Hide the Title Bar:
       Open Firefox.
       Click on the menu button (three horizontal lines) in the upper right corner.
       Go to Customize.
       In the customization tab, look for the option that says "Title Bar" and uncheck it. This will remove the title bar.

   Hide the Menu Bar:
       If you have the menu bar visible, you can hide it by right-clicking on the menu bar area and unchecking "Menu Bar".

   Use Compact Mode:
       In the same Customize menu, you can also select "Density" and choose "Compact" to make the interface elements smaller.

   Enable UserChrome.css:
       Type about:config in the URL bar and press Enter.
       Search for toolkit.legacyUserProfileCustomizations.stylesheets and set it to true.

   Create the userChrome.css File:
       Navigate to your Firefox profile directory. You can find it by typing about:support in the URL bar and looking for the "Profile Directory" entry.
       Inside your profile directory, create a folder named chrome if it doesn't already exist.
       Inside the chrome folder, create a file named userChrome.css.

   Add CSS Rules:
       Open the userChrome.css file in a text editor and add the following CSS rules to hide the URL bar and other elements:

   /* Hide the URL bar */
   #urlbar {
       display: none !important;
   }

   /* Hide the tab bar */
   #TabsToolbar {
       display: none !important;
   }

   /* Hide the title bar */
   #titlebar {
       display: none !important;
   }

   /* Hide the menu bar */
   #toolbar-menubar {
       display: none !important;
   }

   Restart Firefox:
       Close and reopen Firefox for the changes to take effect.

Method 1: Customize Firefox's Interface Hide the Title Bar: Open Firefox. Click on the menu button (three horizontal lines) in the upper right corner. Go to Customize. In the customization tab, look for the option that says "Title Bar" and uncheck it. This will remove the title bar. Hide the Menu Bar: If you have the menu bar visible, you can hide it by right-clicking on the menu bar area and unchecking "Menu Bar". Use Compact Mode: In the same Customize menu, you can also select "Density" and choose "Compact" to make the interface elements smaller. Method 2: Use a UserChrome.css File If you want more control over the appearance, you can use a userChrome.css file to customize the Firefox interface further. Enable UserChrome.css: Type about:config in the URL bar and press Enter. Search for toolkit.legacyUserProfileCustomizations.stylesheets and set it to true. Create the userChrome.css File: Navigate to your Firefox profile directory. You can find it by typing about:support in the URL bar and looking for the "Profile Directory" entry. Inside your profile directory, create a folder named chrome if it doesn't already exist. Inside the chrome folder, create a file named userChrome.css. Add CSS Rules: Open the userChrome.css file in a text editor and add the following CSS rules to hide the URL bar and other elements: css /* Hide the URL bar */ #urlbar { display: none !important; } /* Hide the tab bar */ #TabsToolbar { display: none !important; } /* Hide the title bar */ #titlebar { display: none !important; } /* Hide the menu bar */ #toolbar-menubar { display: none !important; } Restart Firefox: Close and reopen Firefox for the changes to take effect. Method 3: Use a Firefox Add-on You can also look for add-ons that allow you to customize the Firefox interface. Some add-ons may provide options to hide specific UI elements. Note Keep in mind that while these methods can help you achieve a cleaner look, they may also limit your access to certain features and controls. You can always revert the changes if needed.