修复一些小问题

examples/slider.html

@@ -16,6 +16,8 @@ body{padding:100px 0;}
 
   <div class="layui-container">
     <div id="slideTest1"></div>
+    <br>
+    <div id="slideTest2" style="margin: 45px 30px; display: inline-block;"></div>
   </div>
 
 <script src="../src/layui.js"></script>
@@ -50,6 +52,12 @@ layui.use('slider', function(){
   });
   
   sliderInst.setValue(30);
+
+
+  slider.render({
+    elem: '#slideTest2',
+    type: 'vertical'
+  });
 });
 </script>
 </body>

src/modules/dropdown.js

@@ -495,7 +495,7 @@ layui.define(['jquery', 'laytpl', 'lay'], function(exports){
       
       //是否超出底部屏幕
       if(rect.bottom > _WIN.height()){
-        elemPanel.eq(0).css('margin-top', -(rect.bottom - _WIN.height()));
+        elemPanel.eq(0).css('margin-top', -(rect.bottom - _WIN.height() + 5));
       };
     }).on('mouseleave', ELEM_LI_PAR, function(e){
       var othis = $(this)

src/modules/layer.js

@@ -850,7 +850,7 @@ layer.style = function(index, options, limit){
   }
   
   layero.css(options);
-  btnHeight = layero.find('.'+doms[6]).outerHeight();
+  btnHeight = layero.find('.'+doms[6]).outerHeight() || 0;
   
   if(type === ready.type[2]){
     layero.find('iframe').css({