2026-css-anchor-positioning/anchor-sides.html at main · codegrid/2026-css-anchor-positioning · GitHub

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<!DOCTYPE html>
<html lang="ja">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <link rel="stylesheet" href="style.css">
  <title>ツールチップの位置を上下左右に変える</title>
  <style>
    *, *::before, *::after {
      box-sizing: border-box;
    }

    body {
      /* 画面中央に配置 */
      display: grid;
      place-items: center;
      margin: 0;
      font-family: sans-serif;
      min-height: 100vh;
      background-color: #f5f5f5;
    }

    .anchor {
      anchor-name: --my-anchor;
      padding: 16px 24px;
      background-color: #1a73e8;
      color: #fff;
      border: none;
      border-radius: 4px;
      font-size: 1rem;
      cursor: pointer;
    }

    .tooltip {
      position: absolute;
      position-anchor: --my-anchor;
      margin: 8px;
      padding: 8px 16px;
      background-color: #333;
      color: #fff;
      border-radius: 4px;
      white-space: nowrap;
    }

    .tooltip-top {
      position-area: top center;
    }

    /* 吹き出しの三角（下向き） */
    .tooltip-top::before {
      content: "";
      position: absolute;
      bottom: -6px;
      left: 50%;
      translate: -50% 0;
      border: 6px solid transparent;
      border-bottom: none;
      border-top-color: #333;
    }

    .tooltip-right {
      position-area: center right;
    }

    /* 吹き出しの三角（左向き） */
    .tooltip-right::before {
      content: "";
      position: absolute;
      left: -6px;
      top: 50%;
      translate: 0 -50%;
      border: 6px solid transparent;
      border-left: none;
      border-right-color: #333;
    }

    .tooltip-bottom {
      position-area: bottom center;
    }

    /* 吹き出しの三角（上向き） */
    .tooltip-bottom::before {
      content: "";
      position: absolute;
      top: -6px;
      left: 50%;
      translate: -50% 0;
      border: 6px solid transparent;
      border-top: none;
      border-bottom-color: #333;
    }

    .tooltip-left {
      position-area: center left;
    }

    /* 吹き出しの三角（右向き） */
    .tooltip-left::before {
      content: "";
      position: absolute;
      right: -6px;
      top: 50%;
      translate: 0 -50%;
      border: 6px solid transparent;
      border-right: none;
      border-left-color: #333;
    }
  </style>
</head>
<body>
  <button class="anchor" type="button">アンカー要素</button>
  <div class="tooltip tooltip-top">上</div>
  <div class="tooltip tooltip-right">右</div>
  <div class="tooltip tooltip-bottom">下</div>
  <div class="tooltip tooltip-left">左</div>
</body>
</html>