I found this annoying too – with my failing eyesight, posts were very difficult to read…
I made the following changes (in style.css) via a child theme:
body,
button,
input,
select,
textarea {
color: #333;
font-family: ‘Helvetica Neue’, Helvetica, Arial, sans-serif;
font-size: 14px;
font-size: 1.4rem;
line-height: 1.9;
}
a:hover{
color: #f00;
}
#secondary li, #tertiary li{
padding-bottom: 5px;
padding-top: 5px;
border-bottom: 1px solid #EFEFEF;
color: #333;
}
#secondary li a{
color: #333;
font-weight: bold;
.entry-content a:hover, .entry-summary a:hover{
color: #333;
}
Hope that helps.