Check out example codes for "css grid layout". It will help you in understanding the concepts better.

Code Example 1

<!DOCTYPE html>
<html>
<head>
<style>
.grid-container {
  display: grid;
  grid-template-columns: auto auto auto;
  background-color: #2196F3;
  padding: 10px;
}
.grid-item {
  background-color: rgba(255, 255, 255, 0.8);
  border: 1px solid rgba(0, 0, 0, 0.8);
  padding: 20px;
  font-size: 30px;
  text-align: center;
}
</style>
</head>
<body>

  <div class="grid-container">
    <div class="grid-item">1</div>
    <div class="grid-item">2</div>
    <div class="grid-item">3</div>  
    <div class="grid-item">4</div>
    <div class="grid-item">5</div>
    <div class="grid-item">6</div>  
    <div class="grid-item">7</div>
    <div class="grid-item">8</div>
    <div class="grid-item">9</div>  
  </div>

</body>

Code Example 2

<!DOCTYPE html>
<html>
<head>
<style>
.grid-container {
  display: grid;
  grid-template-columns: auto auto auto;
  background-color: #2196F3;
  padding: 10px;
}
.grid-item {
  background-color: rgba(255, 255, 255, 0.8);
  border: 1px solid rgba(0, 0, 0, 0.8);
  padding: 20px;
  font-size: 30px;
  text-align: center;
}
</style>
</head>
<body>

  <div class="grid-container">
    <div class="grid-item">1</div>
    <div class="grid-item">2</div>
    <div class="grid-item">3</div>  
    <div class="grid-item">4</div>
    <div class="grid-item">5</div>
    <div class="grid-item">6</div>  
    <div class="grid-item">7</div>
    <div class="grid-item">8</div>
    <div class="grid-item">9</div>  
  </div>

</body>

Code Example 3

.container {
  display: grid | inline-grid;
}

Code Example 4

@supports (display: grid) {
  main { 
    max-width: 10000px;
    margin: 0;
  }
  .grid-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 2fr));
    grid-gap: 1rem;
  }
}

Code Example 5

.item-a {
  grid-area: header;
}
.item-b {
  grid-area: main;
}
.item-c {
  grid-area: sidebar;
}
.item-d {
  grid-area: footer;
}

.container {
  display: grid;
  grid-template-columns: 50px 50px 50px 50px;
  grid-template-rows: auto;
  grid-template-areas: 
    "header header header header"
    "main main . sidebar"
    "footer footer footer footer";
}

Code Example 6

/* Answer to: "css display grid" */

/*
  The CSS Grid Layout Module offers a grid-based layout system,
  with rows and columns, making it easier to design web pages
  without having to use floats and positioning.

  An HTML element becomes a grid container when its display property
  is set to grid or inline-grid.

  For more information, go to:
  https://www.w3schools.com/css/css_grid.asp
*/

.grid-container {
  display: grid;
}

/* or */

.grid-container {
  display: inline-grid;
}

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