style: 使用CSS变量统一占位文本颜色

将硬编码的颜色值#d1d5db替换为CSS变量--secondary-color-text，提高样式可维护性

@@ -13,6 +13,7 @@
   --color-text: #9CA3AF;
   --primary-color-rgb: 84, 171, 174;
   --secondary-color-bg: #E7E7E7;
+  --secondary-color-text: #d1d5db;
 }
 
 .bg-blue-500 {

 <!--
  * @Date: 2025-08-27 17:44:53
  * @LastEditors: hookehuyr hookehuyr@gmail.com
- * @LastEditTime: 2025-09-22 10:51:07
+ * @LastEditTime: 2025-09-22 10:53:04
  * @FilePath: /lls_program/src/pages/CreateFamily/index.vue
  * @Description: 创建家庭
 -->
@@ -79,7 +79,7 @@
                     type="text"
                     v-model="familyMotto[index]"
                     :placeholder="familyMottoPlaceholder[index]"
-                    placeholder-style="color: #d1d5db;"
+                    placeholder-style="color: var(--secondary-color-text);"
                     @input="(e) => handleInputChange(index, e.target.value)"
                     @focus="focusedIndex = index"
                     @blur="handleBlur(index)"

 <!--
  * @Date: 2025-08-27 17:44:53
  * @LastEditors: hookehuyr hookehuyr@gmail.com
- * @LastEditTime: 2025-09-22 10:51:28
+ * @LastEditTime: 2025-09-22 10:53:14
  * @FilePath: /lls_program/src/pages/EditFamily/index.vue
  * @Description: 文件描述
 -->
@@ -77,7 +77,7 @@
                     type="text"
                     v-model="familyMotto[index]"
                     :placeholder="familyMottoPlaceholder[index]"
-                    placeholder-style="color: #d1d5db;"
+                    placeholder-style="color: var(--secondary-color-text);"
                     @input="(e) => handleInputChange(index, e.target.value)"
                     @focus="focusedIndex = index"
                     @blur="handleBlur(index)"