Slider text not quite centered

I took what you gave me on Increase the width of the slider content area, plus some info on setting a transparent background for the slider text that I found elsewhere on these forums, and updated my miboxdallas.com site. Today, I then took the same css and copied it to my theo.solutions site (which I just upgraded to Adventurous Pro), except that I changed the slider text to be at the bottom of the slider instead of the top. For some reason I never noticed before, or maybe ran out of time, but the text area is not quite centered left-to-right on either of these sites ... there's a little more spacing on the left than on the right. It's particularly noticeable on small screens. http://miboxdallas.com/

/* Slider title/text area */
#main-slider .entry-container {
    bottom: auto;
    top: 15%;
    left: 10%;
    width: 80%;
    background:rgba(0, 0, 0, 0.4);
    color: #ffffff;
    font-family: "Palatino Linotype", "Book Antiqua", Palatino, serif;
    font-style: italic;
    padding: 1em 1em;
    padding: 1rem 1rem;
}

http://theo.solutions/

/* Slider title/text area */
#main-slider .entry-container {
    top: auto;
    bottom: 15%;
    left: 10%;
    width: 80%;
    background:rgba(0, 0, 0, 0.4);
    color: #ffffff;
    padding: 1em 1em;
    padding: 1rem 1rem;
}