Can’t expand sidebar width for Amazon Banner

I’m not able to customize the sidebar width to include an Amazon advertisement (IFrame or JavaScript) being served by them without the ad image (300×250) being cut off on the right. Every change thus far I’ve made to style.css makes other adjustments, but not the one I need.

I don’t mind increasing the width of the whole document body if I will be able to accomplish getting all to look good.

I’m including the style.css. Thank you.

/*
Theme Name: Dovetail
Version:2.0.1
Author:James R Whitehead and David Coveney at spectacu.la
Author URI:https://spectacu.la/
Tags: brown, red, white, two-columns, fixed-width, threaded-comments

Release: 2.0.1 Edited readme file, added quick and dirty print stylesheet for nicer printing of content.
Release: 2.0 Added new features, more modern visuals and GPL license. Based on Grassland 2 now, rather than Grassland 1
*/

@import “typography.css”;
* {
margin:0;
padding:0;
outline:0 none;
}

fieldset, form {
border: 0 none;
}

.clear{ /* 1px prop for opening floated boxs and other fun things. */
clear:both;
height:1px;
width:1px;
overflow:hidden;
visibility:hidden
}

.alignright {
float:right;
margin:0.2em 0 0.2em 0.75em;
clear:right
}

.alignleft {
float:left;
margin:0.2em 0.75em 0.2em 0;
clear:left
}

.aligncenter {
display: block;
margin: 1em auto;
clear:both;
text-align: center;
}

/* Basic layout */
html {
margin:0;
padding:0;
background:url(images/background.jpg) repeat-x left top #604830;
height: 100%;
min-width: 950px;
}
body{
color:#6f6060;
margin:0;padding:0;
}
/* #layer1 {
background:url(images/background.png) repeat-x center 105px transparent;
} This repeats along the bottom of the header area, if you need it */

#container{
width:950px;
margin:0 auto;
min-height:100%;
position: relative;
}

#header{
height:166px;
width:950px;
position: relative;
top: 0;
z-index:0;
background:url(images/header.png) no-repeat top center transparent;

}

#documentBody {
position: relative;
padding: 42px 20px 20px;
margin-bottom: 20px;
width: 910px;
background: url(images/content.gif) no-repeat top center transparent
}
#navigationBar {
position:absolute;
top:10px;
right:20px;
width:415px;
height:20px;
}

#content{
width:600px;
display:inline;
float:left;
}

#sidebar{
width:290px;
margin-left: 620px;
z-index: 10;
}

#footer {
clear:both;
text-align:center;
}
#footer * {
color:#3e331c;
}

/* Header */
#titles{
margin:0;
position: absolute;
top: 50px;
left: 10px;
}
.login a:hover,
h1#siteTitle a:hover {
color:#fe6
}

.login{
position:absolute;
right: 0;
z-index: 10;
}

.login,
.login a{
color:#666666;
font-size:8pt;
background-color:transparent;
}

/* Navigation Bar */

#headerPages {
width:500px;
}

#headerPages li {
list-style-type: none;
display:inline;
margin-right: 10px;
}

#headerRSS {
position:absolute;
width: 70px;
height: 70px;
left:-9px;
top:-45px;
}

#headerSearcher {
position: absolute;
right: 0;
top: 0;
height: 20px;
width:290px;
background: url(images/searchtext.gif) no-repeat left top transparent;
}

#headerSearcher .searchInput {
border:0 none;
padding: 2px 10px;
overflow:hidden;
background-color:transparent;
width: 250px;
height: 16px;
}

#headerSearcher .searchSubmit {
line-height:20px;
height: 16px;
border: 0 none;
background-color: transparent;
background: url(images/search.gif) no-repeat left top transparent;
position: absolute;
right: 0;
top:0;
width: 20px;
height: 20px;
}
.searchInput {
color:#999
}
.searchForm {position:relative}

.errorMessage {
position: absolute;
color: #900;
background-color: #fff;
padding: 5px 20px;
border:solid 1px #990000;
top: -10px;
left:-10px;
font-weight: bold;
-moz-border-radius: 5px;
-webkit-border-radius: 5px;
}
.searchInput.focused {
color: #000;
}

/* Posts */
.postFrame{
margin-bottom:24px;
width:600px;
position:relative;
overflow:hidden;
}

.postFrameTop,
.postFrameBottom{
width:600px;
height:16px;
background:url(images/post.png) no-repeat -1200px 0px transparent;
display:block;
}

.postFrameTop{
background-position: -600px 0px;
}

.postContent{
background:url(images/post.png) repeat-y 0 0 white;
padding:0 12px 0px 12px;
width:576px;
}
.commentmetadata *,
.commentmetadata,
.postMeta,
.postMeta *{
font-size:8pt;
color: #999;
}

