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CSS

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JavaScript

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HTML 

              
                <section>
<h3>This grid uses 1fr 1fr 1fr</h3>
<div class="grid grid-equal">
   <div class="item">      
     <img class="kitten" alt="Kitten">
   </div>
   <div class="item">                    
     <img class="kitten" alt="Kitten">
   </div>
   <div class="item">                    
     <img class="kitten" alt="Kitten">
   </div>                
   <div class="item">                    
     <img class="kitten" alt="Kitten">
   </div>
   <div class="item">                    
     <img class="kitten" alt="Kitten">
   </div>               
   <div class="item">                    
     <img class="kitten" alt="Kitten">
   </div>               
</div>
</section>

<section>
<h3>This grid uses 2fr 1fr 1fr</h3>
<div class="grid grid-2fr">
   <div class="item">      
     <img class="kitten" alt="Kitten">
   </div>
   <div class="item">                    
     <img class="kitten" alt="Kitten">
   </div>
   <div class="item">                    
     <img class="kitten" alt="Kitten">
   </div>                
   <div class="item">                    
     <img class="kitten" alt="Kitten">
   </div>
   <div class="item">                    
     <img class="kitten" alt="Kitten">
   </div>               
   <div class="item">                    
     <img class="kitten" alt="Kitten">
   </div>               
</div>
</section>

<section>
<h3>This grid uses 1fr 200px 1fr</h3>
<div class="grid grid-200px">
   <div class="item">     
<!-- Text from http://www.catipsum.com  -->
     <p>Mark territory. Try to jump onto window and fall while scratching at wall. Chew on cable. Lick the curtain just to be annoying sleep everywhere, but not in my bed, plop down in the middle where everybody walks yet chase dog then run away. Chill on the couch table lie in the sink all day poop in litter box, scratch the walls cat snacks. Claw drapes hunt anything that moves kick up litter munch, munch, chomp, chomp so you call this cat food. Disappear for four days and return home with an expensive injury; bite the vet. Find a way to fit in tiny box eats owners hair then claws head.</p>
   </div>
   <div class="item">                    
     <img class="kitten" alt="Kitten">
   </div>
   <div class="item">         
     <p>Munch on tasty moths dont wait for the storm to pass, dance in the rain, knock dish off table head butt cant eat out of my own dish for open the door, let me out, let me out, let me-out, let me-aow, let meaow, meaow!, scratch the furniture do i like standing on litter cuz i sits when i have spaces, my cat buddies have no litter i live in luxury cat life. Pushes butt to face eat grass, throw it back up meow</p>
   </div>                                 
</div>
</section>
!

CSS 

              
                .grid {
    display: grid;
    grid-template-rows: 200px 150px;
    grid-auto-rows: 110px;    
    grid-gap: 20px;    
}

.grid-equal {
    grid-template-columns: 1fr 1fr 1fr;
}

.grid-2fr {
    grid-template-columns: 2fr 1fr 1fr; 
}

.grid-200px {
      grid-template-columns: 1fr 200px 1fr; 
     grid-template-rows: 1fr;
}

.grid .item {
    background-color: gainsboro;
    border: 2px solid grey;
    border-radius: 3px;  
    text-align: center;    
    display: flex;      
    justify-content: center;
    align-items: center;
}

.grid .item:nth-child(odd) {
    background-color: lavender;
    border: 2px solid grey;
}

section {
  margin-top: 50px;
}
!

JS 

              
                 class PlaceKittenUrl {
   constructor() {
     this.height = 100
     this.width = 100
     this.image = Math.floor(Math.random() * 16)
   }        

   height(newHeight) {
     this.height = newHeight
     return this
   }

   width(newWidth) {
     this.width = newWidth
     return this
   }

   url() {
     return  `https://placekitten.com/${this.width}/${this.height}?image=${this.image}`
   }
 }

const section1Kittens = document.getElementsByClassName("kitten")
for(const kitten of section1Kittens) {
  kitten.src = new PlaceKittenUrl().url()       
}
!
999px

Console