It would helpful to add more detail to your request. Can you clarify
- "change the size of an image" - do you mean the Add-on icon? do you mean an image displayed in the view?
- "the style is being referenced to jive.css file" - this shouldn't happen if you are using add-on security with an apps domain. Are you on-prem?
Screenshots of Chrome with inspector or a code sample would be most helpful.
I have added the screenshots for your reference
We have created a custom add-on for a functionality to create accounts in another application. The add-on functionality is available below the Apps menu from the pencil icon.
When we click on the function here the below screen opens.
I have marked the image which needs to be changed in a blue box. We need to increase it to 18px. It is currently taking the default 16px. Is there any option to change the size of the image which is marked in blue box.
The use of the 16x16, 64x64 and 128x128 icons by the add-on are probably something you can't change.
But, since you have a custom theme, you can change this in the CSS. I would would probably update the template to show the 64x64 icon and then downsize it to 18x18