Ensure that elements mimicking buttons are focusable and keyboard accessible

Hi there!

In the current layout of some elements, such as buttons in the "View pull requests" dropdown menu, styles are applied to make them look like buttons, but in the HTML markup, they are not actual button elements (e.g., they might be div or span). This creates an accessibility issue, as these elements cannot be focused using the keyboard, making it more difficult for users who rely on keyboard navigation to interact with the interface.

This issue starts to create even bigger problems if you are using Vimium. Due to layout issues, there is no way to close the pop-up window using the keyboard

Steps to reproduce:

Open the "View pull requests" dropdown menu. Try to focus on the close element using the "Tab" key. Notice that the element cannot be focused and is not accessible for keyboard navigation. Expected result: All elements that look like buttons should be elements or have appropriate attributes (e.g., role="button") and should be focusable and interactable with the keyboard.

Suggested solution:

Replace elements that mimic buttons with actual elements or add necessary accessibility attributes (e.g., tabindex="0" and role="button"). Ensure that all interactive elements are keyboard accessible and can be activated via keyboard.