モーダルダイアログの構造
fixed配置とz-indexのユーティリティを使い、背景オーバーレイ、スクロール可能なコンテンツ領域、閉じるボタンを備えた中央配置のモーダルを構築します。
「モーダルダイアログの構造」はCoddyKit上の無料Tailwind CSS Academyレッスンです。 これはレッスン1/4です。 下記で完全なレッスンを無料で読むことができます。その後、ブラウザ内の組み込みコードエディタと24時間対応のAIチューターでハンズオン演習できます。 これはTailwind CSS Academy学習パスの一部であり、ウェブとCoddyKitアプリ全体で進捗が同期されます。 Tailwind CSS Academyコースには全4レッスンが含まれています。
このレッスンの一部はまだ翻訳されておらず、英語で表示されています。
What Is a Modal Dialog
A modal dialog is an overlay panel that appears on top of the page to capture the user's attention for a specific task — confirmation, a form, or detailed information — before returning them to the underlying page.
A modal consists of three parts: a backdrop overlay that dims the background, the dialog panel centered on screen, and a close mechanism (a button, Escape key, or backdrop click). All three must work together for a polished, accessible component.
Full-Screen Backdrop Overlay
The backdrop dims the page content behind the modal, focusing the user's attention on the dialog. Use fixed inset-0 bg-black/50 z-40 to cover the entire viewport with a 50% opaque black layer.
The backdrop should be a separate element from the dialog panel so you can independently animate them. Clicking the backdrop should close the modal — this is achieved with a JavaScript click handler on the backdrop element.
<div
id="modal-backdrop"
class="fixed inset-0 bg-black/50 z-40"
onclick="closeModal()">
</div>Centering the Dialog Panel
The dialog panel sits inside a centering container that uses fixed inset-0 flex items-center justify-center z-50 p-4. This container covers the full viewport as a flex container that centers its single child — the dialog box — both horizontally and vertically.
The p-4 ensures the dialog has breathing room from the screen edges on small screens, preventing it from touching the sides on mobile devices.
<!-- Centering container -->
<div class="fixed inset-0 flex items-center justify-center z-50 p-4">
<!-- Dialog panel -->
<div class="bg-white rounded-2xl shadow-2xl w-full max-w-lg">
<!-- Modal content -->
</div>
</div>Dialog Header With Close Button
The modal header contains the dialog title and a close button. Use flex items-center justify-between px-6 py-4 border-b border-gray-100 to space the title and close button on opposite ends of the header row.
The title uses text-lg font-semibold text-gray-900 and the close button is a small icon button at the far right. The button must have an aria-label='Close modal' for screen reader users who cannot see the × icon.
<div class="flex items-center justify-between px-6 py-4 border-b border-gray-100">
<h2 class="text-lg font-semibold text-gray-900" id="modal-title">
Confirm Action
</h2>
<button
onclick="closeModal()"
aria-label="Close modal"
class="p-1 text-gray-400 hover:text-gray-600 hover:bg-gray-100
rounded-lg transition-colors">
<svg class="w-5 h-5" fill="none" viewBox="0 0 24 24" stroke="currentColor">
<path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M6 18L18 6M6 6l12 12"/>
</svg>
</button>
</div>Dialog Body Content
The modal body holds the main content of the dialog. Use px-6 py-5 for comfortable padding. For long content, constrain the height with max-h-96 overflow-y-auto so the modal does not grow taller than the viewport.
Body text uses text-sm text-gray-600 leading-relaxed for readable paragraph spacing. Add icons or illustrations for visual clarity in confirmation and alert dialogs.
<div class="px-6 py-5">
<div class="flex items-start gap-4">
<!-- Warning icon -->
<div class="flex-shrink-0 w-12 h-12 rounded-full bg-red-100 flex items-center justify-center">
<svg class="w-6 h-6 text-red-600" fill="none" viewBox="0 0 24 24" stroke="currentColor">
<path stroke-linecap="round" stroke-linejoin="round" stroke-width="2"
d="M12 9v2m0 4h.01m-6.938 4h13.856c1.54 0 2.502-1.667 1.732-3L13.732 4c-.77-1.333-2.694-1.333-3.464 0L3.34 16c-.77 1.333.192 3 1.732 3z"/>
</svg>
</div>
<div>
<p class="text-base font-semibold text-gray-900">Delete this record?</p>
<p class="mt-1 text-sm text-gray-600 leading-relaxed">
This action cannot be undone. All data associated with this record will be permanently removed from our servers.
</p>
</div>
</div>
</div>Dialog Footer With Action Buttons
The modal footer holds the action buttons. Use flex items-center justify-end gap-3 px-6 py-4 border-t border-gray-100 to right-align the buttons and visually separate them from the body content.
