how can I make bottom navigation full width?

I’ve troubleshooted this code for hours. I used https://premium.wpmudev.org/blog/move-wordpress-theme-menus/ to help move the navigation bar to the bottom. It is using the Adament theme. When the navi bar is at the top, it displays full width but when I put it at the bottom it doesnt do full width anymore. How can I fix this? Here’s the code:

.site-header .container {
background-color: #121212;
position:fixed;
bottom:0;
left: 0;
height:100px;
width:100% !important;

}

.main-navigation {
clear: both;
display: block;
float: left;
width: 100%;
font-size: 14px;
text-transform: uppercase;
margin-top:5px;
}
.main-navigation ul {
list-style: none;
margin: 0;
padding-left: 0;
}

Also, the mobile view toggle is not working anymore (the menu wont open) how can I fix this?

/* Small menu */
.menu-toggle {
cursor: pointer;
display: none;
background: #fff;
border: none;
}

.menu-toggle:hover{
background: #fff;
box-shadow: none;
border:none;
}

@media screen and (max-width: 767px) {
.menu-toggle,
.main-navigation.toggled .nav-menu {
display: block;
}

.main-navigation ul {
display: none;
}
}