/*
<Group description="PopularPosts Backgrounds" selector="#PopularPosts1">
<Variable name="PopularPosts.background.color1" description="background color1" type="color" default="#fa4242" value="#fa4242"/>
<Variable name="PopularPosts.background.color2" description="background color2" type="color" default="#ee6107" value="#ee6107"/>
<Variable name="PopularPosts.background.color3" description="background color3" type="color" default="#f0f" value="#f0f"/>
<Variable name="PopularPosts.background.color4" description="background color4" type="color" default="#ff0" value="#ff0"/>
<Variable name="PopularPosts.background.color5" description="background color5" type="color" default="#0ff" value="#0ff"/>
</Group>
*/

#PopularPosts1 ul{margin:0;padding:5px 0;list-style-type:none}
#PopularPosts1 ul li{position:relative;margin:5px 0;border:0;padding:10px}
#PopularPosts1 ul li:first-child{background:$(PopularPosts.background.color1);width:90%}
#PopularPosts1 ul li:first-child:after{content:"1"}
#PopularPosts1 ul li:first-child + li{background:$(PopularPosts.background.color2);width:85%}
#PopularPosts1 ul li:first-child + li:after{content:"2"}
#PopularPosts1 ul li:first-child + li + li{background:$(PopularPosts.background.color3);width:80%}
#PopularPosts1 ul li:first-child + li + li:after{content:"3"}
#PopularPosts1 ul li:first-child + li + li + li{background:$(PopularPosts.background.color4);width:75%}
#PopularPosts1 ul li:first-child + li + li + li:after{content:"4"}
#PopularPosts1 ul li:first-child + li + li + li + li{background:$(PopularPosts.background.color5);width:70%}
#PopularPosts1 ul li:first-child + li + li + li + li:after{content:"5"}
#PopularPosts1 ul li:first-child:after,#PopularPosts1 ul li:first-child + li:after,#PopularPosts1 ul li:first-child + li + li:after,#PopularPosts1 ul li:first-child + li + li + li:after,#PopularPosts1 ul li:first-child + li + li + li + li:after{position:absolute;top:20px;right:-15px;border-radius:50%;background:#0a960a;width:30px;height:30px;line-height:1em;text-align:center;font-size:28px;color:#fff}
#PopularPosts1 ul li .item-thumbnail{float:left;border:0;margin-right:10px;background:transparent;padding:0;width:40px;height:40px}
#PopularPosts1 ul li a{font-size:12px;color:#444;text-decoration:none}
#PopularPosts1 ul li a:hover{color:#222;text-decoration:none}

<b:widget id='PopularPosts1' locked='false' title='Popular Posts' type='PopularPosts'>
  <b:includable id='main'>
   <b:if cond='data:title'>
    <h2><data:title/></h2>
   </b:if>
   <div class='widget-content popular-posts'>
    <ul>
     <b:loop values='data:posts' var='post'>
      <li>
       <b:if cond='data:showThumbnails == &quot;false&quot;'>
        <b:if cond='data:showSnippets == &quot;false&quot;'>
         <a expr:href='data:post.href' rel='bookmark' expr:title='data:post.title'><data:post.title/></a>
        <b:else/>
         <a expr:href='data:post.href' rel='bookmark' expr:title='data:post.snippet'><data:post.title/></a>
        </b:if>
       <b:else/>
        <b:if cond='data:showSnippets == &quot;false&quot;'>
         <b:if cond='data:post.thumbnail'>
          <img expr:alt='data:post.title' class='item-thumbnail' expr:src='data:post.thumbnail'/>
         <b:else/>
          <img alt='no image' class='item-thumbnail' src='https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgZnJqKHlviZxij8txD3yGtp8mLJyhYJanvTXhus_b7zIn14a0aULBDzPNF8QLJ-5rVBnvZaj6Ym258ilznNqN7vO24Ip4EFGUyVwzI70XJKNDme3seEK1c7RvAh1XwWoRJNWSbKc-XOsYJ/'/>
         </b:if>
         <a expr:href='data:post.href' rel='bookmark' expr:title='data:post.title'><data:post.title/></a>
         <div class='clear'/>
        <b:else/>
         <b:if cond='data:post.thumbnail'>
          <img expr:alt='data:post.title' class='item-thumbnail' expr:src='data:post.thumbnail'/>
         <b:else/>
          <img alt='no image' class='item-thumbnail' src='https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgZnJqKHlviZxij8txD3yGtp8mLJyhYJanvTXhus_b7zIn14a0aULBDzPNF8QLJ-5rVBnvZaj6Ym258ilznNqN7vO24Ip4EFGUyVwzI70XJKNDme3seEK1c7RvAh1XwWoRJNWSbKc-XOsYJ/'/>
         </b:if>
         <a expr:href='data:post.href' rel='bookmark' expr:title='data:post.snippet'><data:post.title/></a>
         <div class='clear'/>
        </b:if>
       </b:if>
      </li>
     </b:loop>
    </ul>
   </div>
  </b:includable>
 </b:widget>

Để dễ dàng cho mọi người thay đổi màu nền mình đã sử dụng Trình thiết kế Mẫu của Blogger. Bạn vào Thiết kế → Trình thiết kế Mẫu → Nâng cao → PopularPosts Backgrounds và thay đổi lần lượt background color1, background color2, background color3, background color4, background color5 theo ý muốn.

