:root {
  --bg-primary: #ffffff;
  --bg-secondary: #f8fafc;
  --bg-tertiary: #f1f5f9;
  --bg-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  --text-primary: #1e293b;
  --text-secondary: #64748b;
  --text-muted: #94a3b8;
  --border-color: #e2e8f0;
  --border-focus: #3b82f6;
  --shadow: rgba(0, 0, 0, 0.08);
  --shadow-hover: rgba(0, 0, 0, 0.12);
  --shadow-lg: rgba(0, 0, 0, 0.15);
  --priority-low: #10b981;
  --priority-medium: #f59e0b;
  --priority-high: #ef4444;
  --success: #10b981;
  --warning: #f59e0b;
  --danger: #ef4444;
  --info: #06b6d4;
  --spacing-xs: 0.25rem;
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --spacing-lg: 1.5rem;
  --spacing-xl: 2rem;
  --spacing-2xl: 3rem;
  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  --transition-fast: 0.15s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-normal: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 0.5s cubic-bezier(0.4, 0, 0.2, 1);
}

[data-theme="dark"] {
  --bg-primary: #0f172a;
  --bg-secondary: #1e293b;
  --bg-tertiary: #334155;
  --bg-gradient: linear-gradient(135deg, #1e3a8a 0%, #7c3aed 100%);
  --text-primary: #f8fafc;
  --text-secondary: #cbd5e1;
  --text-muted: #94a3b8;
  --border-color: #334155;
  --border-focus: #60a5fa;
  --shadow: rgba(0, 0, 0, 0.3);
  --shadow-hover: rgba(0, 0, 0, 0.4);
  --shadow-lg: rgba(0, 0, 0, 0.5);
}

[data-theme="dark"] .add-task-form,
[data-theme="dark"] .task-item,
[data-theme="dark"] .modal-content {
  background: rgba(15, 23, 42, 0.95);
  border-color: rgba(255, 255, 255, 0.1);
}

[data-theme="dark"] .header,
[data-theme="dark"] .empty-state,
[data-theme="dark"] .stats-footer,
[data-theme="dark"] .filter-buttons {
  background: rgba(15, 23, 42, 0.1);
  border-color: rgba(255, 255, 255, 0.1);
}

[data-theme="dark"] input,
[data-theme="dark"] select {
  background: rgba(15, 23, 42, 0.9);
  border-color: rgba(255, 255, 255, 0.2);
}

[data-theme="dark"] input:focus,
[data-theme="dark"] select:focus {
  background: rgba(15, 23, 42, 1);
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen,
    Ubuntu, Cantarell, sans-serif;
  line-height: 1.6;
  color: var(--text-primary);
  background: var(--bg-gradient);
  background-attachment: fixed;
  min-height: 100vh;
  transition: all var(--transition-normal);
}

.container {
  max-width: 600px;
  margin: 0 auto;
  padding: var(--spacing-lg);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  position: relative;
}

.container::before {
  content: "";
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: var(--bg-gradient);
  opacity: 0.1;
  z-index: -1;
}

.header {
  text-align: center;
  margin-bottom: var(--spacing-2xl);
  background: rgba(255, 255, 255, 0.1);
  backdrop-filter: blur(10px);
  border-radius: var(--radius-xl);
  padding: var(--spacing-xl);
  border: 1px solid rgba(255, 255, 255, 0.2);
  box-shadow: 0 8px 32px var(--shadow-lg);
}

.app-title {
  font-size: 3rem;
  font-weight: 800;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: var(--spacing-sm);
  text-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

.task-counter {
  font-size: 1.1rem;
  color: var(--text-secondary);
  font-weight: 600;
  background: rgba(255, 255, 255, 0.1);
  padding: var(--spacing-sm) var(--spacing-md);
  border-radius: var(--radius-lg);
  display: inline-block;
}

.add-task-section {
  margin-bottom: var(--spacing-xl);
}

.add-task-form {
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(20px);
  border-radius: var(--radius-xl);
  padding: var(--spacing-xl);
  box-shadow: 0 20px 40px var(--shadow-lg);
  border: 1px solid rgba(255, 255, 255, 0.3);
  transition: all var(--transition-normal);
}

