# CommonHTML Output Processor Options

The options below control the operation of the CommonHTML output processor that is run when you include `'output/chtml'` in the `load` array of the `loader` block of your MathJax configuration, or if you load a combined component that includes the CommonHTML output jax. They are listed with their default values. To set any of these options, include a `chtml` section in your `MathJax` global object.

## The Configuration Block

    MathJax = {
      chtml: {
        scale: 1,                      // global scaling factor for all expressions
        minScale: .5,                  // smallest scaling factor to use
        mtextInheritFont: false,       // true to make mtext elements use surrounding font
        merrorInheritFont: true,       // true to make merror text use surrounding font
        mathmlSpacing: false,          // true for MathML spacing rules, false for TeX rules
        skipAttributes: {},            // RFDa and other attributes NOT to copy to the output
        exFactor: .5,                  // default size of ex in em units
        displayAlign: 'center',        // default for indentalign when set to 'auto'
        displayIndent: '0',            // default for indentshift when set to 'auto'
        matchFontHeight: true,         // true to match ex-height of surrounding font
        fontURL: '[mathjax]/components/output/chtml/fonts/woff-v2',   // The URL where the fonts are found
        adaptiveCSS: true              // true means only produce CSS that is used in the processed equations
      }
    };

## Option Descriptions

matchFontHeight: true

  This setting controls whether MathJax will scale the mathematics so that the ex-height of the math fonts matches the ex-height of the surrounding fonts. This makes the math match the surroundings better, but if the surrounding font does not have its ex-height set properly (and not all fonts do), it can cause the math to not match the surrounding text. While this will make the lower-case letters match the surrounding fonts, the upper case letters may not match (that would require the font height and ex-height to have the same ratio in the surrounding text as in the math fonts, which is unlikely).

fontURL: '[mathjax]/components/output/chtml/fonts/woff-v2'

  This is the URL to the location where the MathJax fonts are stored. In the default, `[mathjax]` is replaced by the location from which you have loaded MathJax. You should include a complete URL to the location of the fonts you want to use.

adaptiveCSS: true

  This setting controls how the CommonHTML output jax handles the CSS styles that it generates. When true, this means that only the CSS needed for the math that has been processed on the page so far is generated. When false, the CSS needed for all elements and all characters in the MathJax font are generated. This is an extremely large amount of CSS, and that can have an effect on the performance of your page, so it is best to leave this as `true`. You can reset the information about what CSS is needed by using the command

      MathJax.startup.document.output.clearCache();

  to clear the font cache.

The remaining options are described in the Options Common to All Output Processors section.