用于横幅元素布局的 CSS，以尊重文本内容、最大高度和长宽比

Question

我正在尝试在网站上构建横幅元素，但在使其满足我所追求的标准时遇到问题。理想情况下，我希望有一个仅 CSS 的解决方案。

布局非常简单 - 背景图像，覆盖居中的文本。如下图：

按照优先级顺序，我需要元素执行以下操作：

1. 元素必须始终足够高以容纳其中的文本。这来自 CMS，因此可以是任意长度。
2. 只要不违反第一个标准，元素高度不得高于80svh
3. 只要不违反第一个和第二个标准，元素就必须尊重背景图像的长宽比。同样，这是来自 CMS，因此我可以在任何

   aspect-ratio

   CSS 中使用图像宽度和高度。

我的第一次尝试是这样的：

div.wrapper {
  display: grid;
  grid-template-rows: repeat(1, minmax(0, 1fr));
  grid-template-columns: repeat(1, minmax(0, 1fr));
}

div.image-holder {
  width: 100%;
  min-height: 80svh;
  grid-row-start: 1;
  grid-column-start: 1;
  position: relative;
}

div.text-holder {
  padding: 2rem;
  display: flex;
  justify-content: center;
  align-items: center;
  grid-row-start: 1;
  grid-column-start: 1;
  position: relative;
  z-index: 30;
}

p {
  max-width: 760px;
  font-size: 1.8rem;
  line-height: 2.3rem;
  font-weight: 700;
  text-align: center;
  font-family: sans-serif;
}

img {
  object-fit: cover;
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  width: 100%;
  height: 100%;
  display: block;
  opacity: 0.5;
}

<div class="wrapper">
  <div class="image-holder">
    <img
  src="https://placebear.com/1200/800" alt="Bears" />
  </div>
  <div class="text-holder">
    <p>Central text element, amount of text unknown. Solution must work for any amount of added text.</p>
  </div>
</div>

这满足了标准 1，但只要元素足够大以容纳文本，整体高度始终设置为 80svh，并且不会对图像的纵横比进行任何操作。

然后我尝试了以下方法：

div.wrapper {
      display: grid;
      grid-template-rows: repeat(1, minmax(0, 1fr));
      grid-template-columns: repeat(1, minmax(0, 1fr));
    }

    div.image-holder {
      width: 100%;
      grid-row-start: 1;
      grid-column-start: 1;
      position: relative;
    }

    div.text-holder {
      padding: 2rem;
      display: flex;
      justify-content: center;
      align-items: center;
      grid-row-start: 1;
      grid-column-start: 1;
      position: relative;
      z-index: 30;
    }

    p {
      max-width: 760px;
      font-size: 1.8rem;
      line-height: 2.3rem;
      font-weight: 700;
      text-align: center;
      font-family: sans-serif;
    }

    img {
      object-fit: cover;
      position: absolute;
      top: 0;
      left: 0;
      right: 0;
      bottom: 0;
      width: 100%;
      height: 100%;
      display: block;
      opacity: 0.5;
    }

<div class="wrapper">
      <div class="image-holder">
        <img
      src="https://placebear.com/1200/800" alt="Bears" />
      </div>
      <div class="text-holder" style="aspect-ratio: 1200 / 800; // This is inlined as it is pulled from the image size from the CMS">
        <p>Central text element, amount of text unknown. Solution must work for any amount of added text.</p>
      </div>
    </div>

这更接近，并且满足标准 1 和 3，但现在我没有将元素的最大高度设置为 80svh。因此该元素将以纵横比缩放到任意高度。

我不知道下一步该尝试什么。我希望这不是一个不寻常的布局目标，并且之前有人已经做到了这一点。如果我需要依靠 javascript 来实现这一点，我会的，但如果可能的话，我希望用 CSS 来完成它。

