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CSS

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HTML 

              
                <main class="deals">
  <article class="sale-item">
    <h1>Computer Starter Kit</h1>
    <p>This is the best computer money can buy, if you don’t have much money.</p>
    <ul>
      <li>Computer</li>
      <li>Monitor</li>
      <li>Keyboard</li>
      <li>Mouse</li>
    </ul>
    <img src="https://www.w3.org/TR/css-flexbox-1/images/computer.jpg" alt="You get: a white computer with matching peripherals">
    <button>BUY NOW</button>
  </article>
  
  <article class="sale-item">
    <h1>Printer</h1>
    <p>Only capable of printing ASCII art.</p>
    <ul>
      <li>Paper and ink not included.</li>
    </ul>
    <img src="https://www.w3.org/TR/css-flexbox-1/images/printer.png"
         alt="You get: a dot-matrix printer.">
    <button>BUY NOW</button>
  </article>

  <article class="sale-item">
    <h1>Printer 2</h1>
    <p>A la 1989.</p>
    <img src="https://www.w3.org/TR/css-flexbox-1/images/printer.png"
         alt="You get: a dot-matrix printer.">
    <button>BUY NOW</button>
  </article>

  <article class="sale-item">
    <h1>Mouse</h1>
    <p>A computer mouse is a pointing device (hand control) that detects two-dimensional motion relative to a surface. This motion is typically translated into the motion of a pointer on a display, which allows a smooth control of the graphical user interface. Clickity Click!</p>
    <button>BUY NOW</button>
  </article>

  <article class="sale-item">
    <h1>Macintosh 8500</h1>
    <p>This is the best computer money can buy, if you don’t have much money. This computer was state of the art in 1995.</p>
    <img src="https://www.w3.org/TR/css-flexbox-1/images/computer.jpg"
         alt="You get: a white computer with matching peripherals.">
    <button>BUY NOW</button>
  </article>
</main>
!

CSS 

              
                * {
  box-sizing: border-box;
}
body {
  padding: 1rem;
}

/* Just for the fallback layout */

main {
  max-width: 500px;
  margin: 0 auto;
}
article {
  margin: 1rem 0;
}

/* Now lets do a Grid-based layout */

@supports (display: grid) {
  main { 
    max-width: 10000px;
    margin: 0;
  }
  article {
    margin: 0;
  }
  .deals {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    grid-gap: 1rem;
  }
}
  
.deals {
  font-family: Avenir, Roboto, Helvetica, san-serif; 
  font-size: 80%;
}
.sale-item {
  display: flex;
  flex-flow: column;
  border:  1px solid black;
  border-radius: 1rem;
  padding: 2rem;
}
.sale-item > h1 {
  margin: 1rem 1rem 0;
}
.sale-item > ul {
  margin: 0 0 1rem;
}
.sale-item > p {
  margin: 0.25em 1rem 1rem;
}
.sale-item > img {
  order: -1;
  align-self: center;
}
.sale-item > button {
  margin-top: auto; 
  background: teal;
  color: white;
  padding: 0.5rem;
  border: none;
  border-radius: 1rem;
  font-size: 1.2rem;
}
!

JS
!
999px

Console