Bootstrap卡在示例中没有显示

Question

为什么我的Bootstrap卡看起来很奇怪？在示例中，它们看起来像带有边框和白色填充的卡片，但我看起来只有文字而没有填充和白色背景。

例如：

我不知道代码是否会对您有所帮助，但现在是：

HTML：

<div class="container">

    <div class="row">
        <div class="col-md-3">
            <div class="card">
                <img class="card-img-top" src="http://www.themdfactor.com/wp-content/uploads/2015/09/card1.jpg" alt="Card image cap">
                <div class="card-block">
                    <h4 class="card-title">This is Card #1</h4>
                    <p class="card-text">Some quick example text to build on the card title and make up the bulk of the card's content.</p>
                    <a href="http://v4-alpha.getbootstrap.com/components/card/" class="btn btn-primary">Learn More</a>
                </div>
            </div>
        </div>
    </div>
</div>

CSS：

.container {
  left:0;
  right:0;
  bottom:-340px;
  text-align: middle;
  position:absolute;
}

Answer 1

Bootstrap 4 card功能已经从之前的v4-alpha版本更改为v4-beta版本。但是，Bootstrap网站上的示例仍使用较旧的类名。卡仍然呈现，但如果使用较旧的类名，则填充将丢失。

使用card-body班级（CSS）的当前（2017年9月）示例：

<div class="card" style="width: 20rem;">
  <img class="card-img-top" src="..." alt="Card image cap">
  <div class="card-body">
    <h4 class="card-title">Card title</h4>
    <p class="card-text">Some quick example text to build on the card title and make up the bulk of the card's content.</p>
    <a href="#" class="btn btn-primary">Go somewhere</a>
  </div>
</div>

以下是similar answer到related question。

Answer 2

我觉得很好。您必须确保链接版本4样式表。

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-alpha.2/css/bootstrap.min.css" integrity="sha384-y3tfxAZXuh4HwSYylfB+J125MxIs6mR5FOHamPBG064zB+AFeWH94NdvaCBm8qnd" crossorigin="anonymous">

Answer 3

将来自boostrap4版本的卡css复制到bootstrap3解决方案中，对我有用。如果你被困在bootstrap3上很好。

只需将CSS中的以下内容放入其中即可。

.card {
    position: relative;
    display: -webkit-box;
    display: -webkit-flex;
    display: -ms-flexbox;
    display: flex;
    -webkit-box-orient: vertical;
    -webkit-box-direction: normal;
    -webkit-flex-direction: column;
    -ms-flex-direction: column;
    flex-direction: column;
    background-color: #fff;
    border: 1px solid rgba(0, 0, 0, 0.125);
    border-radius: 0.25rem;
}

.card-block {
    -webkit-box-flex: 1;
    -webkit-flex: 1 1 auto;
    -ms-flex: 1 1 auto;
    flex: 1 1 auto;
    padding: 1.25rem;
}

.card-title {
    margin-bottom: 0.75rem;
}

.card-subtitle {
    margin-top: -0.375rem;
    margin-bottom: 0;
}

.card-text:last-child {
    margin-bottom: 0;
}

.card-link:hover {
    text-decoration: none;
}

.card-link + .card-link {
    margin-left: 1.25rem;
}

.card > .list-group:first-child .list-group-item:first-child {
    border-top-right-radius: 0.25rem;
    border-top-left-radius: 0.25rem;
}

.card > .list-group:last-child .list-group-item:last-child {
    border-bottom-right-radius: 0.25rem;
    border-bottom-left-radius: 0.25rem;
}

.card-header {
    padding: 0.75rem 1.25rem;
    margin-bottom: 0;
    background-color: #f7f7f9;
    border-bottom: 1px solid rgba(0, 0, 0, 0.125);
}

.card-header:first-child {
    border-radius: calc(0.25rem - 1px) calc(0.25rem - 1px) 0 0;
}

.card-footer {
    padding: 0.75rem 1.25rem;
    background-color: #f7f7f9;
    border-top: 1px solid rgba(0, 0, 0, 0.125);
}

.card-footer:last-child {
    border-radius: 0 0 calc(0.25rem - 1px) calc(0.25rem - 1px);
}

.card-header-tabs {
    margin-right: -0.625rem;
    margin-bottom: -0.75rem;
    margin-left: -0.625rem;
    border-bottom: 0;
}

.card-header-pills {
    margin-right: -0.625rem;
    margin-left: -0.625rem;
}

.card-primary {
    background-color: #0275d8;
    border-color: #0275d8;
}

.card-primary .card-header,
.card-primary .card-footer {
    background-color: transparent;
}

.card-success {
    background-color: #5cb85c;
    border-color: #5cb85c;
}

.card-success .card-header,
.card-success .card-footer {
    background-color: transparent;
}

.card-info {
    background-color: #5bc0de;
    border-color: #5bc0de;
}

.card-info .card-header,
.card-info .card-footer {
    background-color: transparent;
}

.card-warning {
    background-color: #f0ad4e;
    border-color: #f0ad4e;
}

.card-warning .card-header,
.card-warning .card-footer {
    background-color: transparent;
}

.card-danger {
    background-color: #d9534f;
    border-color: #d9534f;
}

.card-danger .card-header,
.card-danger .card-footer {
    background-color: transparent;
}

.card-outline-primary {
    background-color: transparent;
    border-color: #0275d8;
}

.card-outline-secondary {
    background-color: transparent;
    border-color: #ccc;
}

