opencode/app/packages/web/src/components/diffview.module.css

.diff {
  display: grid;
  grid-template-columns: 1fr 1fr;
  border: 1px solid var(--sl-color-divider);
  background-color: var(--sl-color-bg-surface);
  border-radius: 0.25rem;
}

.column {
 display: flex;
  flex-direction: column;
  overflow-x: auto;
  min-width: 0;
  align-items: flex-start;

  &:first-child {
    border-right: 1px solid var(--sl-color-divider);
  }

  & > [data-section="cell"]:first-child {
    padding-top: 0.5rem;
  }
  & > [data-section="cell"]:last-child {
    padding-bottom: 0.5rem;
  }
}

[data-section="cell"] {
  position: relative;
  flex: none;
  width: max-content;
  padding-left: 1.5ch;
  padding: 0.1875rem 0.5rem 0.1875rem 1.5ch;
  margin: 0;

  pre {
    background-color: var(--sl-color-bg-surface) !important;
    white-space: pre;

    code > span:empty::before {
      content: "\00a0";
      white-space: pre;
      display: inline-block;
      width: 0;
    }
  }
}

[data-diff-type="removed"] {
  background-color: var(--sl-color-red-low);

  pre {
    background-color: var(--sl-color-red-low) !important;
  }

  &::before {
    content: "-";
    position: absolute;
    left: 0.5ch;
    user-select: none;
    color: var(--sl-color-red-high);
  }
}

[data-diff-type="added"] {
  background-color: var(--sl-color-green-low);

  pre {
    background-color: var(--sl-color-green-low) !important;
  }

  &::before {
    content: "+";
    position: absolute;
    left: 0.6ch;
    user-select: none;
    color: var(--sl-color-green-high);
  }
}