Percentages and fr units in CSS grids

Also, along with fr, you can use values ​​in %, which also determine what part of the container the column will occupy. In this case, the column size in % will be calculated first, and the remaining free space will be divided into fractions:

html<div id="parent">
  <div>1</div>
  <div>2</div>
  <div>3</div>
  <div>4</div>
  <div>5</div>
  <div>6</div>
  <div>7</div>
  <div>8</div>
</div>

css#parent {
  display: grid;
  grid-template-columns: 50% 1fr 2fr 30%;
  border: 2px solid #696989;
  padding: 10px;
  width: 600px;
}
#parent > div {
  padding: 10px;
  border: 1px solid #696989;
}

Результат: