You can't clear the Opacity from text.
You have to set the background-color according to the need.
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <title>Pretty Simple Content Slider with jQuery and CSS3</title>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
    <meta name="description" content="Pretty Simple Content Slider with jQuery and CSS3" />
    <meta name="keywords" content="jquery,css3, content slider, slide, auto-play" />
</head>
<body>
        <style>
            * {
                margin: 0;
                padding: 0;
            }
            body {
                font-family: Arial;
                /*background:#C1C7D5 url(title.png) no-repeat top center;*/
            }
            a.back {
                /*background:transparent url(back.png) no-repeat top left;*/
                position: fixed;
                width: 150px;
                height: 27px;
                outline: none;
                bottom: 0px;
                left: 0px;
            }
            #content {
                margin: 150px auto 10px auto;
            }
            .reference {
                clear: both;
                width: 800px;
                margin: 30px auto;
            }
                .reference p a {
                    text-transform: uppercase;
                    text-shadow: 1px 1px 1px #fff;
                    color: #666;
                    text-decoration: none;
                    font-size: 10px;
                }
                    .reference p a:hover {
                        color: #333;
                    }
            .rotator {
                background-color: #222;
                width: 800px;
                height: 300px;
                margin: 0px auto;
                position: relative;
                font-family: 'Myriad Pro',Arial,Helvetica,sans-serif;
                color: #fff;
                text-transform: uppercase;
                letter-spacing: -1px;
                border: 3px solid #f0f0f0;
                overflow: hidden;
                -moz-box-shadow: 0px 0px 10px;
                -webkit-box-shadow: 0px 0px 10px #222;
                box-shadow: 0px 0px 10px #222;
            }
            img.bg {
                position: absolute;
                top: 0px;
                left: 0px;
            }
            .rotator ul {
                list-style: none;
                position: absolute;
                right: 0px;
                top: 0px;
                margin-top: 6px;
                z-index: 999999;
            }
                .rotator ul li {
                    display: block;
                    float: left;
                    clear: both;
                    width: 260px;
                }
                    .rotator ul li a {
                        width: 230px;
                        float: right;
                        clear: both;
                        padding-left: 10px;
                        text-decoration: none;
                        display: block;
                        height: 52px;
                        line-height: 52px;
                        background-color: #222;
                        margin: 1px -20px 1px 0px;
                        opacity: 0.7;
                        color: #f0f0f0;
                        font-size: 20px;
                        border: 2px solid #000;
                        border-right: none;
                        outline: none;
                        text-shadow: -1px 1px 1px #000;
                        -moz-border-radius: 10px 0px 0px 20px;
                        -webkit-border-top-left-radius: 100px;
                        -webkit-border-bottom-left-radius: 200px;
                        border-top-left-radius: 10px;
                        border-bottom-left-radius: 20px;
                    }
                        .rotator ul li a:hover {
                            text-shadow: 0px 0px 2px #fff;
                        }
            .rotator .heading {
                position: absolute;
                top: 0px;
                left: 0px;
                width: 500px;
            }
                .rotator .heading h1 {
                    text-shadow: -1px 1px 1px #555;
                    font-weight: normal;
                    font-size: 46px;
                    padding: 20px;
                }
            .rotator .description {
                width: 500px;
                height: 80px;
                position: absolute;
                bottom: 0px;
                left: 0px;
                padding: 20px;
                background-color: #222;
                -moz-border-radius: 0px 10px 0px 0px;
                -webkit-border-top-right-radius: 10px;
                border-top-right-radius: 10px;
                /*opacity: 0.7;*/
                /*background-color: rgba(0, 0, 0, 0.7);*/
                /* For IE 5.5 - 7 */
                /*filter: progid:DXImageTransform.Microsoft.gradient(startColorstr=#99000000, endColorstr=#99000000);*/
                /* For IE 8 */
                /*-ms-filter: "progid:DXImageTransform.Microsoft.gradient(startColorstr=#99000000, endColorstr=#99000000)";*/
