I try to use just CSS to add some styles

Hi Nikita,

I just made this Challenge so I have some ideas for you.

First

Think about using Flexbox for all your design. This way you have much more control over how each DIV will be shown on Desktop and Mobile. Right now all designs look ok on the Desktop but when you change to Mobile it not working.

I'm sure this will take some time to understand how Flexbox works but it is standard now to use it in Design to make it more Responsive.

Try here to know about Flexbox:

1. A Complete Guide to Flexbox
2. w3school
3. MDN

This place helps me a lot with Flexbox :).

Some ideas for your Code

Background IMGs

You use now 2 Background IMGs but you do not show where they should show.

body {
  font-size: 12px;
  font-family: 'Spartan', sans-serif;
  background-image: url("images/bg-pattern-top-mobile.svg"), url("images/bg-pattern-bottom-mobile.svg");
  background-repeat: no-repeat;
}

Try something like this to show position of this IMGs:

#example1 {
   background-image: url(../images/bg-pattern-top-desktop.svg), url(../images/bg-pattern-bottom-desktop.svg);
  background-position: left top, right bottom;
  background-repeat: no-repeat, no-repeat;
}

More here: w3school

Look too on your IMG files - right now you use files with Mobile in the name. You should use with Desktop in name

Your problem with text

You use this

.heading {
  color: hsl(300, 43%, 22%);
  text-align: center;
  font-weight: 700;
}

If you want this text to be bigger try to add some font size e.g.

font-size: 18px;

Font weight you use is responsible for how "bold is text" not how big is it :)

** Body **

Right now it looks like this

body {
  font-size: 12px;
  font-family: 'Spartan', sans-serif;
  background-image: url("images/bg-pattern-top-mobile.svg"), url("images/bg-pattern-bottom-mobile.svg");
  background-repeat: no-repeat;
}

Try to add some extra line

 margin: 0; 
 padding: 0;
 height: 100vh;

Margin and padding will "Delete" them from the Browser file. So your www can stretch 100% in Viewport.

Height: 100vh will make your Project 100% Height in Viewport.

I hope this will help little with your project.