HTML Checking for Large Sites
Rocket Validator integrates the W3C Validator HTML checker into an automated web crawler.
The “align” attribute on the “td” element is obsolete. Use CSS instead.
<td> elements no longer accept an align attribute. This can be achieved using CSS like this:
<td style="text-align:center;">content</td>
Related W3C validator issues
A <table> contains a <tr> row that has less <td> columns than the column count established by the first row. Check the table to ensure all rows have the same number of columns.
For example, in the following table, the first <tr> row defines that it’s 2 columns wide, but the second <tr> row tries to use only 1 column:
<table>
<!-- This first row sets the table as 2 columns wide -->
<tr>
<td>First</td>
<td>Second</td>
</tr>
<!-- This second row has only 1 column -->
<tr>
<td>Wrong</td>
</tr>
</table>
Learn more:
The <table> element does not accept a height attribute. Use CSS instead.
A CSS definition for background-image could not be understood by the parser. Check its definition to ensure that it’s well formed and that it contains an appropriate value.
The value on the display property is not valid.
The display CSS property sets whether an element is treated as a block or inline element and the layout used for its children, such as flow layout, grid or flex.
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The specified CSS filter is not a standard one, and may only work in some browsers.
Check out the Filter Effects W3C Working Draft
font-display isn’t a CSS property, it’s a descriptor for use with the @font-face at-rule.
Learn more:
This issue is a false positive by the W3C validator, fixed in the latest versions of Nu Validator.
The value revert is indeed a valid value for the CSS property font-size.
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The @import CSS rule can be used to import a style sheet into another style sheet. It must appear at the top of the document, and after any @charset declaration.
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The max-width CSS property sets the maximum width of an element. It prevents the used value of the width property from becoming larger than the value specified by max-width.
This property can express a value in different units like px, em, % or ch, and keyword values, but auto is not an allowed value.
Some examples of valid values for max-width:
/* <length> value */
max-width: 3.5em;
/* <percentage> value */
max-width: 75%;
/* Keyword values */
max-width: none;
max-width: max-content;
max-width: min-content;
max-width: fit-content(20em);
/* Global values */
max-width: inherit;
max-width: initial;
max-width: revert;
max-width: unset;
Learn more:
An invalid CSS property is being used. Properties starting with mso- are commonly defined by Microsoft products like Office and Outlook.
These properties, like mso-spacerun, mso-fareast-font-family, mso-bidi-font-weight, mso-margin-bottom-alt, mso-margin-top-alt and others starting with mso- are not standard CSS properties.
Padding properties, unline margin properties, don’t accept negative values. Read more about the CSS box model
CSS styles could not be parsed, check the indicated line to find what caused the parser to fail. Common causes are unclosed curly brackets or comments, missing semicolons or unexpected or empty properties.
Read more about CSS: Cascading Style Sheets syntax
The value break-word for the property word-break is deprecated, you should replace it with a valid value.
According to the CSS Text Module Level 3 spec:
For compatibility with legacy content, the word-break property also supports a deprecated
break-wordkeyword. When specified, this has the same effect asword-break: normalandoverflow-wrap: anywhere, regardless of the actual value of theoverflow-wrapproperty.
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The value specified for the transform CSS attribute is not valid.
The transform CSS property lets you rotate, scale, skew, or translate an element. It modifies the coordinate space of the CSS visual formatting model.
Learn more:
The ::file-selector-button has not been recognized by the W3C Validator. This seems to be a bug in the W3C Validator, which has already been reported.
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The value specified for a width attribute in CSS is not valid.
The width CSS property sets an element’s width. There are many allowed values for this attribute, for example:
/* <length> values */
width: 300px;
width: 25em;
/* <percentage> value */
width: 75%;
/* Keyword values */
width: max-content;
width: min-content;
width: fit-content(20em);
width: auto;
/* Global values */
width: inherit;
width: initial;
width: revert;
width: unset;
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CSS can’t be properly processed because a computed style is missing a value it depends on.
A CSS definition for an X property could not be understood by the parser. Check it to ensure that it’s well formed and that it contains an appropriate value.
When specifying a numeric value for a CSS property, remember to always include the units, like 3px or 3em. Only the 0 value can go without units, and instead of 0px you can just use 0.
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A <table> contains an incoherent number of columns on one of its rows. Check the structure of the table to find the invalid row.
For example, in the following table, the first <tr> row defines that it’s 2 columns wide, but the second <tr> row tries to use 5 columns by means of a colspan attribute:
<table>
<!-- This first row sets the table as 2 columns wide -->
<tr>
<td>First</td>
<td>Second</td>
</tr>
<!-- This second row tries to use 5 columns -->
<tr>
<td colspan="5">Wrong</td>
</tr>
</table>
Learn more:
The <big> tag is now obsolete. It was used to increase the size of text, you can do that using CSS instead. For example:
<p>Now this is <span style="font-size: larger;">big</span></p>
Read more:
<img> tags no longer accept a border attribute. This can be defined using CSS instead, for example:
<img src="..." alt="..." style="border:0;" />
The <center> tag is no longer valid in HTML, you should use CSS instead, for example:
<p style="text-align:center">this text will be centered</p>
The <font> element, used to define the font face, size and color in previous versions of HTML, is no longer valid in HTML5. Instead, you should rely on CSS styles.
For example, you can define a font size of 12px, bold text with inline styles like this:
<p style="font-size: 12px; font-weight: bold;">some text</p>
Learn more about CSS fonts:
The <tt> tag, used in HTML4 to apply a monospaced (fixed width) font to the text, was deprecated in HTML5. Instead, you should use CSS to apply the desired font.
Example, instead of this deprecated code:
<tt>This is deprecated</tt>
You can define a monospaced text using font-family:
<span style="font-family: monospace;">This is monospaced text</span>
Learn more:
The HTML <style> element contains style information for a document, or part of a document, defined in CSS. This element does not need the type attribute anymore, so it should be omitted.
For example, this style defines that <p> elements should be in red color.
<style type="text/css">
p {
color: red;
}
</style>
<p>This text will be red.</p>
But, the type attribute is not used anymore, so we can just use this:
<style>
p {
color: red;
}
</style>
<p>This text will be red.</p>
Read more:
<td> elements no longer accept a valign attribute. This can be achieved using CSS like this:
<td style="vertical-align:middle;">content</td>
Both <table> and <td> elements no longer accept a width attribute. Instead, you should use CSS as in this example:
<table style="width:100%;">
<tr>
<td style="width:50px;">Name</td>
</tr>
</table>
You’re using an attribute X that is no longer valid for element Y, but you can use CSS to achieve the same effect.
Still checking your large sites one page at a time?
Save time using our automated web checker. Let our crawler check your web pages on the W3C Validator.