body.class background image size - css

Question

hi all i am having problems with background images and i wonder can someone help.
i created a template that i am working from now the pages that i create from the template i am giving them class names so i can change the background of them which is working fine, but the problem is when the page re-sizes it goes back to the original background i will paste my css see if anyone can help thanks.
/*!
* Start Bootstrap - Business Casual Bootstrap Theme (http://startbootstrap.com)
* Code licensed under the Apache License v2.0.
* For details, see http://www.apache.org/licenses/LICENSE-2.0.
*/
body {
font-family: "Open Sans","Helvetica Neue",Helvetica,Arial,sans-serif;
-webkit-background-size: cover;
-moz-background-size: cover;
background-size: cover;
-o-background-size: cover;
background-attachment: fixed;
background-repeat: no-repeat;
background-position: center center;
-webkit-background-size: cover;
background-image: url(../img/event%20places%20pictures/3arena.jpg);
color: #000;
}
h1,
h2,
h3,
h4,
h5,
h6 {
text-transform: uppercase;
font-family: "Josefin Slab","Helvetica Neue",Helvetica,Arial,sans-serif;
font-weight: 700;
letter-spacing: 1px;
text-align: left;
}
p {
line-height: 1.6;
color: #000;
}
hr {
max-width: 400px;
border-color: #000000;
}
.brand,
.address-bar {
display: none;
}
.navbar-brand {
text-transform: uppercase;
font-weight: 900;
letter-spacing: 2px;
}
.navbar-nav {
text-transform: uppercase;
font-weight: 500;
letter-spacing: 3px;
}
.img-full {
min-width: 100%;
}
.brand-before,
.brand-name {
text-transform: capitalize;
}
.brand-before {
margin: 15px 0;
}
.brand-name {
margin: 0;
font-size: 4em;
}
.tagline-divider {
margin: 15px auto 3px;
max-width: 250px;
border-color: #999999;
}
.box {
margin-bottom: 20px;
padding: 30px 15px;
background-color: rgba(255,255,255,0.6);
}
.intro-text {
text-transform: uppercase;
font-size: 1.25em;
font-weight: 400;
letter-spacing: 1px;
}
.img-border {
float: none;
margin: 0 auto 0;
border: #999999 solid 1px;
}
.img-left {
float: none;
margin: 0 auto 0;
}
.navbar-footer {
background: rgba(255,255,255,0.8);
}
footer p {
margin: 0;
padding: 50px 0;
}
#media screen and (min-width:768px) {
.brand {
display: inherit;
margin: 0;
padding: 30px 0 10px;
text-align: center;
text-shadow: 1px 1px 2px rgba(0,0,0,0.5);
font-family: "Josefin Slab","Helvetica Neue",Helvetica,Arial,sans-serif;
font-size: 5em;
font-weight: 700;
line-height: normal;
color: #fff;
background-color:rgba(51,51,51,0.7);
text-shadow: 2px 2px #000;
}
.top-divider {
margin-top: 0;
}
.img-left {
float: left;
margin-right: 25px;
}
.address-bar {
display: inherit;
margin: 0;
padding: 0 0 40px;
text-align: center;
text-shadow: 1px 1px 2px rgba(0,0,0,0.5);
text-transform: uppercase;
font-size: 1.25em;
font-weight: 400;
letter-spacing: 3px;
color: #fff;
background-color: rgba(51,51,51,0.7);
text-shadow: 2px 2px #000;
}
.social{
background-color: rgba(51,51,51,0.7);
display: inherit;
margin: 0;
padding-bottom:20px
}
.social li{
display:inline;
}
.fb-share-button{
position:relative
top:-7px;
}
.fb-like > span {
vertical-align: baseline !important;
}
.navbar {
border-radius: 0;
}
.navbar-header {
display: none;
}
.navbar {
min-height: 0;
}
.navbar-default {
border: none;
background:rgba(255,255,255,0.8);
}
.nav>li>a {
padding: 25px;
}
.navbar-nav>li>a {
line-height: normal;
}
.navbar-nav {
display: table;
float: none;
margin: 0 auto;
table-layout: fixed;
font-size: 1.15em;
}
}
#media screen and (min-width:1200px) {
.box:after {
content: '';
display: table;
clear: both;
}
/* start of css for each of the venue pages*/
body.gallery{
background-image:url(../img/event%20places%20pictures/3arena.jpg)
}
body.academy{
background-image:url(../img/event%20places%20pictures/the%20academy.jpg)
}
body.vicar{
background-image:url(../img/event%20places%20pictures/vicar%20st.jpg)
}
body.Ambassador{
background-image:url(../img/event%20places%20pictures/Ambassador.jpg)
}
body.aviva{
background-image:url(../img/event%20places%20pictures/aviva.jpg)
}
body.arena{
background-image:url(../img/event%20places%20pictures/02-Arena.jpg))
}
body.croke{
background-image:url(../img/event%20places%20pictures/croke%20park.jpg)
}
body.gaiety{
background-image:url(../img/event%20places%20pictures/gaiety-theater.jpg)
}
body.gate{
background-image:url(../img/event%20places%20pictures/gate%20theatre.jpg)
}
body.grand{
background-image:url(../img/event%20places%20pictures/grand%20social.jpg)
}
body.laughter{
background-image:url(../img/event%20places%20pictures/laughter%20lounge.jpg)
}
body.marlay{
background-image:url(../img/event%20places%20pictures/marlay%20park.jpg)
}
body.olympia{
background-image:url(../img/event%20places%20pictures/the-olympia-photo.jpg)
}
body.rds{
background-image:url(../img/event%20places%20pictures/rds.jpg)
}
body.button{
background-image:url(../img/event%20places%20pictures/The_Button_Factory.jpg)
}
body.whelans{background-image:url(../img/event%20places%20pictures/whelans.jpg)
}
body.signup{background-image:url(../img/bianca%20photos/IMG-20150717-WA0024.jpg)
}
body.events{
background-image:url(../img/bianca%20photos/10402046_118490843153454`enter code here`3_1165711705389334252_n.jpg)
}
.events-box{
background-color: rgba(255,255,255,0.9);
}

Answer 1

You've placed those background images within a media query targeting min-width:1200px, so at any width under 1200px that won't apply and you'll just see the default body background image.
So just remove those background rules from the media query.

Answer 2

You forgot to close media query bracket }.