body {
  padding: 20px;
  font-family: Arial, Helvetica, sans-serif;
  background-image: url("https://www.shutterstock.com/image-photo/empty-seats-cinema-this-photo-600nw-2150027277.jpg");
  background-size: cover;       
  background-position: center;  
  background-attachment: scroll;
  background-repeat: no-repeat;
  min-height: 100vh;
  margin: 0;
  background-color: #111;
}

main {
  background-color: gray;
  width: 80%;
  margin:70px auto 70px auto;
  padding: 20px;
  max-width: 500px;
  border-radius: 25px;
}

.heading {
  display: block;
  text-align: center;
  padding: 10px;
}

h1 {
  color: firebrick;
  font-size: 40px;
  margin-top: 0;
  margin-bottom: 15px;
}

.item {
  display: block;
  font-size: 25px;
  text-align: left;
  margin-left: auto;
  margin-right: auto;
  background-color: darkgray;
  margin-bottom: 15px; 
  padding: 10px;       
  border-radius: 10px;
}

.todo-list {
  display: block;
  padding: 5px;
}

ul {
  list-style-type: none;
}

.sub-item {
  font-size: 18px;
  margin-top: 0px;
  margin-bottom: 20px;
  list-style-type: square;
  padding-top: 5px;
}

.sub-item-link {
  text-decoration: none;
  color: crimson;
}

.sub-item-link:hover {
  color: sienna;
}

.sub-item-link:visited {
  color: maroon;
}

.sub-item-link:focus {
  color: salmon;
  outline: solid;
}

.sub-item-link:active {
  color: pink;
}

.add-input {
  margin-bottom: 25px;
  padding-top: 5px;
  width: 70%;      
  padding: 8px;    
  border-radius: 5px;
  border: none;
}

.add-btn {
  font-weight: bold;
  font-size: 20px;
  color: white;
  margin-right: 10px;
  cursor: pointer; 
}

input[type="checkbox"]:checked + label {
  text-decoration: line-through;
  color: #555; 
}