diff --git a/src/utils/ModalManager.js b/src/utils/ModalManager.js
new file mode 100644
index 0000000..54b5b76
--- /dev/null
+++ b/src/utils/ModalManager.js
@@ -0,0 +1,218 @@
+/**
+ * ModalManager - Unified modal system with accessibility support
+ * @version 4.0.0
+ */
+export class ModalManager {
+    #modal;
+    #backdrop;
+    #options;
+    #lastFocusedElement;
+    #focusableElements;
+    #eventListeners;
+    #isOpen;
+
+    static #openModals = [];
+
+    constructor(element, options = {}) {
+        this.#modal = typeof element === 'string' ? document.querySelector(element) : element;
+        this.#options = {
+            closeOnBackdrop: true,
+            closeOnEscape: true,
+            focusFirst: true,
+            onOpen: null,
+            onClose: null,
+            ...options
+        };
+        this.#isOpen = false;
+        this.#eventListeners = [];
+        this.#init();
+    }
+
+    #init() {
+        // Ensure modal has required attributes
+        if (!this.#modal.hasAttribute('role')) {
+            this.#modal.setAttribute('role', 'dialog');
+        }
+        if (!this.#modal.hasAttribute('aria-modal')) {
+            this.#modal.setAttribute('aria-modal', 'true');
+        }
+
+        // Find or create backdrop
+        this.#backdrop = this.#modal.querySelector('.modal-backdrop');
+
+        // Setup close triggers
+        this.#setupCloseTriggers();
+    }
+
+    #setupCloseTriggers() {
+        // Close button
+        const closeBtn = this.#modal.querySelector('.modal-close');
+        if (closeBtn) {
+            const handler = (e) => {
+                e.preventDefault();
+                this.close();
+            };
+            closeBtn.addEventListener('click', handler);
+            this.#eventListeners.push({ el: closeBtn, type: 'click', handler });
+        }
+
+        // Elements with data-close attribute
+        const closeTriggers = this.#modal.querySelectorAll('[data-close]');
+        closeTriggers.forEach(el => {
+            if (el.classList.contains('modal-backdrop') && !this.#options.closeOnBackdrop) {
+                return;
+            }
+            const handler = (e) => {
+                e.preventDefault();
+                this.close();
+            };
+            el.addEventListener('click', handler);
+            this.#eventListeners.push({ el, type: 'click', handler });
+        });
+    }
+
+    #getFocusableElements() {
+        const selector = [
+            'button:not([disabled])',
+            'input:not([disabled])',
+            'select:not([disabled])',
+            'textarea:not([disabled])',
+            'a[href]',
+            '[tabindex]:not([tabindex="-1"])'
+        ].join(', ');
+
+        return Array.from(this.#modal.querySelectorAll(selector))
+            .filter(el => el.offsetParent !== null && !el.classList.contains('modal-backdrop'));
+    }
+
+    #trapFocus(e) {
+        if (e.key !== 'Tab') return;
+
+        const focusable = this.#getFocusableElements();
+        if (focusable.length === 0) return;
+
+        const firstEl = focusable[0];
+        const lastEl = focusable[focusable.length - 1];
+
+        if (e.shiftKey) {
+            if (document.activeElement === firstEl) {
+                e.preventDefault();
+                lastEl.focus();
+            }
+        } else {
+            if (document.activeElement === lastEl) {
+                e.preventDefault();
+                firstEl.focus();
+            }
+        }
+    }
+
+    #handleKeydown(e) {
+        if (e.key === 'Escape' && this.#options.closeOnEscape) {
+            e.preventDefault();
+            this.close();
+        }
+        this.#trapFocus(e);
+    }
+
+    open() {
+        if (this.#isOpen) return;
+
+        // Store last focused element
+        this.#lastFocusedElement = document.activeElement;
+
+        // Track open modals
+        ModalManager.#openModals.push(this);
+
+        // Show modal
+        this.#modal.classList.add('open');
+        this.#isOpen = true;
+
+        // Prevent body scroll
+        document.body.style.overflow = 'hidden';
+
+        // Add keyboard listener
+        const keydownHandler = (e) => this.#handleKeydown(e);
+        document.addEventListener('keydown', keydownHandler);
+        this.#eventListeners.push({ el: document, type: 'keydown', handler: keydownHandler });
+
+        // Focus first element
+        if (this.#options.focusFirst) {
+            requestAnimationFrame(() => {
+                const focusable = this.#getFocusableElements();
+                if (focusable.length > 0) {
+                    focusable[0].focus();
+                }
+            });
+        }
+
+        // Callback
+        if (this.#options.onOpen) {
+            this.#options.onOpen(this);
+        }
+
+        // Dispatch custom event
+        this.#modal.dispatchEvent(new CustomEvent('modal:open'));
+    }
+
+    close() {
+        if (!this.#isOpen) return;
+
+        // Remove from open modals
+        const index = ModalManager.#openModals.indexOf(this);
+        if (index > -1) {
+            ModalManager.#openModals.splice(index, 1);
+        }
+
+        // Hide modal
+        this.#modal.classList.remove('open');
+        this.#isOpen = false;
+
+        // Restore body scroll if no modals open
+        if (ModalManager.#openModals.length === 0) {
+            document.body.style.overflow = '';
+        }
+
+        // Remove keyboard listener
+        const keydownListener = this.#eventListeners.find(
+            l => l.el === document && l.type === 'keydown'
+        );
+        if (keydownListener) {
+            document.removeEventListener('keydown', keydownListener.handler);
+            this.#eventListeners = this.#eventListeners.filter(l => l !== keydownListener);
+        }
+
+        // Restore focus
+        if (this.#lastFocusedElement && typeof this.#lastFocusedElement.focus === 'function') {
+            this.#lastFocusedElement.focus();
+        }
+
+        // Callback
+        if (this.#options.onClose) {
+            this.#options.onClose(this);
+        }
+
+        // Dispatch custom event
+        this.#modal.dispatchEvent(new CustomEvent('modal:close'));
+    }
+
+    isOpen() {
+        return this.#isOpen;
+    }
+
+    destroy() {
+        // Close if open
+        if (this.#isOpen) {
+            this.close();
+        }
+
+        // Remove all event listeners
+        this.#eventListeners.forEach(({ el, type, handler }) => {
+            el.removeEventListener(type, handler);
+        });
+        this.#eventListeners = [];
+    }
+}
+
+// Export for use in renderer
+window.ModalManager = ModalManager;