.add-task-form:hover {
  transform: translateY(-2px);
  box-shadow: 0 25px 50px var(--shadow-lg);
}

.input-group {
  display: flex;
  gap: var(--spacing-sm);
  flex-wrap: wrap;
  align-items: center;
}

.input-group input,
.input-group select {
  flex: 1;
  min-width: 120px;
}

.input-group input[type="date"] {
  min-width: 140px;
}

.input-group select {
  min-width: 100px;
}

input,
select,
button {
  font-family: inherit;
  font-size: 1rem;
  border: 2px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: var(--spacing-md) var(--spacing-lg);
  background: rgba(255, 255, 255, 0.9);
  color: var(--text-primary);
  transition: all var(--transition-fast);
  font-weight: 500;
}

input:focus,
select:focus {
  outline: none;
  border-color: var(--border-focus);
  box-shadow: 0 0 0 4px rgba(59, 130, 246, 0.1);
  background: rgba(255, 255, 255, 1);
  transform: translateY(-1px);
}

input::placeholder {
  color: var(--text-muted);
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-sm);
  padding: var(--spacing-md) var(--spacing-lg);
  border: 2px solid transparent;
  border-radius: var(--radius-lg);
  font-size: 1rem;
  font-weight: 600;
  text-decoration: none;
  cursor: pointer;
  transition: all var(--transition-fast);
  white-space: nowrap;
  position: relative;
  overflow: hidden;
}

.btn::before {
  content: "";
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(
    90deg,
    transparent,
    rgba(255, 255, 255, 0.2),
    transparent
  );
  transition: left var(--transition-normal);
}

.btn:hover::before {
  left: 100%;
}

.btn:disabled {
  opacity: 0.6;
  cursor: not-allowed;
}

.btn-primary {
  background: linear-gradient(135deg, #3b82f6 0%, #1d4ed8 100%);
  color: white;
  border-color: #3b82f6;
  box-shadow: 0 4px 15px rgba(59, 130, 246, 0.3);
}

.btn-primary:hover:not(:disabled) {
  background: linear-gradient(135deg, #2563eb 0%, #1e40af 100%);
  border-color: #2563eb;
  transform: translateY(-2px);
  box-shadow: 0 8px 25px rgba(59, 130, 246, 0.4);
}

.btn-secondary {
  background: rgba(255, 255, 255, 0.1);
  color: var(--text-primary);
  border-color: rgba(255, 255, 255, 0.3);
  backdrop-filter: blur(10px);
}

.btn-secondary:hover:not(:disabled) {
  background: rgba(255, 255, 255, 0.2);
  border-color: rgba(255, 255, 255, 0.4);
  transform: translateY(-2px);
}

.btn-danger {
  background: linear-gradient(135deg, #ef4444 0%, #dc2626 100%);
  color: white;
  border-color: #ef4444;
  box-shadow: 0 4px 15px rgba(239, 68, 68, 0.3);
}

.btn-danger:hover:not(:disabled) {
  background: linear-gradient(135deg, #dc2626 0%, #b91c1c 100%);
  border-color: #dc2626;
  transform: translateY(-2px);
  box-shadow: 0 8px 25px rgba(239, 68, 68, 0.4);
}

.btn-icon {
  padding: var(--spacing-md);
  background: rgba(255, 255, 255, 0.1);
  border: 2px solid rgba(255, 255, 255, 0.3);
  backdrop-filter: blur(10px);
  border-radius: 50%;
  width: 48px;
  height: 48px;
}

.btn-icon:hover:not(:disabled) {
  background: rgba(255, 255, 255, 0.2);
  border-color: rgba(255, 255, 255, 0.4);
  transform: scale(1.1);
}

.btn-text {
  display: none;
}

@media (min-width: 480px) {
  .btn-text {
    display: inline;
  }
}

.controls-section {
  margin-bottom: var(--spacing-xl);
}

.filters {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-md);
  margin-bottom: var(--spacing-lg);
}