DEMO

<div style="background:#ddd url(https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjx7_X6hpb-XEJEbTD1cl_ZP8BIISRx-wUyqcIXHiC3iOPzvEYVHHGBxEoRLwZ1B-M8dUIzZvGyd1wppmHSBSeriU21Ngjvsq6zvKQlBTB-R8eJTrp_kBdah0OT4iiCU-88tQnceLhpLe2v/) no-repeat left; border-top:#999 1px solid; border-bottom:#999 1px solid; padding-left:19px;padding-right:2px;width:100%;">
<marquee onmouseout="this.start()" direction="left" behavior="50" scrollamount="5" height="60" onmouseover="this.stop()" scrolldelay="50" width="511">
<a href="URL liên kết 1" target="blank" ><img style="width: 220px; height: 60px;" src="Link logo 1"/> </a>
<a href="URL liên kết 2" target="blank" ><img style="width: 220px; height: 60px;" src="Link logo 2"/> </a>
<a href="URL liên kết 3" target="blank" ><img style="width: 220px; height: 60px;" src="Link logo 3"/> </a>
<a href="URL liên kết 4" target="blank" ><img style="width: 220px; height: 60px;" src="Link logo 4"/> </a>
<a href="UR Lliên kế 5" target="blank" ><img style="width: 220px; height: 60px;" src="Link logo 5"/> </a>
</marquee></div>

<a href="UR Lliên kế 6" target="blank" ><img style="width: 220px; height: 60px;" src="Link logo 6"/> </a>

<a expr:dir='data:blog.languageDirection' expr:href='data:label.url'><data:label.name/></a>
</b:if>
<b:if cond='data:showFreqNumbers'>
<span dir='ltr'>(<data:label.count/>)</span>
</b:if>

<b:if cond='data:showFreqNumbers'>
<a expr:dir='data:blog.languageDirection' expr:href='data:label.url' expr:title='data:label.count + &quot; Bài đăng trong nhãn &quot; + data:label.name'><data:label.name/></a>
<b:else/>
<a expr:dir='data:blog.languageDirection' expr:href='data:label.url'><data:label.name/></a>
</b:if>
</b:if>

<a expr:dir='data:blog.languageDirection' expr:href='data:label.url'><data:label.name/></a>
</b:if>
<b:if cond='data:showFreqNumbers'>
<span class='label-count' dir='ltr'>(<data:label.count/>)</span>
</b:if>

<b:if cond='data:showFreqNumbers'>
<a expr:dir='data:blog.languageDirection' expr:href='data:label.url' expr:title='data:label.count + &quot; Bài đăng trong nhãn &quot; + data:label.name'><data:label.name/></a>
<b:else/>
<a expr:dir='data:blog.languageDirection' expr:href='data:label.url'><data:label.name/></a>
</b:if>
</b:if>

.sidebar .list-label-widget-content li{display:inline;font-size:10px;text-transform:uppercase;white-space:nowrap;line-height:2.5em}
.sidebar .list-label-widget-content li a{-moz-border-radius:4px;-o-border-radius:4px;-webkit-border-radius:4px;border-radius:4px;border:1px solid #BBB;padding:3px 6px;opacity:0.7}
.sidebar .list-label-widget-content li a:hover{border:1px solid #F26535}

.list-label-widget-content li{display:inline;font-size:10px;text-transform:uppercase;white-space:nowrap;line-height:2.5em}
.list-label-widget-content li a{-moz-border-radius:4px;-o-border-radius:4px;-webkit-border-radius:4px;border-radius:4px;border:1px solid #BBB;padding:3px 6px;opacity:0.7}
.list-label-widget-content li a:hover{border:1px solid #F26535}

Theo: vngreenzone.com 

<script type='text/javascript'>
window.onload = detectarCarga;
function detectarCarga() {
document.getElementById("loading").style.display="none";
}
</script>

<style>
#circleG{
width:149.33333333333334px;
}
.circleG{
background-color:#48c7a9;
float:left;
height:32px;
margin-left:17px;
width:32px;
-webkit-animation-name:bounce_circleG;
-webkit-border-radius:21px;
-webkit-animation-duration:1.35s;
-webkit-animation-iteration-count:infinite;
-webkit-animation-direction:linear;
-moz-animation-name:bounce_circleG;
-moz-border-radius:21px;
-moz-animation-duration:1.35s;
-moz-animation-iteration-count:infinite;
-moz-animation-direction:linear;
opacity:0.3}
#circleG_1{
-webkit-animation-delay:0.27s;
-moz-animation-delay:0.27s}
#circleG_2{
-webkit-animation-delay:0.63s;
-moz-animation-delay:0.63s}
#circleG_3{
-webkit-animation-delay:0.8099999999999999s;
-moz-animation-delay:0.8099999999999999s}
@-webkit-keyframes bounce_circleG{
0%{
opacity:0.3}
50%{
opacity:1;
background-color:#19409a}
100%{
opacity:0.3}
}
@-moz-keyframes bounce_circleG{
0%{
opacity:0.3}
50%{
opacity:1;
background-color:#19409a}
100%{
opacity:0.3}
}
</style>
<div border="0" style="position:fixed; width: 100%; height: 70px; z-index: 1; top: 300px; left: 0;" id="loading" align="center"> <table border="0" width="150" cellspacing="0" cellpadding="0" style="border-collapse: collapse" bordercolor="#003300"> <tr> <td align="center"> <div border="0" style="background-color: #000; color: #fff;filter: alpha(opacity=70); opacity: .7; width: 190px; height: 70px; z-index: 1; border-collapse: collapse;-moz-border-radius: 5px;
-webkit-border-radius: 5px;" bordercolor="#006600" align="center"> <b>Đang tải dữ liệu...</b><br /><div id="circleG">
<div id="circleG_1" class="circleG">
</div>
<div id="circleG_2" class="circleG">
</div>
<div id="circleG_3" class="circleG">
</div>
</div> Nhấn F5 nếu đợi quá lâu</div> </td> </tr> </table> </div>