:root {
  --bg: #f4f5f7;
  --surface: #ffffff;
  --text: #1f2933;
  --muted: #7b8794;
  --accent: #3b82f6;
  --accent-hover: #2563eb;
  --border: #e4e7eb;
  --done: #9aa5b1;
  --danger: #ef4444;
  --radius: 10px;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.5;
}

.app {
  max-width: 520px;
  margin: 6vh auto 0;
  padding: 24px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: 0 8px 30px rgba(0, 0, 0, 0.06);
}

h1 {
  margin: 0 0 20px;
  font-size: 28px;
  letter-spacing: -0.02em;
}

#todo-form {
  display: flex;
  gap: 8px;
  margin-bottom: 16px;
}

#todo-input {
  flex: 1;
  padding: 10px 12px;
  font-size: 16px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  outline: none;
}

#todo-input:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.15);
}

#todo-form button {
  padding: 10px 18px;
  font-size: 16px;
  font-weight: 600;
  color: #fff;
  background: var(--accent);
  border: none;
  border-radius: var(--radius);
  cursor: pointer;
}

#todo-form button:hover {
  background: var(--accent-hover);
}

.filters {
  display: flex;
  gap: 6px;
  margin-bottom: 12px;
}

.filter {
  padding: 5px 12px;
  font-size: 14px;
  background: transparent;
  border: 1px solid transparent;
  border-radius: 999px;
  color: var(--muted);
  cursor: pointer;
}

.filter:hover {
  color: var(--text);
}

.filter.active {
  color: var(--accent);
  background: rgba(59, 130, 246, 0.1);
  border-color: rgba(59, 130, 246, 0.3);
}

.todo-list {
  list-style: none;
  margin: 0;
  padding: 0;
}

.todo-item {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 4px;
  border-bottom: 1px solid var(--border);
}

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

.todo-item input[type="checkbox"] {
  width: 18px;
  height: 18px;
  flex-shrink: 0;
  cursor: pointer;
  accent-color: var(--accent);
}

.todo-item .text {
  flex: 1;
  font-size: 16px;
  word-break: break-word;
}

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

.todo-item .delete {
  flex-shrink: 0;
  padding: 4px 10px;
  font-size: 14px;
  color: var(--danger);
  background: transparent;
  border: none;
  border-radius: 6px;
  cursor: pointer;
  visibility: hidden;
}

.todo-item:hover .delete,
.todo-item .delete:focus-visible {
  visibility: visible;
}

.todo-item .delete:hover {
  background: rgba(239, 68, 68, 0.1);
}

.statusbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-top: 14px;
  font-size: 14px;
  color: var(--muted);
}

.clear {
  padding: 4px 8px;
  font-size: 14px;
  color: var(--muted);
  background: transparent;
  border: none;
  border-radius: 6px;
  cursor: pointer;
}

.clear:hover {
  color: var(--danger);
  background: rgba(239, 68, 68, 0.1);
}

.empty {
  margin: 24px 0 0;
  text-align: center;
  color: var(--muted);
}