I found the other ideas on this page to lose their efficacy when used on small buttons with small text lettering. This answer expands on RobertPitt's answer.
Here is the minor tweak:
text-shadow: 1px 1px transparent, -1px -1px black;
$('button').click(function(){
$('button').removeClass('btnActive');
$(this).addClass('btnActive');
});
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body{background:#666;}
.btnActive{
border: 1px solid #aaa;
border-top: 1px solid #333;
border-left: 1px solid #333;
color: #ecf0f8;
background-color: #293d70;
background-image: none;
text-shadow: 1px 1px transparent, -1px -1px black;
outline:none;
}
button{
border: 1px solid #446;
border-radius: 3px;
color: white;
background-color: #385499;
background-image: linear-gradient(-180deg,##7d94cf,#1c294a 90%);
cursor: pointer;
font-size: 14px;
font-weight: 600;
padding: 6px 12px;
xxtext-shadow: 1px 1px 2px navy;
}
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<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<button class="btnActive">Option One</button>
<button>Option Two</button>
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I used this site to finesse the color shades.