Place the secondary action (Cancel) to the left of the primary action (Confirm/Delete) to match the spatial convention of safe action on the left and destructive action on the right.
<div class="flex items-center justify-end gap-3 px-6 py-4 border-t border-gray-100">
<button
onclick="closeModal()"
class="px-4 py-2 text-sm font-semibold text-gray-700 border border-gray-300
rounded-lg hover:bg-gray-50 transition-colors">
Cancel
</button>
<button
class="px-4 py-2 text-sm font-semibold text-white bg-red-600
rounded-lg hover:bg-red-700 transition-colors">
Delete Record
</button>
</div>Showing and Hiding the Modal
The modal starts hidden with hidden on both the backdrop and the centering container. When triggered, JavaScript removes hidden from both elements and adds overflow-hidden to the body to prevent background scrolling while the modal is open.
The close function reverses all three operations. Connect the trigger to any button with an onclick handler.
<script>
const modal = document.getElementById('modal');
const backdrop = document.getElementById('modal-backdrop');
function openModal() {
modal.classList.remove('hidden');
backdrop.classList.remove('hidden');
document.body.classList.add('overflow-hidden');
}
function closeModal() {
modal.classList.add('hidden');
backdrop.classList.add('hidden');
document.body.classList.remove('overflow-hidden');
}
// Escape key closes the modal
document.addEventListener('keydown', (e) => {
if (e.key === 'Escape') closeModal();
});
</script>Scrollable Modal for Long Content
When modal content is longer than the available viewport height, make only the body scrollable while the header and footer remain fixed. Apply max-h-screen overflow-hidden flex flex-col to the dialog panel, and flex-1 overflow-y-auto to the body section.
This prevents the modal from growing off-screen and keeps the action buttons always visible without the user needing to scroll past the content.
<div class="fixed inset-0 flex items-center justify-center z-50 p-4">
<div class="bg-white rounded-2xl shadow-2xl w-full max-w-lg
max-h-[90vh] flex flex-col">
<!-- Fixed header -->
<div class="flex items-center justify-between px-6 py-4 border-b border-gray-100 flex-shrink-0">
<h2 class="text-lg font-semibold">Terms of Service</h2>
<button onclick="closeModal()" aria-label="Close">×</button>
</div>
<!-- Scrollable body -->
<div class="flex-1 overflow-y-auto px-6 py-5">
<p class="text-sm text-gray-600 leading-relaxed">
Very long terms of service content that may exceed the viewport height...
<!-- many paragraphs -->
</p>
</div>
<!-- Fixed footer -->
<div class="flex justify-end gap-3 px-6 py-4 border-t border-gray-100 flex-shrink-0">
<button onclick="closeModal()" class="px-4 py-2 text-sm font-semibold text-gray-700 border border-gray-300 rounded-lg">Decline</button>
<button class="px-4 py-2 text-sm font-semibold text-white bg-blue-600 rounded-lg">Accept</button>
</div>
</div>
</div>Modal Size Variants
Modals come in different sizes depending on their content. Control the size with max-w-* on the dialog panel:
- Small:
max-w-sm— for simple confirmation dialogs - Medium:
max-w-lg— for forms and moderate content - Large:
max-w-2xl— for detailed views or complex forms - Full:
max-w-5xl— for image viewers or rich content
Always include a minimum w-full so the modal shrinks appropriately on small screens even when the max-width is large.
<!-- Small modal -->
<div class="bg-white rounded-xl shadow-2xl w-full max-w-sm p-6">
<p class="text-sm text-gray-700">Are you sure?</p>
<div class="flex justify-end gap-3 mt-4">
<button class="px-3 py-1.5 text-xs font-semibold border border-gray-300 rounded-lg">No</button>
<button class="px-3 py-1.5 text-xs font-semibold text-white bg-red-600 rounded-lg">Yes, delete</button>
</div>
</div>ARIA Roles for Modal Accessibility
An accessible modal requires specific ARIA attributes. Add role='dialog' aria-modal='true' to the dialog panel so screen readers know it is a modal and that the rest of the page content is inert.
Link the dialog's title to the panel with aria-labelledby pointing to the heading's id. This allows screen readers to announce the dialog name when focus moves into it. For modals without a visible title, use aria-label on the dialog element directly.
