Just pressing right or left button is no good for me - it makes too big skips. Using mouse by clicking and dragging the slide bar is better, but still I have a feeling that my hand is too rough and it doesn't scroll by pixels. How can I do horizontal scrolling by pixels? I am especially interested in Firefox and Chrome browsers.
In Chrome, I don't think there is a built-in way of single pixel scrolling. An alternative you might try is what they call "auto-scrolling", which is smooth scrolling and not high velocity. You hold down the middle mouse button or wheel and move the cursor in the direction you want the display to be moved.