style.css

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
:root {
  --Bright-orange: hsl(31, 77%, 52%);
  --Dark-cyan: hsl(184, 100%, 22%);
  --Very-dark-cyan: hsl(179, 100%, 13%);
  --Very-light-gray: hsl(0, 0%, 95%);
  --Transparent-white: hsla(0, 0%, 100%, 0.75);
}
body {
  display: flex;
  align-items: center;
  flex-direction: column;
  height: calc(100vh - 1px);
  font-size: 15px;
  background-color: white;
}
.container {
  width: 960px;
  margin: auto;
 
}
.sub-container {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  margin: 4%;
}
.boxs {
  padding: 40px;
}
.boxs h1 {
  font-family: "Big Shoulders Display", cursive;
  font-weight: 300;
  text-transform: uppercase;
  color: white;
  margin: 10% 0;
  font-size: 40px;
}
.boxs p {
  line-height: 25px;
  font-family: "Lexend Deca", sans-serif;
  color: var(--Transparent-white);
  margin: 0% 0 10% 0;
}
.boxs a {
  text-decoration: none;
  background-color: hsl(0, 0%, 95%);
  padding: 13px 27px;
  border-radius: 26px;
  margin-top: 60px;
  display: inline-block;
  border: 2px solid hsl(0, 0%, 95%);
}
.boxs:nth-child(1) {
  background-color: var(--Bright-orange);
  border-top-left-radius: 12px;
  border-bottom-left-radius: 12px;
}
.boxs:nth-child(2) {
  background-color: var(--Dark-cyan);
}
.boxs:nth-child(3) {
  background-color: var(--Very-dark-cyan);
 border-top-right-radius:12px ;
  border-bottom-right-radius: 12px;
}
/* ////////////////////////////////////*/
.boxs:nth-child(1) > a {
  color: var(--Bright-orange);
}
.boxs:nth-child(2) > a {
  color: var(--Dark-cyan);
}
.boxs:nth-child(3) > a {
  color: var(--Very-dark-cyan);
}
.attribution{
    font-size: 13px; text-align: center;
    font-weight: 700;
}
.attribution a {
    color: hsl(228, 45%, 44%);
}
.boxs > a:hover{
    background-color: transparent;
    color: white;
}

/* ////////////////////////////////////*/
@media screen and (max-width: 768px) {
    .sub-container {
        grid-template-columns: repeat(1, 1fr);
    }

}
@media screen and (max-width: 425px) {
    .container {
        width: 340px;
        margin: 20% 4%;
    }
    .boxs:nth-child(1){
    border-top-right-radius: 12px;
    border-top-left-radius:12;
    border-bottom-left-radius:0;

    }
    .boxs:nth-child(3) {
        background-color: var(--Very-dark-cyan);
        border-top-right-radius:0 ;
        border-bottom-right-radius:12px ;
        border-bottom-left-radius: 12px;
      }
      .boxs > a{
          margin-top: 10px;
      }
      .boxa > h1{
          margin: 11% 0;
      }
}