diff --git a/dialog.js b/dialog.js
new file mode 100644
index 0000000..4098ae5
--- /dev/null
+++ b/dialog.js
@@ -0,0 +1,79 @@
+export class Dialog extends HTMLElement {
+  constructor() {
+    super()
+    this.attachShadow({mode: 'open'})
+    this.headerEl = document.createElement('div')
+    this.headerEl.classList.add('header')
+    this.bodyEl = document.createElement('div')
+    this.bodyEl.classList.add('body')
+    this.footerEl = document.createElement('div')
+    this.footerEl.classList.add('footer')
+    this.dialogEl = document.createElement('dialog')
+    this.dialogEl.replaceChildren(
+      this.headerEl, this.bodyEl, this.footerEl
+    )
+    this.dialogEl.addEventListener('click', e => {
+      const rect = this.dialogEl.getBoundingClientRect();
+      const clickedInDialog = (
+        rect.top <= e.clientY &&
+        e.clientY <= rect.top + rect.height &&
+        rect.left <= e.clientX &&
+        e.clientX <= rect.left + rect.width
+      )
+      if (e.target === this.dialogEl && !clickedInDialog) {
+        this.close()
+      }
+    })
+    this.shadowRoot.appendChild(this.dialogEl)
+  }
+
+  connectedCallback() {
+    const style = document.createElement('style')
+    style.textContent = `
+      dialog {
+        margin-top: 120px;
+        min-width: 200px;
+        border: 1px solid rgba(0, 0, 0, 0.3);
+        border-radius: 6px;
+        box-shadow: 0 3px 7px rgba(0, 0, 0, 0.3);
+      }
+      dialog::backdrop {
+        opacity: 0;
+        transition: opacity 0.3s ease-in;
+        background-color: rgba(0, 0, 0, .25);
+      }
+      dialog.opened::backdrop {
+        opacity: 1;
+      }
+      dialog.closing {
+        visibility: hidden;
+      }
+      dialog.closing::backdrop {
+        visibility: visible;
+      }
+      .header, .footer, .body {
+        display: flex;
+        align-items: stretch;
+        flex-direction: column;
+      }
+    `
+    this.shadowRoot.append(style)
+    this.headerEl.setAttribute('part', 'header')
+    this.bodyEl.setAttribute('part', 'body')
+    this.footerEl.setAttribute('part', 'footer')
+  }
+
+  open() {
+    this.dialogEl.showModal();
+    this.dialogEl.classList.add('opened')
+  }
+
+  close() {
+    this.dialogEl.classList.remove('opened')
+    this.dialogEl.classList.add('closing')
+    setTimeout(() => {
+      this.dialogEl.close()
+      this.dialogEl.classList.remove('closing')
+    }, 500)
+  }
+}
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