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

body {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  min-height: 100vh;
  color: #333;
  padding: 20px;
}

.container {
  max-width: 500px;
  margin: 40px auto;
  background: white;
  border-radius: 16px;
  box-shadow: 0 15px 35px rgba(0,0,0,0.2);
  overflow: hidden;
}

.header {
  background: #4a6ee0;
  color: white;
  padding: 25px 30px;
  text-align: center;
}

.header h1 {
  font-size: 2rem;
  font-weight: 600;
}

.add-task {
  display: flex;
  padding: 20px;
  background: #f8f9fa;
  border-bottom: 1px solid #eee;
}

.add-task input[type="text"] {
  flex: 1;
  padding: 14px 18px;
  border: 2px solid #ddd;
  border-radius: 12px 0 0 12px;
  font-size: 1.1rem;
  outline: none;
  transition: border-color 0.3s;
}

.add-task input[type="text"]:focus {
  border-color: #4a6ee0;
}

.add-task button {
  padding: 0 24px;
  background: #4a6ee0;
  color: white;
  border: none;
  border-radius: 0 12px 12px 0;
  font-size: 1.1rem;
  cursor: pointer;
  transition: background 0.3s;
}

.add-task button:hover {
  background: #3b5bc5;
}

.todo-list {
  padding: 10px 0;
}

.todo-item {
  display: flex;
  align-items: center;
  padding: 18px 30px;
  border-bottom: 1px solid #f0f0f0;
  transition: all 0.2s;
}

.todo-item:last-child {
  border-bottom: none;
}

.todo-item:hover {
  background: #f8fbff;
}

input[type="checkbox"] {
  width: 22px;
  height: 22px;
  margin-right: 16px;
  accent-color: #4a6ee0;
  cursor: pointer;
}

.todo-text {
  flex: 1;
  font-size: 1.15rem;
  color: #333;
  transition: all 0.3s;
}

input[type="checkbox"]:checked + .todo-text {
  text-decoration: line-through;
  color: #888;
  opacity: 0.8;
}

.delete-btn {
  background: none;
  border: none;
  color: #e74c3c;
  font-size: 1.4rem;
  cursor: pointer;
  padding: 0 8px;
  opacity: 0.7;
  transition: all 0.2s;
}

.delete-btn:hover {
  opacity: 1;
  transform: scale(1.2);
}

.empty-state {
  text-align: center;
  padding: 60px 20px;
  color: #777;
  font-size: 1.2rem;
}