flexbox page-vendor prefixes

by ian_smithz

HTML

<header>
      <nav>
        <ul>
          <li><h1><a href="#">Logo</a></h1></li>
          <li><a href="#">Home</a></li>
          <li><a href="#">About</a></li>
          <li><a href="#">Work</a></li>
          <li><a href="#">Blog</a></li>
        </ul>
      </nav> 
    </header> <!-- end of header element -->

    <div class="banner">
      <h2>Flexbox makes things easier!</h2>
    </div> <!-- end of .banner element -->

    <main>
      <section class="about">
        <h3>About</h3>
        <div>
          <section>
            <h4>Our Story</h4>
            <p>Duis autem vel eum iriure dolor in hendrerit in vulputate velit esse molestie consequat, vel illum dolore eu feugiat nulla facilisis at vero eros et accumsan et iusto odio dignissim qui blandit praesent luptatum zzril delenit augue duis dolore te feugait nulla facilisi. Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy.
            </p>
          </section>
          <section>
            <h4>Our Name</h4>
            <p>Duis autem vel eum iriure dolor in hendrerit in vulputate velit esse molestie consequat, vel illum dolore eu feugiat nulla facilisis at vero eros et accumsan et iusto odio dignissim qui blandit praesent. Ut wisi enim ad minim veniam, quis nostrud exerci tation ullamcorper.
            </p>
          </section>
          <section>
            <h4>Our Values</h4>
            <p>Duis autem vel eum iriure dolor in hendrerit in vulputate velit esse molestie consequat, vel illum dolore eu feugiat nulla facilisis at vero eros et accumsan et iusto odio dignissim qui blandit praesent et iusto odio dignissim.
            </p>
          </section>
        </div>
      </section> <!-- end of section.about element -->
      <aside>
        <h3>Latest Blogs</h3>
        <ul>
          <li>
            <article>
              <h4>Article 1</h4>
              <p>At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est...

CSS

/*------------------------------------------------------------------
  							RESET STYLES
-------------------------------------------------------------------*/

h1, h2, h3, h4, p, ul, li {
	margin: 0;
}

ul, li {
	list-style: none;
	padding: 0;
}

a {	
	display: inline-block;
	text-decoration: none;
	color: black;
}

hr {
	border-color: lightblue;
}


body {
	margin: 2px;
	font-family: sans-serif;
	background-color: #ededed;
}

h1{
	font-size: 1.5em;
}



/*------------------------------------------------------------------
  							HEADER STYLES
-------------------------------------------------------------------*/

header ul {
	display: -webkit-box;
	display: -webkit-flex;
	display: -ms-flexbox;
	display: flex;
	-webkit-box-align: center;
	-webkit-align-items: center;
	-ms-flex-align: center;
	align-items: center;
	background-color: steelblue;
	height: 80px;
}

header li {
	height: 30px;
	padding: 10px;
	text-align: center;
	line-height: 30px;
	margin-right: 15px;
	position: relative;
	border-radius: 5px;	
}

header li:not(:first-child) {
	-webkit-flex-basis: 60px;
	-ms-flex-preferred-size: 60px;
	flex-basis: 60px;
}

header li:not(:first-child):hover {
	background: lightblue;
	-webkit-transition: all .4s ease-in-out;
	transition: all .4s ease-in-out;
}

header li:first-child {
	-webkit-flex-basis: 70px;
	-ms-flex-preferred-size: 70px;
	flex-basis: 70px;
	margin: 0 auto 0 15px;
	background: #ADD8E6;
}

header li:not(:first-child):not(:last-child):after, 
footer li:not(:last-child):after {
	content: "";
	height: 12px;
	width: 2px;
	display: inline-block;	
	position: absolute;
}

header li:not(:first-child):not(:last-child):after {
	top: 19px;
	right: -8.5px;
	background: lightblue;
}

footer li:not(:last-child):after {
	top: 10px;
	right: -8.5px;
	background: #6495ED;
}


/*------------------------------------------------------------------
  							DIV.BANNER STYLES
-------------------------------------------------------------------*/

.banner {
	margin-top:...