Remove the toolbox absolute position to properly display "Table of Content".
Adjust the padding of drop-down item to avoid overflow.
Adjust the CSS selector of drop-down item to support the TOC extension.
Adjust the padding of navigator.
消除工具栏绝对定位，调整下拉条上下边距、以及CSS选择器，调整导航栏上下边距。
Remove the toolbox absolute position to properly display "Table of Content". Adjust the padding of drop-down item to avoid overflow. Adjust the CSS selector of drop-down item to support the TOC extension. Adjust the padding of navigator. 消除工具栏绝对定位，调整下拉条上下边距、以及CSS选择器，调整导航栏上下边距。