style(views/checkin): 调整按钮样式和颜色

修改浮动按钮位置和返回顶部按钮颜色，提升视觉一致性

 <!--
   * @Date: 2025-05-29 15:34:17
  * @LastEditors: hookehuyr hookehuyr@gmail.com
- * @LastEditTime: 2025-12-18 22:47:39
+ * @LastEditTime: 2025-12-18 22:58:48
  * @FilePath: /mlaj/src/views/checkin/IndexCheckInPage.vue
   * @Description: 文件描述
 -->
@@ -702,7 +702,7 @@ const formatData = (data) => {
 }
 
 .van-back-top {
-  background-color: #4caf50;
+  background-color: #22c55e;
 }
 
 .calendar-selected {
@@ -828,7 +828,7 @@ const formatData = (data) => {
 /* 紧凑模式（圆形按钮） */
 .floating-checkin-button.is-compact {
   left: auto;
-  right: 1.5rem;
+  right: 1rem;
   width: auto;
   padding: 0;
 }