You can use line-height: 50px;, you won't need vertical-align: middle; there.
Demo
The above will fail if you've multiple lines, so in that case you can wrap your text using span and than use display: table-cell; and display: table; along with vertical-align: middle;, also don't forget to use width: 100%; for #abc
Demo
#abc{
font:Verdana, Geneva, sans-serif;
font-size:18px;
text-align:left;
background-color:#0F0;
height:50px;
display: table;
width: 100%;
}
#abc span {
vertical-align:middle;
display: table-cell;
}
Another solution I can think of here is to use transform property with translateY() where Y obviously stands for Y Axis. It's pretty straight forward... All you need to do is set the elements position to absolute and later position 50% from the top and translate from it's axis with negative -50%
div {
height: 100px;
width: 100px;
background-color: tomato;
position: relative;
}
p {
position: absolute;
top: 50%;
transform: translateY(-50%);
}
Demo
Note that this won't be supported on older browsers, for example IE8, but you can make IE9 and other older browser versions of Chrome and Firefox by using -ms, -moz and -webkit prefixes respectively.
For more information on transform, you can refer here.