<!-- *********************************************** navbar ***********************************************-->

.navbar-center {
  display: inline-block;
  float: none;
  vertical-align: top;
}


.navbar-collapse-center {
  text-align: center;
}

.navbar-brand {
  font-size: 45px;
}


***.navbar {
    overflow: hidden;
    background-color: #333;
    font-family: Arial, Helvetica, sans-serif;
}

.navbar a {
    float: left;
    font-size: 16px;
    color: white;
    text-align: center;
    padding: 14px 16px;
    text-decoration: none;
}

.dropdown {
    float: left;
    overflow: hidden;
}

.dropdown .dropbtn {
    font-size: 16px;    
    border: none;
    outline: none;
    color: white;
    padding: 14px 16px;
    background-color: inherit;
    font-family: inherit;
    margin: 0;
}

.navbar a:hover, .dropdown:hover .dropbtn {
    background-color: red;
}

.dropdown-content {
    display: none;
    position: absolute;
    background-color: #f9f9f9;
    min-width: 160px;
    box-shadow: 0px 8px 16px 0px rgba(0,0,0,0.2);
    z-index: 1;
}

.dropdown-content a {
    float: none;
    color: black;
    padding: 12px 16px;
    text-decoration: none;
    display: block;
    text-align: left;
}

.dropdown-content a:hover {
    background-color: #ddd;
}

.dropdown:hover .dropdown-content {
    display: block;
}


<!-- *********************************************** General Settings *********************************************** -->

.bottom-header {
    padding-top: 240px;
    padding-bottom: 280px;
}

.img-responsive {
  display: block;
  margin-left: auto;
  margin-right: auto;
}


p {
  font-size: 16px;
}


li {
  font-size: 16px;
}


img.headline {
  max-width: 940px;
  margin-left: auto;
  margin-right:auto;
}


<!-- *********************************************** Home *********************************************** -->

img.decorating-image-rounded-corners {
     border-radius: 25px;
}


img.auto-size {
  max-width: 100%;
  width: auto;
  height: auto;
}


<!-- *********************************************** About Us *********************************************** -->


<!-- *********************************************** Services *********************************************** -->


<!-- *********************************************** Portfolio *********************************************** -->

#porfolio_heading {
  font-size: 50px;
  text-align: center;
  font-family: Impact, Charcoal, sans-serif;
}


img.auto-size {
  max-width: 100%;
  width: auto;
  height: auto;
  align: center;
}

.case-list-caption {
  font-size: 18px;
    text-align: center;
}

.case-list-font {
  font-size: 24px;

}


<!-- *********************************************** Contact Us *********************************************** -->


<!-- *********************************************** China Concrete *********************************************** -->

.china_concrete_iframe_align {
  margin: auto;
}

.ad_border {
  border-style: solid;
  border-width: 1px;
  border-radius: 10px;
  padding: 50px 550px 50px;
  padding-left: 200px;
  padding-right: 200px;
 
}