Unable to apply custom styling an HTML field (TinyMCE editor); cannot set a custom background-colorIssue <!-- div.margin { padding: 10px 40px 40px 30px; } table.tocTable { border: 1px solid; border-color: #e0e0e0; background-color: #fff; } .title { color: #d1232b; font-weight: normal; font-size: 28px; } h1 { color: #d1232b; font-weight: normal; font-size: 21px; margin-bottom: 5px; border-bottom-width: 2px; border-bottom-style: solid; border-bottom-color: #cccccc; } h2 { color: #646464; font-weight: bold; font-size: 18px; } h3 { color: #000000; font-weight: bold; font-size: 16px; } h4 { color: #666666; font-weight: bold; font-size: 15px; } h5 { color: #000000; font-weight: bold; font-size: 13px; } h6 { color: #000000; font-weight: bold; font-size:14px; } ul, ol { margin-left: 0; list-style-position: outside; } --> Symptoms On the platform side, the typical way of applying custom styling to fields is right-clicking the label of a field and choosing Configure Styles. In case of wanting to set a custom background color, you simply fill in something like 'background-color: #000;' under 'Styles' . However, this does not work on the HTML field type, aka the TinyMCE editor. Also, trying to target the same type of field on Service Portal with custom CSS on the Widget does not work. Release All Cause The TinyMCE editor is a third-party editor and so ServiceNow has limited control over it. Resolution Unfortunately, there is no OOB method for changing the background color of the TinyMCE editor.