Fixing Unexpected SVG Scaling: Diagnosing the SVGO removeDimensions Plugin

The Problem: SVGs Expanding to Fill Containers

After running an SVG through SVGO, you may find that an icon or illustration that previously had a fixed size (e.g., 32x32px) now expands to fill the entire width of its parent container or disappears entirely. This usually happens because the removeDimensions plugin has stripped the width and height attributes from the <svg> tag, leaving only the viewBox.

While removing dimensions is often desired for responsive design, it causes rendering issues when the surrounding CSS does not explicitly define the SVG's size, as browsers default to 100% width and height in these scenarios.

Diagnostic Matrix

Symptom	Likely Cause	Verification Point
SVG fills entire screen/container	removeDimensions active; no CSS width defined	Check <svg> tag for missing width/height
SVG is invisible (0px height)	removeDimensions active; parent container has no height	Inspect computed height in Browser DevTools
SVG renders at original size	removeDimensions disabled or not applied	Check <svg> tag for existing width attribute

Step-by-Step Resolution

1. Verify Attribute Stripping

Compare the source file with the optimized file. If the original file contains width="100" height="100" but the optimized file only contains viewBox="0 0 100 100", the removeDimensions plugin is the cause.

2. Determine the Implementation Goal

Decide if the SVG should be fixed-size (e.g., a UI icon) or fluid (e.g., a full-width hero illustration). This determines which fix to apply.

3. Apply the Fix

Option A: Disable the Plugin (For Fixed-Size Assets)

If you need the SVG to carry its own dimensions to ensure consistent rendering across different environments without relying on external CSS, disable the plugin in your svgo.config.js file.

module.exports = {
  plugins: [
    {
      name: 'removeDimensions',
      active: false,
    },
  ],
};

Option B: Control via CSS (For Responsive Assets)

If you prefer the SVG to be fluid, keep the plugin active but define the constraints in your stylesheet. This is the modern standard for web development as it separates content from presentation.

/* Target the SVG specifically or via a class */
.icon-logo {
  width: 48px;
  height: 48px;
}

Verification and Testing

To verify the fix, run the SVGO CLI on a test file. Assuming you are using the CLI globally with permissions to write to the local directory:

# Run SVGO on a specific file
svgo input.svg -o output.svg

Check: Open output.svg in a text editor. If you disabled the plugin, the width and height attributes must be present. If you chose the CSS route, verify in the browser's Computed tab that the element is not defaulting to 100%.

Limitations and Risks

• Legacy Browsers: Some very old browsers do not scale viewBox correctly if width and height are missing. If you support legacy software, keep dimensions active.
• Parent Containers: If the SVG is inside a <div> with display: flex or grid, removing dimensions can lead to unpredictable stretching unless align-items or justify-content are explicitly set.

Rollback Procedure

If disabling the plugin causes your SVGs to stop scaling responsively, revert the svgo.config.js change by setting active: true or removing the plugin override entirely to return to SVGO defaults.