Как я понимаю, вы хотите, чтобы этот эффект был на обеих сторонах вкладки "Обо мне", если это реальная потребность, вот решение, если вам нужно что-то еще, не стесняйтесь спрашивать ...
body
{
background-color: #363636;
margin: 0;
height: 100vh;
}
.tab-content
{
left: 7%;
top: 15%;
position: absolute;
}
.tablist
{
padding: 0;
list-style-type: none;
}
.tab
{
float: left;
margin-left: 0px;
width: 180px;
line-height: 35px;
background-color: #33691e;
color: #DDDDDD;
font-family: verdana;
letter-spacing: .025em;
font-size: 13px;
text-align: center;
text-decoration: none;
outline: none;
margin-right: 8px;
-webkit-transform: translateZ(0);
-ms-transform: translateZ(0);
transform: translateZ(0);
}
.one
{
float: left;
margin-left: 0px;
width: 180px;
line-height: 35px;
background-color: #191919;
color: #DDDDDD;
font-family: verdana;
letter-spacing: .025em;
font-size: 13px;
text-align: center;
text-decoration: none;
outline: none;
margin-right: 8px;
-webkit-transform: translateZ(0);
-ms-transform: translateZ(0);
transform: translateZ(0);
}
.curl-top-left
{
-webkit-transform: translateZ(0);
-ms-transform: translateZ(0);
transform: translateZ(0);
}
.curl-top-left:before
{
pointer-events: none;
position: absolute;
content: "";
width: 0;
height: 0;
left: 0;
top: 0;
background: -webkit-linear-gradient(315deg, white 45%, #aaaaaa 50%, #cccccc 56%, white 80%);
background: linear-gradient(135deg, #363636 45%, #aaaaaa 50%, #cccccc 56%, white 80%);
filter: progid:DXImageTransform.Microsoft.gradient(GradientType=0, startColorstr='#ffffff', endColorstr='#000000');
z-index: 100;
-webkit-transition-duration: 0.3s;
transition-duration: 0.3s;
-webkit-transition-property: width, height;
transition-property: width, height;
}
.curl-top-left:hover:before, .curl-top-left:active:before, .curl-top-left:focus:before
{
width: 20px;
height: 20px;
}
.curl-top-right
{
-webkit-transform: translateZ(0);
-ms-transform: translateZ(0);
transform: translateZ(0);
}
.curl-top-right:before
{
pointer-events: none;
position: absolute;
content: "";
width: 0;
height: 0;
top: 0;
right: 0;
background: -webkit-linear-gradient(225deg, white 45%, #aaaaaa 50%, #cccccc 56%, white 80%);
background: linear-gradient(225deg, #363636 45%, #aaaaaa 50%, #cccccc 56%, white 80%);
filter: progid:DXImageTransform.Microsoft.gradient(GradientType=0, startColorstr='#ffffff', endColorstr='#000000');
z-index: 100;
-webkit-transition-duration: 0.3s;
transition-duration: 0.3s;
-webkit-transition-property: width, height;
transition-property: width, height;
}
.curl-top-right:hover:before, .curl-top-right:active:before, .curl-top-right:focus:before
{
width: 20px;
height: 20px;
}
.test-1
{
-webkit-transform: translateZ(0);
-ms-transform: translateZ(0);
transform: translateZ(0);
}
.test-1:before
{
pointer-events: none;
position: absolute;
content: "";
width: 0;
height: 0;
top: 0;
background: -webkit-linear-gradient(315deg, white 45%, #aaaaaa 50%, #cccccc 56%,
white 80%);
background: linear-gradient(135deg, #363636 45%, #aaaaaa 50%, #cccccc 56%, white
80%);
filter: progid:DXImageTransform.Microsoft.gradient(GradientType=0,
startColorstr='#ffffff', endColorstr='#000000');
z-index: 100;
-webkit-transition-duration: 0.3s;
transition-duration: 0.3s;
-webkit-transition-property: width, height;
transition-property: width, height;
}
.test-1:hover:before, .test-1:focus:before, .test-1:active:before
{
width: 20px;
height: 20px;
}
.test-2
{
-webkit-transform: translateZ(0);
-ms-transform: translateZ(0);
transform: translateZ(0);
}
.test-2:before
{
pointer-events: none;
position: absolute;
content: "";
width: 0;
height: 0;
top: 0;
right: 0;
background: -webkit-linear-gradient(225deg, white 45%, #aaaaaa 50%, #cccccc 56%, white 80%);
background: linear-gradient(225deg, #363636 45%, #aaaaaa 50%, #cccccc 56%, white 80%);
filter: progid:DXImageTransform.Microsoft.gradient(GradientType=0, startColorstr='#ffffff', endColorstr='#000000');
z-index: 100;
-webkit-transition-duration: 0.3s;
transition-duration: 0.3s;
-webkit-transition-property: width, height;
transition-property: width, height;
}
.test-1:after {
pointer-events: none;
position: absolute;
content: "";
width: 0;
height: 0;
left: 0;
top: 0;
background: -webkit-linear-gradient(315deg, white 45%, #aaaaaa 50%, #cccccc 56%, white 80%);
background: linear-gradient(135deg, #363636 45%, #aaaaaa 50%, #cccccc 56%, white 80%);
filter: progid:DXImageTransform.Microsoft.gradient(GradientType=0, startColorstr='#ffffff', endColorstr='#000000');
z-index: 100;
-webkit-transition-duration: 0.3s;
transition-duration: 0.3s;
-webkit-transition-property: width, height;
transition-property: width, height;
}
.test-2:hover:before, .test-1:hover:after, .test-2:focus:before, .test-1:focus:after, .test-2:active:before, .test-1:active:after
{
width: 20px;
height: 20px;
}
.tab:hover, .tab:active, .tab:focus
{
color: #DDDDDD;
cursor: pointer;
background-color: #191919;
}
<body>
<div class="tab-content">
<ul class="tablist" role="tablist">
<li id="tab1" class="tab curl-top-left" aria-controls="panel1" role="tab" aria-selected="true" tabindex="0">Home</li>
<li id="tab2" class="tab test-1 test-2" aria-controls="panel2" role="tab" aria-selected="false" tabindex="0">About me</li>
<li id="tab3" class="tab curl-top-right" aria-controls="panel3" role="tab" aria-selected="false" tabindex="0">Contact</li>
</ul>
</div>
</body>