style.css

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

body {
  display: flex;
  justify-content: center;
  font-family: 'Work Sans', sans-serif;
  font-weight: bolder;
  background-color: #16b2a9;
  background-image: url("img/Background_image.jpg");
  background-repeat: no-repeat;
  background-size: cover;
}

#todo_list {
  width: 1000px;
  text-align: center;
  margin-top: 13vh;
}

#todo_list > h2 {
  font-size: 38px;
  letter-spacing: 0.4px;
  margin-bottom: 30px;
}

#add_input {
  border-radius: 7px 7px;
  border: none;
  outline: none;
  height: 40px;
  width: 40%;
  padding-left: 20px;
  margin-bottom: 30px;
}

#items_list {
  list-style-type: none;
  justify-content: center;
  flex-direction: column;
  display: flex;
}

li.items {
  border-radius: 7px 7px;
  font-size: 20px;
  background: #f0f0e6;
  opacity: 0.8;
  padding: 10px;
  width: 40%;
  margin: 0 auto;
  margin-bottom: 15px;
  font-weight: bold;
  display: flex;
  flex-direction: row;
  justify-content: space-between;
}

.del_btn {
  width: auto;
  padding: 4px 6px;
  background: #dd4e4e;
  color: #fff;
  font-weight: bold;
  cursor: pointer;
  outline: none;
  border: none;
  border-radius: 5px;
}