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Styling and Formatting HtmlTextBox

The HtmlTextBox enables you to control the style of its text presentation by supporting a set of HTML tags and CSS attributes.

Supported HTML Tags

The following HtmlTextBoxVarious formatting options are available and provide control over the HtmlTextBox text presentation:

Font, color (), and size (relative size against the font size of the item). The default size value is 3 out of the 1-7 range.
Bold, Italic, Underline (,, , , and ).
Subscript, Superscript ( and ).
HyperLink (<a href target>).
Lists (<ol>, <ul>, and <li>).
Text organization in paragraphs (<div>, ,,  , and <center>).
Images (<img>) - for embedding inline images within HTML content.

While the HtmlTextBox does not support the table tag, you can use the native Telerik Reporting Table, Crosstab, and List report items instead.

Image Support

The <img> tag support was introduced in the 2026 Q1 release.

The HtmlTextBox supports the <img> tag for embedding images inline within HTML content.

Supported `<img>` Attributes

The following HTML attributes control the image source, dimensions, and accessibility:

src - Image source (supports HTTP/HTTPS URLs, file paths, base64 data URIs).
width - Image width in absolute units (px, cm, mm, in, pt, pc) or percentages (relative to parent container width). Default unit is pixels if not specified.
height - Image height in absolute units (px, cm, mm, in, pt, pc) or percentages (relative to parent container height). Default unit is pixels if not specified.
alt - Alternative text for accessibility.

Em units are not supported for width and height attributes.

Example Usage

Basic image with dimensions and styling:

html

<img src="https://example.com/logo.png" width="200" height="100" alt="Company Logo" style="display: block; margin: auto;" />

Data-driven image with embedded expressions:

html

<img src="{Fields.ProductImage}" width="150" alt="{Fields.ProductName}" style="margin: 10px;" />

When you import content that contains HTML markup, the data is always parsed by the HtmlTextBox first. Because only a subset of HTML tags is supported, the HTML that is shown in the rendered report may differ from your original HTML.

Also, according to the HTML specification and the general XML specification, the &, < and > characters are considered as markup delimiters and you have to encode them so that they are treated as regular text. For example, you can escape the & character as & entity. For more information, refer to the w3.org article.

Any other HTML markup tags will be ignored during the processing of the report. If the HTML represented by the expression in the HtmlTextBox is badly formatted, the HtmlTextBox will throw an exception. Note that all HTML tags are case-insensitive.

Text Elements

The HtmlTextBox supports the following CSS attributes for styling text elements:

background-color
border, border-color, border-width, border-style
text-align (center, left, right, and justify), text-decoration (none, underline, and line-through)
(Specify it on a block item.) text-indent
font-family, font-size, font-weight
padding, padding-bottom, padding-top, padding-right, padding-left
color

Images

The following CSS attributes are supported for <img> tags:

margin, margin-top, margin-right, margin-bottom, margin-left (supports auto for centering)
padding, padding-top, padding-right, padding-bottom, padding-left
display (block, inline, inline-block)
float (left, right)