/* ==========================================================================
   TaskFlow Pro - Modern Design System & Global Styles
   ========================================================================== */

:root {
  /* Default: Clean & Crisp Light Theme */
  --bg-primary: #f8fafc;
  --bg-secondary: #ffffff;
  --bg-tertiary: #f1f5f9;
  --bg-card: #ffffff;
  --bg-card-hover: #ffffff;
  --bg-glass: rgba(0, 0, 0, 0.02);
  --border-color: #e2e8f0;
  --border-subtle: #edf2f7;
  --border-focus: rgba(79, 70, 229, 0.5);

  --text-primary: #0f172a;
  --text-secondary: #475569;
  --text-muted: #94a3b8;

  /* Brand Accents */
  --primary: #4f46e5;
  --primary-light: #6366f1;
  --primary-dark: #4338ca;
  --primary-glow: rgba(79, 70, 229, 0.2);

  --secondary: #0891b2;
  --secondary-glow: rgba(8, 145, 178, 0.2);

  /* Status Colors */
  --status-todo: #64748b;
  --status-todo-bg: #f1f5f9;
  --status-inprogress: #0284c7;
  --status-inprogress-bg: #e0f2fe;
  --status-inreview: #d97706;
  --status-inreview-bg: #fef3c7;
  --status-done: #059669;
  --status-done-bg: #d1fae5;

  /* Priority Colors */
  --priority-urgent: #dc2626;
  --priority-urgent-bg: #fee2e2;
  --priority-high: #ea580c;
  --priority-high-bg: #ffedd5;
  --priority-medium: #ca8a04;
  --priority-medium-bg: #fef9c3;
  --priority-low: #2563eb;
  --priority-low-bg: #dbeafe;

  /* Typography & Sizing */
  --font-family: 'Prompt', 'Plus Jakarta Sans', system-ui, -apple-system, sans-serif;
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-xl: 24px;
  --radius-full: 9999px;

  --shadow-sm: 0 1px 3px 0 rgba(0, 0, 0, 0.05), 0 1px 2px -1px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.07), 0 2px 4px -2px rgba(0, 0, 0, 0.05);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.08), 0 4px 6px -4px rgba(0, 0, 0, 0.04);
  --shadow-glow: 0 0 20px rgba(79, 70, 229, 0.15);

  --transition-fast: 0.15s ease;
  --transition-normal: 0.25s ease;
  --transition-slow: 0.4s cubic-bezier(0.16, 1, 0.3, 1);
}

/* Dark Theme Overrides */
[data-theme="dark"] {
  --bg-primary: #0b0f19;
  --bg-secondary: #111827;
  --bg-tertiary: #1f2937;
  --bg-card: rgba(17, 24, 39, 0.75);
  --bg-card-hover: rgba(31, 41, 55, 0.85);
  --bg-glass: rgba(255, 255, 255, 0.04);
  --border-color: rgba(255, 255, 255, 0.08);
  --border-subtle: rgba(255, 255, 255, 0.04);
  --border-focus: rgba(99, 102, 241, 0.5);

  --text-primary: #f9fafb;
  --text-secondary: #9ca3af;
  --text-muted: #6b7280;

  --primary: #6366f1;
  --primary-light: #818cf8;
  --primary-dark: #4f46e5;

  --status-todo-bg: rgba(100, 116, 139, 0.15);
  --status-inprogress-bg: rgba(14, 165, 233, 0.15);
  --status-inreview-bg: rgba(245, 158, 11, 0.15);
  --status-done-bg: rgba(16, 185, 129, 0.15);

  --priority-urgent-bg: rgba(239, 68, 68, 0.15);
  --priority-high-bg: rgba(249, 115, 22, 0.15);
  --priority-medium-bg: rgba(234, 179, 8, 0.15);
  --priority-low-bg: rgba(59, 130, 246, 0.15);

