---
title: "How do CSS selectors work in visual monitoring? — Lemwatch…"
description: "Restrict visual monitoring to a specific region using a CSS selector so Lemwatch only diffs the part of the page that matters, like pricing or hero."
canonical: "https://lemwatch.com/help/visual-monitoring-selectors"
source: "https://lemwatch.com"
---

# How do CSS selectors work in visual monitoring?

> Restrict visual monitoring to a specific region using a CSS selector so Lemwatch only diffs the part of the page that matters, like pricing or hero.

## Quick answer

 Add a CSS selector (e.g., #pricing , main .hero ) to each monitored page and Lemwatch will crop the screenshot to that element before running the visual diff.

## When to use selectors

- Pricing tables you want to track word-for-word

- Hero copy that must never regress

- Legal footers

- Any critical widget wrapped in dynamic chrome

## Where to find it in Lemwatch

 **Site → Visual Monitoring → Monitored Pages → CSS Selector**.

## FAQ

### Which selectors are supported?

 Any valid CSS selector: id, class, attribute, descendant, :nth-child.

### What if the selector matches nothing?

 We fall back to a full-page screenshot and warn in the UI.

## Related

- Ignore zones

- Diff threshold


## Related

- [Help centre](https://lemwatch.com/help)
- [How do I stop visual monitoring flagging ads or rotating banners?](https://lemwatch.com/help/visual-monitoring-ignore-zones)
- [What is the visual monitoring diff threshold?](https://lemwatch.com/help/visual-monitoring-diff-threshold)
- [Lemwatch pricing](https://lemwatch.com/pricing)
- [Set up visual monitoring for a page](https://lemwatch.com/help/visual-monitoring-setup)