Question

我正在努力开发响应式网页设计，特别是在达到576px的屏幕尺寸时，集中在列容器内的图像。我已经尝试过这个我在其他地方看到过的声明：

@media(max-width: 576px)
{
.first-pic-container {
    float: none;
    margin: 0 auto;

}

但它没有做太多。我也尝试过使用Bootstrap的offset类，但它也没有做任何事情。

以下是相关的HTML：

<div class="col-sm-4 first-pic-container">
    <img class="first-step" src="step1image.png" alt="firstpic">
                <div class= "row">
                    <div class="col-sm-12 col-md-12 col-lg-10 first-p-container">
     <p class="step-one-p"> Enter the classes you are looking to take for next semester! </p>
                    </div>
                </div>
            </div>

用于视觉参考的codepen。我在firstpic和first-pic-container周围添加了边框，我试图将其放在中心位置：https://codepen.io/gkunthara/pen/VWdrYj

Answer 1

将text-align: center提交给first-pic-container

@media(max-width: 576px) {
        .first-pic-container {
            text-align: center;
        }
    }

Answer 2

默认情况下，图像是内联元素，因此您只需添加text-align：center;它的父元素。如果你想使用保证金：0 auto;然后你需要设置图像显示：block;

Answer 3

执行此操作的一种方法是text-align: center;您的父div，在您的情况下，即.first-pic-container

@media(max-width: 576px) {
    .first-pic-container {
        text-align: center;
    }
}

Codepen：https://codepen.io/junaidkbr/pen/VWOWvK

Answer 4

你需要

@media only screen and (max-width: 576px)
{
    .first-pic-container {
        text-align:center;
    }
}

body{
    font-family: Futura;
}

.navbar-toggle{
    background-color: transparent;
    border: none;
}

.active {
    border-bottom: #F48A2C solid 2px;
}
.nav-item{
    margin-right: 50px;
}
.nav-link{
    color: #62697A;
}

.navbar {
    margin-top: 25px;
}

.jumbotron {
    color: #8E9299;
    text-align: center;
}

p {
    color: #8E9299;
}


.first-p-container {
    margin-top: 10px;
}

.step-one-p {
    text-align: center;
}

.second-p-container {
    margin-top: 10px;
}

.step-three-p {
    text-align: center;
}


.third-p-container {
    margin-top: 20px;
}

.step-two-p {
    text-align: center;
}

.step-container {
    margin-left: 25px;
}

/* when the screen size goes below 374 px... */
@media (max-width: 374px)
{
    .navbar-toggler {
    display: none;
    }    

}

@media (min-width: 320px)
{
    .small-sub-header{
        display: none;
    }
}

@media (max-width: 320px)
{
   .main-header{
       display: none;
    }
    .sub-header{
        display: none;
    }
    .small-sub-header{
        display: inline-block;
    }
}


@media (max-width: 425px)
{
    h1{
        font-size: 32px;
    }
    .sub-header{
        margin-top: 25px;
    }

}


@media only screen and (max-width: 576px)
{
    .first-pic-container {
        border: solid;
        text-align:center;
    }
    .first-step{
        border: solid;
    }
    
}

<head>
    <title> Schedule Builder &middot Class Registration Done Easy</title>
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-alpha.6/css/bootstrap.min.css" integrity="sha384-rwoIResjU2yc3z8GV/NPeZWAv56rSmLldC3R/AZzGRnGxQQKnKkoFVhFQhNUwEyJ" crossorigin="anonymous">
    <script src="https://code.jquery.com/jquery-3.1.1.slim.min.js" integrity="sha384-A7FZj7v+d/sdmMqp/nOQwliLvUsJfDHW+k9Omg/a/EheAdgtzNs3hpfag6Ed950n" crossorigin="anonymous"></script>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/tether/1.4.0/js/tether.min.js" integrity="sha384-DztdAPBWPRXSA/3eYEEUWrWCy7G5KFbe8fFjk5JAIxUYHKkDx6Qin1DkWx51bBrb" crossorigin="anonymous"></script>
    <script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-alpha.6/js/bootstrap.min.js" integrity="sha384-vBWWzlZJ8ea9aCX4pEW3rVHjgjt7zpkNpZk+02D9phzyeVkE+jo0ieGizqPLForn" crossorigin="anonymous"></script>
    <link rel="stylesheet" type="text/css" href="custom.css">
</head>


<body>

    <div class = "container header-container">

     <nav class="navbar navbar-toggleable-md navbar-light">
        <button class="navbar-toggler navbar-toggler-right" type="button" data-toggle="collapse" data-target="#navbarNav" aria-controls="navbarNav" aria-expanded="false" aria-label="Toggle navigation">
            <span class="navbar-toggler-icon"></span>
        </button>
        <a class="navbar-brand" href="#">
            <img alt="logo" src="logo.png" width="250px;">
        </a>

        <div class="collapse navbar-collapse" id="navbarNav">
            <ul class="navbar-nav ml-auto">
                <li class="nav-item active">
                    <a class="nav-link" href="#">Home <span class="sr-only">(current)</span></a>
                </li>
                <li class="nav-item">
                    <a class="nav-link" href="#">Build</a>
                </li>
                <li class="nav-item">
                    <a class="nav-link" href="#">About</a>
                </li>
            </ul>
        </div>
    </nav>



        <div class="jumbotron" style="background-color: transparent;">
            <h1 class="main-header display-5"> We know that class registration is a hassle. </h1>
            <h1 class= "sub-header display-5"> Let Schedule Builder help! </h1>
            <h1 class= "small-sub-header display-5"> Schedule Builder is here to help! </h1>
        </div>


        <div class="container step-container">
            <div class="row">

                <div class="col-sm-4 first-pic-container">
                    <img class="first-step" src="https://upload.wikimedia.org/wikipedia/commons/thumb/2/27/Square_200x200.svg/200px-Square_200x200.svg.png" alt="firstpic" width="100">
                    <div class= "row">
                        <div class="col-sm-12 col-md-12 col-lg-10 first-p-container">
                            <p class="step-one-p"> Enter the classes you are looking to take for next semester! </p>
                        </div>
                    </div>
                </div>


                <div class="col-sm-4 second-pic-container">
                    <img class="second-step" src="step2image.png" alt="secondpic">
                    <div class= "row">
                        <div class="col-sm-12 col-md-12 col-lg-11 second-p-container">
                            <p class="step-two-p"> Schedule Builder will get right to work and create all possible schedules for you!</p>
                        </div>
                    </div>
                </div>


                <div class="col-sm-4 third-pic-container">
                    <img class="third-step" src="step3image.png" alt="thirdpic">
                    <div class= "row">
                        <div class="col-sm-12 col-md-12 col-lg-10 third-p-container">
                            <p class="step-three-p"> Pick your ideal schedule, check out our schedule ratings, and share it with your friends!</p>
                        </div>
                    </div>
                </div>
                
            </div>

        </div>


    </div>



</body>

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4 个答案: