Sometimes an issue is easily solved by implementing some codes to change and fix the elements of your theme. Most of the time, when a user reports an issue, we provide the CSS to directly solve the issue. As a lot of users are not familiar with the HTML codes, Tumblr made a simple inbox where you can put the CSS easily.
- Click ‘Customize’ button on your blog
- On the bottom of Edit theme menu, there’s ‘Advanced menu’. Click it.
- And you will see the ADD CUSTOM CSS inbox. Put your code there.
Also, when you are installing a theme, make sure you remove those Custom CSSs to prevent your previous theme from massing up the newly installed one.