.postBody {
padding-top: 0.5em;
clear:both;
}

.postFooter {
margin-top: 1em;
padding: 0.5em 0.65em 0.5em;
background-color: #ccc5bd;
/* background:url(images/post-footer.jpg) no-repeat center bottom white; */
}
.postFooter .postCategories {
width: 280px;
list-style-type:none;
margin-bottom:0;
float: left;
}

.postFooter .postTags {
margin-left: 290px;
}
.postFooter strong{
display: block;
}

/* Post body stuff. */

.editMeLink {
position:relative;
left:4em
}

/* Foot of post/page section */
#pageNavigation {
margin-bottom: 1em;
font-size: 18px;
line-height:1.5em;

}
#pageNavigation a {
color: #fe3;
text-decoration:none;
}
#pageNavigation a:hover {
color: #fec;
text-decoration:underline;
}

#previousPosts {
width: 40%;
float:left
}
#nextPosts {
margin-left:300px;
width:300px;
text-align:right;
}

/* Widgets */
.widget{
width:290px;
margin-bottom:12px
}

.widgetCentre,
.widgetTop,
.widgetBottom{
width:290px;
height:16px;
background:url(images/widget.png) no-repeat -580px 0 transparent;
display:block;
color:black;
}

.widgetTop {
background-position:-290px 0;
}

.widgetCentre{
overflow:hidden;
background-position:0 0;
background-repeat:repeat-y;
width:270px;
height:auto;
padding:0 10px;
}

.widget ul li {
list-style-type: none;
}

.widget ul {
margin-left: 16px;
list-style-type: none;
}

.expandToggle {
cursor:pointer;
display:inline-block;
position:relative;
left:-16px;
margin-right: -10px;
height: 9px;
width: 9px;
background: url(images/plusminus.gif) no-repeat 0 0 transparent;
overflow:hidden;
}
.expandToggle.active {
background-position: 0 -9px;
}

/* Some of the default widgets need a little bit of attention */
table#wp-calendar{
margin:0 auto 10px auto
}

table#wp-calendar th{
width: 25px
}

table#wp-calendar tr{
height: 25px;
line-height:2em;
text-align:center
}

table#wp-calendar td{
border:solid 1px #f3f3f3;
color: silver;
background-color:white;
padding:0;
margin:0
}

table#wp-calendar td a{
background-color: #f3f3f3;
color:#6F6060;
display: block;
line-height: 2.1em;
width:100%;
height:2.1em
}

table#wp-calendar td a:hover{
color:black;
background-color: silver
}

table#wp-calendar td.pad{
border:0
}

table#wp-calendar caption{
font-size:18pt;
margin:0 auto 10px auto
}

div.widget_calendar h3{
display:none
}

/* Comments */
#commentsBlock {margin-top: 16px;}
#commentlist li {list-style-type: none;}
#commentlist li.depth-1{width: 580px;}
#commentlist li.depth-1 li {margin-left: 20px; }

#commentlist ul ul {
}
#commentlist li > div {
padding: 5px;
border: solid 1px;
margin-bottom: 1em;
}

#commentlist li.even > div { background-color: #ffffff;}
#commentlist li.odd > div { background-color: #efefef;}
#commentsBlock li.bypostauthor > div:first-child .avatar {border:solid 2px #aa0;padding:1px;background-color:#fff;}

#commentlist .toggle {
cursor:pointer;
border:solid 1px;
background-color: #eeeeff;
padding: 5px;
line-height: 16px;
margin-bottom: 1em;
}
#commentlist .toggle span.posterName {
font-weight:bold;
font-style:oblique;
}

#commentlist .depth-1 div,
#commentlist .depth-2 div {border-color:#ddd}
#commentlist .depth-3 div {border-color:#aa0}
#commentlist .depth-4 div {border-color:#0a0}
#commentlist .depth-5 div {border-color:#00a}
#commentlist .depth-6 div {border-color:#aa0}
#commentlist .depth-7 div {border-color:#0a0}
#commentlist .depth-8 div {border-color:#00a}
#commentlist .depth-9 div {border-color:#aa0}
#commentlist .depth-10 div {border-color:#0a0}

#commentlist .depth-2 .toggle {background-color:#ffd;border-color:#aa0}
#commentlist .depth-3 .toggle {background-color:#dfd;border-color:#0a0}
#commentlist .depth-4 .toggle {background-color:#ddf;border-color:#00a}
#commentlist .depth-5 .toggle {background-color:#ffd;border-color:#aa0}
#commentlist .depth-6 .toggle {background-color:#dfd;border-color:#0a0}
#commentlist .depth-7 .toggle {background-color:#ddf;border-color:#00a}
#commentlist .depth-8 .toggle {background-color:#ffd;border-color:#aa0}
#commentlist .depth-9 .toggle {background-color:#dfd;border-color:#0a0}
#commentlist .depth-10 .toggle {background-color:#ddf;border-color:#00a}

