You can edit and customize the background for any Tumblr theme. However, the options available to fix your theme background vary depending on the theme you have installed on the blog. You can perform certain fixes for some themes, like changing the background color, in the Customize tool. The Customize tool enables you to change theme elements without directly editing HTML code. The default Tumblr theme enables you to change the background color from the tool. However, you can also access the HTML code to fix theme issues using the HTML editor.

Theme Variations

The Tumblr platform provides a set of tools for the non-techical blogger to use to customize her blogs. However, the options available to you when fixing your Tumblr blog background are limited to the flexibility of your theme. For example, some themes provide a method for uploading background images through the interface without editing code, some themes provide both background color and image options, but for other themes these options are not available. However, experienced coders can directly modify the HTML and CSS in any Tumblr theme.

Customize Tool

Open the Customize tool by logging in to your Tumblr dashboard and then clicking the name of the blog to edit in the right sidebar menu. Click the “Customize” link under the blog name to open the theme with the Customize tool. Check for one or more entries named “Background” in the Appearance section of the Customize menu. For example, the default theme will have an option for changing the background color. Click the color swatch in the “Background” entry to open the color picker. Click the desired color, then click “Save” to save your background settings. For some themes, you can upload a background image using the Customize tool.

Edit HTML

Open the HTML code page for the theme by clicking the “Edit HTML” link in the Customize tool under the name of the theme. To edit the background HTML or CSS code, locate the “background” tags in the code. Change the "content=" attribute in the "color:Background" tag to the hex code for the desired color. To change the background image, replace the existing URL in the "image:Background" tag with the URL to the background image to apply. Click "Update Preview" to view the changes in the Preview window, then click "Save" to save the modifications. Click “Exit” to close the tool and return to your dashboard.

Find Tool

To quickly locate the background tags in the HTML code, open the Find tool by pressing “Ctrl-F.” The Find toolbar opens at the top of the HTML editor. Type “background” in the Search field to find each instance of the “background” tag. Edit the background color, image and other attributes; when finished, click “Update Preview“ and then "Save."

Additional Theme Customizations

To change the hyperlink color, click the color swatch in the "Link" entry, if available, then click the desired color from the color picker. On some themes, you can also enable and disable the Endless Scrolling and Notes features from the Customize tool. All themes include the "Add a Page" tab, which enables you to add standalone pages to each of your blogs. Disqus-enabled themes provide a field for your Disqus short name. When this field is populated, Disqus comment sections are integrated into each of your posts.