CSS is not compatible with some SMIL features. Most incompatibilities will throw an error, preventing useless output. However, it's possible that some remain undetected, so be sure to check the output file in a browser.

Below is a list of unsupported SMIL features.

• Motion path elements: <animateMotion>,<mpath>.
• Unmatching repeatCount per display element. read more
• Reptitions with an initial delay. read more
• Interrupting non-discrete animations. read more

• Animation event attributes: onbegin,onend,onload,onrepeat.
• Additive and cumulative behaviors.
• Specific time values:
  • accessKey, event, repeat and wallclock-sync time values.
  • Some syncbase values. read more