.animate() 方法只可以操作以下样式

：
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    * backgroundPosition
    * borderWidth
    * borderBottomWidth
    * borderLeftWidth
    * borderRightWidth
    * borderTopWidth
    * borderSpacing
    * margin
    * marginBottom
    * marginLeft
    * marginRight
    * marginTop
    * outlineWidth
    * padding
    * paddingBottom
    * paddingLeft
    * paddingRight
    * paddingTop
    * height
    * width
    * maxHeight
    * maxWidth
    * minHeight
    * maxWidth
    * font
    * fontSize
    * bottom
    * left
    * right
    * top
    * letterSpacing
    * wordSpacing
    * lineHeight
    * textIndent
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如果想用js控制背景可以这样写：$("#hideme").css("background","#000")