Looking at the page http://jigsaw.w3.org/css-validator/validator?uri=https://www.draculacars.co.uk/index.html, a number of things strike me.
The first is that any line that is complaining about a property that starts with -moz-, -o-, -webkit- or -ms- can be pretty much ignored, as all browser-specific properties are non-standard, but as long as they are written in accordance with the specs from the browser manufacturers they will be absolutely fine.
The second is that bootstrap.min.css is a complete load of garbage. As well as being an advanced case of mammoth bloat, it uses all sorts of non-standard code which looks to me like various hacks, most of which are utter nonsense. Take, for example, the line
There is no possible reason ever to give a CSS measurement to that level of precision, let alone to provide some browser-specific hack that adjusts it by 0.1%, other than that it was written by someone who is completely clueless.
A further problem is that because it's been compressed onto a single line and made completely illegible, in the vain hope of shaving a nanosecond or two off the download time, the validator is complaining of every single error being on "line 9", which makes it all but impossible to figure out what it is referring to.
The best thing you can do with that CSS is to rip it up, throw it in the bin and write the code that you want from scratch.