Here is a method:
css <- "
.nav-tabs > li.active > a {
background-color: lightgrey;
}
.tab-pane.active {
background-color: lightgrey;
position: absolute;
width: -webkit-fill-available;
height: -webkit-fill-available;
}
"
library(shiny)
ui <- fluidPage(
tags$head(
tags$style(HTML(css))
),
tabsetPanel(
tabPanel("t0", h2("tab 0")),
tabPanel("t1", h2("tab 1"))
)
)
server <- function(input, output) {}
shinyApp(ui = ui, server = server)
The initial portion of the CSS pertains to the styling of the tab handle, while the latter part focuses on the tab content.
Please be aware that the CSS attribute -webkit-fill-available
may not be supported by all web browsers. It functions correctly in Chrome and Edge. Searching for it online should provide you with the corresponding property name for other browsers.