How will website updates affect SEO?

Question

css

Hello!
We plan to rewrite the site from scratch, the question arose: "How will this affect SEO?".
Of course, I would not say that everything is super in terms of SEO right now, rather everything is just the opposite. Specifically, we are interested in the TIC indicator, will we lose it if some of the links lead to a 404 page?
Please share your experience.

Answer 1

li a {
  line-height: 30px;
}

It?

Answer 2

The picture needs to be a background.
Something like this:

<ul>
  <li><a class="" href="#">Li1 text</a></li>
  <li><a class="" href="#">Li2 Text</a></li>
</ul>

a {
  background-image: url(_include/img/icon_side.png);
  background-position: center;
  line-height: 30px;
  text-align: center;
}

Answer 3

Make sure the url stays the same, and if you change it, make a 301 redirect. Titz will be the same if you don't change the domain

Answer 4

do 301 redirects for all addresses.

Answer 5

As written above, keep the original URLs, if they are not completely terrible.
The second solution is to set up redirects, but it will take a long time for search engines to take them into account.