eleventy-plugin-syntaxhighlighting-chroma/demo/test.css

.highlight-line {
  display: inline-block;
}

/* allow highlighting empty lines */
.highlight-line:empty:before {
  content: " ";
}

.highlight-line:not(:last-child) {
  min-width: 100%;
}
.highlight-line .highlight-line:not(:last-child) {
  min-width: 0;
}