style.css

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

body {
  background: linear-gradient(
    to right,
    rgba(116, 139, 255, 0.5),
    rgb(61, 41, 153, 0.5)
  );
}

.todo-container,
header {
  display: flex;
  justify-content: center;
  align-items: center;
  margin: 30px;
}

header {
  margin-top: 150px;
}

h1 {
  font-size: 50px;
  font-weight: 900;
  color: #25273c;
  font-family: "Times New Roman", Times, serif;
}

.todo-container {
  margin-top: 30px;
}

.todo-input {
  padding: 10px;
  border-radius: 20px;
  border: 0;
  color: #fff;
  background-color: #25273c;
  outline: none;
  width: 400px;
  height: 60px;
}

.todo-button {
  padding: 10px;
  border-radius: 20px;
  border: 0;
  color: #fff;
  background-color: #25273c;
  margin-left: 3px;
  cursor: pointer;
  width: 60px;
  height: 60px;
}

.todo-list {
  user-select: none;
  list-style: none;
  margin-top: 30px;
  justify-content: center;
  align-items: center;
  display: flex;
  flex-direction: column;
}

.todo {
  padding: 10px;
  border-radius: 20px;
  border: 0;
  color: #fff;
  background-color: #25273c;
  margin-top: 10px;
  outline: none;
  cursor: pointer;
  margin-bottom: 10px;
  align-items: center;
  display: flex;
  justify-content: space-between;
  width: 463px;
  text-align: center;
  height: 60px;
  font-family: "Times New Roman", Times, serif;
}

.trash-btn {
  height: 60px;
  width: 60px;
  border-radius: 10px;
  border: 0;
  color: #fff;
  background-color: #25273c;
  outline: none;
  cursor: pointer;
}

.todo-item {
  font-family: Arial, Helvetica, sans-serif;
}

.completed {
  text-decoration: line-through;
}