HTML Guide

The padding property in CSS requires a numerical value followed by a unit. For example, pixels (px), percentages (%), em units (em), etc. Setting padding: px without a number is invalid.

To fix the issue, specify a numerical value before the unit. Here’s how you can correct this:

Example of incorrect HTML with inline CSS:

<div style="padding: px;">Content</div>

Corrected HTML with inline CSS:

<div style="padding: 10px;">Content</div>

In the above example, 10px is a valid value.

Alternatively, if using an external CSS file, the incorrect CSS might look like this:

.example {
  padding: px;
}

Correct the external CSS by specifying a numerical value:

.example {
  padding: 10px;
}

Padding properties, unline margin properties, don’t accept negative values.

The <table> element does not accept a height attribute. Use CSS instead.

The autocomplete attribute on an input, textarea, select or form element lets web developers specify how autocompleting should be handled.

The value none is not valid, instead the value off should be used to disable autocompletion.

Here is an example of how you can adjust your HTML code:

Incorrect usage:

<input type="text" name="username" autocomplete="none">

Correct usage: If you want to disable autofill for an input field, you can use the value off instead of none:

<input type="text" name="username" autocomplete="off">

The attribute value is either the keyword off or on, or a space-separated token list that describes the meaning of the autocompletion value, for example name, email, postal-code and others. Refer to the linked guide to see the full list of accepted values for the autcomplete property.

The text-anchor attribute is used within SVG elements like text or textPath to specify the alignment of text relative to a given point, but it’s not allowed on g container elements.

Here’s an example of how you can correctly use the text-anchor attribute on a <text> element in SVG:

<svg width="200" height="200">
  <text x="100" y="100" text-anchor="middle">Centered text</text>
</svg>

In this example:

• The text-anchor="middle" attribute is applied directly to the <text> element.
• It aligns the text in the middle horizontally around the specified x-coordinate.

You can use the text-anchor element with the SVG elements text, textPath, tref or tspan.

The allowed values for the text-anchor attribute are start, middle or end. The value none is not valid for this attribute.

To query for the size of the viewport (or the page box on page media), the width, height and aspect-ratio media features should be used, rather than device-width, device-height and device-aspect-ratio, which refer to the physical size of the device regardless of how much space is available for the document being laid out. The device-* media features are also sometimes used as a proxy to detect mobile devices. Instead, authors should use media features that better represent the aspect of the device that they are attempting to style against.

The width media feature describes the width of the targeted display area of the output device. For continuous media, this is the width of the viewport including the size of a rendered scroll bar (if any).

In the following example, this media query expresses that the style sheet is only linked if the width of the viewport 768px maximum:

<link rel="stylesheet" media="only screen and (max-width: 768px)" href="styles.css">

To query for the size of the viewport (or the page box on page media), the width, height and aspect-ratio media features should be used, rather than device-width, device-height and device-aspect-ratio, which refer to the physical size of the device regardless of how much space is available for the document being laid out. The device-* media features are also sometimes used as a proxy to detect mobile devices. Instead, authors should use media features that better represent the aspect of the device that they are attempting to style against.

The width media feature describes the width of the targeted display area of the output device. For continuous media, this is the width of the viewport including the size of a rendered scroll bar (if any).

In the following example, this media query expresses that the style sheet is only linked if the width of the viewport is greater than 768px:

<link rel="stylesheet" media="only screen and (min-width: 768px)" href="styles.css">

The sizes attribute for an img element requires valid CSS syntax, and auto is not an acceptable value within that attribute.

The sizes attribute allows you to specify a list of media conditions and corresponding sizes for the images. Each condition determines which size of the image should be displayed at different viewport widths, ensuring responsive image delivery. The syntax for sizes should be a comma-separated list of media queries followed by a value denoting the corresponding width of the image. This width value may be in pixels (px) or as a percentage (vw, vh), but auto is not valid in this context.

Here is a breakdown of a correct sizes attribute usage:

• 50vw: This denotes that the image should take up 50% of the viewport’s width.
• (max-width: 600px) 100vw, 50vw: When the viewport is at most 600 pixels wide, the image should occupy the full width (100vw). Otherwise, it should take 50 percent of the viewport width.

Remove “auto” from your sizes value and provide a valid, contextually correct CSS value.

Example

<!DOCTYPE html>
<html lang="en">
<head>
  <title>Responsive Images Example</title>
</head>
<body>
  <img
    src="image.jpg"
    sizes="(max-width: 472px) 100vw, 472px"
    srcset="image-small.jpg 300w, image-medium.jpg 600w, image-large.jpg 1000w"
    alt="A description of the image"
  >
</body>
</html>

In this example, if the viewport width is less than or equal to 472 pixels, the image will take up the entire width (100vw). For larger widths, the srcset specifies different image files for varying resolutions.

The issue you’re encountering indicates that the CSS property align-items is being set to a value of auto, which is not a valid value for this property according to the CSS specification. The align-items property is used in flexbox and grid layouts to define how items are aligned along the cross axis.

Fixing the Issue:

• Understand Valid Values: The valid values for the align-items property include:

  /* Basic keywords */
  align-items: normal;
  align-items: stretch;
  
  /* Positional alignment */
  /* align-items does not take left and right values */
  align-items: center;
  align-items: start;
  align-items: end;
  align-items: flex-start;
  align-items: flex-end;
  align-items: self-start;
  align-items: self-end;
  align-items: anchor-center;
  
  /* Baseline alignment */
  align-items: baseline;
  align-items: first baseline;
  align-items: last baseline; /* Overflow alignment (for positional alignment only) */
  align-items: safe center;
  align-items: unsafe center;
  
  /* Global values */
  align-items: inherit;
  align-items: initial;
  align-items: revert;
  align-items: revert-layer;
  align-items: unset;
  

• Choose a Correct Value: Based on the desired alignment, choose one of the valid values. For instance:

  • Use flex-start to align items to the start of the container.
  • Use center to align items in the center.
  • Use stretch to stretch items to fill the container.

• Example Correction: If your original CSS was:

   .container {
     display: flex;
     align-items: auto; /* This is invalid */
   }

  You could change it to:

   .container {
     display: flex;
     align-items: center; /* This is valid */
   }

Conclusion:

Replace the invalid auto value with a valid option that suits the design you aim for, making sure to test the layout after applying changes to confirm that the items align as intended.

The aspect-ratio CSS property allows you to define the desired width-to-height ratio of an element’s box. This means that even if the parent container or viewport size changes, the browser will adjust the element’s dimensions to maintain the specified width-to-height ratio. The specified aspect ratio is used in the calculation of auto sizes and some other layout functions.

The box’s preferred aspect ratio is the specified ratio of width / height. If height and the preceding slash character are omitted, height defaults to 1.

Here are some examples of this property:

aspect-ratio: 1 / 1;
aspect-ratio: 1;

/* Global values */
aspect-ratio: inherit;
aspect-ratio: initial;
aspect-ratio: revert;
aspect-ratio: revert-layer;
aspect-ratio: unset;