Try changing the width in the rule in webassist/themes/Goldsmiths/css/purple_styles.css (line 58)
#cssmw li a {
display: block;
padding: 10px 18px;
text-decoration: none;
width: 105px; /* changed from 90px */
}
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Also, altering the height from 35 to 37 in #navwrapper webassist/themes/Goldsmiths/css/purple_styles.css (line 405) would get rid of the space between levels 0 and 1, and make the hover color height match the red nav background height