88. deep background9.4.1.1. what9.4.1.2. use when9.4.1.3. why9.4.1.4. how89. few hues, many values9.4.2.1. what9.4.2.2. use when9.4.2.3. why9.4.2.4. how9.4.2.5. examples90. corner treatments9.4.3.1. what9.4.3.2. use when9.4.3.3. why9.4.3.4. how9.4.3.5. examples91. borders that echo fonts9.4.4.1. what9.4.4.2. use when9.4.4.3. why9.4.4.4. how9.4.4.5. examples92. hairlines9.4.5.1. what9.4.5.2. use when9.4.5.3. why9.4.5.4. how9.4.5.5. examples93. contrasting font weights9.4.6.1. what9.4.6.2. use when9.4.6.3. why9.4.6.4. how9.4.6.5. examples94. skins9.4.7.1. what9.4.7.2. use when9.4.7.3. why9.4.7.4. how