  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.4), 0 2px 4px -2px rgba(0, 0, 0, 0.3);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.5), 0 4px 6px -4px rgba(0, 0, 0, 0.4);
}

/* Base Reset */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html, body {
  height: 100%;
  font-family: var(--font-family);
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
  transition: background-color var(--transition-normal), color var(--transition-normal);
}

/* Custom Scrollbar */
::-webkit-scrollbar {
  width: 8px;
  height: 8px;
}
::-webkit-scrollbar-track {
  background: var(--bg-primary);
}
::-webkit-scrollbar-thumb {
  background: #cbd5e1;
  border-radius: var(--radius-full);
}
[data-theme="dark"] ::-webkit-scrollbar-thumb {
  background: var(--bg-tertiary);
}
::-webkit-scrollbar-thumb:hover {
  background: var(--text-muted);
}

/* Ambient Background Glow */
.bg-ambient-glow {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  pointer-events: none;
  z-index: 0;
  overflow: hidden;
}
.glow-orb-1 {
  position: absolute;
  top: -10%;
  right: 5%;
  width: 550px;
  height: 550px;
  background: radial-gradient(circle, rgba(79, 70, 229, 0.07) 0%, rgba(79, 70, 229, 0) 70%);
  border-radius: 50%;
  filter: blur(45px);
}
.glow-orb-2 {
  position: absolute;
  bottom: 5%;
  left: -5%;
  width: 500px;
  height: 500px;
  background: radial-gradient(circle, rgba(8, 145, 178, 0.06) 0%, rgba(8, 145, 178, 0) 70%);
  border-radius: 50%;
  filter: blur(45px);
}

/* App Container */
.app-container {
  position: relative;
  z-index: 1;
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

/* ==========================================================================
   Header & Navigation
   ========================================================================== */
.header {
  position: sticky;
  top: 0;
  z-index: 100;
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  background: rgba(255, 255, 255, 0.88);
  border-bottom: 1px solid var(--border-color);
  padding: 0.75rem 1.5rem;
  box-shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.03);
  transition: all var(--transition-normal);
}
[data-theme="dark"] .header {
  background: rgba(11, 15, 25, 0.85);
}

.header-inner {
  max-width: 1600px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.brand-logo {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  text-decoration: none;
  color: var(--text-primary);
  font-weight: 700;
  font-size: 1.25rem;
  letter-spacing: -0.02em;
}
.brand-icon {
  width: 36px;
  height: 36px;
  background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  color: #ffffff;
  box-shadow: 0 4px 12px var(--primary-glow);
}
.brand-badge {
  font-size: 0.7rem;
  font-weight: 600;
  padding: 2px 8px;
  background: #ede9fe;
  color: var(--primary);
  border-radius: var(--radius-sm);
  border: 1px solid #ddd6fe;
}
[data-theme="dark"] .brand-badge {
  background: var(--bg-tertiary);
  color: var(--primary-light);
  border-color: var(--border-color);
}

/* View Mode Nav Tabs */
.nav-tabs {
  display: flex;
  align-items: center;
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 4px;
  gap: 4px;
}
.nav-tab-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.45rem 1rem;
  border-radius: var(--radius-md);
  border: none;
  background: transparent;
  color: var(--text-secondary);
  font-family: inherit;
  font-size: 0.875rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-fast);
  white-space: nowrap;
}
.nav-tab-btn:hover {
  color: var(--text-primary);
  background: rgba(0, 0, 0, 0.04);
}
[data-theme="dark"] .nav-tab-btn:hover {
  background: var(--bg-glass);
}
.nav-tab-btn.active {
  background: var(--bg-secondary);
  color: var(--primary);
  box-shadow: var(--shadow-sm);
}
[data-theme="dark"] .nav-tab-btn.active {
  background: var(--primary);
  color: #ffffff;
  box-shadow: 0 2px 8px var(--primary-glow);
}

/* Header Action Controls */
.header-actions {
  display: flex;
  align-items: center;
  gap: 0.6rem;
}