Answer 1

假设我们可以更改 HTML 结构，我们可以将

max-height: 100%

添加到文本和图像容器的容器中（在本示例中我使用

both-holder

），然后还将

max-height: 80svh

添加到主

wrapper

:

div.wrapper {
  display: grid;
  grid-template-rows: repeat(1, minmax(0, 1fr));
  grid-template-columns: repeat(1, minmax(0, 1fr));
  max-height: 80svh;
}

div.image-holder {
  z-index: 5;
}

div.both-holder {
  display: flex;
  justify-content: center;
  align-items: center;
  grid-row-start: 1;
  grid-column-start: 1;
  position: relative;
  max-height: 100%;
}

.text-holder {
  z-index: 30;
  padding: 2rem;
}

p {
  max-width: 760px;
  font-size: 1.8rem;
  line-height: 2.3rem;
  font-weight: 700;
  text-align: center;
  font-family: sans-serif;
}

img {
  object-fit: cover;
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  width: 100%;
  height: 100%;
  display: block;
  opacity: 0.5;
}

<div class="wrapper">
  <div class="both-holder" style="aspect-ratio: 1200 / 800; // This is inlined as it is pulled from the image size from the CMS">
    <div class="image-holder">
      <img src="https://placebear.com/1200/800" alt="Bears" />
    </div>
    <div class="text-holder">
      <p>Central text element, amount of text unknown. Solution must work for any amount of added text.</p>
    </div>
  </div>
</div>

Answer 2

对于你的情况，你需要添加一些技巧。例如，另一张图像将具有相对于

position: absolute;

的

.wrapper

，以防

.image-holder

的高度太小。
例如，这样的事情：

body{
  min-width: 320px;
  margin: 0;
}

.wrapper {
  display: grid;
  grid-template-areas: 'a';
  position: relative;
  --max-img-height: 80svh;
}

.image-holder {
  grid-area: a;
  height: fit-content(var(--max-img-height));
  display: grid;
  opacity: 0.5;
}

.image-holder img {
  width: 100%;
}

.image-holder img:first-child {
  max-height: var(--max-img-height);
}

.image-holder img:last-child {
  position: absolute;
  height: 100%;
  object-fit: cover;
}

.text-holder {
  padding: 2rem;
  position: relative;
  z-index: 1;
  grid-area: a;
  display: grid;
  place-items: center;
}

.text-holder p {
  max-width: 760px;
  font-size: 1.8rem;
  line-height: 2.3rem;
  font-weight: 700;
  text-align: center;
  font-family: sans-serif;
  margin: 0;
}

<div class="wrapper">
  <div class="image-holder">
    <img src="https://placebear.com/1200/800" alt="Bears">
    <img src="https://placebear.com/1200/800" alt="Bears">
  </div>
  <div class="text-holder">
    <p>Central text element, amount of text unknown. Solution must work for any amount of added text. Central text element, amount of text unknown.</p>
  </div>
</div>

Answer 3

body {
  min-width: 320px;
  margin: 0;
}

.wrapper {
  display: grid;
  grid-template-areas: 'a';
  position: relative;
  --max-img-height: 80vh;
}

.image-holder {
  grid-area: a;
  min-height: 100%; /* Ensure it's tall enough to accommodate the text */
  max-height: var(--max-img-height); /* Not taller than 80vh */
  display: grid;
  opacity: 0.5;
}

.image-holder img {
  width: 100%;
  height: 100%;
  object-fit: cover; /* Maintain aspect ratio and cover the container */
}

.text-holder {
  padding: 2rem;
  position: relative;
  z-index: 1;
  grid-area: a;
  display: grid;
  place-items: center;
}

.text-holder p {
  max-width: 760px;
  font-size: 1.8rem;
  line-height: 2.3rem;
  font-weight: 700;
  text-align: center;
  font-family: sans-serif;
  margin: 0;
}

<div class="wrapper">
  <div class="image-holder">
    <img src="https://placebear.com/1200/800" alt="Bears">
    <img src="https://placebear.com/1200/800" alt="Bears">
  </div>
  <div class="text-holder">
    <p>Central text element, amount of text unknown. Solution must work for any amount of added text. Central text element, amount of text unknown.</p>
  </div>
</div>