Do you mean that the Tab bar gets higher (takes more vertical space) ?

The colored buttons are likely the .titlebar-buttonbox-container element.

it does this

tunesrcoolII said

it does this

Is that what the "green button" does? (Similar to maximizing a window on Windows.)

thats what double clicking the tab bar does, its not supposed to do that, its in the code

Did you try to add the code I posted in this reply to userChrome.css ?

• https://support.mozilla.org/en-US/questions/1279191?page=1#answer-1287808

tried it and responded too

i copied like 3 different codes from recent posts, but i just get this mess, why does it work for everyone else but me

the header on top gets taken off with the pages title, the tab bar acts all different if i hit it

Best is to leave it with the code that worked and try not to double-click on the Tab bar as that seems to trigger the default OS pointer event for double-clicking the title bar. Code that is about the title bar (#titlebar) and the caption buttons (.titlebar-buttonbox-container) is most problematic on Mac. I don't know what code for the menubar (#toolbar-menubar) is doing on Mac because the OS handles the menu bar and not Firefox.

You would have to use the Browser Toolbox to check out what code is applied. The code in the last "NEXT FILE" section would be worth to check out.

• https://developer.mozilla.org/en-US/Tools/Browser_Toolbox

:root {
  --colored_menubar_background_image: linear-gradient(#f9f9fa,#f9f9fa);
  --general_toolbar_color_toolbars: linear-gradient(#f9f9fa,#f9f9fa);
  --general_toolbar_color_navbar: linear-gradient(#f9f9fa,#f9f9fa);
  --tabs_toolbar_color_tabs_not_on_top: linear-gradient(#f9f9fa,#f9f9fa);
  --tabs_toolbar_border-tnot_normal_mode_size: 1px;
  --tabs_toolbar_border-tnot_normal_mode: var(--tabs-border-color);
  --classic_squared_tabs_tab_text_color: black;
  --classic_squared_tabs_new_tab_icon_color: black;
  --classic_squared_tabs_tab_text_shadow: transparent;
  --tab-min-height_tnot: 32px;
}

:root[uidensity=compact]  {
  --tab-min-height_tnot: 28px;
}

:root[uidensity=touch] {
  --tab-min-height_tnot: 40px;
}


/* ========================== NEXT FILE ============================= */

#main-window[tabsintitlebar][sizemode="normal"] #toolbar-menubar {
  margin-top: 24px !important;
}
#main-window[tabsintitlebar][sizemode="maximized"] #toolbar-menubar {
  margin-top: 24px !important;
}


/* ========================== NEXT FILE ============================= */

#main-window:not([chromehidden*="toolbar"]) #navigator-toolbox {
  padding-bottom: calc(1px + var(--tab-min-height_tnot)) !important;
}

#TabsToolbar {
  position: absolute !important;
  display:block !important;
  bottom: 0 !important;
  width: 100vw !important;
}

#tabbrowser-tabs {
  width: 100vw !important;
}

/* make sure button icon colors set correctly */
#main-window:not(:-moz-lwtheme) #TabsToolbar-customization-target toolbarbutton .toolbarbutton-icon,
#main-window:not([style*='--lwt-header-image']):-moz-lwtheme:-moz-lwtheme-darktext #TabsToolbar-customization-target toolbarbutton .toolbarbutton-icon {
  fill: var(--classic_squared_tabs_new_tab_icon_color) !important;
  color: var(--classic_squared_tabs_new_tab_icon_color) !important;
}

#main-window[tabsintitlebar]:not([inDOMFullscreen="true"]) #toolbar-menubar .titlebar-buttonbox-container {
  /*display: none !important;*/
  visibility: hidden !important;
}

/* move caption buttons to windows top right position */
#main-window[tabsintitlebar]:not([inDOMFullscreen="true"]) #toolbar-menubar ~ #TabsToolbar .titlebar-buttonbox-container {
  position: fixed !important;
  right: 0 !important;
  visibility: visible !important;
  display: block !important;
}

/* caption button position in maximized mode after moving to the top */
#main-window[tabsintitlebar]:not([inDOMFullscreen="true"]) #toolbar-menubar ~ #TabsToolbar .titlebar-buttonbox-container,
#main-window[tabsintitlebar][sizemode="maximized"]:not([inDOMFullscreen="true"]) #TabsToolbar .titlebar-buttonbox-container {
  top: -14px !important;
}

/* tweaks for fullscreen mode */
#main-window[tabsintitlebar][sizemode="fullscreen"] #toolbar-menubar ~ #TabsToolbar .titlebar-buttonbox-container,
#main-window[tabsintitlebar][sizemode="fullscreen"] #navigator-toolbox #PanelUI-button,
#main-window #TabsToolbar #window-controls {
  display: none !important;
}

/* hide non-required items */
#TabsToolbar .private-browsing-indicator,
#TabsToolbar #window-controls,
#TabsToolbar *[type="caption-buttons"],
#TabsToolbar *[type="pre-tabs"],
#TabsToolbar *[type="post-tabs"] {
  display: none !important;
}

