In short: Chrome 156 brings the CSS random() function, SQLite-backed IndexedDB and DevTools features for AI agents; Firefox 158 adds typed arithmetic in calc(). Both fixed dozens of security flaws. The new CSS features help cut JavaScript and make websites faster.
Both major browsers updated at the end of October: Chrome 156 reached the stable channel and Firefox 158/159 brought new CSS capabilities. Both also fixed dozens of security flaws. Here is this week’s web development news in brief: what is new for web developers and what it means for your website.
Chrome 156: CSS random() and a faster IndexedDB
Chrome 156 reached stable around 20 October. The changes that matter most to developers:
- The CSS random() function: random values directly in stylesheets, for animations, card offsets or decorative elements without JavaScript.
- Single-axis scroll containers work better.
- IndexedDB uses SQLite for newly created stores, which should make web apps that store data in the browser more reliable.
- WebTransport supports HTTP request and response headers, and the WebGPU Shading Language gained a fragment depth extension.
On 27 October Chrome received a stable update with 52 security fixes, four of them critical. Chrome 157 is in beta.
Chrome DevTools: tools for AI agents and anchor positioning
In October DevTools added CSS style inspection for AI agents and an interactive position-area editor for CSS anchor positioning. Anchor positioning lets you attach, for example, a dropdown or tooltip to a button with CSS alone, without JavaScript libraries.
Firefox 158 and 159: typed arithmetic in calc()
- Firefox 158 added typed arithmetic to CSS calc(): values with units can be divided and multiplied, which makes fluid typography and layout maths easier.
- Firefox 158.0.1 blocked compromised eMudhra certificates and fixed bugs.
- Mozilla’s security advisory of 27 October fixes 167 vulnerabilities, and Firefox 159 adds new features as well.
What it means for your website
- New CSS features reduce JavaScript. Less JavaScript means a faster site on mobile and better Core Web Vitals, which also affect SEO. Read more about website speed and SEO.
- Use new features progressively. Safari and older browsers may not support them yet, so the site must work without them.
- Test your website in new browser versions. Updates can change layouts or form behaviour. If something breaks, see website improvements.
- Speed and technical SEO go together: see speed optimisation and our technical SEO audit.
Also this week in WordPress: the WordPress 7.1.4 security update and vulnerable plugins and what is new in WordPress 7.2.
Frequently asked questions
What is new in Chrome 156 for web developers?
The CSS random() function, better single-axis scroll container support, SQLite-backed IndexedDB, WebTransport headers and WebGPU updates.
What is CSS random()?
It is a CSS function that returns a random value within a given range directly in the stylesheet, without JavaScript.
What is CSS anchor positioning?
It positions an element, such as a tooltip or menu, relative to another element using CSS alone. Chrome DevTools now has an interactive editor for it.
Do I need to change my website because of browser updates?
Usually not, but check that layout, forms and payments work in the new versions. New CSS features can be used to make your site faster.
Is your website fast and working in every browser? Run a free website audit or contact us. We build new websites with modern technology: see website development.
