style.css

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  height: 100vh;
  width: 100vw;
  background: url(./weather.jpg);
  background-size: cover; /* <------ */
  background-repeat: no-repeat;
  /* background-position: center center;  */
}

header {
  display: flex;
  justify-content: center;
  margin-top: 5%;
  margin-bottom: 3%;
  align-items: center;
}

header input {
  width: 40%;
  padding: 15px 10px;
  font-size: 1.5rem;
  outline: none;
  border-radius: 5px;
  border: none;
  color: whitesmoke;
  background-color: rgba(217, 248, 219, 0.445);
}
header input:focus {
  background-color: rgba(217, 248, 219, 0.781);
}
::placeholder {
  /* Chrome, Firefox, Opera, Safari 10.1+ */
  color: white;
  opacity: 1; /* Firefox */
}

main {
  /* flex: 1 1 100%; */
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  text-align: center;
  padding: 15px 25px;
  margin: 15px 10px;
}

.location .city {
  font-size: 2.5rem;
  color: rgb(0, 0, 0);
  margin: 10% 0 10% 0;
}

.current .temp {
  font-size: 3.5rem;
  margin-bottom: 10%;
  text-shadow: 2px 3px 6px rgb(255, 198, 9);
}

.current .weather {
  color: rgba(54, 53, 53, 0.863);
  font-size: 1.5rem;
  margin-bottom: 10%;
  font-style: italic;
}

.current .hi-low {
  font-size: 1.5rem;
  color: rgb(0, 0, 0);
  font-style: italic;
}

.card {
  background-color: rgba(255, 255, 255, 0.692);
  padding: 15px 60px;
  padding-bottom: 40px;
  box-shadow: black 5px 5px 12px;
}

@media (max-width: 424px) {
  header input {
    font-size: 1rem;
  }

  .location .city {
    font-size: 2rem;
  }
  .current .temp {
    font-size: 3rem;
  }
  .current .hi-low {
    font-size: 1rem;
  }
}