Dictate that windows on Emscripten will fill the whole browser window.
Defined in <SDL3/SDL_hints.h>
#define SDL_HINT_EMSCRIPTEN_FILL_DOCUMENT "SDL_EMSCRIPTEN_FILL_DOCUMENT"When enabled, the canvas element fills the entire document. Resize events will be generated as the browser window is resized, as that will adjust the canvas size as well. The canvas will cover anything else on the page, including any controls provided by Emscripten in its generated HTML file (in fact, any elements on the page that aren't the canvas will be moved into a hidden div element).
Often times this is desirable for a browser-based game, but it means several things that we expect of an SDL window on other platforms might not work as expected, such as minimum window sizes and aspect ratios.
This hint overrides SDL_PROP_WINDOW_CREATE_EMSCRIPTEN_FILL_DOCUMENT_BOOLEAN properties when creating an SDL window.
This hint only applies to the Emscripten platform.
This hint can be set at any time (before creating the window, or to toggle its state later). Only one window can fill the document at a time.
This hint is available since SDL 3.4.0.