style.css

* {
  box-sizing: border-box;
}

body {
  background-color:aquamarine;
  color: red;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
}

h1 {
  color: rgb(23, 14, 104);
  font-size: 3rem;
  text-align: center;
  
}

form {
  box-shadow: 0 5px 12px rgba(151, 150, 150, 0.1);
  max-width: 100%;
  width: 400px;
}

.input {
  border: none;
  color:  rgba(116, 112, 112, 0.644);
  font-size: 1rem;
  padding: 1rem 2rem;
  display: block;
  width: 100%;
}

.input::placeholder {
  color: #a3a2a2;
}

.input:focus {
  outline-color: rgb(23, 14, 104);
}

.todos {
  background-color: #fff;
  padding: 0;
  margin: 0;
  list-style-type: none;
}

.todos li {
  border-top: 1px solid #e5e5e5;
  cursor: pointer;
  font-size: 1.5rem;
  padding: 1rem 2rem;
}

.todos li.completed {
  color:rgb(23, 14, 104);
  text-decoration: line-through;
}