models.py
---------

class Post(ReadOnlyModel):
    content = models.TextField(db_column='post_content')

class Style(models.Model):
    fontColor = models.CharField(max_length=255)


class Element(models.Model):
    post = models.ForeignKey(Post)
    style = models.ForeignKey(Style)

    def __str__(self):
        return "%s-%s" % (self.post, self.style)


class Page(models.Model):
    name = models.CharField(max_length=255, blank=False, unique=True)
    elements = models.ManyToManyField(Element)


---------------
admin.py:

class ElementInline(admin.TabularInline):
    model = Page.elements.through
    extra = 2


class PageAdmin(admin.ModelAdmin):
    inlines = [ElementInline,]
    exclude = ('elements',)

admin.site.register(Page, PageAdmin)