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

body {
  overflow-x: hidden;
}

.container{
  width: 100%;
  min-height: 100vh;
  background: linear-gradient(135deg, #153677, #4e085f);
  padding: 10px;
}

.todo-app{
  width: 100%;
  max-width: 540px;
  background:#ffff;
  margin: 50px auto 20px;
  padding: 40px 30px 70px;
  border-radius: 10px;
  box-shadow: 0 10px 30px rgba(0,0,0,0.3);
}

.todo-app h2{
  color: #002765;
  display: flex;
  align-items: center;
  margin-bottom: 20px;
  font-size: 24px;
}

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

.row{
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-radius: 30px;
  padding-left: 20px;
  margin-bottom: 25px;
  background: #edeef0;
}

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

button{
  border: none;
  outline: none;
  padding: 16px 50px;
  background: #002765;
  color: #fff;
  border-radius: 40px;
  cursor: pointer;
  font-size: 16px;
  transition: background 0.3s ease;
}

button:hover {
  background: #003875;
}

ul li{
  list-style: none;
  font-size: 17px;
  padding: 12px 8px 12px 50px;
  user-select: none;
  cursor: pointer;
  position: relative;
  border-bottom: 1px solid #f0f0f0;
  transition: background 0.2s ease;
}

ul li:hover {
  background: #f8f9fa;
}

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

.checked{
  color: #555;
  text-decoration: line-through;
}

.checked::before{
  background-image: url(checked.png);
}

ul li span{
  position: absolute;
  right: 0;
  top: 5px;
  font-size: 22px;
  width: 40px;
  height: 40px;
  color: #555;
  line-height: 40px;
  text-align: center;
  border-radius: 50%;
  transition: background 0.2s ease;
}

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

/* Additional content sections */
.stats-section {
  background: rgba(255,255,255,0.1);
  margin: 30px auto;
  max-width: 540px;
  padding: 30px;
  border-radius: 10px;
  text-align: center;
  color: white;
}

.stats-section h3 {
  margin-bottom: 20px;
  font-size: 20px;
}

.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
  gap: 15px;
  margin-top: 20px;
}

.stat-item {
  background: rgba(255,255,255,0.2);
  padding: 15px;
  border-radius: 8px;
  text-align: center;
}

.stat-number {
  font-size: 24px;
  font-weight: bold;
  color: #00E5FF;
}

.stat-label {
  font-size: 12px;
  margin-top: 5px;
  opacity: 0.9;
}

.tips-section {
  background: rgba(255,255,255,0.1);
  margin: 30px auto;
  max-width: 540px;
  padding: 30px;
  border-radius: 10px;
  color: white;
}

.tips-section h3 {
  margin-bottom: 20px;
  font-size: 20px;
  text-align: center;
}

.tip-item {
  background: rgba(255,255,255,0.1);
  padding: 15px;
  margin-bottom: 10px;
  border-radius: 8px;
  border-left: 4px solid #00E5FF;
}

.tip-item:last-child {
  margin-bottom: 0;
}

/* Mobile First - Base styles for mobile */
@media (max-width: 480px) {
  .container {
    padding: 5px;
  }

  .todo-app {
    margin: 20px auto 10px;
    padding: 20px 15px 40px;
    max-width: 95%;
  }

  .todo-app h2 {
    font-size: 20px;
    flex-direction: column;
    text-align: center;
    gap: 10px;
  }

  .todo-app h2 img {
    margin-left: 0;
    width: 25px;
  }

  .row {
    flex-direction: column;
    gap: 15px;
    padding: 15px;
    border-radius: 15px;
  }

  input {
    padding: 12px;
    font-size: 16px;
    width: 100%;
    border-radius: 25px;
    background: white;
    border: 1px solid #ddd;
  }

  button {
    padding: 12px 30px;
    font-size: 14px;
    width: 100%;
  }

  ul li {
    font-size: 15px;
    padding: 15px 8px 15px 45px;
  }

  ul li::before {
    width: 24px;
    height: 24px;
    top: 15px;
  }

  ul li span {
    font-size: 18px;
    width: 35px;
    height: 35px;
    line-height: 35px;
    top: 8px;
  }

  .stats-section,
  .tips-section {
    margin: 20px auto;
    padding: 20px 15px;
    max-width: 95%;
  }

  .stats-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: 10px;
  }

  .stat-item {
    padding: 12px;
  }

  .stat-number {
    font-size: 20px;
  }

  .tip-item {
    padding: 12px;
    font-size: 14px;
  }
}

/* Tablet styles */
@media (min-width: 481px) and (max-width: 768px) {
  .container {
    padding: 15px;
  }

  .todo-app {
    margin: 40px auto 15px;
    padding: 35px 25px 60px;
    max-width: 90%;
  }

  .todo-app h2 {
    font-size: 22px;
  }

  .row {
    padding-left: 25px;
  }

  input {
    padding: 12px;
    font-size: 15px;
  }

  button {
    padding: 14px 40px;
    font-size: 15px;
  }

  ul li {
    font-size: 16px;
    padding: 14px 8px 14px 48px;
  }

  ul li::before {
    width: 26px;
    height: 26px;
    top: 14px;
  }

  ul li span {
    font-size: 20px;
    width: 38px;
    height: 38px;
    line-height: 38px;
    top: 7px;
  }

  .stats-section,
  .tips-section {
    margin: 25px auto;
    padding: 25px 20px;
    max-width: 90%;
  }

  .stats-grid {
    grid-template-columns: repeat(3, 1fr);
    gap: 12px;
  }
}

/* Desktop styles */
@media (min-width: 769px) and (max-width: 1024px) {
  .container {
    padding: 20px;
  }

  .todo-app {
    margin: 60px auto 20px;
    max-width: 600px;
  }

  .stats-section,
  .tips-section {
    max-width: 600px;
  }

  .stats-grid {
    grid-template-columns: repeat(4, 1fr);
  }
}

/* Large desktop styles */
@media (min-width: 1025px) {
  .container {
    padding: 30px;
    display: flex;
    flex-direction: column;
    align-items: center;
    min-height: 100vh;
  }

  .todo-app {
    margin: 80px auto 20px;
    max-width: 640px;
    padding: 50px 40px 80px;
  }

  .todo-app h2 {
    font-size: 26px;
  }

  button {
    padding: 18px 60px;
    font-size: 17px;
  }

  ul li {
    font-size: 18px;
    padding: 15px 8px 15px 52px;
  }

  ul li::before {
    width: 30px;
    height: 30px;
    top: 15px;
  }

  ul li span {
    font-size: 24px;
    width: 42px;
    height: 42px;
    line-height: 42px;
    top: 6px;
  }

  .stats-section,
  .tips-section {
    max-width: 640px;
    padding: 40px;
  }

  .stats-section h3,
  .tips-section h3 {
    font-size: 22px;
  }

  .stats-grid {
    grid-template-columns: repeat(4, 1fr);
    gap: 20px;
  }

  .stat-item {
    padding: 20px;
  }

  .stat-number {
    font-size: 28px;
  }

  .stat-label {
    font-size: 14px;
  }

  .tip-item {
    padding: 18px;
    font-size: 16px;
  }
}

/* Extra large screens */
@media (min-width: 1200px) {
  .todo-app,
  .stats-section,
  .tips-section {
    max-width: 720px;
  }
}