Cutom CSS code to get the old font style back.
Before installing the style, make sure you have installed the user style manager extension to your browser, such as Stylus (recommended) or Stylish.
After adding the extension to your browser, you can now install the style. There are two options:
You can directly download the style here and everything will automatically be set up.
Here's an example of how to manually install the style to your browser with Stylus. Firstly, go to Tumblr and click the Stylus icon on the toolbar. When the dropdown menu appears, click "Manage".
Next you will be redirected to the management panel for all your installed styles. Now click "Write new style".
Finally, copy and paste the code into the style editor then click "Save".
Now you've successfully installed the style. If nothing has changed, try refresh the page or restart your browser.