style.css

* {
  margin: 0;
  padding: 0;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
    Oxygen, Ubuntu, Cantarell, "Open Sans", "Helvetica Neue", sans-serif;
  font-weight: 500;
}

.container {
  width: 100%;
  min-height: 100vh;
  padding: 15px;
  background: linear-gradient(150deg, #86a7fc, #3468c0);
}

.todo-app {
  width: 100%;
  max-width: 540px;
  background-color: #ffdd95;
  margin: 100px auto 30px;
  padding: 50px 30px 70px;
  border-radius: 10px;
}

.todo-app h2 {
  color: #3468c0;
  display: flex;
  align-items: center;
  margin-bottom: 20px;
}

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

.row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  border-radius: 30px;
  padding-left: 20px;
  margin-bottom: 20px;
  background: #fff0ce;
}

input {
  flex: 1;
  border: none;
  outline: none;
  padding: 10px;
  font-weight: 16px;
  background: transparent;
  color: gray;
}

button {
  background-color: #ff9843;
  color: #fff;
  border: none;
  outline: none;
  padding: 10px 40px;
  cursor: pointer;
  border-radius: 30px;
  font-size: 16px;
}

ul li {
  list-style: none;
  font-size: 16px;
  font-weight: 400;
  padding: 10px 10px 10px 50px;
  cursor: pointer;
  user-select: none;
  position: relative;
}

ul li::before {
  content: "";
  position: absolute;
  height: 25px;
  width: 25px;
  border-radius: 50%;
  background-image: url(./Images/circle-unchecked.png);
  background-size: cover;
  background-position: center;
  top: 8px;
  left: 8px;
}

ul li.checked {
  color: gray;
  text-decoration: line-through;
}
ul li.checked::before {
  background-image: url(./Images/circle-check.svg);
}

ul li span {
  position: absolute;
  top: 5px;
  right: 0;
  width: 40px;
  height: 40px;
  font-size: 22px;
  color: #3468c0;
  line-height: 40px;
  text-align: center;
  border-radius: 50%;
}

ul li span:hover {
  background-color: #ff9843;
  color: #ffdd95;
}