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

body {
  font-family: Arial, Helvetica, sans-serif;
  background-color: rgb(52, 99, 133);
  padding: 32px 0;
}

.app {
  width: min(520px, 92%);
  margin: 0 auto;
  border-radius: 14px;
  overflow: hidden;
  box-shadow: 0 10px 25px rgba(0, 0, 0, 0.12);
}

.header {
  background-color: #3ba6c7;
  padding: 22px 18px;
  color: white;
  text-align: center;
}

.header h1 {
  font-size: 30px;
  font-weight: 800;
  margin-bottom: 12px;
}

.row {
  display: flex;
  gap: 10px;
  align-items: center;
  justify-content: center;
}

.task {
  flex: 1;
  padding: 10px 12px;
  font-size: 15px;
  border: none;
  outline: none;
  border-radius: 10px;
}

.addBtn {
  padding: 10px 14px;
  font-size: 15px;
  font-weight: 800;
  border: none;
  cursor: pointer;
  background: #206a7f;
  color: #ffffff;
  border-radius: 10px;
  transition: 0.2s;
  min-width: 90px;
}

.addBtn:hover {
  background: #0a99c9;
}

.list {
  list-style: none;
}

.list li {
  cursor: pointer;
  position: relative;
  padding: 14px 14px 14px 48px;
  font-size: 16px;
  font-weight: bold;
  color: #ffffff;
  user-select: none;
  transition: 0.2s;
  background: #3788c7;
  border-top: 1px solid rgba(255, 255, 255, 0.3);
}

.list li:hover {
  background: #1c75a2;
}

.list li.checked {
  background: #1b66a0;
  text-decoration: line-through;
}

.list li.checked::before {
  content: "";
  position: absolute;
  left: 18px;
  top: 50%;
  transform: translateY(-50%) rotate(45deg);
  height: 14px;
  width: 7px;
  border: solid #fff;
  border-width: 0 2px 2px 0;
}

.close {
  position: absolute;
  right: 0;
  top: 0;
  padding: 14px 14px;
  font-size: 18px;
}

.close:hover {
  background-color: #f16157;
  color: white;
}

@media (max-width: 520px) {
  body {
    padding: 22px 0;
  }

  .header h1 {
    font-size: 26px;
  }

  .addBtn {
    min-width: 80px;
  }
}