Update black mana symbol contrast.

cockatrice/resources/icons/mana/B.svg

@@ -43,5 +43,5 @@
   <path
           d="m 299.67889,84.945431 c -118.26949,0 -214.122988,83.892719 -214.122988,187.357619 0,58.63289 30.863828,110.90901 79.041488,145.28579 8.02961,5.77129 12.71356,15.13917 11.29165,25.0089 l -7.86234,55.37086 c -1.17098,8.02962 5.01851,15.22281 13.13176,15.22281 h 64.98968 v -46.83939 c 0,-3.68025 3.01111,-6.69135 6.69135,-6.69135 h 13.38268 c 3.68024,0 6.69135,3.0111 6.69135,6.69135 v 46.83939 h 53.53075 v -46.83939 c 0,-3.68025 3.01111,-6.69135 6.69134,-6.69135 h 13.38269 c 3.68023,0 6.69134,3.0111 6.69134,6.69135 v 46.83939 h 64.98967 c 8.11327,0 14.30275,-7.19319 13.13177,-15.22281 l -7.86234,-55.37086 c -1.4219,-9.78609 3.1784,-19.23761 11.29165,-25.0089 48.17767,-34.37678 79.0415,-86.6529 79.0415,-145.28579 0,-103.4649 -95.8535,-187.357619 -214.123,-187.357619 z M 219.38277,352.59917 c -29.52555,0 -53.53075,-24.0052 -53.53075,-53.53075 0,-29.52555 24.0052,-53.53075 53.53075,-53.53075 29.52555,0 53.53075,24.0052 53.53075,53.53075 0,29.52555 -24.0052,53.53075 -53.53075,53.53075 z m 160.59225,0 c -29.52555,0 -53.53075,-24.0052 -53.53075,-53.53075 0,-29.52555 24.0052,-53.53075 53.53075,-53.53075 29.52555,0 53.53075,24.0052 53.53075,53.53075 0,29.52555 -24.0052,53.53075 -53.53075,53.53075 z"
           id="path1"
-          style="fill:#333333;fill-opacity:1;stroke:#000000;stroke-width:0.836419;stroke-opacity:1"/>
+          style="fill:#4d4d4d;fill-opacity:1;stroke:#000000;stroke-width:0.836419;stroke-opacity:1"/>
 </svg>