图像轮播尺寸不恒定/不均匀

Question

我的画廊中的图像没有以恒定的尺寸显示。我想要恒定大小的图像（缩略图类型） 谢谢！

                                

                                <a href="img/portfolio/footwear1.jpeg" title="Add Description">
                                    <img src="img/portfolio/footwear1.jpeg" class="img-responsive" alt="portfolio 01">

                                    <div class="portfolio-item-overlay">
                                        <div class="portfolio-item-details text-center">

                                            <!-- Item Header -->
                                            <h3>Logo</h3>

                                            <!-- Item Strips -->
                                            <span></span>

                                            <!-- Item Description -->
                                            <p>Desktop, Design</p>

                                        </div>

                                    </div>
                                </a>

                            </div>

                        </div>

                        <div class="col-md-3 col-sm-6 col-xs-12 web">