.sync-status-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.35rem 0.75rem;
  border-radius: var(--radius-full);
  font-size: 0.8rem;
  font-weight: 600;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  color: var(--text-secondary);
  cursor: pointer;
  box-shadow: var(--shadow-sm);
  transition: all var(--transition-fast);
}
.sync-status-badge:hover {
  border-color: var(--border-focus);
}
.sync-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: #10b981;
  box-shadow: 0 0 6px #10b981;
}
.sync-dot.offline {
  background: #94a3b8;
  box-shadow: none;
}
.sync-dot.syncing {
  background: #f59e0b;
  animation: pulse-sync 1.5s infinite;
}

@keyframes pulse-sync {
  0%, 100% { opacity: 1; transform: scale(1); }
  50% { opacity: 0.4; transform: scale(1.2); }
}

/* Standard Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.45rem;
  padding: 0.5rem 1rem;
  border-radius: var(--radius-md);
  font-family: inherit;
  font-size: 0.875rem;
  font-weight: 600;
  cursor: pointer;
  border: 1px solid transparent;
  transition: all var(--transition-fast);
  text-decoration: none;
}
.btn-primary {
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
  color: #ffffff;
  box-shadow: 0 2px 6px var(--primary-glow);
}
.btn-primary:hover {
  transform: translateY(-1px);
  box-shadow: 0 4px 12px var(--primary-glow);
}
.btn-secondary {
  background: var(--bg-secondary);
  border-color: var(--border-color);
  color: var(--text-primary);
  box-shadow: var(--shadow-sm);
}
.btn-secondary:hover {
  background: var(--bg-tertiary);
  border-color: #cbd5e1;
}
.btn-icon {
  width: 38px;
  height: 38px;
  padding: 0;
  border-radius: var(--radius-md);
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  color: var(--text-secondary);
  box-shadow: var(--shadow-sm);
}
.btn-icon:hover {
  color: var(--text-primary);
  background: var(--bg-tertiary);
}
.btn-sm {
  padding: 0.35rem 0.65rem;
  font-size: 0.8rem;
}
.btn-danger {
  background: #fee2e2;
  color: #dc2626;
  border-color: #fca5a5;
}
.btn-danger:hover {
  background: #dc2626;
  color: #ffffff;
}

/* ==========================================================================
   Main Content Layout
   ========================================================================== */
.main-content {
  flex: 1;
  max-width: 1600px;
  width: 100%;
  margin: 0 auto;
  padding: 1.5rem;
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.view-section {
  display: none;
  animation: fadeIn 0.25s ease-out;
}
.view-section.active {
  display: block;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(6px); }
  to { opacity: 1; transform: translateY(0); }
}

/* ==========================================================================
   To-Do List View Toolbar & Filters
   ========================================================================== */
.toolbar-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 1.25rem;
  display: flex;
  flex-direction: column;
  gap: 1rem;
  box-shadow: var(--shadow-sm);
}

.quick-add-form {
  display: flex;
  gap: 0.75rem;
  align-items: center;
}
.quick-input-group {
  flex: 1;
  position: relative;
}
.form-input {
  width: 100%;
  padding: 0.65rem 1rem;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  color: var(--text-primary);
  font-family: inherit;
  font-size: 0.9rem;
  transition: all var(--transition-fast);
}
.form-input:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px var(--primary-glow);
}

.filter-bar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  border-top: 1px solid var(--border-color);
  padding-top: 1rem;
}

.filter-group {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  flex-wrap: wrap;
}

.select-input {
  padding: 0.5rem 0.85rem;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  color: var(--text-primary);
  font-family: inherit;
  font-size: 0.85rem;
  cursor: pointer;
  outline: none;
}
.select-input:focus {
  border-color: var(--primary);
}

.search-box {
  position: relative;
  min-width: 220px;
}
.search-box .form-input {
  padding-left: 2.2rem;
}
.search-icon {
  position: absolute;
  left: 0.75rem;
  top: 50%;
  transform: translateY(-50%);
  color: var(--text-muted);
  pointer-events: none;
}

