Why this matters
When using scoped, Vue adds a unique data attribute selector (e.g., [data-v-xxxxxxx]) to each rule. Element selectors combined with attribute selectors (e.g., button[data-v-xxxxxxx]) can be significantly less performant in browsers compared to class selectors combined with attribute selectors (e.g., .my-button[data-v-xxxxxxx]). Using classes improves CSS performance.