html - Bootstrap 缩略图忽略居中 css

Question

无论我在平板电脑尺寸或更小尺寸上尝试什么，我都无法将我的 Bootstrap 缩略图图像居中。一旦缩略图达到这些尺寸，它们将不再滚动以保持在屏幕中央。我已经尝试了所有我能想到的方法，从将中心 block 添加到我的缩略图类和我的 img 响应类的 HTML 到 text-algin center 和 margin auto 0。没有任何改变。

这是我的html

<div class="portfolio">
    <div class="container">
  <a name="porty"></a>
      <h1 class="text-center" id = "port">My Work</h1>
      <div class="row">


        <div class="col-md-4">
          <div class="thumbnail ">
            <div class="caption">
              <h4 class="text-center">A Berine Sanders Tribute page made with HTML,CSS, and Bootstrap</h4> <a href="http://codepen.io/kgoode517/full/WwjNqp/"><i class="fa fa-codepen fa-5x fa-fw" id="first"></i> </a>
            </div>
            <img src="http://goodedevelopment.com/images/Bernie.PNG" class="img-responsive center-block" alt="tribute">
          </div>
          <legend>Tribute page</legend>
        </div>

        <div class="col-md-4">
          <div class="thumbnail">
            <div class="caption">
              <h4 class="text-center">Google mockup page made with HTML,CSS,and Bootstrap</h4>
              <a href="http://codepen.io/kgoode517/full/yYddbb/"><i class="fa fa-codepen fa-5x fa-fw" id ="second"></i> </a>
            </div>
            <img src="http://goodedevelopment.com/images/google.png" class="img-resposive center-block" alt="google">
          </div>
          <legend>Google homepage</legend>
        </div>

        <div class="col-md-4">
          <div class="thumbnail">
            <div class="caption">
              <h4 class="text-center">A cannon game made with HTML,CSS, and Javascript</h4>
              <a href="http://codepen.io/kgoode517/full/LNdxKE/"><i class="fa fa-codepen fa-5x fa-fw" id ="icon"></i> </a>
            </div>
            <img src="http://goodedevelopment.com/images/cannon.png" class="img-responsive center-block" alt="cannon">
          </div>
          <legend>Cannon game</legend>
        </div>
      </div>

这是我的 CSS

/*Portfolio*/

.portfolio {
background-color:#706C61;
  padding-top: 50px;
  padding-bottom: 100px;
  display: inline-block;
  width: 100%;
  height: 800px;
 position:relative;
}

.portfolio h1 {
  font-size: 65px;
  font-family: "Roboto",serif !important;
  color: #0d0d0d !important;
}

.row {
  padding-top: 100px;
}

.thumbnail {
  height: 250px;
  display: flex;
  justify-content: center;
  align-items: center;
  position: relative;
  overflow: hidden;
  border: 1px solid black !important;
  border-radius: 5px !important;
}

.caption img {
  flex-shrink: 0;
  max-width 100%;
  max-height: 100%;
}

.caption {
  position: absolute;
  top: 0;
  right: 0;
  background: rgba(128, 128, 128, 0.75);
  width: 100%;
  height: 100%;
  padding: 2%;
  display: none;
  text-align: center;
  color: #fff !important;
  z-index: 2;
  font-family: "Montserrat",serif !important;
}

.caption a {
  text-decoration: none;
  color: white;
}

.caption h4 {
  position: relative;
  left: 5px;
  bottom: 10px;
  font-size: 25px;
}

.caption i:hover {
  color: orange !important;
}

legend {
  font-family: "Roboto",serif !important;
  border-bottom: none !important;
  color: #0d0d0d !important;
  font-size:22px; !important;
  height:200px;
}

#first {
  position: relative !important;
  bottom: -35px !important;
}

#second {
  position: relative !important;
  bottom: -35px !important;
}

#icon {
  position: relative;
  top: 30px;
}



@media screen and (min-width:767px) and (max-width:1199px) {
  #first {
    position: relative;
    bottom: 20px;
  }
  #icon {
    top: 50px !important;
  }
  .caption h4 {
    font-size: 20px;
  }
}

@media screen and (min-width:767px) and (max-width:991px) {
  #first {
    position: relative;
    top: 50px;
  }
  .caption h4 {
    font-size: 30px;
  }
  .caption {
    font-size: 15px;
  }
  .caption i {
    position: relative;
    top: 50px;
  }
  #icon {
    position: relative;
    top: 65px !important;
  }
  .caption .fa {
    font-size: 50px;
  }
}




@media screen and (max-width: 1200px) {
  .portfolio h1 {
    font-size: 55px;
  }
}


@media screen and (max-width: 991px){
    .thumbnail {
    height: 369px;
    width: 440px;
    position: relative;
    right: -142px;
    bottom: 48px;
}

.portfolio{
height: 2650px;
}

#profile li {
    position: relative;
    left: 60px;
}
.caption h4 {
    font-size: px !important;
}
.caption .fa {
    font-size: 80px !important;

}

legend {
    height: 80px;
    position: relative;
    left: 139px;
    bottom: 53px;
}
}

@media screen and (max-width: 965px) {
  .portfolio {
    margin-top: -150px !important;
  }
}

@media screen and (max-width:767px) {
  #first {
    position: relative;
    top: 25px;
  }
  .caption h4 {
    font-size: 30px;
  }
  .caption {
    font-size: 15px;
  }
 #port{
    width: 50%;
    height: 50%;
    overflow: auto;
    margin: auto;
    position: absolute;
    top: -1285px;
    left: 0;
    bottom: 0;
    right: 0;
}

.thumbnail {
    position: relative;
    bottom: 0px;
}
legend
{
    position: relative;
    bottom: 13px;
}
}

@media screen and (max-width: 454px){
  .caption h4{
  font-size:25px;
  }
  #first{
   top:15px;
  }
  #second{
   top:15px;
  }
}



@media screen and (max-width:400px) {
  #icon {
    position: relative;
    bottom: 20px;
  }
}

@media screen and (max-width:397px) {
  #icon {
    position: relative;
    top: 0px;
  }
}
@media screen and (max-width:390px) {
  #first{
  top:5px;
  }
  }
@media screen and (max-width:325px) {
  .caption .fa {
  font-size:60px;
  }
  }
@media screen and (max-width:307px) {
  #first{
   top:-5px; 
  }
  }

/*End Portfolio*/

Here is the website

最后是我所遇到的屏幕截图，将不胜感激，谢谢!

Answer 1

除了使用 class="col-md-4"之外，您还应该包含针对不同屏幕尺寸的 Bootstrap 的“说明”。使用多个类，如 class="col-xs-12 col-sm-6 col-md-4"会调整各种屏幕尺寸下的列数，使每列内容居中变得容易，只需使用图像上的“img-responsive”类，因此它们将始终适合它们所在的列。然后当屏幕尺寸较小时，将显示较少的列，但列的内容保持不变并保持在列的中心。如果你想让列在屏幕上居中而不填充屏幕的宽度(比如使用 col-xs-10 所以它不会填充 12 col 的宽度)那么使用 col-x-offset-x 类来在您的 div 将显示的位置左侧创建一个“空白”列。您可以根据需要使用屏幕尺寸和偏移量的组合。网格使得在不同尺寸下获得您想要的对齐方式变得非常容易，而无需使用 CSS 来定义边距等的精确像素。一旦你开始用“其他指令”覆盖 CSS 的高度/宽度，事情就会变得愚蠢......