@-webkit-keyframes typing {
from { width: 0 }
to { width:16.3em }
}

@-moz-keyframes typing {
from { width: 0 }
to { width:16.3em }
}

@-webkit-keyframes blink-caret {
from, to { border-color: transparent }
50% { border-color: black }
}

@-moz-keyframes blink-caret {
from, to { border-color: transparent }
50% { border-color: black }
}

body { font-family: Consolas, monospace; }

h4 {
font-size:150%;
width:16.3em;
white-space:nowrap;
overflow:hidden;
border-right: .1em solid black;

-webkit-animation: typing 17s steps(30, end), /* # of steps = # of characters */
blink-caret 1s step-end infinite;
-moz-animation: typing 17s steps(30, end), /* # of steps = # of characters */
blink-caret 1s step-end infinite;
}

<h4>Typing animation in CSS3!</h4>