Changing the font size also changes the font to a more readable one. You can change the font size on any website (including this one). Most popular browsers support the following keyboard shortcuts for increasing/decreasing the magnification level:
Windows:

Press the Ctrl and the + (plus) keys together to increase.
Press the Ctrl and the – (minus) keys together to decrease.
Press the Ctrl and the 0 (zero) keys together to reset the size.

Mac:

Press the Cmd and the + (plus) keys together to increase the size of the entire page content. Hold down the ⌥ (option) key as well to increase the font size alone.
Press the Cmd and the – (minus) keys together to decrease the size of the entire page content. Hold down the ⌥ (option) key as well to decrease the font size alone.
Press the Cmd and the 0 (zero) keys together to reset all content to its default size (normally 100%).

Press the Ctrl and the + (plus) keys together to increase.
Press the Ctrl and the – (minus) keys together to decrease.
Press the Ctrl and the 0 (zero) keys together to reset the size.

Mac:

Press the Cmd and the + (plus) keys together to increase the size of the entire page content. Hold down the ⌥ (option) key as well to increase the font size alone.
Press the Cmd and the – (minus) keys together to decrease the size of the entire page content. Hold down the ⌥ (option) key as well to decrease the font size alone.
Press the Cmd and the 0 (zero) keys together to reset all content to its default size (normally 100%).