initBox

pub fn initBox(num_cols: usize, num_rows: usize, border_external_w: f32, border_internal_w: f32) Borders {
        return .{
            .external = Rect.all(border_external_w),
            .internal = .{ .w = border_internal_w, .h = border_internal_w },
            .num_cols = num_cols,
            .num_rows = num_rows,
        };
    }