Customizing validation errors

Question

First of all I want to take moment in conveying my thanks to each and everone who helped me several times and who spend a lot of their valuable time in helping other developers like me.
Here's my question:
When the validation errors show up in the notification, they are formatted with yellow triangles. (apex 3.2). How can I remove these yellow triangles?
I have a page level validation which throws multiple lines of error messages. I want them all to be a bulleted list.
So, basically I want all item and page level (which may be more than one line of errors)error messages to be a bulleted list.
How can it be done?
If bulleted list is hard, then I would atleast like to get rid of yellow triangles because they don't work good for page level validation which throws multiple error messages. Each traingle indicates one error which may not be the case when my page level validation fails.
Thanks for looking into this thread,
RN

Answer 1

Thanks Jari for prompt reply.
Your solution worked by putting code in page html header section. Yellow triangles got replaced with bullet points.
Can you please direct me where you found the code
li     {
list-style-image: url(Bullet.gif);
}My actual problem is more complicated. Changing bullets did not solve what I want. I did not describe my problem properly earlier and got carried away in wrong direction.
I would like to explain again what I want:
All validation errors show up as a bulleted list. Each bulleted point shows one validation error. But I have a page level validation that checks multiple business rules and throws error lines like this:
Product Category should be defined. <br>
Product needs atleast two approvals before moving it to next status.So far, these both error lines show under one bullet because it is result of one validation failure. But I want there two lines to show up under two different bullets because these are two errors.
If I can't show them this way, then I don't want any error message to be bulleted because bullets will give user wrong impression about number of errors.
I do want all error messages(from all different validations) show up in new line for the readilibility.
Hope I explained my requirement better this time.
Thanks,