diff --git a/style-extension.css.txt b/style-extension.css.txt
new file mode 100644
index 0000000..6a35436
--- /dev/null
+++ b/style-extension.css.txt
@@ -0,0 +1,61 @@
+/* 扩展样式：补充核心样式未覆盖的细节 */
+
+/* Toast提示优化 */
+#dynamicToast {
+    transition: opacity 0.3s ease, transform 0.3s ease;
+    transform: translateX(-50%) translateY(0);
+}
+#dynamicToast.hide {
+    opacity: 0;
+    transform: translateX(-50%) translateY(20px);
+}
+
+/* 导入/导出按钮样式 */
+.backup-group {
+    display: flex;
+    gap: 12px;
+}
+
+/* 加载状态优化 */
+.book-cover.loading {
+    background: linear-gradient(90deg, #e6f0ff 25%, #d9e6fc 50%, #e6f0ff 75%);
+    background-size: 200% 100%;
+    animation: loadingShimmer 1.5s infinite;
+}
+@keyframes loadingShimmer {
+    0% { background-position: 200% 0; }
+    100% { background-position: -200% 0; }
+}
+
+/* 表单验证样式 */
+.input-error {
+    border-color: #ef4444 !important;
+    box-shadow: 0 0 0 3px rgba(239, 68, 68, 0.2) !important;
+}
+.error-message {
+    color: #ef4444;
+    font-size: 0.75rem;
+    margin: -8px 0 12px 16px;
+    display: none;
+}
+.error-message.show {
+    display: block;
+}
+
+/* 移动端优化 */
+@media (max-width: 480px) {
+    .header {
+        padding: 16px 20px;
+        border-radius: 24px;
+    }
+    .logo-area h1 {
+        font-size: 1.4rem;
+    }
+    .book-card {
+        min-width: unset;
+    }
+    .modal-content {
+        padding: 24px 20px;
+        border-radius: 24px;
+    }
+}
\ No newline at end of file