Fix styles in Docs Tabs hideBorder demo

[jxzho]

• Tabs Hide Border Docs Link

• The rounded corner on the left is hidden due to leftSpace being 0.
• The Effect after the fix:
  

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.85%. Comparing base (9e5ceed) to head (5ecdbe6).
Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #862   +/-   ##
=======================================
  Coverage   98.85%   98.85%           
=======================================
  Files         198      198           
  Lines        3046     3046           
  Branches      668      668           
=======================================
  Hits         3011     3011           
  Misses         34       34           
  Partials        1        1           

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