屏幕尺寸縮小時圖像未垂直居中

Question

當屏幕尺寸約為 993px（高度）或更大時，我有一個垂直居中的圖像。 當它縮小時，圖像會偏離中心。 如果當圖像低於 993px 時我弄亂了行高，它似乎使圖像再次居中，但我仍然希望自定義行高。 我正在使用 bootstrap.min

這是 css：

/*!
    Title: Dev Portfolio Template
    Version: 1.2.1
    Last Change: 08/28/2017
    Author: Ryan Fitzgerald
    Repo: https://github.com/RyanFitzgerald/devportfolio-template
    Issues: https://github.com/RyanFitzgerald/devportfolio-template/issues

    Description: This file contains all the styles associated with the page
    that don't come from third party libraries. This file gets compiled using
    Gulp and send to the /css folder which is then loaded on the page.
*/
body {
    font-family: 'Lato', sans-serif;
    font-size: 16px
}

body.active {
    overflow: hidden;
    z-index: -1
}

.no-js #experience-timeline > div {
    background: #fff;
    padding: 10px;
    margin-bottom: 10px;
    border: 1px solid #dcd9d9
}

.no-js #experience-timeline > div h3 {
    font-size: 1.5em;
    font-weight: 300;
    color: #374054;
    display: inline-block;
    margin: 0
}

.no-js #experience-timeline > div h4 {
    font-size: 1.2em;
    font-weight: 300;
    color: #7e8890;
    margin: 0 0 15px 0
}

.no-js #experience-timeline > div p {
    color: #74808a;
    font-size: 0.9em;
    margin: 0
}

.no-js #experience-timeline:before,
.no-js #experience-timeline:after {
    content: none
}

@keyframes dropHeader {
    0% {
        transform: translateY(-100%)
    }

    100% {
        transform: translateY(0)
    }
}

header {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    text-align: center;
    z-index: 10;
    animation-name: dropHeader;
    animation-iteration-count: 1;
    animation-timing-function: ease;
    animation-duration: 0.75s
}

header ul {
    display: inline-block;
    background: #fff;
    text-align: center;
    padding: 10px;
    margin: 0;
    border-bottom-right-radius: 4px;
    border-bottom-left-radius: 4px
}

header li {
    display: inline-block
}

header a {
    display: block;
    color: #3498db;
    padding: 10px
}

header a:hover {
    color: #217dbb;
    text-decoration: none;
    background: #eee;
    border-radius: 4px
}

header a:focus {
    color: #3498db;
    text-decoration: none
}

header.active {
    display: block
}

header.sticky {
    position: fixed;
    z-index: 999
}

#menu.active {
    display: block
}

#mobile-menu-open {
    display: none;
    cursor: pointer;
    position: fixed;
    right: 15px;
    top: 10px;
    color: #3498db;
    font-size: 1.5em;
    z-index: 20;
    padding: 0 7px;
    border-radius: 4px;
    background: #fff
}

#mobile-menu-close {
    display: none;
    text-align: right;
    width: 100%;
    background: #fff;
    font-size: 1.5em;
    padding-right: 15px;
    padding-top: 10px;
    cursor: pointer;
    color: #3498db
}

#mobile-menu-close span {
    font-size: 0.5em;
    text-transform: uppercase
}

#mobile-menu-close i {
    vertical-align: middle
}

footer {
    padding: 50px 0
}

.copyright {
    padding-top: 20px
}

.copyright p {
    margin: 0;
    color: #74808a
}

.top {
    text-align: center
}

.top span {
    cursor: pointer;
    display: block;
    margin: 15px auto 0 auto;
    width: 35px;
    height: 35px;
    border-radius: 50%;
    border: 3px solid #b9bfc4;
    text-align: center
}

.top i {
    color: #74808a
}

.social {
    text-align: right
}

.social ul {
    margin: 5px 0 0 0;
    padding: 0
}

.social li {
    display: inline-block;
    font-size: 1.25em;
    list-style: none
}

.social a {
    display: block;
    color: #74808a;
    padding: 10px
}

.social a:hover {
    color: #3498db
}

.btn-rounded-white {
    display: inline-block;
    color: #fff;
    padding: 15px 25px;
    border: 3px solid #fff;
    border-radius: 30px;
    transition: .5s ease all
}

