如何应用 :focus 于多个相同的选择器？

Question

我试图在输入类型编号聚焦时更改底部边框颜色。我部分成功了，但 css 并未应用于所有选择器。问题是这样的：

左侧（比索）未获得焦点，但它具有与 Kg 相同的选择器。这是代码：https://jsfiddle.net/snake93/nLdrcv71/1/

input[type=number] {
    color: #666;
    border-width: 0px 0px 1px 0px !important;
    border-color: #dcdcdc !important;
    border-radius: 0px !important;
    background: #fafafa00;
}

.input-group-text {
    display: -ms-flexbox;
    display: flex;
    -ms-flex-align: center;
    align-items: center;
    padding: .375rem .75rem;
    margin-bottom: 0px;
    font-size: 1rem;
    font-weight: 400;
    line-height: 1.5;
    color: #495057;
    background-color: #ffffff00 !important;
    border: 1px solid #dcdcdc !important;
    border-radius: .25rem;
    border-width: 0px 0px 1px 0px !important;
    border-radius: 0px !important;
}

.form-control:focus,
.form-control:focus + span {
    color: #00a1ff;
    background-color: #fff0;
    border-color: #00a1ff !important;
    outline: 0;
    box-shadow: none !important;
    border: solid;
    border-width: 0px 0px 2px 0px !important;
}

.input-group-text:focus {
    background:red !important;
}

<link href="https://cdn.jsdelivr.net/npm/bootstrap@5.1.1/dist/css/bootstrap.min.css" rel="stylesheet">
<script src="https://cdn.jsdelivr.net/npm/@popperjs/core@2.9.3/dist/umd/popper.min.js"></script>
<script src="https://cdn.jsdelivr.net/npm/bootstrap@5.1.1/dist/js/bootstrap.min.js" ></script>

<div class="input-group mb-3">
  <span class="input-group-text">Peso</span>
  <input type="number" class="form-control">
  <span class="input-group-text">Kg</span>
</div>

Answer 1

选择器.form-control:focus + span仅影响该类元素后面的跨度.form-control。相反，您可以使用.input-group:focus-within span它将您的样式应用于子级跨度，当具有该类的元素.input-group获得焦点时。

.form-control:focus,
.input-group:focus-within span {
    color: #00a1ff;
    background-color: #fff0;
    ...

编辑：我添加了完整的标记来证明该解决方案确实有效。

input[type=number] {
    color: #666;
    border-width: 0px 0px 1px 0px !important;
    border-color: #dcdcdc !important;
    border-radius: 0px !important;
    background: #fafafa00;
}

.input-group-text {
    display: -ms-flexbox;
    display: flex;
    -ms-flex-align: center;
    align-items: center;
    padding: .375rem .75rem;
    margin-bottom: 0px;
    font-size: 1rem;
    font-weight: 400;
    line-height: 1.5;
    color: #495057;
    background-color: #ffffff00 !important;
    border: 1px solid #dcdcdc !important;
    border-radius: .25rem;
    border-width: 0px 0px 1px 0px !important;
    border-radius: 0px !important;
}

.form-control:focus,
.input-group:focus-within span {
    color: #00a1ff;
    background-color: #fff0;
    border-color: #00a1ff !important;
    outline: 0;
    box-shadow: none !important;
    border: solid;
    border-width: 0px 0px 2px 0px !important;
}

.input-group-text:focus {
    background:red !important;
}

<link href="https://cdn.jsdelivr.net/npm/bootstrap@5.1.1/dist/css/bootstrap.min.css" rel="stylesheet">
<script src="https://cdn.jsdelivr.net/npm/@popperjs/core@2.9.3/dist/umd/popper.min.js"></script>
<script src="https://cdn.jsdelivr.net/npm/bootstrap@5.1.1/dist/js/bootstrap.min.js" ></script>

<div class="input-group mb-3">
  <span class="input-group-text">Peso</span>
  <input type="number" class="form-control">
  <span class="input-group-text">Kg</span>
</div>