blog/assets/scss/partials/_404.scss

#page.error-404 {
  justify-content: center;
  align-items: center;
}
.banner-404 {
  font-size: 1.5em;
  padding: 1em;
}
.btn-404 > a {
  display: inline-block;
  font-size: .8em;
  border: 1px solid;
  border-radius: 4px;
  padding: .2em .4em;
  margin-bottom: .4em;
}