UI

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];

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);
             }];