2026-css-anchor-positioning/position-area-explorer.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>position-area の値を試す</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: 100dvh;
      background-color: #f5f5f5;
    }

    .anchor {
      anchor-name: --my-anchor;
      padding: 12px 20px;
      background-color: #1a73e8;
      color: #fff;
      border: none;
      border-radius: 4px;
      font-size: 1rem;
      cursor: pointer;
    }

    .tooltip {
      position: absolute;
      position-anchor: --my-anchor;
      position-area: bottom center;
      margin: 8px;
      padding: 8px 12px;
      background-color: #333;
      color: #fff;
      border-radius: 4px;
      white-space: nowrap;
      font-family: monospace;
      font-size: 14px;
    }

    .controls {
      position: fixed;
      top: 0;
      left: 0;
      right: 0;
      padding: 12px 16px;
      background-color: #fff;
      border-bottom: 1px solid #e0e0e0;
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 8px;
    }

    .controls label {
      font-size: 14px;
      font-family: monospace;
    }

    .controls select {
      padding: 6px 8px;
      border-radius: 4px;
      border: 1px solid #ccc;
      font-size: 14px;
      font-family: monospace;
    }
  </style>
</head>
<body>
  <button class="anchor" type="button">アンカー要素</button>
  <div class="tooltip" id="tooltip">bottom center</div>

  <div class="controls">
    <label for="select">position-area:</label>
    <select id="select"></select>
  </div>

  <script>
    const select = document.getElementById('select');
    const tooltip = document.getElementById('tooltip');

    const groups = [
      ['top', [
        'top left',
        'top center',
        'top right',
        'top',
        'top span-all',
      ]],
      ['bottom', [
        'bottom left',
        'bottom center',
        'bottom right',
        'bottom',
        'bottom span-all',
      ]],
      ['left', [
        'left top',
        'left center',
        'left bottom',
        'left',
        'left span-all',
      ]],
      ['right', [
        'right top',
        'right center',
        'right bottom',
        'right',
        'right span-all',
      ]],
      ['center', [
        'center',
        'span-all',
      ]],
    ];

    groups.forEach(([label, values]) => {
      const group = document.createElement('optgroup');
      group.label = label;
      values.forEach((value) => {
        const option = document.createElement('option');
        option.value = value;
        option.textContent = value;
        if (value === 'bottom center') option.selected = true;
        group.appendChild(option);
      });
      select.appendChild(group);
    });

    select.addEventListener('change', () => {
      tooltip.style.setProperty('position-area', select.value);
      tooltip.textContent = select.value;
    });
  </script>
</body>
</html>