use gpui::{    App, Application, Bounds, Context, Hsla, Window, WindowBounds, WindowOptions, div, prelude::*,    px, rgb, size,}; // https://en.wikipedia.org/wiki/Holy_grail_(web_design)struct HolyGrailExample {} impl Render for HolyGrailExample {    fn render(&mut self, _window: &mut Window, _cx: &mut Context<Self>) -> impl IntoElement {        let block = |color: Hsla| {            div()                .size_full()                .bg(color)                .border_1()                .border_dashed()                .rounded_md()                .border_color(gpui::white())                .items_center()        };         div()            .gap_1()            .grid()            .bg(rgb(0x505050))            .size(px(500.0))            .shadow_lg()            .border_1()            .size_full()            .grid_cols(5)            .grid_rows(5)            .child(                block(gpui::white())                    .row_span(1)                    .col_span_full()                    .child("Header"),            )            .child(                block(gpui::red())                    .col_span(1)                    .h_56()                    .child("Table of contents"),            )            .child(                block(gpui::green())                    .col_span(3)                    .row_span(3)                    .child("Content"),            )            .child(                block(gpui::blue())                    .col_span(1)                    .row_span(3)                    .child("AD :(")                    .text_color(gpui::white()),            )            .child(                block(gpui::black())                    .row_span(1)                    .col_span_full()                    .text_color(gpui::white())                    .child("Footer"),            )    }} fn main() {    Application::new().run(|cx: &mut App| {        let bounds = Bounds::centered(None, size(px(500.), px(500.0)), cx);        cx.open_window(            WindowOptions {                window_bounds: Some(WindowBounds::Windowed(bounds)),                ..Default::default()            },            |_, cx| cx.new(|_| HolyGrailExample {}),        )        .unwrap();        cx.activate(true);    });}