.btn-rounded-white:hover {
    color: #3498db;
    background: #fff;
    text-decoration: none
}

.shadow {
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.12), 0 1px 2px rgba(0, 0, 0, 0.24)
}

.shadow-large {
    box-shadow: 0 3px 6px rgba(0, 0, 0, 0.08), 0 3px 6px rgba(0, 0, 0, 0.15)
}

.heading {
    position: relative;
    display: inline-block;
    font-size: 2em;
    font-weight: 300;
    margin: 0 0 30px 0
}

.heading:after {
    position: absolute;
    content: '';
    top: 100%;
    height: 1px;
    width: 50px;
    left: 0;
    right: 0;
    margin: 0 auto;
    background: #3498db
}

.background-alt {
    background: #f2f2f5
}

#lead {
    position: relative;
    height: 100vh;
    min-height: 500px;
    max-height: 1080px;
    background: url(../images/lead-bg.jpg);
    background-size: cover;
    padding: 15px;
    overflow: hidden
}

#lead-content {
    position: absolute;
    z-index: 10;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    text-align: center
}

#lead-content h1,
#lead-content h2 {
    margin: 0
}

#lead-content h1 {
    color: #fff;
    font-weight: 900;
    font-size: 5em;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    line-height: 0.9em
}

#lead-content h2 {
    color: #a0cfee;
    font-weight: 500;
    font-size: 2.25em;
    margin-bottom: 15px
}

#lead-overlay {
    position: absolute;
    height: 100%;
    width: 100%;
    top: 0;
    right: 0;
    bottom: 0;
    left: 0;
    background: rgba(33, 125, 187, 0.8);
    z-index: 1
}

#lead-down {
    position: absolute;
    left: 0;
    right: 0;
    width: 100%;
    text-align: center;
    z-index: 10;
    bottom: 15px;
    color: #fff
}

#lead-down span {
    cursor: pointer;
    display: block;
    margin: 0 auto;
    width: 35px;
    height: 35px;
    border-radius: 50%;
    border: 3px solid #a0cfee;
    text-align: center
}

#lead-down i {
    animation: pulsate 1.5s ease;
    animation-iteration-count: infinite;
    padding-top: 5px
}

@keyframes pulsate {
    0% {
        transform: scale(1, 1)
    }

    50% {
        transform: scale(1.2, 1.2)
    }

    100% {
        transform: scale(1, 1)
    }
}

#about {
    padding: 75px 15px;
    border-bottom: 1px solid #dcd9d9
}

#about h2 {
    color: #374054
}

#about p {
    color: #74808a;
    margin: 0
}

#experience {
    padding: 50px 15px;
    text-align: center;
    border-bottom: 1px solid #dcd9d9
}

#experience h2 {
    color: #374054
}

#experience-timeline {
    margin: 30px auto 0 auto;
    position: relative;
    max-width: 1000px
}

#experience-timeline:before {
    position: absolute;
    content: '';
    top: 0;
    bottom: 0;
    left: 303px;
    right: auto;
    height: 100%;
    width: 3px;
    background: #3498db;
    z-index: 0
}

#experience-timeline:after {
    position: absolute;
    content: '';
    width: 3px;
    height: 40px;
    background: #3498db;
    background: linear-gradient(to bottom, #3498db, rgba(52, 152, 219, 0));
    top: 100%;
    left: 303px
}

.vtimeline-content {
    margin-left: 350px;
    background: #fff;
    border: 1px solid #e6e6e6;
    padding: 15px;
    border-radius: 3px;
    text-align: left
}

.vtimeline-content h3 {
    font-size: 1.5em;
    font-weight: 300;
    color: #374054;
    display: inline-block;
    margin: 0
}

.vtimeline-content h4 {
    font-size: 1.2em;
    font-weight: 300;
    color: #7e8890;
    margin: 0 0 15px 0
}

.vtimeline-content p {
    color: #74808a;
    font-size: 0.9em;
    margin: 0
}

.vtimeline-point {
    position: relative;
    display: block;
    vertical-align: top;
    margin-bottom: 30px
}

.vtimeline-icon {
    position: relative;
    color: #fff;
    width: 50px;
    height: 50px;
    background: #3498db;
    border-radius: 50%;
    float: left;
    z-index: 99;
    margin-left: 280px
}

