readjust Horizontal menu to resolution - html

Question

I'm new to this, so I'm clueless.
Whenever I go to my site with a different resolution the menu changes a lot and does not align correctly. Just tell me if i need more of the html or css.
My webpage is Aulan.co
My code:
ul {
font-size: 25px;
color: black;
text-align: center;
list-style-type: none;
margin-bottom: 2em;
line-height: 150%;
margin-left: 3em;
margin-right: 5em;
}
#menu {
list-style-type: none;
margin: auto;
width: 90%;
height: auto;
padding: auto;
overflow: hidden;
background-color: #353B4E;
text-align: center;
font-size: 18px;
}
li {
text-align: center;
}
li a {
display: block;
color: white;
text-align: center;
padding: 5px 70px;
text-decoration: none;
height: auto;
}
li a:hover {
background-color: #111;
display: inline;
}
#menus {
float: left;
<h1> AuLan </h1>
<ul id="menu">
<li id="menus"><a class="active">Forside</a></li>
<li id="menus">Informasjon</li>
<li id="menus">Regler</li>
<li id="menus">Crew</li>
<li id="menus">Kontakt oss</li>
<li id="menus">Seatmap</li>
<li id="menus">Timeplan</li>
</ul>

Answer 1

it's not really clear what you want to achieve, but I tried to change your code in a way that I think you might want. I took out a lot of unneccessary code from the CSS and added some. In the HTML, i change the menusID to a class, since IDs should only be used once per page.
You can adjust especially the min-width and padding setting in the menu li a rule to your needs (but also the other width and padding settings)
#menu {
font-size: 25px;
list-style-type: none;
width: 90%;
background-color: #353B4E;
font-size: 18px;
padding: 10px 20px;
}
#menu li {
display: inline-block;
line-height: 150%;
}
#menu li a {
display: block;
min-width: 100px;
color: white;
padding: 5px 15px;
text-decoration: none;
}
#menu li a:hover {
background-color: #111;
}
<h1> AuLan </h1>
<ul id="menu">
<li class="menus"><a class="active">Forside</a></li>
<li class="menus">Informasjon</li>
<li class="menus">Regler</li>
<li class="menus">Crew</li>
<li class="menus">Kontakt oss</li>
<li class="menus">Seatmap</li>
<li class="menus">Timeplan</li>
</ul>