* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
}

body {
  min-height: 100vh;
  background-color: #0a0a0a;
  color: #e0e0e0;
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 2rem;
}

h1 {
  text-align: center;
  margin-bottom: 2rem;
  font-size: 2rem;
  font-weight: 600;
  color: #ffffff;
  text-shadow: 0 2px 4px rgba(0, 0, 0, 0.3);
}

.container {
  width: 100%;
  max-width: 600px;
  background-color: #131313;
  border-radius: 12px;
  padding: 2rem;
  box-shadow: 0 8px 16px rgba(0, 0, 0, 0.2);
}

.add-todo-input {
  width: 100%;
  padding: 0.8rem 1rem;
  margin-bottom: 1.5rem;
  border: none;
  border-radius: 8px;
  background-color: #1e1e1e;
  color: #ffffff;
  font-size: 1rem;
  outline: none;
  transition: all 0.3s ease;
}

.add-todo-input:focus {
  box-shadow: 0 0 0 2px #4a6fa5;
}

.todos-container {
  display: flex;
  flex-direction: column;
  gap: 0.8rem;
}

.todo-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.8rem 1rem;
  background-color: #1e1e1e;
  border-radius: 8px;
  transition: all 0.2s ease;
  cursor: pointer;
}

.todo-item:hover {
  background-color: #252525;
}

.todo-item.completed {
  opacity: 0.8;
}

.todo-item.completed span {
  text-decoration: line-through;
  color: #8a8a8a;
}

.remove-btn {
  padding: 0.4rem 0.8rem;
  border: none;
  border-radius: 6px;
  background-color: #4a4a4a;
  color: #e0e0e0;
  font-size: 0.85rem;
  cursor: pointer;
  transition: all 0.2s ease;
}

.remove-btn:hover {
  background-color: #ff5a5a;
  color: white;
  opacity: 1;
}

.remove-btn:disabled {
  opacity: 0.3;
  cursor: not-allowed;
  background-color: #4a4a4a;
  color: #e0e0e0;
}

@media (max-width: 640px) {
  body {
    padding: 1rem;
  }

  .container {
    padding: 1.5rem;
  }

  h1 {
    font-size: 1.8rem;
  }
}