<div
role="dialog"
aria-modal="true"
aria-labelledby="dlg-title"
class="bg-white rounded-2xl shadow-2xl w-full max-w-lg">
<div class="flex items-center justify-between px-6 py-4 border-b border-gray-100">
<h2 id="dlg-title" class="text-lg font-semibold text-gray-900">
Confirm Deletion
</h2>
<button onclick="closeModal()" aria-label="Close dialog" class="p-1 text-gray-400 hover:text-gray-600 rounded-lg">×</button>
</div>
<div class="px-6 py-5">
<p class="text-sm text-gray-600">This will permanently delete the selected item.</p>
</div>
<div class="flex justify-end gap-3 px-6 py-4 border-t border-gray-100">
<button onclick="closeModal()" class="px-4 py-2 text-sm font-semibold border border-gray-300 rounded-lg">Cancel</button>
<button class="px-4 py-2 text-sm font-semibold text-white bg-red-600 rounded-lg">Delete</button>
</div>
</div>Putting the Full Modal Together
A complete modal implementation has two HTML sections: the backdrop and the centering container with the dialog panel inside. Both start hidden with hidden.
The trigger button is somewhere in the page content. When clicked, both elements are shown, body scroll is locked, and focus moves into the modal. When dismissed (button, backdrop, or Escape), both elements are hidden again and body scroll is restored.
<!-- Trigger -->
<button onclick="openModal()" class="px-4 py-2 bg-red-600 text-white text-sm font-semibold rounded-lg">Delete Account</button>
<!-- Backdrop -->
<div id="modal-backdrop" onclick="closeModal()"
class="hidden fixed inset-0 bg-black/50 z-40"></div>
<!-- Dialog -->
<div id="modal" role="dialog" aria-modal="true" aria-labelledby="m-title"
class="hidden fixed inset-0 flex items-center justify-center z-50 p-4">
<div class="bg-white rounded-2xl shadow-2xl w-full max-w-md">
<div class="flex items-center justify-between px-6 py-4 border-b border-gray-100">
<h2 id="m-title" class="text-lg font-semibold text-gray-900">Delete Account</h2>
<button onclick="closeModal()" aria-label="Close" class="p-1 text-gray-400 hover:text-gray-600 rounded">×</button>
</div>
<div class="px-6 py-5">
<p class="text-sm text-gray-600">Are you sure? This cannot be undone.</p>
</div>
<div class="flex justify-end gap-3 px-6 py-4 border-t border-gray-100">
<button onclick="closeModal()" class="px-4 py-2 text-sm font-semibold border border-gray-300 rounded-lg">Cancel</button>
<button class="px-4 py-2 text-sm font-semibold text-white bg-red-600 rounded-lg">Delete</button>
</div>
</div>
</div>Quick Check
Test your understanding of Tailwind CSS Mastery concepts from this lesson.
Lesson Recap
In this lesson you learned: modal structure consists of a backdrop overlay (fixed inset-0 bg-black/50 z-40) and a centering container (fixed inset-0 flex items-center justify-center z-50) with the dialog panel inside; scrollable modals use flex flex-col max-h-[90vh] with flex-1 overflow-y-auto on the body; and ARIA attributes role='dialog' aria-modal='true' aria-labelledby are required for screen reader accessibility. Next up we animate modal open and close transitions.
よくある質問
「モーダルダイアログの構造」レッスンは無料ですか？
はい。「モーダルダイアログの構造」の完全なテキストはこのウェブで無料で読めます。インタラクティブに演習し（組み込みコードエディタと24時間対応のAIチューター）、Tailwind CSS Academyコースの残りをアンロックするには、CoddyKit PROにアップグレードしてください。 Tailwind CSS Academyコースには全4レッスンが含まれています。
「モーダルダイアログの構造」で何を学びますか？
fixed配置とz-indexのユーティリティを使い、背景オーバーレイ、スクロール可能なコンテンツ領域、閉じるボタンを備えた中央配置のモーダルを構築します。 ブラウザで直接実行するハンズオンコードでTailwind CSS Academyを演習し、24時間対応のAIチューターがレッスンを進める中での質問に答えます。
Tailwind CSS Academyを始めるのに経験は必要ですか？
事前経験は必要ありません。CoddyKitのTailwind CSS Academyは初級者から上級者向けに構成されているため、ここから始めるか最初から始めて、自分のペースで進むことができます。 これはレッスン1/4です。
「モーダルダイアログの構造」レッスンにはどのくらい時間がかかりますか？
ほとんどのCoddyKitレッスンは約5～10分かかります。各レッスンはコンパクトでインタラクティブなので、着実に進歩し、ウェブとアプリ全体で正確に前回の場所から再開できます。
このTailwind CSS Academyレッスンでコードを書いて実行できますか？
はい。すべてのTailwind CSS Academyレッスンに組み込みコードエディタが含まれているため、ブラウザでリアルコードを書いて実行し、即座のAIフィードバックを取得できます。ローカル設定は不要です。