How to create Curved & Overlapping Menu Tabs in CSS

Question

I want to make a menu, in which the ends of the menus overlap and they have curved borders and slightly slanting edges.

Without using a background image, is it possi

Answer 1

• Skew the :before and :after pseudo elements,
• set pseudos to some - offset
• add left-top border-radius to :before and right-top to :after
• if needed (to remove the top hard edge) add top border radius to the A element
• add z-index:1; to the :after
• add z-index:1; to the .active's :before element.

nav li {
  display: inline-block;
  border-bottom: 1px solid #8BBF50;
  margin-left: -20px;
}

nav a {
  text-decoration: none;
  color: #fff;
  background: #8BBF50;
  position: relative;
  display: inline-block;
  margin: 0 22px;
  padding: 8px 11px;
  text-shadow: 0 1px 0 rgba(0, 2, 0, 0.4);
  border-radius: 7px 7px 0 0; /* just to smooth the top edges */
}

nav a:before,
nav a:after {
  content: " ";
  position: absolute;
  top: 0;
  width: 23px;
  height: 100%;
  background-color: inherit;
}

nav a:before {
  border-radius: 12px 0 0 0;
  transform: skew(-24deg);
  left: -13px; /* play with this one to give the LI border ~2px extrusion */
}

nav a:after {
  border-radius: 0 12px 0 0;
  transform: skew(24deg);
  right: -13px; /* play with this one to give the LI border ~2px extrusion */
  border-right: 1px solid #628E2F;
  z-index: 1; /* overlap next element */
}


/* LI ACTIVE  */

nav li.active {
  border-bottom: 1px solid #fff;
}

nav li.active a {
  color: #8BBF50;
  background: #fff;
}

nav li.active a:before {
  z-index: 1; /* overlap prev element */
}

nav li.active a:after {
  border-bottom: 1px solid #fff;
}

  

    
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The above does not provide the concave curvature at the bottom of the tab, instead I used the LI element border-bottom 2px extrusion to give a slight feeling to the eye. Not perfect but still a nice solution.

live demo on jsBin