Fix course page's tab-bar

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (a71f5cb) 66.43% compared to head (af50696) 64.38%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #1252 +/- ## ========================================== - Coverage 66.43% 64.38% -2.06% ========================================== Files 144 144 Lines 6042 6042 Branches 1434 1434 ========================================== - Hits 4014 3890 -124 - Misses 1889 1992 +103 - Partials 139 160 +21 ``` | [Flag](https://app.codecov.io/gh/rage/mooc.fi/pull/1252/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=rage) | Coverage Δ | | |---|---|---| | [backend](https://app.codecov.io/gh/rage/mooc.fi/pull/1252/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=rage) | `64.38% <ø> (-2.06%)` | :arrow_down: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=rage#carryforward-flags-in-the-pull-request-comment) to find out more.

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