main.css

:root {
  --blue: #2B3252;
  --yellow: #FAD744;
  --red: #EF5455;
  --white: #EEE;
}

html {
  height: 100%;
  margin: 0;
  padding: 0;
}

body {
  display: grid;
  grid-template-columns: 1fr  1.61803398875fr;
  grid-template-rows: 100px auto  85px;
  grid-template-areas:
    "header header"
    "aside  main"
    "footer footer";
  height: 100%;
  margin: 0;
  padding: 0;
  font-family: 'Raleway', sans-serif;
}

h1, h2, h3 {
  font-family: 'Righteous', cursive;
}

header {
  background-color: var(--blue);
  color: var(--yellow);
  grid-area: header;
  padding: 1rem;
}

main {
  background-color: var(--white);
  grid-area: main;
}

article {
 columns: 3;
 margin: 1rem;
}

aside {
  background-color: var(--yellow);
  color: var(--blue);
  grid-area: aside;
  padding: 1rem;
}

article img,
aside img {
  width: 100%;
}

footer {
  background-color: var(--red);
  color: var(--yellow);
  grid-area: footer;
}

footer ul {
  list-style-type: none;
  padding: 0;
  display: flex;
  justify-content: space-between;
  padding: 1rem;
}

@media (max-width: 600px) {
  body {
    display: grid;
    grid-template-columns: 100%;
    grid-template-rows: 100px auto auto 85px;
    grid-template-areas:
      "header"
      "main"
      "aside"
      "footer";
    height: 100%;
    margin: 0;
    padding: 0;
  }

  article {
   columns: 1;
  }
}