.vtimeline-icon i {
    display: block;
    font-size: 2em;
    margin-top: 10px
}

.vtimeline-date {
    width: 260px;
    text-align: right;
    position: absolute;
    left: 0;
    top: 10px;
    font-weight: 300;
    color: #374054
}

#education {
    padding: 50px 15px 20px 15px;
    border-bottom: 1px solid #dcd9d9;
    text-align: center
}

#education h2 {
    color: #374054;
    margin-bottom: 50px
}

.education-block {
    max-width: 700px;
    margin: 0 auto 30px auto;
    padding: 15px;
    border: 1px solid #dcd9d9;
    text-align: left
}

.education-block h3 {
    font-weight: 500;
    float: left;
    margin: 0;
    color: #374054
}

.education-block span {
    color: #74808a;
    float: right
}

.education-block h4 {
    color: #74808a;
    clear: both;
    font-weight: 500;
    margin: 0 0 15px 0
}

.education-block p,
.education-block ul {
    margin: 0;
    color: #74808a;
    font-size: 0.9em
}

.education-block ul {
    padding: 0 0 0 15px
}

#projects {
    padding: 50px 15px;
    border-bottom: 1px solid #dcd9d9;
    text-align: center
}

#projects h2 {
    color: #374054;
    margin-bottom: 50px
}

.project {
    
    position: relative;  
    max-width: 900px;
    margin: 0 auto 30px auto;
    overflow: hidden;
    background: #fff;
    border-radius: 4px;
    min-height: 200px;
    display: inline-block;
    
}

.project-image {
    float: left;
    width: 50%;
    height: 100%;
    background-color: yellow;
    
    
}

.projectImg {
    border: 2px solid black;
  
}

.row {
  display: flex; /* equal height of the children */
}

.col {
  flex: 1; /* additionally, equal width */
  padding: 1em;
}

.project-info {
    padding: 15px;
    float: right;
    width: 50%;
    height: 100%;
    
}


.project-info h3 {
    font-size: 1.5em;
    font-weight: 300;
    color: #374054;
    margin: 0 0 15px 0
}

.project-info p {
    color: #74808a;
    margin: 0 0 15px 0;
    font-size: 0.9em
}

.no-image .project-info {
    margin: 0;
    padding: 30px 15px;
}

#more-projects {
    display: none
}

#skills {
    padding: 50px 15px;
    text-align: center
}

#skills h2 {
    color: #374054;
    margin-bottom: 50px
}

#skills ul {
    display: block;
    margin: 0 auto;
    padding: 0;
    max-width: 800px
}

#skills li {
    display: inline-block;
    margin: 7px;
    padding: 5px 10px;
    color: #374054;
    background: #e4e4ea;
    list-style: none;
    cursor: default;
    font-size: 1.2em
}

#contact {
    padding: 50px 15px;
    background: #3498db;
    text-align: center
}

#contact h2 {
    margin: 0 0 15px 0;
    color: #fff;
    font-weight: 500
}

#contact-form {
    max-width: 500px;
    margin: 0 auto
}

#contact-form input,
#contact-form textarea {
    display: block;
    width: 100%;
    padding: 10px;
    border-radius: 4px;
    border: none;
    margin-bottom: 10px;
    background: #1d6fa5;
    color: #fff;
    transition: .5s ease all
}

#contact-form input::-webkit-input-placeholder,
#contact-form textarea::-webkit-input-placeholder {
    color: #fff
}

#contact-form input:-moz-placeholder,
#contact-form textarea:-moz-placeholder {
    color: #fff;
    opacity: 1
}

#contact-form input::-moz-placeholder,
#contact-form textarea::-moz-placeholder {
    color: #fff;
    opacity: 1
}

#contact-form input:-ms-input-placeholder,
#contact-form textarea:-ms-input-placeholder {
    color: #fff
}

#contact-form input:focus,
#contact-form textarea:focus {
    outline: none;
    background: #16527a
}

#contact-form textarea {
    height: 150px;
    resize: none
}

#contact-form button {
    display: block;
    width: 100%;
    background: #fff;
    border-radius: 4px;
    padding: 5px 10px;
    border: none;
    color: #3498db;
    font-weight: 700;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.12), 0 1px 2px rgba(0, 0, 0, 0.24);
    transition: .5s ease all
}

