修改Math.ceil为 floor。review by 于良

@@ -72,8 +72,8 @@ export default class SixLinesFloor extends Component{
 let {width} = Dimensions.get('window');
 const DEVICE_WIDTH_RATIO = width / 320;
 
-let imageWidth = Math.ceil(width / 2);
-let imageHeight = Math.ceil(imageWidth * 180 / 375);
+let imageWidth = Math.floor(width / 2);
+let imageHeight = Math.floor(imageWidth * 180 / 375);
 
 
 let styles = StyleSheet.create({