/* adjust tabs toolbar padding */
#main-window:-moz-any([sizemode="normal"],[sizemode="maximized"],[sizemode="fullscreen"]) #navigator-toolbox #toolbar-menubar[autohide="true"][inactive="true"] ~ #TabsToolbar,
#main-window[tabsintitlebar]:-moz-any([sizemode="normal"],[sizemode="maximized"],[sizemode="fullscreen"]) #navigator-toolbox #toolbar-menubar[autohide="true"][inactive="true"] ~ #TabsToolbar,
#main-window:-moz-any([sizemode="normal"],[sizemode="maximized"],[sizemode="fullscreen"]) #navigator-toolbox #TabsToolbar,
#main-window[tabsintitlebar]:-moz-any([sizemode="normal"],[sizemode="maximized"],[sizemode="fullscreen"]) #navigator-toolbox #TabsToolbar {
 -moz-padding-start: 0px !important;
 -moz-margin-start: 0px !important;
}

/* hide line above navigation toolbar appearing in some cases */
#main-window:not([tabsintitlebar]) #nav-bar,
#main-window:not([tabsintitlebar]) #navigator-toolbox {
  border-top: 0 !important;
  box-shadow: unset !important;
}

/* disable Mozillas tab jumping nonsense when moving tabs */
#navigator-toolbox[movingtab] > #titlebar > #TabsToolbar {
  padding-bottom: unset !important;
}
#navigator-toolbox[movingtab] #tabbrowser-tabs {
  padding-bottom: unset !important;
  margin-bottom: unset !important;
}
#navigator-toolbox[movingtab] > #nav-bar {
  margin-top: unset !important;
}

/* size of new tab tabs '+' icon */
:-moz-any(.tabs-newtab-button,#tabs-newtab-button) .toolbarbutton-icon {
  padding: 0px !important;
  margin: 0px !important;
  width: 18px !important;
  height: 18px !important;
}

/* show window caption buttons in fullscreen mode */
#main-window:not([inDOMFullscreen="true"])[sizemode="fullscreen"] #TabsToolbar #window-controls {
  position: absolute !important;
  display: block !important;
  top: 0 !important;
  right: 0 !important;
  margin-top: -32px !important;
  z-index: 1000 !important;
}

#main-window:not([inDOMFullscreen="true"])[sizemode="fullscreen"] #nav-bar {
  -moz-padding-end: 60px !important;
}

#main-window:not([inDOMFullscreen="true"])[sizemode="fullscreen"] #TabsToolbar #window-controls toolbarbutton,
#main-window:not([inDOMFullscreen="true"])[sizemode="fullscreen"] #TabsToolbar #window-controls toolbarbutton .toolbarbutton-icon {
  padding: 0 !important;
  margin: 0 !important;
}


/* ========================== NEXT FILE ============================= */

#main-window[tabsintitlebar]:not([sizemode="fullscreen"]):not([inDOMFullscreen="true"]) #navigator-toolbox {
  margin-top: calc(-1px + var(--tab-min-height_tnot)) !important;
}

#main-window:not([chromehidden*="toolbar"]) #navigator-toolbox {
  padding-bottom: calc(0px + var(--tab-min-height_tnot)) !important;
}

#TabsToolbar {
  height: var(--tab-min-height_tnot) !important;
}

#main-window[tabsintitlebar]:not([sizemode="fullscreen"]):not([inDOMFullscreen="true"]) .titlebar-buttonbox-container,
#main-window[tabsintitlebar]:not([inDOMFullscreen="true"]) #toolbar-menubar ~ #TabsToolbar .titlebar-buttonbox-container  {
  position: fixed !important;
  display:block !important;
  top: 0 !important;
  left: 0 !important;
  right: unset !important;
}

#tabbrowser-tabs .tabbrowser-arrowscrollbox {
  margin-top: -1px !important;
  margin-bottom: 1px !important;
}

/* caption button position in maximized mode after moving to the top */
#main-window[tabsintitlebar]:not([inDOMFullscreen="true"]) #toolbar-menubar[autohide="true"] ~ #TabsToolbar .titlebar-buttonbox-container,
#main-window[tabsintitlebar][sizemode="maximized"]:not([inDOMFullscreen="true"]) #TabsToolbar .titlebar-buttonbox-container {
  top: 0 !important;
}

#PersonalToolbar {
  padding-top: 4px !important;
  padding-bottom: 4px !important;
  height: unset !important;
  max-height: unset !important;
}

#main-window[tabsintitlebar]:not([sizemode="fullscreen"]) #titlebar {
  margin-top: calc(-1 * var(--tab-min-height_tnot)) !important;
  padding-top: var(--tab-min-height_tnot) !important;
}

so i just got a new computer and it turns out theres a setting in preferences that makes the double click do that. there never was one before so sorry guys

i have everything i want to adjust where the colored things are, up and down, center them it throws off the whole integrity of the computer

and there used to be a web page header that said the title of the page

and i do know i used to double click anywhere on the tab bar for a new tab like alot of people but im not installing tab mix plus

theres a firefox setting for the title bar

still need a new tab on double click

edit, and ill be damned that setting just brought back the double click new tab on the tab bar