Bootstrap 4为此增加了新的css类：

<p class="text-sm-right">Right aligned text on viewports sized SM (small) or wider.</p>
<p class="text-md-right">Right aligned text on viewports sized MD (medium) or wider.</p>
<p class="text-lg-right">Right aligned text on viewports sized LG (large) or wider.</p>
<p class="text-xl-right">Right aligned text on viewports sized XL (extra-large) or wider.</p>

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在GitHub上找到了这个gem：https://github.com/twbs/bootstrap/issues/11292
它为左右文本添加了响应类

.text-left-not-xs, .text-left-not-sm, .text-left-not-md, .text-left-not-lg {
    text-align: left;
}
.text-center-not-xs, .text-center-not-sm, .text-center-not-md, .text-center-not-lg {
    text-align: center;
}
.text-right-not-xs, .text-right-not-sm, .text-right-not-md, .text-right-not-lg {
    text-align: right;
}
.text-justify-not-xs, .text-justify-not-sm, .text-justify-not-md, .text-justify-not-lg {
    text-align: justify;
}

@media (max-width: 767px) {
    .text-left-not-xs, .text-center-not-xs, .text-right-not-xs, .text-justify-not-xs {
        text-align: inherit;
    }
    .text-left-xs {
        text-align: left;
    }
    .text-center-xs {
        text-align: center;
    }
    .text-right-xs {
        text-align: right;
    }
    .text-justify-xs {
        text-align: justify;
    }
}
@media (min-width: 768px) and (max-width: 991px) {
    .text-left-not-sm, .text-center-not-sm, .text-right-not-sm, .text-justify-not-sm {
        text-align: inherit;
    }
    .text-left-sm {
        text-align: left;
    }
    .text-center-sm {
        text-align: center;
    }
    .text-right-sm {
        text-align: right;
    }
    .text-justify-sm {
        text-align: justify;
    }
}
@media (min-width: 992px) and (max-width: 1199px) {
    .text-left-not-md, .text-center-not-md, .text-right-not-md, .text-justify-not-md {
        text-align: inherit;
    }
    .text-left-md {
        text-align: left;
    }
    .text-center-md {
        text-align: center;
    }
    .text-right-md {
        text-align: right;
    }
    .text-justify-md {
        text-align: justify;
    }
}
@media (min-width: 1200px) {
    .text-left-not-lg, .text-center-not-lg, .text-right-not-lg, .text-justify-not-lg {
        text-align: inherit;
    }
    .text-left-lg {
        text-align: left;
    }
    .text-center-lg {
        text-align: center;
    }
    .text-right-lg {
        text-align: right;
    }
    .text-justify-lg {
        text-align: justify;
    }
}

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你可以简单地使用CSS重写它：

@media (max-width: 767px) {
    footer .text-right { text-align:center }
}

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xs大小适用于767px和更低的分辨率。

在2021年，我仍然在不改变原始Bootstrap样式的情况下解决了Flexbox的类似问题。在任何屏幕分辨率下看起来都很棒。

<div class="row" style="display: flex; justify-content: center; align-items: center;">
 <div class="col-md-6 text-right" style="align-self: center; margin: auto;">
 ...
 </div>
 <div class="col-md-6" style="align-self: center; margin: auto;">
 ...
 </div>
</div>

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您可以将“样式”设置为“类”并创建它们。
29”超宽：

的数据
移动的：

的

对于Bootstrap 5，我们可以使用已经提供的类

<p class="text-start">Start aligned text on all viewport sizes.</p>
<p class="text-center">Center aligned text on all viewport sizes.</p>
<p class="text-end">End aligned text on all viewport sizes.</p>

<p class="text-sm-start">Start aligned text on viewports sized SM (small) or wider.</p>
<p class="text-md-start">Start aligned text on viewports sized MD (medium) or wider.</p>
<p class="text-lg-start">Start aligned text on viewports sized LG (large) or wider.</p>
<p class="text-xl-start">Start aligned text on viewports sized XL (extra-large) or wider.</p>

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来源：https://getbootstrap.com/docs/5.3/utilities/text/