如果 windows 高度缩小，我有一个图像将主体推离 html 元素

Question

我正在建一个网站，主页上 256X480 的图片从 body 中脱离出来，将 body 推离 html 元素，我有点困惑如何处理这个图像及其容器似乎根本不响应最大高度属性。有人可以解释为什么会这样，或者给我指出一些资源来解释这个问题以及如何解决这个问题，谢谢。

https://jsfiddle.net/9oy5n0he/

html{
    height: 100%;
}
body{
    margin: 0px;
    background-image: linear-gradient( 0, rgba(0,0,0,.8) 30%, rgba(0,150,255,.8) 100%), url("images/mainCover.jpg");
    background-repeat: no-repeat;
    background-size: cover;
    height: 100%;
}
img{
    max-width: 100%;
}
/*nav and header*/
header{
    background-color: rgba(255,165,0,.8);
    display: flex;
    flex-flow: row wrap;
    justify-content: center;
    border-bottom: 8px solid black;
}
nav ul {
        list-style: none;
        padding: 0;
}
header h1{
    text-align: center;
    margin: 0;
    padding: 15px;
    text-shadow: 5px 5px 5px rgba(0,0,0,.3);
}
header h1, nav a{
    font-weight: 700;
    font-family: arial;
}
header nav{
    display: none;
}

.main-nav{
    margin: 4px;
}
nav ul li{ 
    text-align: center;
    margin: 0 4px;
    border: 1px solid white;
    border-radius: 15px;
    font-size: 1.2rem;
}
a{
    text-decoration: none;
}

 nav a:visited, nav a,h1{
   color: white; 
}

.current-page{ 
    background-color: rgba(0,0,0,.5);
}

footer nav{
    position: fixed;
    width: 100%;
    bottom: 0px;
}

footer nav ul{
    margin: 0;
}
footer nav li{
    background-color: rgba(255,165,0,.8);
}
/*home page*/
.bookWrapper{
    width: 25%;
    margin: auto;
}
 .bookLink {
    display: block;
    margin: auto;
}

.bookImage{
    margin: auto;
    display: block;
}

.amazonBookLabel{
    background-color: rgba(0,0,0,.5);
    color: white;
    padding: 10px;
    font-size: 1.5em;
    font-weight: 600;
    width: 50%;
    border-radius: 20px;
    margin: 30px auto;
    text-align: center;
    position: relative;
}
.amazonBookLabel:after{
    content: "";
    width: 30px;
    height: 5px;
    background-color: rgba(0,0,0,.5);
    position: absolute;
    bottom: -5px;
    left: calc(50% - 17px);    
}
.amazonBookLabel:before{
    content: "";
    width: 0;
    height: 0;
    border-left:  40px solid rgba(0,0,0,.5);
    border-top: 40px solid transparent;
    position: absolute;
    bottom: -45px;
    transform: rotate(-45deg);
    transform-origin: top left;
    left: calc(50% - 30px);
}

/***responsive***/
@media screen and (min-width: 400px){
        header{
            height: 130px;
            display: flex;
            justify-content: center;
        }
      header h1{
                font-size: 2em;
                align-self: flex-start;
                white-space: nowrap;
                border: 8px solid black;
            }
     header nav{
                display: block;
                align-self: flex-end;
            }
      .main-nav{
                display: flex;
                justify-content: flex-end;
            }
     .main-nav li{
                border-radius: 8px;
                padding: 5px;
                font-size: 1.3rem;
            }
    .characters:hover {
            position: relative;
            border-radius: 8px 8px 0 0;
            }

     .drop-menu{
            position: absolute;
            visibility: hidden;
            display: block;
            top: 33px;
            white-space: nowrap;
            left: -2px;
            background-color: rgba(255,165,0,.8);
            border: 1px solid rgba(0,0,0,.02);
            box-shadow: 5px 5px 5px 2px rgba(0,0,0,.3);
            opacity: 0;
            transition: opacity 300ms ease-in-out 0s;
            z-index: 1;
            }
    .characters:hover .drop-menu{
             visibility: visible;
             opacity:1;
        }

    .drop-menu li{
        margin: 0;
        border-radius: 0;
    } 

    footer nav{
                display: none;
            }
}
@media screen and (min-width:860px){
    header{
        height: 120px;
        justify-content: space-between;
    }
    header h1{
        margin: 0 0 0 20px;
    }
    .main-nav li{
        font-size: 1.5rem;
    }
    header nav{
        margin: 0 40px 0 0;
    }
}    

@media screen and (min-width: 1109px){
    header h1{
        font-size: 3em;
        margin: 0 0 0 80px;
    }
    .main-nav > li{
        margin: 0 8px;
    }
    header nav{
        margin: 0 80px 0 0;
    }
}

Answer 1

这是因为 html 上的 height: 100% 限制了高度，从技术上讲图像会溢出 html/body，所以您不会在溢出中看到背景。

更好的技术是删除 html 上的 height（不是必需的）并在 body

上使用 min-height: 100vh

body {
  margin: 0px;
  background-image: linear-gradient( 0, rgba(0, 0, 0, .8) 30%, rgba(0, 150, 255, .8) 100%), url("images/mainCover.jpg");
  background-repeat: no-repeat;
  background-size: cover;
  min-height: 100vh;
}

img {
  max-width: 100%;
}


/*nav and header*/

header {
  background-color: rgba(255, 165, 0, .8);
  display: flex;
  flex-flow: row wrap;
  justify-content: center;
  border-bottom: 8px solid black;
}

nav ul {
  list-style: none;
  padding: 0;
}

header h1 {
  text-align: center;
  margin: 0;
  padding: 15px;
  text-shadow: 5px 5px 5px rgba(0, 0, 0, .3);
}

