Changing banner width affects entire board

[CollieflowersBark]

werifesteria.freeforums.net/

Hopefully I can get a little help with this issue because it's got me stumped. I added a banner to my CSS style sheet. When I resize it and attempt to make it smaller, the entire site is affected. All of my boards are cut off along with the banner. I would like to only adjust the banner elements.

.p-banner {
width: 3000px;
padding-top: 0px;
background: url(https://i.imgur.com/EFsIf5N.jpg);
background-position: top;
background-attachment: static;
border-bottom: 5px solid border -color;
text-align: left;
overflow: hidden;
background-repeat: no-repeat;

}
.p-banner2 {
margin-top: 0px;
height: 740px;
background: url(https://i.imgur.com/FBftnAG.png);
background-position: bottom 30px;
background-repeat: no-repeat;
background-attachment: fixed;
border-bottom: 5px solid border -color;
text-align: center;
padding-right: 450px;
overflow: visible;
}