This extension will not be updated. Kindly install Better Text View (https://addons.mozilla.org/en-US/firefox/addon/better-text-view/), which is parent version of Small Text Big and has same / more functionality, to get bug-fixes and new features. This extension enlarges text and makes it higher contrast, so that website text is easier to read. Font size within threshold is enlarged inversely with font size. That means small text made bigger than large text. Text contrast can be increased by the 'Strength' slider, with high positive values making text more black / white and negative values keeping text color unchanged. The strength slider also determines the Zoom %, with default zero strength giving 175% (1.75) zoom value. All text within size of Threshold setting is increased in size with text closer to Font Threshold size increasing less than text much lower size than Threshold, depending of Font Increase % setting.