/* Batch Action Bar */
.batch-bar {
  display: none;
  align-items: center;
  justify-content: space-between;
  background: #ede9fe;
  border: 1px solid #c4b5fd;
  padding: 0.65rem 1.25rem;
  border-radius: var(--radius-md);
}
[data-theme="dark"] .batch-bar {
  background: linear-gradient(90deg, rgba(99, 102, 241, 0.2), rgba(6, 182, 212, 0.2));
  border-color: var(--primary-glow);
}
.batch-bar.show {
  display: flex;
}

/* ==========================================================================
   Task Items & Cards (List View)
   ========================================================================== */
.task-list {
  display: flex;
  flex-direction: column;
  gap: 0.65rem;
}

.task-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 0.9rem 1.25rem;
  box-shadow: var(--shadow-sm);
  transition: all var(--transition-fast);
}
.task-item:hover {
  border-color: #cbd5e1;
  box-shadow: var(--shadow-md);
  transform: translateX(2px);
}
[data-theme="dark"] .task-item:hover {
  background: var(--bg-card-hover);
  border-color: rgba(255, 255, 255, 0.15);
}
.task-item.completed {
  opacity: 0.7;
  background: #f0fdf4;
}
[data-theme="dark"] .task-item.completed {
  background: rgba(16, 185, 129, 0.04);
}
.task-item.completed .task-title {
  text-decoration: line-through;
  color: var(--text-muted);
}

.task-left {
  display: flex;
  align-items: center;
  gap: 0.9rem;
  flex: 1;
  min-width: 0;
}

.task-checkbox {
  width: 20px;
  height: 20px;
  border-radius: 6px;
  border: 2px solid #94a3b8;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: all var(--transition-fast);
  background: transparent;
  flex-shrink: 0;
}
.task-checkbox.checked {
  background: var(--status-done);
  border-color: var(--status-done);
  color: #ffffff;
}

.task-info {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
  min-width: 0;
}
.task-title {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text-primary);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  cursor: pointer;
}
.task-meta {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  flex-wrap: wrap;
  font-size: 0.8rem;
  color: var(--text-muted);
}

.task-right {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  flex-shrink: 0;
}

/* Badges & Tags */
.badge {
  display: inline-flex;
  align-items: center;
  gap: 0.3rem;
  padding: 2px 8px;
  border-radius: var(--radius-full);
  font-size: 0.75rem;
  font-weight: 600;
}
.badge-priority-urgent {
  background: var(--priority-urgent-bg);
  color: var(--priority-urgent);
  border: 1px solid rgba(220, 38, 38, 0.25);
}
.badge-priority-high {
  background: var(--priority-high-bg);
  color: var(--priority-high);
  border: 1px solid rgba(234, 88, 12, 0.25);
}
.badge-priority-medium {
  background: var(--priority-medium-bg);
  color: var(--priority-medium);
  border: 1px solid rgba(202, 138, 4, 0.25);
}
.badge-priority-low {
  background: var(--priority-low-bg);
  color: var(--priority-low);
  border: 1px solid rgba(37, 99, 235, 0.25);
}

.badge-status-todo {
  background: var(--status-todo-bg);
  color: var(--status-todo);
  border: 1px solid var(--border-color);
}
.badge-status-inprogress {
  background: var(--status-inprogress-bg);
  color: var(--status-inprogress);
}
.badge-status-inreview {
  background: var(--status-inreview-bg);
  color: var(--status-inreview);
}
.badge-status-done {
  background: var(--status-done-bg);
  color: var(--status-done);
}

.badge-tag {
  background: var(--bg-tertiary);
  color: var(--text-secondary);
  border: 1px solid var(--border-color);
}

