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

body {
  font-family: Arial, sans-serif;
  background: #f4f7fb;
  color: #222;
  min-height: 100vh;
  display: flex;
  justify-content: center;
  padding: 40px 16px;
}

.app {
  width: 100%;
  max-width: 600px;
  background: #fff;
  padding: 24px;
  border-radius: 16px;
  box-shadow: 0 10px 25px rgba(0, 0, 0, 0.08);
}

h1 {
  margin-bottom: 8px;
  font-size: 2rem;
}

.subtitle {
  color: #666;
  margin-bottom: 24px;
}

#task-form {
  display: flex;
  gap: 12px;
  margin-bottom: 20px;
}

#task-input {
  flex: 1;
  padding: 12px;
  border: 1px solid #ccc;
  border-radius: 10px;
  font-size: 1rem;
}

#task-input:focus {
  outline: 2px solid #4f8cff;
  border-color: #4f8cff;
}

#task-form button,
.filter-btn,
.delete-btn {
  cursor: pointer;
  border: none;
  border-radius: 10px;
  font-size: 0.95rem;
}

#task-form button {
  padding: 12px 18px;
  background: #4f8cff;
  color: white;
}

.filter-section {
  display: flex;
  gap: 10px;
  margin-bottom: 20px;
}

.filter-btn {
  padding: 10px 14px;
  background: #e9eefc;
  color: #333;
}

.filter-btn.active {
  background: #4f8cff;
  color: white;
}

#task-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.task-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
  padding: 14px;
  border: 1px solid #e5e5e5;
  border-radius: 12px;
  background: #fafafa;
}

.task-left {
  display: flex;
  align-items: center;
  gap: 12px;
  flex: 1;
}

.task-text.completed {
  text-decoration: line-through;
  color: #888;
}

.delete-btn {
  background: #ff5c5c;
  color: white;
  padding: 8px 12px;
}

@media (max-width: 600px) {
  #task-form {
    flex-direction: column;
  }

  .filter-section {
    flex-wrap: wrap;
  }

  .task-item {
    align-items: flex-start;
    flex-direction: column;
  }

  .delete-btn {
    align-self: flex-end;
  }
}