Fix Send button UI and improve TextArea UI

[joshenx]

• No more grey rectangle behind resultDisplay
• No more White Button

Closes #122

[codecov-commenter]

Codecov Report

Merging #130 (9581671) into master (8650a76) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master     #130   +/-   ##
=========================================
  Coverage     62.93%   62.93%           
  Complexity      538      538           
=========================================
  Files            94       94           
  Lines          1921     1921           
  Branches        216      216           
=========================================
  Hits           1209     1209           
  Misses          631      631           
  Partials         81       81           

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[didymental]

LGTM