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

body {
  font-family: 'Roboto', 'Open Sans', Arial, sans-serif;
  background: #f4f4f9;
  min-height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  padding: 20px;
}

#app {
  background: #fff;
  border-radius: 12px;
  padding: 30px;
  width: 100%;
  max-width: 480px;
  box-shadow: 0 10px 40px rgba(0, 0, 0, 0.15);
}

h1 {
  text-align: center;
  color: #333;
  margin-bottom: 20px;
  font-weight: 600;
}

.todo-input {
  display: flex;
  gap: 10px;
  margin-bottom: 20px;
}

#taskInput {
  flex: 1;
  padding: 10px 14px;
  border: 2px solid #e0e0e0;
  border-radius: 8px;
  font-size: 16px;
  outline: none;
  transition: border-color 0.3s;
}

#taskInput:focus {
  border-color: #2196f3;
}

#addBtn {
  padding: 10px 20px;
  background: #2196f3;
  color: #fff;
  border: none;
  border-radius: 8px;
  font-size: 16px;
  cursor: pointer;
  transition: background 0.3s;
}

#addBtn:hover {
  background: #1976d2;
}

#taskList {
  list-style: none;
}

#taskList li {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 12px 14px;
  border: 1px solid #f0f0f0;
  border-radius: 8px;
  margin-bottom: 8px;
  background: #fafafa;
  transition: background 0.2s;
}

#taskList li:hover {
  background: #f0f6ff;
}

#taskList li .task-text {
  flex: 1;
  cursor: pointer;
}

#taskList li .task-text.completed {
  text-decoration: line-through;
  color: #999;
}

#taskList li .delete-btn {
  background: none;
  border: none;
  color: #e74c3c;
  font-size: 18px;
  cursor: pointer;
  padding: 0 4px;
  transition: color 0.2s;
}

#taskList li .delete-btn:hover {
  color: #c0392b;
}

.filters {
  display: flex;
  gap: 8px;
  margin-top: 20px;
}

.filter-btn {
  flex: 1;
  padding: 8px 0;
  background: #f0f0f0;
  color: #555;
  border: none;
  border-radius: 8px;
  font-size: 14px;
  cursor: pointer;
  transition: background 0.2s, color 0.2s;
}

.filter-btn:hover {
  background: #e0e0e0;
}

.filter-btn.active {
  background: #2196f3;
  color: #fff;
}