                border-top: 2px solid #000;
                border-right: 2px solid #000;
            }
                .rotator .description p {
                    text-shadow: -1px 1px 1px #000;
                    text-transform: none;
                    letter-spacing: normal;
                    line-height: 26px;
                }
            a.more {
                color: orange;
                text-decoration: none;
                text-transform: uppercase;
                font-size: 10px;
            }
                a.more:hover {
                    color: #fff;
                }
        </style>
        <div id="content">
            <a class="back" href=""></a>
            <!-- ---------First Slider--------- -->
            <div class="rotator">
                <ul id="rotmenu">
                    <li>
                        <a href="rot1">Portfolio</a>
                        <div style="display: none;">
                            <div class="info_image">1.jpg</div>
                            <div class="info_heading">Our Works</div>
                            <div class="info_description">
                                Portfolio: At vero eos et accusamus et iusto odio            
                                <a href="#" class="more">Read more</a>
                            </div>
                        </div>
                    </li>
                    <li>
                        <a href="rot2">Services</a>
                        <div style="display: none;">
                            <div class="info_image">2.jpg</div>
                            <div class="info_heading">We serve</div>
                            <div class="info_description">
                                Services: At vero eos et accusamus et iusto odio                 
                                <a href="#" class="more">Read more</a>
                            </div>
                        </div>
                    </li>
                </ul>
                <div id="rot1">
                    <img src="" width="800" height="300" class="bg" alt="" />
                    <div class="heading">
                        <h1></h1>
                    </div>
                    <div class="description">
                        <p></p>
                    </div>
                </div>
            </div>
            <!-- ---------Second Slider--------- -->
            <div class="rotator">
                <ul id="rotmenu1">
                    <li>
                        <a href="rot11">Portfolio</a>
                        <div style="display: none;">
                            <div class="info_image">1.jpg</div>
                            <div class="info_heading">Our Works</div>
                            <div class="info_description">
                                Portfolio: At vero eos et accusamus et iusto odio            
                                <a href="#" class="more">Read more</a>
                            </div>
                        </div>
                    </li>
                    <li>
                        <a href="rot21">Services</a>
                        <div style="display: none;">
                            <div class="info_image">2.jpg</div>
                            <div class="info_heading">We serve</div>
                            <div class="info_description">
                                Services: At vero eos et accusamus et iusto odio                 
                                <a href="#" class="more">Read more</a>
                            </div>
                        </div>
                    </li>
                </ul>
                <div id="rot11">
                    <img src="" width="800" height="300" class="bg" alt="" />
                    <div class="heading">
                        <h1></h1>
                    </div>
                    <div class="description">
                        <p></p>
                    </div>
                </div>
            </div>
        </div>
        <script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js"></script>
        <script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/jquery-easing/1.4.1/jquery.easing.min.js"></script>
        <script type="text/javascript">
            $(function () {
                //< !-- --------- First Slider--------- -->
                var current = 1;
                var iterate = function () {
                    var i = parseInt(current + 1);
                    var lis = $('#rotmenu').children('li').size();
                    if (i > lis) i = 1;
                    display($('#rotmenu li:nth-child(' + i + ')'));
                }
                display($('#rotmenu li:first'));
                var slidetime = setInterval(iterate, 3000);
                $('#rotmenu li').bind('click', function (e) {
                    clearTimeout(slidetime);
                    display($(this));
                    e.preventDefault();
                });
                function display(elem) {
                    var $this = elem;
