EDS 296: Part 4.1

Theming and styling apps with {bslib} & {fresh}

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Creating custom themes

We’ve built some really cool apps so far, but they all have a pretty standard and similar appearance. In this section, we’ll explore two packages for creating custom themes for your apps.

Learning Objectives - Theming/Styling Apps

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By the end of this section, you should be equipped with:

an understanding of how to use packaged-based tooling for theming and styling your shiny apps and dashboards

Packages introduced:

{bslib}: provides tools for customizing Bootstrap themes directly from R for shiny apps and RMarkdown documents

{fresh}: provides tools for creating custom themes for use with shiny, shinydashboard, and bs4Dash apps

{bslib} & {fresh} both provide tooling for theming your applications

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We won’t cover all the major differences here, but you’ll often find the following recommendations:

Use {bslib} for shiny apps

• Shiny’s default UI components (e.g. fluidPage(), sidebarLayout()) are styled using Bootstrap, a popular front-end framework for designing responsive web applications. The {bslib} package provides tools for modifying Bootstrap variables.
• Try out themes using the real-time theming widget before applying them to your own app

Use {fresh} for shinydashboards

• {bslib} is not (currently) compatible with {shinydashboard}
• {shinydashboard} is built on the AdminLTE framework. {fresh} is specifically designed to modify AdminLTE elements.

{bslib} practice

Let’s start by applying a pre-built Bootswatch theme to our single-file-app using {bslib}, then create / apply a more customized theme.

Apply a pre-built theme with {bslib}

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Apply a pre-built bootswatch theme using bs_theme() (for a list of theme names, run bootswatch_themes() in your console):

~/single-file-app/ui.R

library(shiny)
library(bslib)
# ~ additional libraries omitted for brevity ~

ui <- fluidPage(
  
  theme = bs_theme(bootswatch = "solar"),
  
  # ~ additional UI code omitted for brevity ~
  
)

Check out the complete source code for App #1 (NOTE: applied themes are commented out).

Create a custom theme with {bslib}

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Alternatively, you can customize your own theme. Explore the {bslib} pkgdown site for detailed instructions. A small example here:

~/single-file-app/ui.R

library(shiny)
library(bslib)
# ~ additional libraries omitted for brevity ~

ui <- fluidPage(
  
  theme = bs_theme(
    bg = "#A36F6F", # background color
    fg = "#FDF7F7", # foreground color
    primary = "#483132", # primary accent color
    base_font = font_google("Pacifico")),
  
  # ~ additional UI code omitted for brevity ~
  
)

Check out the complete source code for App #1 (NOTE: applied themes are commented out).

{fresh} practice

We can use {fresh} to theme both shiny apps and dashboards, and the process is a little bit more involved than using {bslib}. Let’s practice on both our two-file-app and our shinydashboard

A general workflow for using {fresh} themes

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Whether you’re working on a shiny app or a shiny dashboard, you’ll need the following:

(1) a www/ folder within your app’s directory – this is where we’ll save the stylesheet (a .css file) that {fresh} will generate for us

(2) a separate script for building our theme using the create_theme() function – I recommend saving this to scratch/ (it seemed to cause issues when saved anywhere within my app directory)

Importantly, create_theme() takes different variables to set the parameters of your theme, depending on what type of app you’re building: for shiny apps, you’ll need to use bs_vars_* variables, and for shiny dashboards you’ll use adminlte_* variables (examples on the following slides).

There are also a couple ways to apply your finished theme to your app, but we’ll use the method of generating a .css file, then calling that file in our app.

Creating a {fresh} theme for two-file-app

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In this example, we update the colors of our app’s body, navbar, and tabPanels using the appropriate {fresh} variables for shiny apps. We specify a file path, two-file-app/www (you’ll need to create the www/ directory, since we don’t have one yet), where our stylesheet (e.g. app-fresh-theme.css, as shown here) file will be saved to. Of course, these color combos are not recommended, but chosen purely for demonstration purposes .

~/scratch/create-fresh-theme-app.R

# load library ----
library(fresh)

# create theme -----
create_theme(
  
  theme = "default", # you can supply a bootstrap theme to begin with
  
  bs_vars_global( # global styling
    body_bg = "#D2D0CA", # beige
    text_color = "#F23ACB", # hot pink
    link_color = "#0E4BE3" # royal blue
  ),
  
  bs_vars_navbar( # navbar styling
    default_bg = "#13CC13", # lime green
    default_color = "#66656C" # gray
  ),
  
  bs_vars_tabs( # tab styling
    border_color = "#F90909" # red
  ),
  
  output_file = here::here("two-file-app", "www", "app-fresh-theme.css") # generate css file & save to www/
)

Apply a {fresh} theme to our app

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To apply our theme, provide the theme argument of your fluidPage() or navbarPage() with the name of our stylesheet. Note: shiny knows to look in the www/ directory, so you can omit that from your file path, as shown below:

~/two-file-app/ui.R

# navbar page ----
ui <- navbarPage(

  theme = "app-fresh-theme.css",
  
  # ~ additional UI code omitted for brevity ~
  
) # END navbarPage

Check out the complete source code for App #2 (NOTE: applied themes are commented out).

Creating a {fresh} theme for our shinydashboard

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In this example, we update the colors of our app’s header, body, and sidebar using the appropriate {fresh} variables for shiny dashboards. We specify a file path, shinydashboard/www/ where our stylesheet (e.g. dashboard-fresh-theme.css, as shown here) file will be saved to. Again, these color combos are not recommended, but chosen purely for demonstration purposes.

~/scratch/create-fresh-theme-dashboard.R

# load libraries ----
library(fresh)

# create theme ----
create_theme(
  
  # change "light-blue"/"primary" color
  adminlte_color(
    light_blue = "#150B5A" # dark blue
  ),
  
  # dashboardBody styling (includes boxes)
  adminlte_global(
    content_bg = "#E7B5B5" # blush pink
  ),
  
  # dashboardSidebar styling
  adminlte_sidebar(
    width = "400px", 
    dark_bg = "#57F8F3", # light blue
    dark_hover_bg = "#BF21E6", # magenta
    dark_color = "#F90000" # red
  ),
  output_file = here::here("shinydashboard", "www", "dashboard-fresh-theme.css") # generate css file & save to www/
)

Apply a {fresh} theme to our dashboard

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To apply our theme, use the fresh::use_theme() function inside your dashboardBody, providing it with the name of your stylesheet. Note: shiny knows to look in the www/ directory, so you can omit that from your file path, as shown below:

~/shinydashboard/ui.R

body <- dashboardBody(
  
  # set theme
  fresh::use_theme("dashboard-fresh-theme.css"),
  
  # ~ additional dashboardBody code omitted for brevity ~
  
)

Check out the complete source code for the shinydashboard (NOTE: applied themes are commented out).

End part 4.1

Up next: fully custom themes using CSS & Sass

05:00