Max Potential First Input Delay
70 ms
The maximum potential First Input Delay that your users could experience is the duration of the longest task. Learn more about the Maximum Potential First Input Delay metric.
Page structure & technical metrics
Words
19
Action candidates
1
Images
0
HTML
559 B
Copy
Title chars
14
Meta chars
0none
H1
1
H2
0
Action
Primary
Learn more
Forms
0
On-site links
0
Off-site links
1
Security & metadata
HTTPS
yes
HSTS
no
CSP
no
nosniff
no
viewport
yes
Icon
yes
JSON-LD
no
Analytics
no
Page
Scripts
0 ext / 0 inline
Lang
en
Third-party hosts
no
Lighthouse
Simulated mobile · Performance
100 / 100
2026-09-05 · Lab data, not field data.
View details
Simulated mobile · Lab data, not field data
2026-09-05T06:31:58.129Z · Lighthouse 13.4.1
Performance100/ 100
Accessibility96/ 100
Best practices96/ 100
SEO80/ 100
LCP · Largest content802 ms
CLS · Layout shift0.000
TBT · Blocking time0 ms
FCP · First content802 ms
SI · Speed index1,531 ms
Results vary by server, network and environment, independently of taste/conversion scores. Diagnostics retain Lighthouse wording.
Document does not have a main landmark.
One main landmark helps screen reader users navigate a web page. Learn more about landmarks.
Elements & resources
{
"type": "table",
"items": [
{
"node": {
"lhId": "1-0-HTML",
"path": "1,HTML",
"type": "node",
"snippet": "<html lang=\"en\">",
"selector": "html",
"nodeLabel": "html",
"explanation": "Fix all of the following:\n Document does not have a main landmark",
"boundingRect": {
"top": 0,
"left": 0,
"right": 412,
"width": 412,
"bottom": 402,
"height": 402
}
}
}
],
"headings": [
{
"key": "node",
"label": "Failing Elements",
"valueType": "node",
"subItemsHeading": {
"key": "relatedNode",
"valueType": "node"
}
}
],
"debugData": {
"tags": [
"cat.semantics",
"best-practice"
],
"type": "debugdata",
"impact": "moderate"
}
}Charset declaration is missing or occurs too late in the HTML
A character encoding declaration is required. It can be done with a `<meta>` tag in the first 1024 bytes of the HTML or in the Content-Type HTTP response header. Learn more about declaring the character encoding.
Document does not have a meta description
Meta descriptions may be included in search results to concisely summarize page content. Learn more about the meta description.
Links do not have descriptive text
1 link found
Descriptive link text helps search engines understand your content. Learn how to make links more accessible.
Elements & resources
{
"type": "table",
"items": [
{
"href": "https://iana.org/domains/example",
"text": "Learn more",
"textLang": "en"
}
],
"headings": [
{
"key": "href",
"label": "Link destination",
"valueType": "url"
},
{
"key": "text",
"label": "Link Text",
"valueType": "text"
}
]
}Environment & raw metrics
{
"finalUrl": "https://example.com/",
"userAgent": "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) HeadlessChrome/151.0.0.0 Safari/537.36",
"formFactor": "mobile",
"throttlingMethod": "simulate",
"throttling": {
"rttMs": 150,
"throughputKbps": 1638.4,
"requestLatencyMs": 562.5,
"uploadThroughputKbps": 675,
"cpuSlowdownMultiplier": 4,
"downloadThroughputKbps": 1474.5600000000002
},
"metrics": [
{
"id": "largest-contentful-paint",
"unit": "millisecond",
"value": 801.932
},
{
"id": "cumulative-layout-shift",
"unit": "unitless",
"value": 0
},
{
"id": "total-blocking-time",
"unit": "millisecond",
"value": 0
},
{
"id": "first-contentful-paint",
"unit": "millisecond",
"value": 801.932
},
{
"id": "speed-index",
"unit": "millisecond",
"value": 1530.7641997650146
}
]
}01 / WHAT WORKS
What makes it work
Immediate communicative clarity
The body copy states the operational boundary in two short sentences without ambiguity or clutter: documentation use is permitted, operational use is prohibited.
Instantaneous load and zero asset overhead
Using native system-ui fonts and default vector rendering without external style sheets or scripts keeps the initial payload minimal across all viewports.
02 / NEXT STEPS
Where to go next
- 01
Clarify destination context on the external action
The CTA text 'Learn more' does not state where the link leads, forcing visitors to inspect the target URL to understand they are navigating to IANA domain documentation.
Update the anchor copy to indicate destination context, such as 'Learn more at IANA', and verify the anchor has an accessible name reflecting its target at https://iana.org/domains/example.
- 02
Constrain vertical drift and preserve centered framing
On 1440px desktop screens, the content card floats near the upper left quadrant with large empty gray space below, while mobile 390px centers the block horizontally.
Enforce a centered max-width container with balanced vertical margin across both desktop and mobile viewports, testing at 1440x900 and 390x844.
03 / DESIGN LANGUAGE
A design system you can reuse
Colors
Background
#eeeeeeText
#000000Typography
- Display font
- system-ui
- Body font
- system-ui
- Heading / body
- 24px / 16px
Spacing & shape
- Section gap
- —
- Component inset
- —
- Card radius
- —
- Button radius
- —
CLEARER WORDS
Copy Revision Diff
Now
Learn more
SUGGESTED COPY
Learn more at IANA
Adding the destination entity clarifies the external link target before the user clicks.04 / EVIDENCE
The detail behind the report
Explore each observation, recommendation and captured record.
Conversion3 observations
Primary action is vague
HighGet started and Learn more do not tell the visitor what happens next. Specific actions convert; generic ones stall.
Name the next step: Start free trial, Book a 15-min demo, Send the menu. One primary verb.
Learn more
Share card is incomplete
HighA blank or generic unfurl on X, Slack, or WeChat wastes the click you already earned. This is distribution, not decoration.
Set og:title, og:description, and a 1200x630 image that matches the live headline.
og:title=no og:image=no
Meta description is missing or thin
MediumThis is the sentence under your link in search and in some chat previews. An empty one wastes that slot.
Write one specific sentence, 70-160 characters, that matches the H1.
(missing)
Launch4 observations
No HSTS header
MediumWithout Strict-Transport-Security, a first visit can still be downgraded to http. Browsers will not pin HTTPS.
Set Strict-Transport-Security: max-age=31536000; includeSubDomains at the edge.
strict-transport-security missing
No Content-Security-Policy
A CSP is the standard way to limit script sources. Vibe-coded pages often load anything, including injected scripts.
Start with a report-only CSP, then default-src 'self' and an explicit script-src.
content-security-policy missing
No X-Content-Type-Options
Without nosniff, browsers may interpret a file as a different type than you sent. It is a one-line header.
Set X-Content-Type-Options: nosniff.
x-content-type-options missing
No Referrer-Policy
The default referrer can leak internal paths and query strings to third parties.
Set Referrer-Policy: strict-origin-when-cross-origin.
referrer-policy missing
05 / MAKE IT HAPPEN
Give your AI a clear next step
Use the improvement prompt for this page, or the design prompt to borrow its visual language. “Recreate” includes references and implementation steps. Paste either into your coding assistant.
Preview full instructions
Update the single page container on https://example.com/. Retain the exact background color #eeeeee, text color #000000, font stack system-ui, H1 size 24px with 700 weight, and body size 16px. Update the link text from 'Learn more' to 'Learn more at IANA' pointing to https://iana.org/domains/example. Ensure the content container has a clean max-width (e.g. 600px) centered both horizontally and with proportional vertical spacing on both desktop (1440x900) and mobile (390x844).