Removing gap in :before :after pseudo elements

Question

I'm trying to make a dropdown menu with mouse hover effects, using the label element. When tag arrow shape slides on the menu image, it has an unexpected gap.

.mask {
    width: 100%;
    height: 100%;
    position: absolute;
    transform: translateX(-120%);
    top: 0;
    background-color:   rgba(255,255,255,0.8);
    -webkit-transition: all 0.6s ease;
    transition:     all 0.6s ease;
    display: flex;
    justify-content: flex-end;
    align-items: center;
}
.mask:before {
    content: "";
    position: absolute;
    top: 0%;
    left: 100%;
    margin-top: 0px;
    width: 20%;
    height: 100%;
    background:
    linear-gradient(to bottom left, transparent 50%, rgba(255,255,255,0.8) 51%) no-repeat top left/30% 50%,
    linear-gradient(to top left, transparent 50%, rgba(255,255,255,0.8) 51%) no-repeat bottom left/30% 50%;
}

jsfiddle

I hope this helps someone.

Answer 1

Do it differently using clip-path

.testmenu {
  max-width: 100%;
  margin-bottom: 2vh;
}

.testmenu a {
  display: block;
  text-decoration: none;
  color: transparent;
  padding-top: calc(100%*168/1218);
}

label {
  display: block;
  margin: 0;
  line-height: 1;
  color: #fff0;
  cursor: pointer;
  width: 100%;
  padding-top: calc(100%*200/1218);
  background-position: left top;
  background-repeat: no-repeat;
  background-size: 100% auto;
}

label[for="testmenu_bar01"] {
  background-image: url(https://placehold.jp/1218x218.png);
}

input {
  display: none;
}

.testmenu ul {
  margin: 0;
  padding: 0;
  background: #f4f4f4;
  list-style: none;
}

.testmenu li {
  height: 0;
  overflow: hidden;
  -webkit-transition: all 0.5s;
  -moz-transition: all 0.5s;
  -ms-transition: all 0.5s;
  -o-transition: all 0.5s;
  transition: all 0.5s;
  background-size: contain;
}

.testmenu li.testmenu01-li-01 {
  background-image: url("https://placehold.jp/1218x168.png");
  background-position: left top;
  background-repeat: no-repeat;
  background-size: 100% auto;
}

.testmenu li.testmenu01-li-02 {
  background-image: url("https://placehold.jp/1218x168.png");
  background-position: left top;
  background-repeat: no-repeat;
  background-size: 100% auto;
}

#testmenu_bar01:checked~#links01 li {
  height: 0;
  padding-bottom: calc(100%*168/1218);
  opacity: 1;
}

#testmenu_bar01:checked+#links01 li.testmenu01-li-01 {
  margin-top: 2vh;
}

.sizing-mask {
  position: relative;
  overflow: hidden;
}

.mask {
  width: 100%;
  height: 100%;
  position: absolute;
  transform: translateX(-120%);
  top: 0;
  background-color: rgba(255, 255, 255, 0.8);
  transition: all 0.6s ease;
  display: flex;
  justify-content: flex-end;
  align-items: center;
  clip-path:polygon(0 0,90% 0%, 100% 50%, 90% 100%,0% 100%);
}

.mask:after {
  content: "";
  width: 10%;
  height: 100%;
}

.testmenu:hover .mask {
  transform: translateX(-61%);
  border-right: hidden;
}

<div id="onlineshop" class="testmenu">
  <div class="sizing-mask">
    <div class="mask">
      <div class="test-caption">
        <p style="color: rgba(0,0,0,1);font-size: 1vw;text-transform: inherit;letter-spacing: 1px;" class="eihe-title">text<span class="break"></span>text</p>
      </div>
    </div>
    <label for="testmenu_bar01"></label>
  </div>
  <input type="checkbox" id="testmenu_bar01" class="accordion">
  <ul id="links01">
    <li class="testmenu01-li-01">
      <a href="#"></a>
    </li>
    <li class="testmenu01-li-02">
      <a href="#"></a>
    </li>
  </ul>
</div>