Browser support matrix

The HTML and CSS that Site Designer exports targets modern browsers. This article defines the support matrix and explains how framework choice affects compatibility.

Supported browsers (output)

Sites built with Site Designer are designed and tested to work in:

These versions were current in 2021 and later. As of 2026, the vast majority of users worldwide are on browser versions well above these minimums.

Internet Explorer 11

IE11 reached end of life in June 2022 and is no longer supported by Microsoft. Site Designer’s output does not guarantee IE11 compatibility:

• CSS Grid is partially supported in IE11 with the old -ms-grid syntax, which Site Designer does not generate.
• CSS custom properties (variables) are not supported at all in IE11.
• Flexbox works in IE11 with bugs (especially in flex item sizing).

If you must support IE11, the Bootstrap 4 framework provides the most IE11-compatible output among the three, since it avoids CSS variables and uses well-tested Flexbox patterns. You’ll still need to manually test and add -ms- prefixes for any Grid layouts.

How framework choice affects browser support

Materialize uses a float-based grid (not Flexbox or CSS Grid), which gives it slightly better IE11 layout compatibility than Foundation or Bootstrap 4, at the cost of less powerful layout tools.

Feature queries for IE11 fallbacks

If you need to ship an IE11 fallback for a specific layout, use @supports to provide a simpler layout to browsers without Grid support:

/* Fallback for IE11 and other browsers without Grid */
.container { display: flex; flex-wrap: wrap; }

/* Modern browsers with CSS Grid support */
@supports (display: grid) {
  .container { display: grid; grid-template-columns: repeat(3, 1fr); }
}

Add @supports blocks in Site Designer via the CSS pane.

Cross-browser testing tools