Отрисовать фиругу. чтобы псевдоэлемент принимал её форму
.dropdawn-block__number {
position: absolute;
top: 0;
left: 10px;
padding: 6px 13px 13px 11px;
clip-path: polygon(0% 0, 100% 0, 100% 70%, 0 100%);
font-family: "Orchidea Pro";
font-size: 50px;
color: rgb(253, 167, 0);
background: rgb(13, 43, 109);
}
.dropdawn-block__number::before {
content: "";
position: absolute;
top: 50%;
left: 50%;
transform: translate(-50%, -50%);
width: 90%;
height: 90%;
border: 1px solid rgba(255, 255, 255, 0.5);
clip-path: polygon(0% 0, 100% 0, 100% 70%, 0 100%);
}
<span class="dropdawn-block__number">1</span>
.dropdawn-block__number {
position: absolute;
top: 0;
left: 10px;
width: 50px;
height: 70px;
display: flex;
align-items: center;
justify-content: center;
clip-path: polygon(0% 0, 100% 0, 100% 73%, 0 100%);
font-family: "Orchidea Pro";
font-size: 50px;
color: rgb(253, 167, 0);
background: rgb(13, 43, 109);
}
.dropdawn-block__number::before,.dropdawn-block__number ::after {
content: "";
position: absolute;
top: 50%;
left: 50%;
display: flex;
align-items: flex-start;
justify-content: center;
width: inherit;
height: inherit;
clip-path: inherit;
background-color: inherit;
}
.dropdawn-block__number::before {
transform: translate(-50%, -50.7%) scale(91%, 92%);
background-color: rgba(255, 255, 255, 0.5);
}
.dropdawn-block__number::after {
content: attr(data-num);
transform: translate(-9%, -9%) scale(87.5%, 89%);
}
<span class="dropdawn-block__number" data-num="1"></span>
Источник: Stack Overflow на русском