求助，关于 Autohide Bookmarks Toolbar v2 (Customizeable)

@namespace url(http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul);


#PersonalToolbar {
  -moz-transform: perspective(1000px) rotateX(-90deg);
  -moz-transform-origin: top !important;
  -moz-transition-timing-function: ease-in;
  -moz-transition-duration: 0.35s, 0.3s;
  -moz-transition-property: margin, -moz-transform;
  -moz-transition-delay: 1s}

#navigator-toolbox:hover > #PersonalToolbar {
  -moz-transform: rotateX(0deg);
  -moz-transition-duration: 0.35s, 0.3s;
  -moz-transition-delay: 0.5s}

#PersonalToolbar {
  visibility: visible !important;
  position: fixed !important;
  margin-top: 90px !important;
  box-shadow: 0 6px 4px -4px #000 !important}

#main-window[stylish-url="about:addons"] #PersonalToolbar, #main-window[stylish-url="about:permissions"] #PersonalToolbar, #main-window[stylish-url="about:preferences"] #PersonalToolbar, #main-window[stylish-url="about:sync-progress"] #PersonalToolbar, #main-window[stylish-url="about:downloads"] #PersonalToolbar {
  position: static !important;
  margin-top: 0px !important;
  box-shadow: none !important;
  -moz-transform: none !important;
  -moz-transition-duration: 0s !important;
  -moz-transition-delay: 0s !important}

请问修改哪里可以让弹出的书签居中，而不是现在的左上角。

还有个疑问，不知道为什么我的标签栏偶尔会变动高度，一会胖一会瘦的，可以在里面加个什么句子固定下标签栏的高度吗？