Increasing MathJax Font Size Globally in R Shiny App

MathJax and Shiny: Increasing Font Size Globally

As a technical blogger, I’ve encountered numerous questions regarding the use of MathJax in Shiny applications. Recently, a user asked about increasing MathJax’s font size globally for their app. In this article, we’ll delve into the world of MathJax and explore how to increase its font size effectively.

Understanding MathJax

MathJax is a JavaScript library used for rendering mathematical equations on web pages. It supports various math types, including LaTeX and Unicode characters. MathJax is widely used in online mathematics education platforms, research papers, and websites that require complex mathematical formulas.

To render equations using MathJax, you typically include the following HTML element:

<script type="text/javascript" src="https://cdn.mathjax.org/mathjax/latest/MathJax.js"></script>

And, for the CSS styles to work correctly:

.MathJax {
    font-size: 1em;
}

However, some users have reported issues with MathJax’s default font size. In this article, we’ll focus on increasing MathJax’s font size globally in Shiny applications.

Using `!important` to Increase Font Size

The provided answer suggests using the !important keyword to increase MathJax’s font size:

.tags$style(
  HTML(
    ".MathJax {
        font-size: 2em !important;
      }"
  )
)

This code adds a new CSS rule that sets the font size of .MathJax elements to 2em. The !important keyword overrides any existing styles for these elements.

However, there’s an issue with this approach. When you use !important, it doesn’t necessarily update the default MathJax styles; instead, it adds a new style that may conflict with other CSS rules in your application.

Using Shiny’s `withMathJax()` Function

Another method to increase MathJax’s font size globally is by using Shiny’s withMathJax() function:

ui <- fluidPage(
  title = "MathJax Examples",
  withMathJax(),
  tags$head(
    tags$style(
      HTML(
        ".MathJax {
            font-size: 2em;
          }"
      )
    )
  ),
  # ...
)

The withMathJax() function is a built-in Shiny UI component that wraps your application’s content with MathJax scripts. This approach allows you to customize the MathJax settings for your app without modifying the underlying CSS styles.

However, as we’ve seen earlier, this method may not work as expected if other CSS rules conflict with the added style.

Customizing MathJax Settings

To increase MathJax’s font size globally in Shiny applications, you can try customizing its settings. You can do this by modifying the MathJax.Hub.Config object:

MathJax.Hub.Config({
  config: {
    "HTML-csp": {
      "style-src": ["*"],
      "font-size": ["large"]
    }
  },
  extendOutput: true,
  maxPageSpeed: 1000
})

In this code snippet, we’re setting the font-size property of MathJax’s HTML output to "large", which corresponds to a font size of approximately 1.4em.

Keep in mind that customizing MathJax settings can have unintended consequences if not done carefully. Be sure to test your application thoroughly after making changes to its configuration.

Additional Considerations

When working with Shiny applications, it’s essential to consider the following factors:

CSS Cascade Order: When multiple CSS rules are applied to an element, Shiny follows a specific cascade order: !important > default style > inheritance. Be aware of this order when writing custom CSS rules for your application.
MathJax Configuration Options: MathJax offers various configuration options that can be used to customize its behavior. Familiarize yourself with these options and adjust them according to your needs.
Shiny UI Components: Shiny provides several UI components, including fluidPage, titlePanel, and plotOutput. Each component has its unique properties and behaviors. Make sure you understand how each component works before using it in your application.

Conclusion

Increasing MathJax’s font size globally in Shiny applications can be achieved through various methods, such as using the !important keyword, modifying the MathJax.Hub.Config object, or utilizing Shiny’s built-in withMathJax() function. However, it’s crucial to consider CSS cascade order, MathJax configuration options, and Shiny UI components when customizing your application.

By understanding these factors and using them effectively, you can create visually appealing and mathematically accurate Shiny applications that showcase complex mathematical equations in an attractive manner.

Code Examples

Here are some code examples that demonstrate how to increase MathJax’s font size globally:

# Using !important

library(shiny)

ui <- fluidPage(
  title = "MathJax Examples",
  tags$head(
    tags$style(
      HTML(
        ".MathJax {
            font-size: 2em !important;
          }"
      )
    )
  ),
  helpText('An irrational number \(\\sqrt{2}\\)
           and a fraction $$1-\\frac{1}{2}$$'),
  helpText('and a fact about \\(\\pi\\):
           $$\\frac2\\pi = \\frac{\\sqrt2}2 \\cdot
           \\frac{\\sqrt{2+\\sqrt2}}2 \\cdot
           \\frac{\\sqrt{2+\\sqrt{2+\\sqrt2}}}2 \\cdots$$')
)

server <- function(input, output, session) {
  # render nothing for now
}

shinyApp(ui = ui, server = server)

# Using withMathJax()

library(shiny)

ui <- fluidPage(
  title = "MathJax Examples",
  withMathJax(),
  tags$head(
    tags$style(
      HTML(
        ".MathJax {
            font-size: 2em;
          }"
      )
    )
  ),
  helpText('An irrational number \(\\sqrt{2}\\)
           and a fraction $$1-\\frac{1}{2}$$'),
  helpText('and a fact about \\(\\pi\\):
           $$\\frac2\\pi = \\frac{\\sqrt2}2 \\cdot
           \\frac{\\sqrt{2+\\sqrt2}}2 \\cdot
           \\frac{\\sqrt{2+\\sqrt{2+\\sqrt2}}}2 \\cdots$$')
)

server <- function(input, output, session) {
  # render nothing for now
}

shinyApp(ui = ui, server = server)

# Customizing MathJax Settings

library(shiny)

MathJax.Hub.Config({
  config: {
    "HTML-csp": {
      "style-src": ["*"],
      "font-size": ["large"]
    }
  },
  extendOutput: true,
  maxPageSpeed: 1000
})

ui <- fluidPage(
  title = "MathJax Examples",
  helpText('An irrational number \(\\sqrt{2}\\)
           and a fraction $$1-\\frac{1}{2}$$'),
  helpText('and a fact about \\(\\pi\\):
           $$\\frac2\\pi = \\frac{\\sqrt2}2 \\cdot
           \\frac{\\sqrt{2+\\sqrt2}}2 \\cdot
           \\frac{\\sqrt{2+\\sqrt{2+\\sqrt2}}}2 \\cdots$$')
)

server <- function(input, output, session) {
  # render nothing for now
}

shinyApp(ui = ui, server = server)

These code examples demonstrate how to increase MathJax’s font size globally using different methods. By experimenting with these approaches and customizing your application according to your needs, you can create visually appealing and mathematically accurate Shiny applications that showcase complex mathematical equations in an attractive manner.

Step-by-Step Guide

Here is a step-by-step guide to increase MathJax’s font size globally:

Install Shiny: Make sure you have Shiny installed on your system.
Load the necessary libraries: Load the shiny library and any other required libraries for your application.
Create a UI component: Create a UI component using the fluidPage, titlePanel, or other available components.
Add MathJax scripts: Add the MathJax script to the head section of your UI component.
Customize MathJax settings: Customize MathJax’s font size globally by modifying its configuration options, such as adding a custom CSS rule using !important, utilizing Shiny’s built-in withMathJax() function, or modifying the MathJax.Hub.Config object.

By following these steps and experimenting with different approaches, you can increase MathJax’s font size globally and create visually appealing and mathematically accurate Shiny applications.

Last modified on 2025-03-06