fix: ensure code exists inside pre before adding clipboard

Jacky Zhao

2023-08-20 7b7064ad2be68e8d6d43123c12529ca94a325fcb

 quartz/styles/base.scss

@@ -320,7 +320,6 @@
  border-radius: 5px;
  overflow-x: auto;
  border: 1px solid var(--lightgray);
  position: relative;

  &:has(> code.mermaid) {
    border: none;