:root {
  --primary: #2563eb;
  --primary-dark: #1d4ed8;
  --bg: #f4f6f9;
  --card-bg: #ffffff;
  --text: #1f2937;
  --muted: #6b7280;
  --border: #e5e7eb;
  --danger: #dc2626;
  --success: #16a34a;
  --warning: #d97706;
  --sunday: #eff6ff;
}

* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
}

.screen { min-height: 100vh; }

/* Login */
#login-screen {
  display: flex;
  align-items: center;
  justify-content: center;
}
.login-card {
  background: var(--card-bg);
  padding: 40px;
  border-radius: 12px;
  box-shadow: 0 10px 30px rgba(0,0,0,0.08);
  width: 100%;
  max-width: 360px;
}
.login-card h1 { margin: 0 0 4px; color: var(--primary); }
.subtitle { color: var(--muted); margin-top: 0; margin-bottom: 24px; font-size: 14px; }
.login-card label { display: block; font-size: 13px; margin: 12px 0 4px; color: var(--muted); }
.login-card input {
  width: 100%; padding: 10px 12px; border: 1px solid var(--border); border-radius: 8px; font-size: 14px;
}
.login-card button {
  margin-top: 20px; width: 100%; padding: 11px; border: none; border-radius: 8px;
  background: var(--primary); color: white; font-size: 15px; font-weight: 600; cursor: pointer;
}
.login-card button:hover { background: var(--primary-dark); }
.error-msg { color: var(--danger); font-size: 13px; margin-top: 10px; min-height: 16px; }

/* App layout */
.topbar {
  display: flex; align-items: center; justify-content: space-between;
  background: var(--card-bg); padding: 12px 24px; border-bottom: 1px solid var(--border);
  flex-wrap: wrap; gap: 12px;
}
.brand { font-weight: 700; font-size: 18px; color: var(--primary); }
#main-nav { display: flex; gap: 8px; flex-wrap: wrap; }
.nav-btn {
  border: none; background: transparent; padding: 8px 14px; border-radius: 8px; cursor: pointer;
  font-size: 14px; color: var(--muted); font-weight: 500;
}
.nav-btn.active, .nav-btn:hover { background: var(--bg); color: var(--primary); }
.user-box { display: flex; align-items: center; gap: 12px; font-size: 14px; }
#logout-btn { border: none; background: var(--bg); padding: 6px 12px; border-radius: 8px; cursor: pointer; }

#main-content { max-width: 900px; margin: 0 auto; padding: 24px; }

.cards { display: flex; gap: 16px; flex-wrap: wrap; }
.card {
  flex: 1; min-width: 140px; background: var(--card-bg); border-radius: 12px; padding: 20px;
  text-align: center; box-shadow: 0 1px 3px rgba(0,0,0,0.06);
}
.card-num { font-size: 32px; font-weight: 700; }
.card-label { color: var(--muted); font-size: 13px; margin-top: 4px; }
.card-pending .card-num { color: var(--primary); }
.card-overdue .card-num { color: var(--danger); }
.card-done .card-num { color: var(--success); }

.view-header { display: flex; justify-content: space-between; align-items: center; margin-bottom: 16px; flex-wrap: wrap; gap: 10px; }
.view-header-actions { display: flex; gap: 10px; align-items: center; }
a.btn-secondary { text-decoration: none; display: inline-block; }
.btn-primary {
  background: var(--primary); color: white; border: none; padding: 9px 16px; border-radius: 8px;
  cursor: pointer; font-size: 14px; font-weight: 600;
}
.btn-primary:hover { background: var(--primary-dark); }
.btn-secondary {
  background: var(--bg); color: var(--text); border: 1px solid var(--border); padding: 9px 16px;
  border-radius: 8px; cursor: pointer; font-size: 14px;
}
.btn-danger { color: var(--danger); background: none; border: none; cursor: pointer; font-size: 13px; }

.tasks-list { display: flex; flex-direction: column; gap: 10px; }
.task-item { background: var(--card-bg); border-radius: 10px; padding: 14px 16px; box-shadow: 0 1px 3px rgba(0,0,0,0.05); }
.task-item.overdue { border-left: 4px solid var(--danger); }
.task-item.done { opacity: 0.6; }
.task-top { display: flex; align-items: center; gap: 10px; }
.task-top input[type=checkbox] { width: 18px; height: 18px; }
.task-title { font-weight: 600; flex: 1; }
.task-title.done-text { text-decoration: line-through; color: var(--muted); }
.task-meta { font-size: 12px; color: var(--muted); margin-top: 2px; }
.task-badge { font-size: 11px; padding: 2px 8px; border-radius: 20px; background: var(--bg); color: var(--muted); }
.task-badge.overdue { background: #fee2e2; color: var(--danger); }
.subtasks { margin: 8px 0 0 28px; display: flex; flex-direction: column; gap: 4px; }
.subtask-row { display: flex; align-items: center; gap: 8px; font-size: 13px; }
.subtask-row.done span { text-decoration: line-through; color: var(--muted); }
.task-desc { font-size: 13px; color: var(--muted); margin: 6px 0 0 28px; }
.task-actions { margin-top: 8px; margin-left: 28px; }

.admin-table { width: 100%; border-collapse: collapse; background: var(--card-bg); border-radius: 10px; overflow: hidden; }
.admin-table th, .admin-table td { text-align: left; padding: 10px 14px; border-bottom: 1px solid var(--border); font-size: 13px; }
.admin-table th { color: var(--muted); font-weight: 600; background: var(--bg); }

/* Modal */
.modal-overlay {
  position: fixed; inset: 0; background: rgba(0,0,0,0.4); display: flex;
  align-items: center; justify-content: center; z-index: 50; padding: 16px;
}
.modal {
  background: var(--card-bg); border-radius: 12px; padding: 24px; width: 100%; max-width: 440px;
  max-height: 90vh; overflow-y: auto;
}
.modal h3 { margin-top: 0; }
.modal label { display: block; font-size: 13px; color: var(--muted); margin: 12px 0 4px; }
.modal input, .modal select, .modal textarea {
  width: 100%; padding: 9px 10px; border: 1px solid var(--border); border-radius: 8px; font-size: 14px; font-family: inherit;
}
.modal-actions { display: flex; justify-content: flex-end; gap: 10px; margin-top: 20px; }
.subtask-input-row { display: flex; gap: 6px; margin-top: 6px; }
.subtask-input-row input { flex: 1; }
.subtask-input-row button { border: none; background: var(--bg); border-radius: 6px; padding: 0 10px; cursor: pointer; font-size: 16px; line-height: 1; }
#tf-subtasks-list { margin-top: 6px; }
.subtask-add-btn { margin-top: 8px; background: none; border: 1px dashed var(--border); border-radius: 8px; padding: 6px 12px; font-size: 13px; color: var(--primary); cursor: pointer; width: 100%; }

@media (max-width: 640px) {
  .topbar { flex-direction: column; align-items: stretch; }
  #main-nav { justify-content: center; }
  .user-box { justify-content: center; }
}