.card-outline-info {
    background-color: transparent;
    border-color: #5bc0de;
}

.card-outline-success {
    background-color: transparent;
    border-color: #5cb85c;
}

.card-outline-warning {
    background-color: transparent;
    border-color: #f0ad4e;
}

.card-outline-danger {
    background-color: transparent;
    border-color: #d9534f;
}

.card-inverse {
    color: rgba(255, 255, 255, 0.65);
}

.card-inverse .card-header,
.card-inverse .card-footer {
    background-color: transparent;
    border-color: rgba(255, 255, 255, 0.2);
}

.card-inverse .card-header,
.card-inverse .card-footer,
.card-inverse .card-title,
.card-inverse .card-blockquote {
    color: #fff;
}

.card-inverse .card-link,
.card-inverse .card-text,
.card-inverse .card-subtitle,
.card-inverse .card-blockquote .blockquote-footer {
    color: rgba(255, 255, 255, 0.65);
}

.card-inverse .card-link:focus, .card-inverse .card-link:hover {
    color: #fff;
}

.card-blockquote {
    padding: 0;
    margin-bottom: 0;
    border-left: 0;
}

.card-img {
    border-radius: calc(0.25rem - 1px);
}

.card-img-overlay {
    position: absolute;
    top: 0;
    right: 0;
    bottom: 0;
    left: 0;
    padding: 1.25rem;
}

.card-img-top {
    border-top-right-radius: calc(0.25rem - 1px);
    border-top-left-radius: calc(0.25rem - 1px);
}

.card-img-bottom {
    border-bottom-right-radius: calc(0.25rem - 1px);
    border-bottom-left-radius: calc(0.25rem - 1px);
}

@media (min-width: 576px) {
    .card-deck {
        display: -webkit-box;
        display: -webkit-flex;
        display: -ms-flexbox;
        display: flex;
        -webkit-flex-flow: row wrap;
        -ms-flex-flow: row wrap;
        flex-flow: row wrap;
    }
    .card-deck .card {
        display: -webkit-box;
        display: -webkit-flex;
        display: -ms-flexbox;
        display: flex;
        -webkit-box-flex: 1;
        -webkit-flex: 1 0 0%;
        -ms-flex: 1 0 0%;
        flex: 1 0 0%;
        -webkit-box-orient: vertical;
        -webkit-box-direction: normal;
        -webkit-flex-direction: column;
        -ms-flex-direction: column;
        flex-direction: column;
    }
    .card-deck .card:not(:first-child) {
        margin-left: 15px;
    }
    .card-deck .card:not(:last-child) {
        margin-right: 15px;
    }
}

@media (min-width: 576px) {
    .card-group {
        display: -webkit-box;
        display: -webkit-flex;
        display: -ms-flexbox;
        display: flex;
        -webkit-flex-flow: row wrap;
        -ms-flex-flow: row wrap;
        flex-flow: row wrap;
    }
    .card-group .card {
        -webkit-box-flex: 1;
        -webkit-flex: 1 0 0%;
        -ms-flex: 1 0 0%;
        flex: 1 0 0%;
    }
    .card-group .card + .card {
        margin-left: 0;
        border-left: 0;
    }
    .card-group .card:first-child {
        border-bottom-right-radius: 0;
        border-top-right-radius: 0;
    }
    .card-group .card:first-child .card-img-top {
        border-top-right-radius: 0;
    }
    .card-group .card:first-child .card-img-bottom {
        border-bottom-right-radius: 0;
    }
    .card-group .card:last-child {
        border-bottom-left-radius: 0;
        border-top-left-radius: 0;
    }
    .card-group .card:last-child .card-img-top {
        border-top-left-radius: 0;
    }
    .card-group .card:last-child .card-img-bottom {
        border-bottom-left-radius: 0;
    }
    .card-group .card:not(:first-child):not(:last-child) {
        border-radius: 0;
    }
    .card-group .card:not(:first-child):not(:last-child) .card-img-top,
    .card-group .card:not(:first-child):not(:last-child) .card-img-bottom {
        border-radius: 0;
    }
}

@media (min-width: 576px) {
    .card-columns {
        -webkit-column-count: 3;
        -moz-column-count: 3;
        column-count: 3;
        -webkit-column-gap: 1.25rem;
        -moz-column-gap: 1.25rem;
        column-gap: 1.25rem;
    }
    .card-columns .card {
        display: inline-block;
        width: 100%;
        margin-bottom: 0.75rem;
    }
}

来源：https://github.com/twbs/bootstrap/blob/v4-dev/dist/css/bootstrap.css#L4055

Answer 4

这可能是旧的，但您是否正在使用自定义的引导程序文件？我最近尝试使用我们的自定义文件处理卡片，同样的事情发生在我身上。然后我意识到bootstrap文件中没有卡类，自定义页面上也没有提到卡片。

http://getbootstrap.com/customize/

对我来说似乎很奇怪，我甚至让一位同事验证了它。希望这会有所帮助。

Answer 5

如果您已通过包管理器安装了引导程序，例如NPM：

对于某些软件包管理器，默认安装的版本为mainFragment =(MainFragment)getSupportFragmentManager().findFragmentById(R.id.main_frame)，但似乎没有此功能。

这可能会产生误导，因为在Bootstrap的入门＆gt;中描述了正确的版本。下载部分found here

要解决此问题，请确保您引用最新的软件包版本bootstrap@4.0.0-beta.2