#contact-form button:hover {
    box-shadow: 0 10px 20px rgba(0, 0, 0, 0.19), 0 6px 6px rgba(0, 0, 0, 0.23)
}

.optional-section {
    padding: 50px 15px;
    text-align: center;
    border-top: 1px solid #dcd9d9
}

.optional-section h2 {
    color: #374054
}

.optional-section-block {
    max-width: 700px;
    margin: 0 auto 30px auto;
    padding: 15px;
    border: 1px solid #dcd9d9;
    background: #fff;
    text-align: left
}

.optional-section-block h3 {
    font-weight: 500;
    margin: 0 0 15px 0;
    color: #374054
}

.optional-section-block h4 {
    color: #74808a;
    clear: both;
    font-weight: 500;
    margin: 0 0 15px 0
}

.optional-section-block p,
.optional-section-block ul {
    margin: 0 0 15px 0;
    color: #74808a;
    font-size: 0.9em
}

.optional-section-block ul {
    padding: 0 0 0 15px
}

@media only screen and (max-width: 750px) {

    #experience-timeline:before,
    #experience-timeline:after {
        left: 23px
    }

    .vtimeline-date {
        width: auto;
        text-align: left;
        position: relative;
        margin-bottom: 15px;
        display: block;
        margin-left: 70px
    }

    .vtimeline-icon {
        margin-left: 0
    }

    .vtimeline-content {
        margin-left: 70px
    }
}

@media only screen and (max-width: 992px) {
    #lead {
        height: auto;
        min-height: auto;
        max-height: auto;
        padding: 100px 15px
    }

    #lead-content {
        position: relative;
        transform: none;
        left: auto;
        top: auto
    }

    #lead-content h1 {
        font-size: 3em
    }

    #lead-content h2 {
        font-size: 1.75em
    }

    #about {
        text-align: center
    }

    #about p {
        text-align: left
    }
}

@media only screen and (max-width: 768px) {
    header {
        position: fixed;
        display: none;
        z-index: 999;
        animation: none;
        bottom: 0;
        height: 100%
    }

    #mobile-menu-open,
    #mobile-menu-close {
        display: block
    }

    #menu {
        height: 100%;
        overflow-y: auto;
        box-shadow: none;
        border-radius: 0;
        width: 100%
    }

    #menu li {
        display: block;
        margin-bottom: 10px
    }

    #lead-content h1 {
        font-size: 2em
    }

    #lead-content h2 {
        font-size: 1.3em
    }

    #lead-content a {
        padding: 10px 20px
    }

    #lead-down {
        display: none
    }

    .education-block h3,
    .education-block span {
        float: none
    }

    .project-image {
        display: none
    }

    .project-info {
        margin: 0;
        padding: 30px 15px;
        top: auto;
        width: 100%;
    }

    footer {
        text-align: center
    }

    .social {
        text-align: center
    }
}

@media only screen and (max-width: 480px) {
    #lead-content h1 {
        font-size: 1.5em
    }

    #lead-content h2 {
        font-size: 1em
    }

    #lead-content a {
        font-size: 0.9em;
        padding: 5px 10px
    }
    
    
}

這是 html：

 <div id="projects" class="background-alt">
    <h2 class="heading">Projects</h2>
    <div class="container">
        <div class="row">
            <div class="project shadow-large">
                
                <div class="col project-image">
                      <img class="img-responsive projectImg" src="images/dirtworks.PNG" />     
                </div>
                
                
                <div class="col project-info">
                    <h3>Website Development</h3>
                    <p>
                        Please check out a sample of my work at dirtworksbyjohnston.com. For this company, I was responsible for designing a website based on its construction business. Customers are now able to see some of their projects, read their posts, and contact DirtWorks.
                        </p>
                    <a href="https://dirtworksbyjohnston.com">View Project</a>         
                </div>
                
            </div>
            <!-- End .project -->
        </div>
    </div>
</div>

任何幫助，將不勝感激。

Answer 1

使用flexbox

<div class="col project-image d-flex align-items-center justify-content-center">
    <img class="img-responsive projectImg" src="images/dirtworks.PNG" />     
</div>