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HTML 

              
                <div class="app">
  <div class="app__nav">
    <div>Home</div>
    <div>About</div>
    <div>Contact</div>
  </div>
  <div class="wrapper">
    <h1>Full Bleed</h1>
    <p>Based on:
      <a href="https://www.joshwcomeau.com/css/full-bleed/">https://www.joshwcomeau.com/css/full-bleed/</a>
    </p>
    <p>Lorem ipsum dolor sit amet consectetur adipisicing elit. Repudiandae, non nostrum alias suscipit, harum explicabo rerum officia et vel commodi, vero perspiciatis dolor! Sed voluptatum sapiente odio quibusdam culpa id.</p>
    <img src="https://picsum.photos/900/600" alt="" class="full-bleed">
    <p>Lorem ipsum dolor sit amet consectetur adipisicing elit. Repudiandae, non nostrum alias suscipit, harum explicabo rerum officia et vel commodi, vero perspiciatis dolor! Sed voluptatum sapiente odio quibusdam culpa id. Lorem ipsum, dolor sit amet consectetur adipisicing elit. Saepe nam distinctio soluta neque, ad fugit quasi at magnam ab in voluptatem culpa officia sed minus cupiditate quod provident quaerat quisquam. Lorem ipsum dolor sit amet consectetur, adipisicing elit. Facilis possimus nobis aut cumque alias, provident consequuntur fugit delectus sapiente dolor voluptatem, eius saepe modi porro temporibus. Voluptate enim eos fugit?</p>
    <p>Lorem ipsum dolor sit amet consectetur, adipisicing elit. Natus mollitia possimus, laboriosam optio vel eveniet veniam velit quae ducimus facere repellat quaerat porro nisi atque excepturi, illum ea commodi reiciendis.</p>
    <p>Lorem ipsum dolor sit amet consectetur adipisicing elit. Repudiandae, non nostrum alias suscipit, harum explicabo rerum officia et vel commodi, vero perspiciatis dolor! Sed voluptatum sapiente odio quibusdam culpa id. Lorem ipsum dolor, sit amet consectetur adipisicing elit. Nulla, placeat adipisci eos optio accusamus vero reprehenderit, cumque, ex sequi quibusdam natus. Sint ipsa eum dolorum deleniti quaerat, dolore eligendi itaque?</p>
    <p>Lorem ipsum dolor sit amet consectetur adipisicing elit. Repudiandae, non nostrum alias suscipit, harum explicabo rerum officia et vel commodi, vero perspiciatis dolor! Sed voluptatum sapiente odio quibusdam culpa id.</p>
  </div>
</div>
!

CSS 

              
                * {
  box-sizing: border-box;
}

home,
body {
  height: 100%;
}
body {
  margin: 0;
  font-size: 20px;
  font-family: system-ui;
}

a {
  color: inherit;
}

@media (prefers-color-scheme: dark) {
  body {
    color: white;
    background-color: black;
  }
}

/* --- app layout and sidebar --- */

.app {
  display: flex;
  flex-direction: row;
}

.app__nav {
  flex-shrink: 0;
  padding: 1em;
  line-height: 1.5;
  width: 20ch;
  border-right: 1px solid;
  position: sticky;
  top: 0;
}

.app__nav {
  height: 100vh;
}

/* --- full bleed --- */

.wrapper {
  display: grid;
  grid-template-columns:
    1fr
    min(65ch, calc(100% - 2em))
    1fr;
  grid-column-gap: 1em;
}
.wrapper > * {
  grid-column: 2;
}
.wrapper .full-bleed {
  width: 100%;
  grid-column: 1 / 4;
}
!

JS
!
999px

Console