Hexagons fixed, navbar fixed, played w/ colors and background

HTML changes (index.html)
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navbar <nav> now all items fit and align and pad (weather looks ok)
small error in carousel caption for item active
<hr> after hexagon row
small error in terms of use and privacy
add class="col-centered" to hexagons for centering

CSS changes (custom.css)
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body background color and image
deleted row margin-top -120px, this is not the best way to adjust hexagons' position
reduce size of hexagon from 440px to 250px to reduce blank space above hexagon row
margin between hexagon row and footer row
reduce the margin after carousel and before hexagon row
changed color of hexagons on hover to the same green as navbar for consistency
centered hexagons in the row (they were a little bit to the left before)
adjust position of hexagon hover text and make <p> in hexagon bigger
played with color of navbar brand font (and hover)
played with color of navbar items (and changed hover to darker green for legibility)
set active navbar item to bold (white text on bright green background is not very legible)

HTML changes (search.html)
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Fixed same navbar issue as in index.html (replace some divs with nav)