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フルスクリーン - グラデーション

★CSS3 ★レスポンシブWebデザイン

フルスクリーン - レスポンシブ

スマートフォン・パソコンでフルスクリーンで表示する

HTML記述例

<!DOCTYPE html>
<html lang="ja">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width">
<title>ヒーローイメージ</title>
<link rel="stylesheet" href="css/style.css">
<link rel="preconnect" href="https://fonts.googleapis.com">
<link rel="preconnect" href="https://fonts.gstatic.com" crossorigin>
<link href="https://fonts.googleapis.com/css2?family=Caveat:wght@400;700&display=swap" rel="stylesheet">
</head>
<body id="top">
<!-- .header -->
<header class="header">
  <div class="container">
    <h1>The Web Design</h1>
    <nav class="gnav">
    <ul>
      <li><a href="#">Portfolio</a></li>
      <li><a href="#">About</a></li>
      <li><a href="#">Contact</a></li>
    </ul>
    </nav>
  </div><!-- /.container -->
</header>
<!-- /.header -->

<!-- .main-content -->
<main class="main-content">
  <a href="#" class="prof">Portfolio</a>
</main>
<!-- /.main-content -->

<!-- .footer -->
<footer class="footer">
  <p><small>&copy; The Web Design</small></p>
</footer>
<!-- /.footer -->
</body>
</html>

CSS記述例

@charset "UTF-8";

/* ------------------------------------------
  reset
------------------------------------------ */
*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
ul, li {
  list-style: none;
}
a {
  color: inherit;
  text-decoration: none;
}

/* ------------------------------------------
  body
------------------------------------------ */
body {
  color: #fff;
  font-size: 16px;
  font-family: 
    "Helvetica Neue",
    Arial,
    "Hiragino Kaku Gothic ProN",
    "Hiragino Sans",
    Meiryo,
    sans-serif;
  line-height: 1.0;
}
#top {
  width: 100%;
  height: 100vh;
  background: linear-gradient(25deg, 
  rgba(178, 5, 5, 0.6), 
  rgba(4, 160, 4, 0.6)), 
  url(../img/grass.jpg);
  background-repeat: no-repeat;
  background-position: center center;
  background-size: cover;
}

/* ------------------------------------------
  header
------------------------------------------ */
.header {
  position: fixed;
  top: 0;
  width: 100%;
}
.container {
  width: min(92%, 960px);
  margin: auto;
  text-align: center;
}
.header h1 {
  padding-top: 2vh;
  margin: 0 auto 1.5vh 0;
  font-size: 2.4em;
  font-family: 'Caveat', cursive;
}
.gnav ul {
  display: flex;
  justify-content: center;
  gap: 30px;
}
  .gnav li {
    font-size: 1.2em;
  }
  .gnav a:hover {
    border-bottom: 2px solid #fff;
    padding-bottom: 2px;
  }
@media screen and (min-width: 768px) {
  .container {
    display: flex;
    align-items: center;
  }
  .header h1 {
    margin: 0 auto 1.5vh 0;
    font-size: 3.6em;
  }
}

/* ------------------------------------------
  main
------------------------------------------ */
.main-content {
  display: flex;
  align-items: center;
  width: min(92%, 960px);
  height: 100vh;
  margin: 0 auto;
  text-align: center;
}
a.prof {
  display: inline-block;
  margin: auto;
  padding: 10px 40px;
  border: 2px solid #fff;
  font-size: 18px;
  font-weight: 600;
  text-align: center;
  letter-spacing: .08em;
}
a.prof:hover {
  background-color: rgb(189, 19, 19);
}

/* ------------------------------------------
  footer
------------------------------------------ */
.footer {
  position: fixed;
  bottom: 0;
  width: 100%;
  height: 40px;
  text-align: center;
}
@media screen and (min-width: 768px) {
  .footer {
    height: 50px;
  }
}

positionで上下左右の中央配置

「absolute」は「fixed」でも可

element {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}

上下左右の中央配置時の幅指定は不要

/* ------------------------------------------
  main
------------------------------------------ */
.main-content {
  position: relative;
  width: min(92%, 960px);
  height: 100vh;
  margin: 0 auto;
  text-align: center;
}
a.prof {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  display: inline-block;
  margin: auto;
  padding: 10px 40px;
  border: 2px solid #fff;
  font-size: 18px;
  font-weight: 600;
  text-align: center;
  letter-spacing: .08em;
}
a.prof:hover {
  background-color: rgb(189, 19, 19);
}

要素の幅・高さが指定されている場合

element {
  position: fixed;
  top: 0;
  right: 0;
  bottom: 0;
  left: 0;
  width: ●●px;
  height: ●●px;
}