<div class="flexbox">
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
</div>

<div class="grid">
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
</div>
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  display: flex;
  justify-content: center;
  padding: 2vw;
}

.flexbox {
  display: flex;
  justify-content: space-between;
  flex-flow: row wrap;
  border: 1px solid #eee;
  box-shadow: 1px 1px 1px rgba(#eee,.5);
  border-radius: 5px;
  margin: 10px;
  width: 40vw;
  counter-reset: number;
 
  .item {
    flex: 1 1 11vw;
    margin: 5px;
    min-height: 15vh;
    background: #f36;
    border-radius: 3px;
    position: relative;
    
    &::before {
      counter-increment: number;
      content: counter(number);
      position: absolute;
      top: 50%;
      left: 50%;
      transform: translate(-50%, -50%);
      font-size: 2rem;
      color: #fff;
    }
  }
}

.grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  grid-gap: 10px;
  padding: 5px;
  border: 1px solid #eee;
  box-shadow: 1px 1px 1px rgba(#eee,.5);
  border-radius: 5px;
  width: 40vw;
  counter-reset: number;
  margin: 10px;
  
  .item {
    min-height: 15vh;
    background: #3a6;
    border-radius: 3px;
    position: relative;
    
    &::before {
      counter-increment: number;
      content: counter(number);
      position: absolute;
      top: 50%;
      left: 50%;
      transform: translate(-50%, -50%);
      font-size: 2rem;
      color: #fff;
    }
  }
}
View Compiled

External CSS

This Pen doesn't use any external CSS resources.

External JavaScript

This Pen doesn't use any external JavaScript resources.