                    var repeat = false;
                    if (current == parseInt($this.index() + 1))
                        repeat = true;
                    if (!repeat)
                        $this.parent().find('li:nth-child(' + current + ') a').stop(true, true).animate({ 'marginRight': '-20px' }, 300, function () {
                            //$(this).animate({ 'opacity': '0.7' }, 700);
                            $(this).css("background-color", "#BD0A72");
                            $(this).css("font-weight", "bold")
                        });
                    current = parseInt($this.index() + 1);
                    var elem = $('a', $this);
                    elem.stop(true, true).animate({ 'marginRight': '0px', 'opacity': '1.0' }, 300).css("background-color", "#FF0094").css("font-weight", "bold");
                    var info_elem = elem.next();
                    $('#rot1 .heading').animate({ 'left': '-420px' }, 500, 'easeOutCirc', function () {
                        $('h1', $(this)).html(info_elem.find('.info_heading').html());
                        $(this).animate({ 'left': '0px' }, 400, 'easeInOutQuad');
                    });
                    $('#rot1 .description').animate({ 'bottom': '-270px' }, 500, 'easeOutCirc', function () {
                        $('p', $(this)).html(info_elem.find('.info_description').html());
                        $(this).animate({ 'bottom': '0px' }, 400, 'easeInOutQuad');
                    })
                    $('#rot1').prepend(
                        $('<img/>', {
                            style: 'opacity:0',
                            className: 'bg'
                        }).load(
                            function () {
                                $(this).animate({ 'opacity': '1' }, 600);
                                $('#rot1 img:first').next().animate({ 'opacity': '0' }, 700, function () {
                                    $(this).remove();
                                });
                            }
                        ).attr('src', 'images/' + info_elem.find('.info_image').html()).attr('width', '800').attr('height', '300')
                    );
                }
                //< !-- --------- Second Slider--------- -->
                var current1 = 1;
                var iterate = function () {
                    var i = parseInt(current1 + 1);
                    var lis = $('#rotmenu1').children('li').size();
                    if (i > lis) i = 1;
                    display1($('#rotmenu1 li:nth-child(' + i + ')'));
                }
                display1($('#rotmenu1 li:first'));
                var slidetime1 = setInterval(iterate, 3000);
                $('#rotmenu1 li').bind('click', function (e) {
                    clearTimeout(slidetime1);
                    display1($(this));
                    e.preventDefault();
                });
                function display1(elem) {
                    var $this = elem;
                    var repeat = false;
                    if (current1 == parseInt($this.index() + 1))
                        repeat = true;
                    if (!repeat)
                        $this.parent().find('li:nth-child(' + current1 + ') a').stop(true, true).animate({ 'marginRight': '-20px' }, 300, function () {
                            $(this).css("background-color", "#BDA0BD");
                            $(this).css("font-weight", "bold");
                        });
                    current1 = parseInt($this.index() + 1);
                    var elem1 = $('a', $this);
                    elem1.stop(true, true).animate({ 'marginRight': '0px', 'opacity': '1.0' }, 300).css("background-color", "#FFD6FF");;
                    var info_elem = elem1.next();
                    $('#rot11 .heading').animate({ 'left': '-420px' }, 500, 'easeOutCirc', function () {
                        $('h1', $(this)).html(info_elem.find('.info_heading').html());
                        $(this).animate({ 'left': '0px' }, 400, 'easeInOutQuad');
                    });
                    $('#rot11 .description').animate({ 'bottom': '-270px' }, 500, 'easeOutCirc', function () {
                        $('p', $(this)).html(info_elem.find('.info_description').html());
                        $(this).animate({ 'bottom': '0px' }, 400, 'easeInOutQuad');
                    })
                    $('#rot11').prepend(
                        $('<img/>', {
                            style: 'opacity:0',
                            className: 'bg'
                        }).load(
                            function () {
                                $(this).animate({ 'opacity': '1' }, 600);
                                $('#rot11 img:first').next().animate({ 'opacity': '0' }, 700, function () {
                                    $(this).remove();
                                });
                            }
                        ).attr('src', 'images/' + info_elem.find('.info_image').html()).attr('width', '800').attr('height', '300')
                    );
                }
            });
        </script>
</body>
</html>