header h1,
nav a {
  font-weight: 700;
  font-family: arial;
}

header nav {
  display: none;
}

.main-nav {
  margin: 4px;
}

nav ul li {
  text-align: center;
  margin: 0 4px;
  border: 1px solid white;
  border-radius: 15px;
  font-size: 1.2rem;
}

a {
  text-decoration: none;
}

nav a:visited,
nav a,
h1 {
  color: white;
}

.current-page {
  background-color: rgba(0, 0, 0, .5);
}

footer nav {
  position: fixed;
  width: 100%;
  bottom: 0px;
}

footer nav ul {
  margin: 0;
}

footer nav li {
  background-color: rgba(255, 165, 0, .8);
}


/*home page*/

.bookWrapper {
  width: 25%;
  margin: auto;
}

.bookLink {
  display: block;
  margin: auto;
}

.bookImage {
  margin: auto;
  display: block;
}

.amazonBookLabel {
  background-color: rgba(0, 0, 0, .5);
  color: white;
  padding: 10px;
  font-size: 1.5em;
  font-weight: 600;
  width: 50%;
  border-radius: 20px;
  margin: 30px auto;
  text-align: center;
  position: relative;
}

.amazonBookLabel:after {
  content: "";
  width: 30px;
  height: 5px;
  background-color: rgba(0, 0, 0, .5);
  position: absolute;
  bottom: -5px;
  left: calc(50% - 17px);
}

.amazonBookLabel:before {
  content: "";
  width: 0;
  height: 0;
  border-left: 40px solid rgba(0, 0, 0, .5);
  border-top: 40px solid transparent;
  position: absolute;
  bottom: -45px;
  transform: rotate(-45deg);
  transform-origin: top left;
  left: calc(50% - 30px);
}


/***responsive***/

@media screen and (min-width: 400px) {
  header {
    height: 130px;
    display: flex;
    justify-content: center;
  }
  header h1 {
    font-size: 2em;
    align-self: flex-start;
    white-space: nowrap;
    border: 8px solid black;
  }
  header nav {
    display: block;
    align-self: flex-end;
  }
  .main-nav {
    display: flex;
    justify-content: flex-end;
  }
  .main-nav li {
    border-radius: 8px;
    padding: 5px;
    font-size: 1.3rem;
  }
  .characters:hover {
    position: relative;
    border-radius: 8px 8px 0 0;
  }
  .drop-menu {
    position: absolute;
    visibility: hidden;
    display: block;
    top: 33px;
    white-space: nowrap;
    left: -2px;
    background-color: rgba(255, 165, 0, .8);
    border: 1px solid rgba(0, 0, 0, .02);
    box-shadow: 5px 5px 5px 2px rgba(0, 0, 0, .3);
    opacity: 0;
    transition: opacity 300ms ease-in-out 0s;
    z-index: 1;
  }
  .characters:hover .drop-menu {
    visibility: visible;
    opacity: 1;
  }
  .drop-menu li {
    margin: 0;
    border-radius: 0;
  }
  footer nav {
    display: none;
  }
}

@media screen and (min-width:860px) {
  header {
    height: 120px;
    justify-content: space-between;
  }
  header h1 {
    margin: 0 0 0 20px;
  }
  .main-nav li {
    font-size: 1.5rem;
  }
  header nav {
    margin: 0 40px 0 0;
  }
}

@media screen and (min-width: 1109px) {
  header h1 {
    font-size: 3em;
    margin: 0 0 0 80px;
  }
  .main-nav > li {
    margin: 0 8px;
  }
  header nav {
    margin: 0 80px 0 0;
  }
}

<main>
  <header>
    <h1>Seraph Chronicles</h1>
    <nav>
      <ul class="main-nav">
        <li class="main-nav-item current-page"><a href="index.html">Home</a></li>
        <li class="main-nav-item"><a href="about.html">About</a></li>
        <li class="main-nav-item characters">
          <a href="characters.html">Characters</a>
          <ul class="drop-menu">
            <li><a href="ethanClarke.html">Ethan Clarke</a></li>
            <li><a href="serenaKiriaga.html">Serena Kiriaga</a></li>
            <li><a href="MarcusFlynn.html">Marcus Flynn</a></li>
            <li><a href="EmilyAshdown.html">Emily Ashdown</a></li>
            <li><a href="MilesWest.html">Director Miles West</a></li>
          </ul>
        </li>
        <li class="main-nav-item"><a href="auther.html">Author</a></li>
      </ul>
    </nav>
  </header>
  <section>
    <p class="amazonBookLabel">Get the first and newest addition of the trilogy here!</p>
    <div class="bookWrapper">
      <a href="https://www.amazon.com/Seraph-Chronicles-Kyle-James-Feller/dp/1520404999/ref=sr_1_3?ie=UTF8&qid=1496613120&sr=8-3&keywords=seraph+chronicles" class="bookLink">
        <img class="bookImage" src="images/bookCover.jpg" alt="image of seraph chronicles: evangelion for purchase">
      </a>
    </div>
  </section>
  <footer>
  </footer>
  <section>
  </section>
  <footer>
    <nav>
      <ul>
        <li><a href="index.html">Home</a></li>
        <li><a href="about.html">About</a></li>
        <li><a href="characters.html">Characters</a></li>
        <li><a href="auther.html">Author</a></li>
      </ul>
    </nav>
  </footer>
</main>

如果 windows 高度缩小，我有一个图像将主体推离 html 元素

I have an image that is pushing the body away from the html element if the windows height shrinks

css

height

image

responsive-design