I'm not sure what you mean.

Do you want to change the font size in some of the tabs that are currently open?

You can use an extension to set a default font size and page zoom on web pages.

• Default FullZoom Level: https://addons.mozilla.org/firefox/addon/default-fullzoom-level/
• NoSquint: https://addons.mozilla.org/firefox/addon/nosquint/

You can change more than just the active/inactive tab fonts, etc.

Firefox users who prefer to change the font sizes, colors and fonts in general can edit the userchrome.css file directly which is located in the chrome directory of the Firefox profile folder. It can be that only a userchrome-example.css is available, just remove the -example part from the url in that case.

/*Change address bar font, color and size*/

1. urlbar {-moz-appearance: none !important;

font-family: Tahoma Bold !important; color: Black !important; font-size: 12pt !important; }

The above code changes the font of the address bar to Tahoma Bold with a font size of 12pt and the black color. Just replace the values with others if you prefer those.

/* Change status bar text color/size*/

1. status-bar {-moz-appearance: none !important; font: bold 12pt Arial; !important;

}

The code above changes the font of the status bar to 12pt Arial.

/* Active tab - good */ .tabbrowser-tab[selected="true"] .tabs-bottom, [class="close-button tabs-closebutton"] { font-weight: bold !important; background-color: rgb(220,220,220) !important; padding-left: 2% !important; padding-right: 2% !important;}

/* Inactive Tab - good */ .tabbrowser-tab:not([selected="true"]) { -moz-appearance: none !important;}

The code above puts more weight to the active tab. You can modify the fonts as well using the examples above.