#tab2, #tab3 {position: fixed; }

.menu1 > a,
.menu1 #tab2:target ~ a:nth-of-type(1),
.menu1 #tab3:target ~ a:nth-of-type(1),
.menu1 > div { padding: 5px; border: 1px solid #909090; }

.menu1 > a { line-height: 28px; background: #1a1a1a; text-decoration: none; }

#tab2,
#tab3,
.menu1 > div,
.menu1 #tab2:target ~ div:nth-of-type(1),
.menu1 #tab3:target ~ div:nth-of-type(1) {display: none; }

.menu1 > div:nth-of-type(1),
.menu1 #tab2:target ~ div:nth-of-type(2),
.menu1 #tab3:target ~ div:nth-of-type(3) { display: block; }

.menu1 > a:nth-of-type(1),
.menu1 #tab2:target ~ a:nth-of-type(2),
.menu1 #tab3:target ~ a:nth-of-type(3) { border-bottom: 2px solid #ffff0d; }