diff --git a/CustomKeyboard/Model/KBKey.h b/CustomKeyboard/Model/KBKey.h
index ba4b7a4..a685dc4 100644
--- a/CustomKeyboard/Model/KBKey.h
+++ b/CustomKeyboard/Model/KBKey.h
@@ -16,7 +16,7 @@ typedef NS_ENUM(NSInteger, KBKeyType) {
     KBKeyTypeSpace,           // 空格
     KBKeyTypeReturn,          // 回车/发送
     KBKeyTypeGlobe,           // 系统地球键
-    KBKeyTypeCustom,          // 自定义功能占位
+    KBKeyTypeCustom,          // 自定义功能占位 AI
     KBKeyTypeSymbolsToggle    // 数字面板内的“#+=/123”切换
 };
 
diff --git a/CustomKeyboard/Resource/KBSkinIconMap.strings b/CustomKeyboard/Resource/KBSkinIconMap.strings
index bffe465..777b71e 100644
--- a/CustomKeyboard/Resource/KBSkinIconMap.strings
+++ b/CustomKeyboard/Resource/KBSkinIconMap.strings
@@ -227,6 +227,7 @@
 "backspace" = "key_del";
 /* Shift（⇧） */
 "shift" = "key_up";
+"shift_upper" = "key_up_upper";
 /* 字母面板左下角 "123" */
 "mode_123" = "key_123";
 /* 数字面板左下角 "abc" */
diff --git a/CustomKeyboard/View/KBKeyButton.m b/CustomKeyboard/View/KBKeyButton.m
index 8a63db7..64ee914 100644
--- a/CustomKeyboard/View/KBKeyButton.m
+++ b/CustomKeyboard/View/KBKeyButton.m
@@ -38,7 +38,7 @@
     if (!self.iconView) {
         UIImageView *iv = [[UIImageView alloc] initWithFrame:CGRectZero];
         // 作为按键的整块皮肤背景，铺满整个按钮区域
-        iv.contentMode = UIViewContentModeScaleAspectFit;
+        iv.contentMode = UIViewContentModeScaleToFill;
         iv.clipsToBounds = YES;
         iv.translatesAutoresizingMaskIntoConstraints = NO;
         [self addSubview:iv];
diff --git a/CustomKeyboard/View/KBKeyboardView.m b/CustomKeyboard/View/KBKeyboardView.m
index 783980b..a28662a 100644
--- a/CustomKeyboard/View/KBKeyboardView.m
+++ b/CustomKeyboard/View/KBKeyboardView.m
@@ -371,12 +371,37 @@
             // 避免对基准按钮自身添加 self == self * k 的无效约束
             if (b == firstChar) continue;
             if (b.key.type == KBKeyTypeCharacter) continue;
+
+            // 对 Shift 和 Backspace 强制做 1:1 按钮（宽度 = 高度），
+            // 主要作用于字母布局第三行左右两侧的两个键，避免被挤压导致图标变形。
+            if (b.key.type == KBKeyTypeShift || b.key.type == KBKeyTypeBackspace) {
+                [b mas_makeConstraints:^(MASConstraintMaker *make) {
+                    make.width.equalTo(b.mas_height);
+                }];
+                continue;
+            }
+
             CGFloat multiplier = 1.5;
-            if (b.key.type == KBKeyTypeSpace) multiplier = 4.0;
-            if (b.key.type == KBKeyTypeReturn) multiplier = 1.8;
-            if (b.key.type == KBKeyTypeModeChange || b.key.type == KBKeyTypeGlobe || b.key.type == KBKeyTypeShift || b.key.type == KBKeyTypeBackspace) {
+
+            // Space 保持原来的长条比例
+            if (b.key.type == KBKeyTypeSpace) {
+                multiplier = 4.0;
+            }
+            // Send 按钮：宽度为基准键的 2.6 倍
+            else if (b.key.type == KBKeyTypeReturn) {
+                multiplier = 2.6;
+            }
+            // 删除、123/ABC、#+=、AI：宽度与基准键一致（1 倍，“接近正方形”）
+            else if (b.key.type == KBKeyTypeModeChange ||
+                     b.key.type == KBKeyTypeSymbolsToggle ||
+                     b.key.type == KBKeyTypeCustom) {
+                multiplier = 1.0;
+            }
+            // 其它特殊键（如 Globe）保持适度放大
+            else if (b.key.type == KBKeyTypeGlobe) {
                 multiplier = 1.5;
             }
+
             [b mas_makeConstraints:^(MASConstraintMaker *make) {
                 make.width.equalTo(firstChar).multipliedBy(multiplier);
             }];