Basics

library(shiny)
library(shinyglass)

ui <- glass_page(
  title = "Liquid Glass",
  persist = TRUE,
  scene = "tahoe",
  plotOutput("p")
)

glass_page() is fluidPage() plus [glass_theme()], the Light / Dark / Auto toggle, intensity slider, and accent wells. Pair it with [observe_glass()] in the server. For a bare page, still pass theme = glass_theme() to fluidPage() / navbarPage() / bslib::page_sidebar().

Presets

Light and dark surface tokens ship as dual CSS custom-property packs on [data-glass-preset]. Switching preset updates document.documentElement.dataset.glassPreset — no Sass recompile and no full page reload.

Runtime updates from the server

ui <- fluidPage(
  theme = glass_theme(preset = "auto"),
  glass_theme_toggle(selected = "auto"),
  selectInput("accent", "Accent", c(
    Blue = "#007AFF", Purple = "#AF52DE", Orange = "#FF9500"
  ))
)

server <- function(input, output, session) {
  observe_glass_theme_toggle(input, session)
  observeEvent(input$accent, {
    update_glass_theme(session, primary = input$accent)
  }, ignoreInit = TRUE)
}

update_glass_theme() accepts:

primary updates Bootstrap accent CSS variables so buttons, checked controls, and other accent surfaces follow without a reload. A few Sass-baked one-offs may still need a full reload to pick up a new color.

Theme toggle helper

ui <- fluidPage(
  theme = glass_theme(preset = "auto"),
  glass_theme_toggle(),           # Light / Dark / Auto buttons
  # ...
)

server <- function(input, output, session) {
  observe_glass_theme_toggle(input, session)
}

Buttons call window.shinyglass.setPreset() immediately and also fire Shiny inputs (glass_toggle_light, …) so the server can stay in sync.

Behavior knobs

glass_theme(
  preset = "auto",
  primary = "#AF52DE",
  blur = 36,
  saturation = 200,
  radius = "1.5rem",
  material = "regular", # or "clear" over media-rich content
  intensity = 0.45,     # 0 Ultra Clear → 1 Tinted (iOS 27)
  tint = TRUE,      # sample plot/image colors into glass surfaces
  specular = TRUE,  # pointer specular highlight
  nav_morph = TRUE  # compact navbar while scrolling down
)

material = "regular" is the adaptive Tahoe-style fill (default). Use "clear" when chrome sits over rich media and labels stay bold.

Use [glass_intensity_slider()] for a live Ultra Clear → Tinted control (same idea as iOS 27 Settings → Appearance → Liquid Glass):

glass_intensity_slider("glass_intensity", value = 0.45)

All three JS behaviors default to TRUE (same as 0.1.x). They respect prefers-reduced-motion: reduce where relevant. Advanced escape hatch: window.__shinyglassDisableTint = true still disables tint.

CSS variables (migration from 0.1.x)

Breaking in 0.2.0: light/dark surfaces are dual CSS packs, not a Bootswatch darkly rebuild. Prefer CSS custom properties over Sass $glass-* tokens when customizing:

:root {
  /* shared knobs also set by glass_theme(blur=..., radius=...) */
  --glass-blur: 36px;
  --glass-radius: 1.25rem;
  --bs-primary: #007AFF;       /* also updated by update_glass_theme(primary=) */
  --glass-primary: #007AFF;
}

:root[data-glass-preset="dark"] {
  /* override a dark-pack value if needed */
  --glass-bg: rgba(255, 255, 255, 0.1);
}

Apps that overrode Sass-only $glass-* tokens should target --glass-* or [data-glass-preset="dark"] instead.

Client helpers

window.shinyglass.setPreset("dark"); // or "light" / "auto"
window.shinyglass.getPreset();       // resolved "light" | "dark"
window.shinyglass.getMode();         // requested mode incl. "auto"
window.shinyglass.setTint(false);
window.shinyglass.setPrimary("#AF52DE");
window.shinyglass.getPrimary();

Teal

options(teal.bs_theme = glass_theme(preset = "auto"))
# then teal::init(...) as usual

Persistence

glass_theme(persist = TRUE) (and glass_page(), which defaults to on) writes preset, intensity, accent, material, and scene to localStorage for this app path so a refresh restores the last look.

Wallpaper scenes

glass_theme(scene = "tahoe") (or "dusk" / "mesh") swaps the page gradient and orbs. wallpaper = "https://..." paints a frosted photo behind the glass. Change scene live with update_glass_theme(session, scene = "dusk").

Plots that match the chrome

output$p <- renderPlot({
  ggplot2::ggplot(mtcars, ggplot2::aes(wt, mpg)) +
    ggplot2::geom_point() +
    theme_glass(input = input)
}, bg = "transparent")

[theme_glass()] is a ggplot2 theme with transparent panels and light/dark ink. [plotly_glass()] and [gt_theme_glass()] do the same for those packages. [glass_plot_colors()] returns ink, grid, fill, and paper.

Reduced motion

When the user prefers reduced motion (prefers-reduced-motion: reduce):

• Navbar morph transforms are disabled (JS + CSS)
• Pointer specular tracking is skipped
• Content tint sampling is skipped
• Decorative transitions on cards/inputs/nav are removed

This is automatic and responds to OS preference changes while the app is open. Reduced-transparency changes also update the surfaces without changing the requested slider value.

To disable only the idle decorative animation, use glass_theme(ambient_motion = FALSE). To disable all optional effects, use:

glass_theme(tint = FALSE, specular = FALSE, nav_morph = FALSE,
            ambient_motion = FALSE)

This retains glass surfaces and blur; it is not a zero-paint-cost mode.

Multiple intensity controls

Intensity is page-wide. The first explicit slider value in each newly inserted group sets that intensity; peer sliders synchronize visually. A restricted-range slider displays the nearest endpoint when the global value is outside its range. Bounds must satisfy 0 <= min < max <= 1, step must be finite and positive, and an explicit value must be within the slider’s range.

Active-on-accent contrast

Bootstrap’s color-contrast() often picks black ink for system blue #007AFF. glass_theme() forces light ink on primary fills so checked checkboxes, radios, switches, and active pagination retain light ink. White on #007AFF is approximately 4.02:1: it meets the 3:1 large-text threshold, but not the 4.5:1 ordinary-text threshold. Choose and test an appropriate darker accent when ordinary white labels must meet that threshold. The QA guide’s --text-aa audit checks size-aware text thresholds; translucent backgrounds, gradients, and focus visibility still need visual review.