css: Use SCSS nesting in app_components.scss for `.tab-switcher`.
css: Use SCSS nesting in app_components.scss for `.tab-switcher`.

kou/zulip,eeshangarg/zulip,rht/zulip,tommyip/zulip,andersk/zulip,brainwane/zulip,shubhamdhama/zulip,shubhamdhama/zulip,timabbott/zulip,synicalsyntax/zulip,hackerkid/zulip,hackerkid/zulip,hackerkid/zulip,eeshangarg/zulip,showell/zulip,kou/zulip,showell/zulip,zulip/zulip,rht/zulip,kou/zulip,kou/zulip,shubhamdhama/zulip,hackerkid/zulip,timabbott/zulip,synicalsyntax/zulip,kou/zulip,punchagan/zulip,synicalsyntax/zulip,kou/zulip,shubhamdhama/zulip,showell/zulip,rishig/zulip,timabbott/zulip,brainwane/zulip,brainwane/zulip,rht/zulip,tommyip/zulip,kou/zulip,punchagan/zulip,brainwane/zulip,andersk/zulip,zulip/zulip,zulip/zulip,brainwane/zulip,eeshangarg/zulip,eeshangarg/zulip,showell/zulip,andersk/zulip,eeshangarg/zulip,brainwane/zulip,showell/zulip,punchagan/zulip,rht/zulip,hackerkid/zulip,zulip/zulip,zulip/zulip,eeshangarg/zulip,rht/zulip,timabbott/zulip,synicalsyntax/zulip,tommyip/zulip,shubhamdhama/zulip,punchagan/zulip,rishig/zulip,rishig/zulip,zulip/zulip,punchagan/zulip,zulip/zulip,shubhamdhama/zulip,showell/zulip,tommyip/zulip,synicalsyntax/zulip,rishig/zulip,timabbott/zulip,andersk/zulip,synicalsyntax/zulip,timabbott/zulip,hackerkid/zulip,rishig/zulip,brainwane/zulip,shubhamdhama/zulip,andersk/zulip,rht/zulip,tommyip/zulip,punchagan/zulip,punchagan/zulip,hackerkid/zulip,eeshangarg/zulip,rishig/zulip,synicalsyntax/zulip,andersk/zulip,tommyip/zulip,rishig/zulip,timabbott/zulip,andersk/zulip,tommyip/zulip,showell/zulip,rht/zulip