moderncss.dev
Data from Aug 21, 2026, 5:31 AM UTC — 13h old.
Built Awesome · 1 measurement · since Aug 21, 2026 · last attempt 13h
Stack
Detected on the same page load as the accessibility pass — the generator
from <meta name="generator"> or the shape of the page,
the host from response headers.
Core Web Vitals field data, origin-level
Real Chrome users, 28-day window (2026-07-23 → 2026-08-19). This is what Google measures you on.
Scores
Lab metrics Lighthouse, mobile
| Metric | Current | Previous | Change | Best | Worst | Trend |
|---|---|---|---|---|---|---|
| LCP Largest Contentful Paint | 1.95 s | — | — | 1.95 s | 1.95 s | |
| CLS Cumulative Layout Shift | 0 | — | — | 0 | 0 | |
| TBT Total Blocking Time | 0 ms | — | — | 0 ms | 0 ms | |
| FCP First Contentful Paint | 904 ms | — | — | 904 ms | 904 ms | |
| Speed Index | 904 ms | — | — | 904 ms | 904 ms | |
| TTFB Time to First Byte | 604 ms | — | — | 604 ms | 604 ms |
What LCP is made of
A flat LCP number tells you something regressed. The subparts tell you whether it was the server, resource discovery, the download, or rendering.
Field data Chrome UX Report, origin-level
Real Chrome users, 28-day trailing window (2026-07-23 → 2026-08-19). This is what Google measures you on.
| Metric | p75 | Rating | Distribution (good / needs work / poor) |
|---|---|---|---|
| LCP CWV | 1.35 s | good | 94% good |
| CLS CWV | 0 | good | 96.3% good |
| FCP | 1.35 s | good | 89.3% good |
| TTFB | 710 ms | good | 80.2% good |
Lab vs field
Lab LCP 1.95 s · field p75 1.35 s · real users are 0.69× faster than the lab.
Field history 25 weeks
Weekly p75 from the CrUX History API, backfilled in a single request.
| Week ending | LCP | INP | CLS | FCP | TTFB |
|---|---|---|---|---|---|
| 2026-08-15 | — | — | — | — | — |
| 2026-08-08 | — | — | — | — | — |
| 2026-08-01 | — | — | — | — | — |
| 2026-07-25 | — | — | — | — | — |
| 2026-07-18 | — | — | — | — | — |
| 2026-07-11 | — | — | — | — | — |
| 2026-07-04 | — | — | — | — | — |
| 2026-06-27 | — | — | — | — | — |
| 2026-06-20 | — | — | — | — | — |
| 2026-06-13 | — | — | — | — | — |
| 2026-06-06 | — | — | — | — | — |
| 2026-05-30 | 1.20 s | — | 0 | 1.20 s | 865 ms |
Page weight
| Metric | Current | Previous | Change | Best | Worst | Trend |
|---|---|---|---|---|---|---|
| Page Weight | 188.2 kB | — | — | 188.2 kB | 188.2 kB | |
| Requests | 13 | — | — | 13 | 13 | |
| Third-party Weight | 76.5 kB | — | — | 76.5 kB | 76.5 kB | |
| Third-party CPU | 7 ms | — | — | 7 ms | 7 ms | |
| Unused JS | 0 B | — | — | 0 B | 0 B | |
| Unused CSS | 0 B | — | — | 0 B | 0 B |
By resource type
Third parties 2 entities
76.5 kB transferred, 7 ms of main thread time. This is the number most likely to regress without anyone on your team shipping anything.
Page health
| Metric | Current | Previous | Change | Best | Worst | Trend |
|---|---|---|---|---|---|---|
| Main Thread Work | 284 ms | — | — | 284 ms | 284 ms | |
| Long Tasks | 1 | — | — | 1 | 1 | |
| DOM Elements | 301 | — | — | 301 | 301 | |
| Axe Violations Violating nodes from a full axe run — stricter than Lighthouse's subset | 0 | — | — | 0 | 0 | |
| A11y Failures | 0 | — | — | 0 | 0 | |
| A11y Failing Nodes | 0 | — | — | 0 | 0 |
Main thread work
Axe violations axe-core 4.13.0, full rule set
0 violating nodes across 0 rules, 475 passing. This is a standalone axe run, stricter than the subset Lighthouse folds into its score above — and it is the second tiebreaker in the ranking.
Hygiene
Changes rarely — which is exactly why a change is worth noticing.
Measurement log
Every stored run for this URL, newest first. Failures are kept as records — "this site was down on Tuesday" is data too.
| When | Perf | LCP | CLS | TBT | Weight | Runs | Spread | Bench | Took |
|---|---|---|---|---|---|---|---|---|---|
| Aug 21, 2026, 5:31 AM UTC | 99 | 1.95 s | 0 | 0 ms | 188.2 kB | 3/3 | ±6 | 2,475 | 28.5s |
Embed this score
Live below, then the markup that produces it. Drop that on any page to show
moderncss.dev's scores, updated whenever this instance
re-measures — more about the component. Don’t forget to bundle the speedlify-score.js component code into your site!
<speedlify-score speedlify-url="https://zachleat.github.io/speedlify2/" url="https://moderncss.dev/"></speedlify-score>