style.css

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
body {
  display: flex;
  justify-content: center;
  font-family: sans-serif;
  background: linear-gradient(#5fdad9, #3bb3e3, #00d4ff);
  background-repeat: no-repeat;
  height: 100vh;
}
.container {
  margin-top: 100px;
}
h1 {
  font-size: 56px;
  margin-bottom: 24px;
}
.main {
  display: grid;
  grid-template-columns: 1fr 60px;
}
#inputbox {
  font-size: 24px;
  padding: 12px 16px;
  outline: none;
  margin-right: 10px;
  border-radius: 4px;
  border: none;
}
#inputbox::placeholder {
  color: #464242;
}
button {
  font-size: 24px;
}
.todocontainer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 0 0 16px;
  margin: 24px 0;
}
button {
  padding: 12px 16px;
  color: #fff;
  border: none;
  outline: none;
  cursor: pointer;
  transition: all 0.2s;
  border-radius: 4px;
  width: 60px;
}
.btn {
  background-color: #763dca;
}
.btn:hover {
  background-color: #614093;
}
.todoclass {
  border: none;
  border-radius: 5px;
}
.tick {
  background-color: green;
}
.close {
  background-color: rgb(231, 76, 60);
}