Language choice affects text overflow in html(bootstrap) (Django) - html

Question

I'm using bootstrap to implement my post detail page.
It works well and fit perfectly into tho format when using Korean.
But, if I wrote english contents, it overflow the format.
What's wrong with it?
Here is the code :
models.py
from django.db import models
from django.core.urlresolvers import reverse
from django.conf import settings
def upload_location(instance, file_name):
return "{}/{}".format(instance.author.username, file_name)
class Post(models.Model):
author = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE)
title = models.CharField(max_length=100)
content = models.TextField()
image = models.ImageField(upload_to=upload_location, blank=True, null=True)
created_at = models.DateTimeField(auto_now_add=True)
updated_at = models.DateTimeField(auto_now=True)
class Meta:
ordering = ('-created_at',)
def __str__(self):
return self.title
def get_absolute_url(self):
return reverse(
"posts:detail",
kwargs={
"pk": self.id,
}
)
def get_image_url(self):
if self.image:
return self.image.url
return "http://placehold.it/300x200"
post_detail.html
{% extends 'chacha_dabang/skeleton/base.html' %}
{% load pipeline %}
{% block content %}
<div class="container">
<section class="post-content-section">
<h2> {{ post.title }} </h2>
<h5 style="text-align: right;"> {{ post.created_at }} </h5>
<hr class="thin">
<img src="{{ post.get_image_url }}" alt="image">
<p> {{ post.content }} </p>
</section>
</br>
<hr class="thin">
</br>
<section id="comment-section" data-post-id={{ post.pk }}>
<h3> 댓 글 (<span id="comment-count"></span>)</h3>
<ul>
</ul>
<form method="POST" action="">
{% csrf_token %}
{{ form.as_p }}
<button type="submit" class="save btn btn-default">Save</button>
</form>
</section>
</div>
{% endblock %}
{% block custom_js %}
{% javascript "comments" %}
{% javascript "message" %}
{% endblock %}