem to be doing anything. I would really appreciate your help. Thank you.

#block-yui_3_17_2_1_1598738503000_45705{
background: #F2EBF8;
padding: 010px  ; 
text-align: left;
}

Hi,
What is the password of your website?

Best,
Leopold