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Grid - бесконечное число блоков в одну строку без переноса.

HTML

<div class="wrap">
  <div class="random"></div>

  <div class="random"></div>

  <div class="random"></div>

  <div class="random"></div>

  <div class="random">lorejhkhkh</div>

  <div class="random"></div>

  <div class="random"></div>

  <div class="random"></div>

  <div class="random"></div>

  <div class="random"></div>

  <div class="random"></div>

  <div class="random"></div>

  <div class="random"></div>

  <div class="random"></div>

  <div class="random"></div>

  <div class="random"></div>

  <div class="random"></div>

  <div class="random"></div>

  <div class="random"></div>

  <div class="random"></div>

  <div class="random"></div>

  <div class="random"></div>
</div>

CSS

@import url('https://fonts.googleapis.com/css2?family=Neucha&display=swap');


* {
  box-sizing: inherit;
}

html {
  box-sizing: border-box;
}

body {
  
  margin: 0;
  font-family: 'Neucha', cursive;
}

.wrap {
  max-width: 90vw;
  display: grid;
  grid-template-rows: repeat(4, 1fr);
  grid-auto-flow: column;
  border: 3px solid red;
}

.random {
  display: inline-block;
  min-width: 50px;
  height: 100px;
  background: var(--bg-color);
}

JavaScript

const colorBlocks = (block) => {
  const items = document.querySelectorAll(block);
  items.forEach(item => {
    let color = (Math.random().toString(16) + '000000').substring(2, 8).toUpperCase();
    item.style.setProperty('--bg-color', '#' + color);
  })
}

colorBlocks('.random');