How to center list items with flexbox?

Question

I am trying to create a navbar with heading on the left, and list items centered. I used flexbox to horizontally line links. Then ı added margin: auto to ul which moved them to left but did'nt centered them symetrically. I am guessing there is no space for the ul to move anymore. I checked other similiar posts but couldn't quite figure what the problem is. Thank you for your time.

HTML

* {
    box-sizing: border-box;
    padding: 0;
    margin: 0;
}

body {
    font-family: 'Open Sans', sans-serif;
    background: #fff;
    color: #333;
    line-height: 1.6;
    background: url('/img/showcase.jpg.jpg');
}


#navbar  {
    display: flex;
    justify-content: center;
    align-items: center;
    flex: 1;
    top: 0;
    width: 100%;
    height: 60px;
    background-color: rgba(10, 10, 10, 0.5);
}

#navbar ul {
    display: flex;
    justify-content: space-around;
    text-align: center;
    margin: 0 auto;
    padding: 0;
}

#navbar li {
    list-style: none;
    padding: 20px;
}

<nav id="navbar">
        <div class="logo">
            <h1>Welcome</h1>
        </div>
        <ul>
            <li><a href="#">Home</a></li>
            <li><a href="#">Home</a></li>
            <li><a href="#">Home</a></li>
            <li><a href="#">Home</a></li>
        </ul>
    </nav>

Answer 1

If I correctly understood your question (please, let me know), this is what you're after:

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  background: #fff;
  background: url('/img/showcase.jpg.jpg');
  color: #333;
  font-family: 'Open Sans', sans-serif;
  line-height: 1.6;
}

#navbar,
#navbar ul {
  display: flex;
}

#navbar {
  align-items: center;
  background-color: rgba(10, 10, 10, 0.5);
  height: 60px;
  justify-content: space-between;
}

#navbar ul {
  justify-content: center;
  width: 100%;
}

#navbar li {
  list-style: none;
  margin: 0 10px 0 10px;
}

.logo {
  margin-left: 20px;
}

<nav id="navbar">
  <div class="logo">
    <h1>Welcome</h1>
  </div>
  <ul>
    <li><a href="#">Home</a></li>
    <li><a href="#">Home</a></li>
    <li><a href="#">Home</a></li>
    <li><a href="#">Home</a></li>
  </ul>
</nav>