:root {
  --bg: #0f172a;
  --surface: #1e293b;
  --surface-2: #273449;
  --border: #334155;
  --text: #e2e8f0;
  --muted: #94a3b8;
  --primary: #2563eb;
  --primary-hover: #1d4ed8;
  --danger: #ef4444;
  --done: #22c55e;
  --radius: 10px;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
}

.screen { min-height: 100vh; }
[hidden] { display: none !important; }

/* Sign-in screen */
#signin-screen {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px;
}
.signin-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 32px 28px;
  max-width: 360px;
  width: 100%;
  text-align: center;
}
.signin-card h1 { margin: 0 0 8px; font-size: 24px; }
.muted { color: var(--muted); font-size: 14px; }
.error-text { color: var(--danger); font-size: 13px; margin-top: 12px; }

.btn {
  border: none;
  border-radius: 8px;
  padding: 10px 16px;
  font-size: 14px;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  transition: background 0.15s ease;
}
.btn-primary { background: var(--primary); color: white; }
.btn-primary:hover { background: var(--primary-hover); }
.btn-google { background: white; color: #1f2937; width: 100%; justify-content: center; margin-top: 20px; padding: 12px; font-weight: 500; }
.btn-google:hover { background: #f1f5f9; }
.btn-ghost { background: transparent; color: var(--muted); border: 1px solid var(--border); }
.btn-ghost:hover { color: var(--text); border-color: var(--muted); }
.btn-small { background: var(--surface-2); color: var(--text); padding: 6px 12px; font-size: 13px; }
.btn-small:hover { background: var(--border); }
.btn-tiny { background: transparent; color: var(--muted); padding: 4px 10px; font-size: 12px; }
.btn-tiny:hover { color: var(--text); }

/* Top bar */
.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 20px;
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  background: var(--bg);
  z-index: 10;
}
.topbar h1 { font-size: 20px; margin: 0; }
.topbar-right { display: flex; align-items: center; gap: 12px; font-size: 13px; }

/* Categories */
.categories-container {
  max-width: 720px;
  margin: 0 auto;
  padding: 16px;
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.category {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 14px 16px;
}
.category-header {
  display: flex;
  align-items: center;
  gap: 8px;
}
.category-title {
  flex: 1;
  font-size: 17px;
  font-weight: 600;
  margin: 0;
  outline: none;
  padding: 2px 4px;
  border-radius: 4px;
}
.category-title[contenteditable="true"] { background: var(--surface-2); }
.collapse-btn {
  background: none;
  border: none;
  color: var(--muted);
  font-size: 14px;
  cursor: pointer;
  width: 22px;
}
.category.collapsed .tasks-list,
.category.collapsed .add-task-form { display: none; }
.category.collapsed .collapse-btn { transform: rotate(-90deg); }

.icon-btn {
  background: none;
  border: none;
  color: var(--muted);
  cursor: pointer;
  font-size: 13px;
  padding: 4px 6px;
  border-radius: 4px;
  line-height: 1;
}
.icon-btn:hover { color: var(--danger); background: rgba(239,68,68,0.1); }

.tasks-list { margin-top: 10px; display: flex; flex-direction: column; gap: 8px; }

.task {
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 8px 10px;
}
.task-header { display: flex; align-items: center; gap: 8px; }
.task-title {
  flex: 1;
  font-size: 14.5px;
  outline: none;
  padding: 2px 4px;
  border-radius: 4px;
}
.task-title[contenteditable="true"] { background: var(--surface); }
.task.done .task-title { text-decoration: line-through; color: var(--muted); }

.subtasks-list { margin: 6px 0 0 26px; display: flex; flex-direction: column; gap: 4px; }
.subtask { display: flex; align-items: center; gap: 8px; }
.subtask-title { flex: 1; font-size: 13.5px; outline: none; padding: 1px 4px; border-radius: 4px; }
.subtask-title[contenteditable="true"] { background: var(--surface); }
.subtask.done .subtask-title { text-decoration: line-through; color: var(--muted); }

input[type="checkbox"] {
  width: 17px;
  height: 17px;
  accent-color: var(--done);
  cursor: pointer;
  flex-shrink: 0;
}

/* Forms */
.add-category-form {
  max-width: 720px;
  margin: 0 auto 24px;
  padding: 0 16px;
  display: flex;
  gap: 8px;
}
.add-task-form, .add-subtask-form {
  display: flex;
  gap: 6px;
  margin-top: 8px;
}
.add-subtask-form { margin-left: 26px; }

input[type="text"] {
  flex: 1;
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 8px 10px;
  color: var(--text);
  font-size: 14px;
}
input[type="text"]:focus { outline: none; border-color: var(--primary); }

@media (max-width: 480px) {
  .topbar h1 { font-size: 17px; }
  #user-email { display: none; }
}