Thanks for contacting Syncfusion support.
We have analyzed your reported query. It might be due to some CSS has overridden for input element width on Autocomplete textbox and so the issue has reproduced. Henceforth could you please ensure any CSS is overriding or not?
Note: We have already ensured with bootstrap.css. It doesn’t collapse our Autocomplete Textbox control styles.
Please let us know if you require further assistance on this.
We regret for the inconvenience caused.
We have tried to reproduce the reported issue “Autocomplete width has not set properly when using Bootstrap.css”. Unfortunately, we were unable to reproduce this issue as you mentioned. But in your given CSS code, we found that max-width property has been set for all input tags from bootstrap.css file. So it may be reason for reported issue, if so please override that CSS class otherwise could you please share a simple sample which reproduces this issue, so that we can analyses the issue in depth and provide you better solution.
We have prepared a simple sample to show case this behaviour. It can be available in following link:
Please let us know if you have further queries.