Answers for "border small 0"

border-bottom smaller div

div {
  width   : 200px;
  height  : 50px;   
  position: relative;
  z-index : 1;
  background: #eee;
}

div:before {
  content : "";
  position: absolute;
  left    : 0;
  bottom  : 0;
  height  : 1px;
  width   : 50%;  /* or 100px */
  border-bottom:1px solid magenta;
}

css border with 8 values

/* Using border radius with 8 Values for more control */
border-radius: 16% 21% 34% 35% / 19% 39% 21% 56%
/* Read the Source for more information */