How do you style containers?

[patientplatypus6]

Maybe it's just me, but styling containers using CSS rules seems overly difficult or I just don't understand.

Consider the following code

use iced::{
    theme,
    Element, Command, Background, Color, 
    Settings, Application, executor, alignment, Length, Alignment};
use iced::widget::{column, text, container, Column};
use iced::widget::container::Container;
use iced_style::container::StyleSheet;
use iced_native::{event, subscription, Event};
use utility::*;

fn main() -> iced::Result{
  HelloWorld::run(Settings::default())
}

struct HelloWorld{
  value: i32,
  inputstring: String
}

#[derive(Debug, Clone, Copy)]
pub enum Message {
    IncrementPressed,
    DecrementPressed,
}

impl Application for HelloWorld {
     
    type Message = Message;
    type Executor = executor::Default;
    type Theme = iced::Theme;
    type Flags = ();

    fn new(_flags:()) -> (Self, Command<Message>) {
       (Self {value : 0, inputstring: "".to_string()}, Command::none())
    }

    fn title(&self) -> String {
      "Iced Hello World Example".to_string()
    }

    fn update(&mut self, message: Message) -> Command<Message> {
        match message {
            Message::IncrementPressed => {
                self.value += 1;
                Command::none()
            }
            Message::DecrementPressed => {
                self.value -= 1;
                Command::none()
            }
        }
    }

    fn view(&self) -> Element<Message> {
        let content = column![
            text(self.title()).size(25)
        ]
        .padding(20)
        .spacing(20)
        .max_width(500)
        .align_items(Alignment::Center);

        column![
            container(content)
            .style() //how do I style this container?
            ))
        ]
        .padding(20)
        .width(iced::Length::FillPortion(100))
        .align_items(Alignment::Center)
        .into()
    }
}

I would expect that for the line

        .style() //how do I style this container?

I should be able to do something along the lines of (pseudocode):

        .style(
            Color:RGBA(1,0.3,1,0.2),
            Background_Color:RGBA(0.1,0.9,1,0.5),
            Border_Color:RGBA(0.5,0.2,0.3,1),
            etc...
        ) //how do I style this container?

but I can't find anything like that in the documentation. I'm supposed to use themes somehow and then pass that theme into the application and then call it again? Why can't I just style each individual container like in CSS? I understand that you want to disaggregate the styling vs the sizing of the elements, but I just find the way that styling works confusing. Maybe take a look at the way that Dart/Flutter implements styling?

Anyway, if you could provide some examples of how to implement a simple styled container that would be useful. Thanks!

EDIT:

OK, I'm taking a look at this answer, and I find it unsatisfactory: #1266. In essence it is non-replicable (an old version of the program being used?) and I can't compile it.