Updates to Side Navigation, Other Layout Fixes

[larissar]

• Fixed z-index issue with error popup window appearing behind modal windows
• Disabled animation on popup in error message and dialogs
• Added temperament detail to feed area on horse page
• Adjusted font sizes on training options (gait, terrain, duration) to prevent oversized fonts at certain screen resolutions
• Adjusted tab sizes on horse page for better fit across various devices and screen sizes
• Reduced width of side nav bar
• Readjusted css breakpoints for when header icons appear/hide, reduced base font size of header icons