Custom CSS Styles

Simply copy and paste this code in the Custom Styles section of the Neater Bookmarks Options page.

Simpler theme (by xendke):

input {
  outline: none;
}
img[src="folder.png"] {
  display: none;
}
#tree {
  padding: 5px 5px;
}
::-webkit-scrollbar {
  width: 6px;
}
::-webkit-scrollbar-track {
  background:transparent;
}
::-webkit-scrollbar-thumb {
  -webkit-border-radius: 10px;
  border-radius: 10px;
  background: #ccc;
  background: rgba(0,0,0,0.2); 
  -webkit-box-shadow: inset 0 0 6px rgba(0,0,0,0); 
}
::-webkit-scrollbar-thumb:window-inactive {
  background: rgba(255,0,0,0); 
}
@-webkit-keyframes blueFade {
  0% {
    background-color: transparent;
  }
  10%{
    background-color: #DCDCDC;
  }
  100% {
    background-color: transparent;
  }
}
#results ul li a:active,
#results ul li a.active,
#results ul li a:focus,
#tree ul li a:active,
#tree ul li span:active,
#tree ul li a.active,
#tree ul li span.active,
#tree ul li a:focus,
#tree ul li span:focus,
menu[type=context] command:focus{
  color: #fff;
  background-color: #585858;
  background-image: none;
  -webkit-box-shadow: 0 -1px #5594d2;	
  text-shadow: 0 0 rgba(255,255,255,.5), 0 1px rgba(0,0,0,.5);
  outline: 0;
}

Custom Google-style scrollbars in popup (by evanshultz):

::-webkit-scrollbar {
  width: 9px;
  background: #eee;
}
::-webkit-scrollbar-thumb {
  background-color: rgba(0,0,0,0.2);
  border-top: 1px solid rgba(0,0,0,0.1);
  border-bottom: 1px solid rgba(0,0,0,0.07);
  border-left: 1px solid rgba(0,0,0,0.1);
}

Larger font size (by cheeaun):

body, #search input, #edit-dialog input {font-size: 14px;}
.dialog-text {font-size: 15px;}

Dark theme (by skoshy):

body {
  background: #333;
}
#search input {
  background: #555;
  border: 0;
  padding: 5px;
  color: #eee;
}
#search input::placeholder {
  color: #aaa;
}
#results ul li a, #tree ul li a, #tree ul li span {
  text-shadow: none;
  color: white;
}
#tree ul a img:not([src="folder.png"]) {
  background: #999;
  border: 1px solid #aaa;
  border-radius: 4px;
  transition: background ease-in-out 100ms;
}
#tree ul a:hover > img:not([src="folder.png"]),
#tree ul a:focus > img:not([src="folder.png"])
{
  background: #fff;
}