#trackbackList { margin-left: 2em;}
#trackbackList .says {display:none}
#trackbackList li { margin-bottom: 1em;}

.vcard { font-size: 16px; }
.avatar {
float: left;
margin-right: 5px;
}
.comment div.commentmetadata {
margin-bottom: 5px;
}
.comment div.reply {
width:100%; /*IE7 FIX*/
}

.comment div.reply a {
text-align:right;
padding-right: 21px;
overflow:hidden;
background-color:#666;
display:block;
height: 16px;
margin-top: 5px;
background: url(images/reply.gif) no-repeat 100% 0 transparent;
}
.comment div.reply a:hover {
background-position: 100% -16px;
}

.toggle span.upArrow {
width: 16px;
height: 16px;
margin-left: 10px;
display: inline-block;
overflow: hidden;
background: url(images/uparrow.gif) no-repeat 0 0 transparent;
}
.toggle:hover span.upArrow { /* This’ll fail in IE6. */
background-position: 0 -16px;
}

#commentForm { margin-top: 20px}
#commentForm label {font-weight:bold;display:inline}
#author, #email, #url, #comment {
border: solid 1px #ddd;
margin-bottom: 10px;
vertical-align: text-top;
width: 50%;
}
#author, #email, #url{
margin-right:10px;
}

#comment {width: 572px; background: 98% 95% #fff; max-width: 572px;}
.commentSubmit {text-align: right;}
.commentSubmit a {color: #900;margin-right:2em;}
.commentSubmit a:hover {color: #f00;}

.wp-caption {
padding: 5px 0;
text-align:center;
border: solid 1px #eee;
-moz-border-radius: 5px;
-webkit-border-radius: 5px;
}

.wp-caption img {
margin: 0;
}

p.wp-caption-text{
font-size: 10px;
margin: 0;
padding: 0.25em 0 0 0;
}

div.postDate{
width: 50px;
height:60px;
position: relative;
top:-4px;
float:right;
background:url(images/calendar.gif) no-repeat center center white
}
span.postMonth{
display:block;
width:50px;
text-align:center;
position:absolute;
top: 1px;
color:white;
font-weight: bold;
background-color:transparent;
left: -1px;
}
span.postDay{
line-height:60px;
font-size:22pt;
display:block;
width:48px;
height:60px;
position:absolute;
letter-spacing:-2px;
text-align:center;
font-weight: 900;
z-index:10;
top:3px;
color: #000;
left: -1px;
}
span.postYear{
display:block;
width:50px;
text-align:center;
position:absolute;
bottom:0;
font-weight: 900;
bottom: 2px;
font-size: 7.5pt;
color: #000;
left: 0px;
}

input.submit {
border: 0 none;
color: #fff;
font-weight: bold;
padding: 1px 10px;
background: url(images/submit.gif) repeat-x left top #000;
}

/* Pagination */

.pageLinks {
text-align:right
}

#commentPagination, .pageNavigationLinks {
clear:both;
text-align: center;
padding: 1em 0 2em;
}
.page-numbers {
line-height: 26px;
height: 26px;
min-width: 20px;
padding: 0 3px;
margin-right: 2px;
display: inline-block;
text-align:center;
text-decoration:none;
-moz-border-radius: 2px;
-webkit-border-radius: 2px;

background-color: #fff;
color:#000;
}

a.page-numbers:focus,
a.page-numbers:hover {
background-color: #ccc;
color: #333;
}

span.dots,
a.prev, a.next {
background-color:transparent;
color: #fff;
}

a.prev, a.next {
font-size: 200%;
vertical-align:top;
}

a.prev:focus,
a.next:focus,
a.prev:hover,
a.next:hover {
color:#ccc;
background-color:transparent;
}

.current {
background-color:#ccc;
color:#999;
}

/*////////////////////*/

.pageLinks .page-numbers,
#commentPagination span.current {
background-color:#eee;
color:#ccc;
}

.pageLinks a {text-decoration:none}

.pageLinks a .page-numbers,
#commentPagination .page-numbers {
color:#5E882F;
background-color: #ddd;
}
#commentPagination span.dots,#commentPagination a.prev,#commentPagination a.next {
background-color:transparent;
color: #333;
}
.pageLinks a:hover .page-numbers,
#commentPagination a.page-numbers:focus,
#commentPagination a.page-numbers:hover {
background-color: #5E882F;
color: #fff;
}

#commentPagination a.prev:focus,
#commentPagination a.next:focus,
#commentPagination a.prev:hover,
#commentPagination a.next:hover {
background-color:transparent;
color:#5E882F;
}

.rssscroller {height:200px}