Post content not same with editor

Hello.

I’m new in wordpress, and i try to develop some themes.
I have a problem when i’m trying to show post content

<Div class="single-detail-content">
<p><?php the_content(); ?></p>
</Div>

the problem is, the post content is different with wysiwyg editor, in wysiwyg editor, i’m uploaded an image and make it center, but when i show it in post, the image doesnt show like that(image is not in center position), i dont know what is the problem, i’m try to see my css in that division but there is no align setting there

.single-detail-content{
    padding:15px;
    font-family: "Opensans","Oswald","Arial";
    line-height: 1.5;
    color: rgb(55, 55, 55);
}