.badge-deadline {
  background: var(--bg-secondary);
  color: var(--text-secondary);
  border: 1px solid var(--border-color);
}
.badge-deadline.overdue {
  background: #fee2e2;
  color: #dc2626;
  border-color: #fca5a5;
  font-weight: 700;
}
.badge-deadline.today {
  background: #ffedd5;
  color: #ea580c;
  border-color: #fdba74;
}

/* Empty State */
.empty-state {
  text-align: center;
  padding: 3.5rem 1rem;
  background: var(--bg-card);
  border: 1px dashed var(--border-color);
  border-radius: var(--radius-lg);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.75rem;
}
.empty-icon {
  font-size: 3rem;
  margin-bottom: 0.5rem;
}

/* ==========================================================================
   Modals
   ========================================================================== */
.modal-overlay {
  position: fixed;
  inset: 0;
  z-index: 999;
  background: rgba(15, 23, 42, 0.5);
  backdrop-filter: blur(4px);
  -webkit-backdrop-filter: blur(4px);
  display: none;
  align-items: center;
  justify-content: center;
  padding: 1rem;
  animation: fadeIn 0.2s ease-out;
}
.modal-overlay.active {
  display: flex;
}

.modal-container {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  width: 100%;
  max-width: 650px;
  max-height: 90vh;
  display: flex;
  flex-direction: column;
  box-shadow: var(--shadow-lg);
  overflow: hidden;
}
.modal-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1.25rem 1.5rem;
  border-bottom: 1px solid var(--border-color);
  background: var(--bg-secondary);
}
.modal-title {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--text-primary);
}
.modal-body {
  padding: 1.5rem;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}
.modal-footer {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: 0.75rem;
  padding: 1rem 1.5rem;
  border-top: 1px solid var(--border-color);
  background: var(--bg-tertiary);
}

.form-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1rem;
}
.form-group-full {
  grid-column: span 2;
}
.form-label {
  display: block;
  font-size: 0.825rem;
  font-weight: 600;
  color: var(--text-secondary);
  margin-bottom: 0.35rem;
}
.form-textarea {
  width: 100%;
  padding: 0.65rem 1rem;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  color: var(--text-primary);
  font-family: inherit;
  font-size: 0.9rem;
  resize: vertical;
  min-height: 80px;
}
.form-textarea:focus {
  outline: none;
  border-color: var(--primary);
}

/* Subtask Manager in Modal */
.subtasks-box {
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 0.85rem;
}
.subtask-add-row {
  display: flex;
  gap: 0.5rem;
  margin-bottom: 0.75rem;
}
.subtask-items-list {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}
.subtask-item-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  padding: 0.4rem 0.75rem;
  border-radius: var(--radius-sm);
  font-size: 0.85rem;
}

/* Toast Notifications */
.toast-container {
  position: fixed;
  bottom: 1.5rem;
  right: 1.5rem;
  z-index: 10000;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  pointer-events: none;
}
.toast {
  background: #0f172a;
  color: #ffffff;
  box-shadow: var(--shadow-lg);
  padding: 0.75rem 1.25rem;
  border-radius: var(--radius-md);
  font-size: 0.875rem;
  display: flex;
  align-items: center;
  gap: 0.6rem;
  pointer-events: auto;
  animation: slideInUp 0.3s cubic-bezier(0.16, 1, 0.3, 1);
}
@keyframes slideInUp {
  from { opacity: 0; transform: translateY(12px); }
  to { opacity: 1; transform: translateY(0); }
}

/* Responsive adjustments */
@media (max-width: 1024px) {
  .header-inner {
    flex-wrap: wrap;
  }
  .nav-tabs {
    order: 3;
    width: 100%;
    overflow-x: auto;
  }
}
@media (max-width: 768px) {
  .form-grid {
    grid-template-columns: 1fr;
  }
  .form-group-full {
    grid-column: span 1;
  }
  .task-item {
    flex-direction: column;
    align-items: flex-start;
  }
  .task-right {
    width: 100%;
    justify-content: space-between;
  }
}