One thing I hate about firefox is how large its header is, using 2 graphical components: One title bar, and one tab pane.

Chrome just has the tabs, enlarging the web page area.

However, I don't trust chrome, I want to keep using firefox. So I installed this really useful addon that allows firefox to hide the titlebar and customize it:
https://addons.mozilla.org/pt-PT/firefox/addon/hide-caption-titlebar-plus-sma/

After installing the addon, go to the addon preferences and on "Look and feel 2" tab untick the "Enable custom Firefox Application "Home"" option.

Now go to "Look and Feel" tab, and on "Custom Minimize, Max & Close Buttons", select the one you prefer (I selected "Auto. Current Theme's Skin (fixed position)") and we got this: