Challenge we solve
How we solve Invalid HTML
In our experience, invalid HTML means the page markup contains errors against the HTML specification, such as unclosed tags, improperly nested elements, duplicate IDs, or missing required attributes, the kind of errors a validator like the W3C markup checker flags. This happens when code is hand written without validation, generated by a CMS/page builder with bugs, or accumulates cruft from repeated edits over time. Severe markup errors can cause browsers and crawlers to parse the DOM incorrectly, which can affect how content, links, and structured data are read and indexed.
How we solve Invalid HTML
In our experience, invalid HTML means the page markup contains errors against the HTML specification, such as unclosed tags, improperly nested elements, duplicate IDs, or missing required attributes, the kind of errors a validator like the W3C markup checker flags. This happens when code is hand written without validation, generated by a CMS/page builder with bugs, or accumulates cruft from repeated edits over time. Severe markup errors can cause browsers and crawlers to parse the DOM incorrectly, which can affect how content, links, and structured data are read and indexed.
Why this happens (and how we fix it)
In our experience, invalid markup accumulates gradually, hand written code without a validation step can introduce unclosed tags or improperly nested elements from the start, and page builders or CMS plugins with their own bugs can generate malformed output a non technical editor has no way to catch. Duplicate IDs are a common repeat offender, appearing when a component gets used more than once on a page but was only ever designed to appear a single time, so its hardcoded ID gets duplicated. Years of incremental edits compound small errors that individually seem harmless but collectively degrade how cleanly the page parses.
What it costs you while it goes unfixed
In our experience, severe markup errors can cause browsers to build an unpredictable DOM, since browsers apply their own error correction rules that don't always match what the author intended, meaning the visible page might render fine while the structure crawlers read is subtly different. That mismatch can affect how content, links, and structured data get parsed, since a mis nested element can accidentally hide or orphan content meant to be part of the body. Duplicate IDs namely break any JavaScript or CSS targeting an element by ID, since the browser only acts on the first match, silently breaking every subsequent instance.
How we resolve it
01 Diagnose
We audit your current setup and identify the root cause.
02 Fix
We implement targeted corrections using proven methods.
03 Verify
We confirm the issue is resolved and monitor for recurrence.
Ready to grow your business with us?
Get a free audit from Arising Media. We identify what is holding your business back and show you exactly how to fix it.