Maintain ratio between column in CSS grid. How grid-column is calculated?

Question

I want my grid to maintain a certain ratio, but a long sentence increases the width of the grid it belongs to.

Answer 1

I added grid-template-columns:repeat(13,1fr);

body {
    display: grid;
  grid-template-columns:repeat(13,1fr);
}

main {
    grid-column: 1 / 8;
    border: 2px solid black;
}

aside {
    grid-column: 8 / 13;
    border: 2px solid black;
}

 
    
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Aside