Fix style tag accumulation when loading dialogs

[Copilot]

Style tags were accumulating in document.head each time a dialog was loaded, causing the style sheet to grow indefinitely.

Root Cause

In loadScreen(), old style tags were removed only for regular scenes, but new style tags were always appended regardless of whether it was a dialog or regular scene:

if (!isDialog) {
  // Remove old style tags
  const styleTags = document.head.getElementsByTagName('style')
  for (const styleTag of styleTags) {
    document.head.removeChild(styleTag)
  }
}
// But always append new style tag
const styleElement = doc.head.getElementsByTagName('style')[0]
document.head.appendChild(styleElement)  // ← Appends every time

This caused dialog styles to accumulate, and dialogs also need their own styles to render properly.

Changes

For regular scenes (!isDialog):

• Remove ALL style tags
• Add the new style tag
• Added null check for templates without style tags

For dialogs (isDialog):

• Remove only old dialog style tags (marked with data-dialog-style attribute)
• Add new dialog style tag with data-dialog-style="true" marker
• This prevents accumulation while ensuring dialog styles are properly applied

if (!isDialog) {
  // Remove old style tags
  const styleTags = document.head.getElementsByTagName('style')
  for (const styleTag of styleTags) {
    document.head.removeChild(styleTag)
  }
  this.gameContainer.innerHTML = mainDiv.innerHTML
  this.drawer.setScreen(this.gameContainer, engineConfig.resolution)
  // Only append style tag for regular scenes
  const styleElement = doc.head.getElementsByTagName('style')[0]
  if (styleElement) {
    document.head.appendChild(styleElement)
  }
} else {
  // ダイアログの場合、古いダイアログ用のスタイルを削除する
  const oldDialogStyles = document.head.querySelectorAll('style[data-dialog-style]')
  oldDialogStyles.forEach((styleTag) => {
    document.head.removeChild(styleTag)
  })
  this.gameContainer.appendChild(mainDiv)
  // ダイアログ用のStyleタグを取り出して、マークを付けてheadタグに追加する
  const styleElement = doc.head.getElementsByTagName('style')[0]
  if (styleElement) {
    styleElement.setAttribute('data-dialog-style', 'true')
    document.head.appendChild(styleElement)
  }
}

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Styleタグが増殖する</issue_title>
<issue_description>

---

Trelloから移行 (doing): https://trello.com/c/J1KHS9hw</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Styleタグが増殖する #118

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[EndoHizumi]

@copilot ダイアログ表示時に古いスタイルが残ってるので、修正をお願いします。

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Project	Deployment	Actions	Updated (UTC)
webtalekit-demo	Error		Mar 22, 2026 4:49pm

[Copilot]

@copilot ダイアログ表示時に古いスタイルが残ってるので、修正をお願いします。

修正しました。ダイアログのスタイルタグに data-dialog-style マーカーを追加し、新しいダイアログを表示する際に古いダイアログのスタイルを削除するようにしました。これにより、ダイアログのスタイルが正しく適用されながら、古いスタイルが残らないようになります。(commit: bb04104)

[EndoHizumi]

LGTM