:root {
  --bg: #f4f5f7;
  --card: #ffffff;
  --text: #1f2933;
  --muted: #7b8794;
  --primary: #4f46e5;
  --primary-dark: #4338ca;
  --border: #e4e7eb;
  --done: #9aa5b1;
  --danger: #e12d39;
  --shadow: 0 10px 30px rgba(15, 23, 42, 0.08);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  display: flex;
  justify-content: center;
  align-items: flex-start;
  padding: 48px 16px;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica,
    Arial, sans-serif;
}

.app {
  width: 100%;
  max-width: 520px;
  background: var(--card);
  border-radius: 16px;
  box-shadow: var(--shadow);
  padding: 28px;
}

.app__header h1 {
  margin: 0;
  font-size: 1.6rem;
}

.app__subtitle {
  margin: 4px 0 20px;
  color: var(--muted);
  font-size: 0.9rem;
}

/* Form */
.todo-form {
  display: flex;
  gap: 8px;
  margin-bottom: 16px;
}

.todo-form__input {
  flex: 1;
  padding: 12px 14px;
  font-size: 1rem;
  border: 1px solid var(--border);
  border-radius: 10px;
  outline: none;
  transition: border-color 0.15s, box-shadow 0.15s;
}

.todo-form__input:focus {
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.15);
}

.todo-form__btn {
  padding: 0 20px;
  font-size: 0.95rem;
  font-weight: 600;
  color: #fff;
  background: var(--primary);
  border: none;
  border-radius: 10px;
  cursor: pointer;
  transition: background 0.15s;
}

.todo-form__btn:hover {
  background: var(--primary-dark);
}

/* Filters */
.filters {
  display: flex;
  gap: 6px;
  margin-bottom: 16px;
}

.filters__btn {
  flex: 1;
  padding: 8px;
  font-size: 0.85rem;
  color: var(--muted);
  background: transparent;
  border: 1px solid var(--border);
  border-radius: 8px;
  cursor: pointer;
  transition: all 0.15s;
}

.filters__btn:hover {
  border-color: var(--primary);
  color: var(--primary);
}

.filters__btn.is-active {
  background: var(--primary);
  border-color: var(--primary);
  color: #fff;
}

/* List */
.todo-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.todo-item {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px 14px;
  border: 1px solid var(--border);
  border-radius: 10px;
  transition: background 0.15s;
}

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

.todo-item__checkbox {
  width: 20px;
  height: 20px;
  flex-shrink: 0;
  cursor: pointer;
  accent-color: var(--primary);
}

.todo-item__text {
  flex: 1;
  font-size: 0.98rem;
  word-break: break-word;
  cursor: pointer;
}

.todo-item.is-done .todo-item__text {
  color: var(--done);
  text-decoration: line-through;
}

.todo-item__delete {
  flex-shrink: 0;
  width: 28px;
  height: 28px;
  display: grid;
  place-items: center;
  font-size: 1.2rem;
  line-height: 1;
  color: var(--muted);
  background: transparent;
  border: none;
  border-radius: 6px;
  cursor: pointer;
  transition: all 0.15s;
}

.todo-item__delete:hover {
  color: var(--danger);
  background: rgba(225, 45, 57, 0.1);
}

.empty-state {
  text-align: center;
  color: var(--muted);
  padding: 24px 0;
  font-size: 0.9rem;
}

/* Footer */
.app__footer {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-top: 20px;
  padding-top: 16px;
  border-top: 1px solid var(--border);
  font-size: 0.85rem;
  color: var(--muted);
}

.link-btn {
  color: var(--muted);
  background: none;
  border: none;
  cursor: pointer;
  font-size: 0.85rem;
  transition: color 0.15s;
}

.link-btn:hover {
  color: var(--danger);
}