Responsive NavBar like StackOverflow

Question

I am trying to create a responsive navigation bar, similar to the one on Stack Overflow. I have attached an image of the layout I'm trying to achieve.

For simplicity, I added some values to make it easier to follow. There is the outer div that encapsulates the whole page, outer-wrapper and the main div that encapsulates the main content (navigation bar, main content, and footer), main-wrapper.

Now suppose that outer-wrapper is 1000px wide and main-wrapper is 800px wide, then there is 100px of buffer on the left and right side. When the window shrinks, I want the buffer to be used up before any of the main content changes.

CSS

    .outer-wrapper {
        width:  100%;
    }

    .main-wrapper {
        width: 800px;
        display: flex;
        flex-direction: column;
        margin-left: auto;
        margin-right: auto;
        position: relative;
    }
    .nav-home {
        position: fixed;
        top: -30px;
        left: -30px;
        height: 60px;
        width: 100%;
        padding: 20px 20px 0px 20px;
        display: flex;
        justify-content: space-around;
    }
}

HTML

    <div class='outer-wrapper'>
      <div class='main-wrapper'>
        <div class='nav-bar'>...</div>
        <div class='main-content'>...</div>
        <div class='footer'>...</div>
      </div>
    </div>

The problem is when the window shrinks to match the width of main-wrapper at 800px, there is still a left and right margin in the navigation bar. How would I ensure the width of the navigation bar matches the width of the main content and footer when the left and right margin is shrunk to 0?

Thanks.

Answer 1

I stripped out some of your styles from the .nav-bar class and it seems to be performing as you require - am I missing something?

I've added colours to help visualise the resizing.

.outer-wrapper {
    background-color: yellow;
    width:  100%;
}

.main-wrapper {
    background-color: blue;
    width: 800px;
    display: flex;
    flex-direction: column;
    margin-left: auto;
    margin-right: auto;
    position: relative;
}

.nav-bar {
    background-color: red;
    justify-content: space-around;
}

.main-content {
  background-color: green;
}

.footer {
  background-color: purple;
}

<div class='outer-wrapper'>
  <div class='main-wrapper'>
    <div class='nav-bar'>Nav Bar</div>
    <div class='main-content'>Main Content</div>
    <div class='footer'>Footer</div>
  </div>
</div>