What's the best way to make a side menu?

Question

css

Good, tostorevchane.
The site is given: broker-sberbank.ru I
made it from scratch, with no experience at all (plus the terrible locations of everything, these are the whims of the management (I was also surprised)), so please don’t cover it with all sorts of things :) At the moment I’m sorting it out a little bit, I clean up the code, I clean up huge shoals.
But at the moment I'm asking for help on the side menu. Now it's the awful "a href" + "hr" (gods).
Question two.
First main. I remember at the very beginning somewhere I found the usual JS + CSS that did not have anything superfluous. The usual ul li and a script for a drop-down list. But there was a beautiful little triangle that spun when you clicked on it, and it further expanded the second level list. Can you suggest something or how to do it? There is one problem with all of this:

<ul>
  <li><a href=#>1</a></li>
  <li><a href=#>2</a></li>
  <li><a href=#>3</a>
    <ul>
      <li><a href=#>3.1</a></li>
    </ul>
  </li>
  <li><a href=#>4</a></li>
</ul>

Those. the link should work both on the page and on the list expansion. So this should be done by :hover, if I'm not mistaken.
Second. The question is purely design. Maybe someone who is more friends with him, and will tell you how he sees this list. The main aspect is that it should be light enough not to draw attention to itself from the whole page, and be in harmony with the scale, theme, etc. as harmoniously as possible. (I don't know what it's called).

Answer 1

Take bootstrap and redesign your site on it. It's simple and fast and has everything you need.
At the same time get a rubber layout. Because it comes from the 90s