.main-container{

    width: 990px;

    margin: 0 auto;

    overflow: hidden;

}

.lg-container{

    width: 730px;

    float:left;

}

.sm-container{

    width: 250px;

    float:right;

}

<link rel="stylesheet" href="{{ url_for('static',filename='front/css/front_base.css') }}">

<div class="main-container">

    {% block body %}

    {% endblock %}

</div>

{% extends "front/front_base.html" %}

{% block title %}

    仙剑论坛

{% endblock %}

{% block head %}

    <link rel="stylesheet" href="{{ static('front/css/front_index.css')  }}">

{% endblock %}

{% block body %}

    <div class="lg-container">

        <div id="carousel-example-generic" class="carousel slide index-banner" data-ride="carousel">

            <!-- 指示器 -->

            <ol class="carousel-indicators">

                <li data-target="#carousel-example-generic" data-slide-to="0" class="active"></li>

                <li data-target="#carousel-example-generic" data-slide-to="1"></li>

                <li data-target="#carousel-example-generic" data-slide-to="2"></li>

            </ol>

            <!-- 轮播图-->

            <div class="carousel-inner" role="listbox">

                <div class="item active">

                    <img src="https://static-image.xfz.cn/1512989310_955.jpg" alt="...">

                    <div class="carousel-caption">

                        ...

                    </div>

                </div>

                <div class="item">

                    <img src="https://static-image.xfz.cn/1528079965_535.jpeg" alt="...">

                    <div class="carousel-caption">

                        ...

                    </div>

                </div>

                ...

            </div>

            <!-- Controls -->

            <a class="left carousel-control" href="#carousel-example-generic" role="button" data-slide="prev">

                <span class="glyphicon glyphicon-chevron-left" aria-hidden="true"></span>

                <span class="sr-only">Previous</span>

            </a>

            <a class="right carousel-control" href="#carousel-example-generic" role="button" data-slide="next">

                <span class="glyphicon glyphicon-chevron-right" aria-hidden="true"></span>

                <span class="sr-only">Next</span>

            </a>

        </div>

    </div>

    <div class="sm-container">

    </div>

{% endblock %}

.index-banner{

    border-radius: 10px;

    overflow: hidden;

    height: 190px;

}

.index-banner img{

    height: 190px;

}