:root {
  --primary-color: #305d6b;
  --secondary-color: #250e4a;
  --background-color: #f7f7f7;
  --text-color: #830808;
  --border-radius: 10px;
  --button-color: #2d1810;
}

* {
  margin: 0;
  padding: 0;
  font-family: sans-serif;
  box-sizing: border-box;
}

.container {
  width: 100%;
  min-height: 100vh;
  background-image: linear-gradient(
    to right,
    var(--primary-color) 0%,
    black 100%
  );
  padding: 10px;
}

.todo-app {
  width: 100%;
  max-width: 540px;
  background: var(--background-color);
  margin: 100px auto 20px;
  padding: 40px 30px 70px;
  border-radius: var(--border-radius);
}

.todo-app h2 {
  color: var(--secondary-color);
  display: flex;
  align-items: center;
  margin-bottom: 20px;
}

.todo-app h2 img {
  width: 30px;
  margin-left: 10px;
}

.row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: #c3c3c4;
  border-radius: 30px;
  padding-left: 20px;
  margin-bottom: 25px;
}

input {
  flex: 1;
  border: none;
  outline: none;
  background: transparent;
  padding: 10px;
  font-weight: 14px;
}

button {
  border: none;
  outline: none;
  padding: 16px 50px;
  background: var(--button-color);
  color: #ffffff;
  font-weight: 600;
  font-size: 16px;
  cursor: pointer;
  border-radius: 40px;
}

ul li {
  list-style: none;
  font-size: 20px;
  padding: 12px 8px 12px 50px;
  user-select: none;
  cursor: pointer;
  position: relative;
}

ul li::before {
  content: "";
  position: absolute;
  height: 28px;
  width: 28px;
  border-radius: 50%;
  background-image: url(images/unchecked.png);
  background-size: cover;
  background-position: center;
  top: 12px;
  left: 8px;
}

ul li.checked {
  color: var(--text-color);
  text-decoration: line-through;
}

ul li.checked::before {
  background-image: url(images/checked.png);
}

ul li span {
  position: absolute;
  right: 0;
  top: 5px;
  width: 40px;
  height: 40px;
  font-size: 22px;
  color: var(--text-color);
  line-height: 40px;
  text-align: center;
}

ul li span:hover {
  background: #edeef0;
}

/* Mobile version */
@media only screen and (max-width: 768px) {
  .todo-app {
    max-width: 90%;
    margin: 50px auto 20px;
    padding: 20px 15px 40px;
  }
  .row {
    padding-left: 10px;
    margin-bottom: 15px;
  }
  input {
    padding: 8px;
  }
  button {
    padding: 12px 30px;
  }
  ul li {
    font-size: 18px;
    padding: 10px 6px 10px 40px;
  }
  ul li span {
    width: 30px;
    height: 30px;
    font-size: 18px;
  }
}