* {
  margin: 0;
  padding: 0;
  font-family: system-ui, -apple-system, 'BlinkMacSystemFont', 'Segoe UI', 'Roboto', 'Oxygen', 'Ubuntu', 'Cantarell', 'Open Sans', 'Helvetica Neue', sans-serif;
 box-sizing: border-box;
}
.container{
  width: 100%;
  min-height: 100vh;
  background: linear-gradient(135deg, #153677, #4e085f);
  padding: 10px;
}
.todo-app{
  width: 100%;
  max-width: 540px;
  background: #fff;
  margin: 100px auto 20px;
  padding: 35px 35px;
  border-radius: 10px;
}
.todo-app h2{
  color: #002765;
  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: #edeef0;
  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: #ff5945;
  color: #fff;
  font-size: 16px;
  cursor: pointer;
  border-radius: 45px;
}
ul li{
  list-style: none;
  font-size: 17px;
  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: #555;
    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: #555;
  line-height: 40px;
  text-align: center;
}
ul li span:hover{
  background: #edeef0;
}