@media (min-width: 480px) {
  .filters {
    flex-direction: row;
    align-items: center;
    justify-content: space-between;
  }
}

.filter-buttons {
  display: flex;
  background: rgba(255, 255, 255, 0.1);
  backdrop-filter: blur(10px);
  border-radius: var(--radius-xl);
  padding: var(--spacing-sm);
  box-shadow: 0 8px 32px var(--shadow-lg);
  border: 1px solid rgba(255, 255, 255, 0.2);
}

.filter-btn {
  flex: 1;
  padding: var(--spacing-md) var(--spacing-lg);
  background: transparent;
  border: none;
  border-radius: var(--radius-lg);
  color: var(--text-secondary);
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-fast);
  position: relative;
}

.filter-btn:hover {
  color: var(--text-primary);
  background: rgba(255, 255, 255, 0.1);
  transform: translateY(-1px);
}

.filter-btn.active {
  background: linear-gradient(135deg, #3b82f6 0%, #1d4ed8 100%);
  color: white;
  box-shadow: 0 4px 15px rgba(59, 130, 246, 0.3);
}

.search-container {
  flex: 1;
  max-width: 300px;
}

.search-container input {
  width: 100%;
}

.actions {
  display: flex;
  gap: var(--spacing-sm);
  justify-content: center;
}

@media (min-width: 480px) {
  .actions {
    justify-content: flex-end;
  }
}

.tasks-section {
  flex: 1;
}

.task-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: var(--spacing-sm);
}

.task-item {
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(20px);
  border-radius: var(--radius-xl);
  padding: var(--spacing-lg);
  box-shadow: 0 8px 32px var(--shadow-lg);
  border: 1px solid rgba(255, 255, 255, 0.3);
  transition: all var(--transition-normal);
  cursor: grab;
  position: relative;
  overflow: hidden;
}

.task-item::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: linear-gradient(90deg, #3b82f6, #8b5cf6, #06b6d4);
  opacity: 0;
  transition: opacity var(--transition-fast);
}

.task-item:hover {
  box-shadow: 0 20px 40px var(--shadow-lg);
  transform: translateY(-4px);
  border-color: rgba(255, 255, 255, 0.5);
}

.task-item:hover::before {
  opacity: 1;
}

.task-item.dragging {
  opacity: 0.5;
  transform: rotate(5deg);
}

.task-item.completed {
  opacity: 0.7;
}

.task-content {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
}

.task-checkbox {
  width: 24px;
  height: 24px;
  border-radius: var(--radius-md);
  border: 2px solid var(--border-color);
  background: rgba(255, 255, 255, 0.9);
  cursor: pointer;
  transition: all var(--transition-fast);
  flex-shrink: 0;
  position: relative;
}

.task-checkbox:hover {
  border-color: var(--border-focus);
  transform: scale(1.1);
}

.task-checkbox:checked {
  background: linear-gradient(135deg, #10b981 0%, #059669 100%);
  border-color: #10b981;
  box-shadow: 0 4px 15px rgba(16, 185, 129, 0.3);
}

.task-checkbox:checked::after {
  content: "✓";
  color: white;
  font-size: 14px;
  font-weight: bold;
  display: flex;
  align-items: center;
  justify-content: center;
  width: 100%;
  height: 100%;
  animation: checkmark 0.3s ease;
}

@keyframes checkmark {
  0% {
    transform: scale(0);
  }
  50% {
    transform: scale(1.2);
  }
  100% {
    transform: scale(1);
  }
}

.task-details {
  flex: 1;
  min-width: 0;
}

.task-title {
  font-size: 1rem;
  font-weight: 500;
  color: var(--text-primary);
  margin-bottom: var(--spacing-xs);
  word-wrap: break-word;
}

.task-title.completed {
  text-decoration: line-through;
  color: var(--text-muted);
}

.task-title.overdue {
  color: var(--danger);
}

.task-meta {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  flex-wrap: wrap;
}

.task-due-date {
  font-size: 0.875rem;
  color: var(--text-secondary);
  padding: var(--spacing-xs) var(--spacing-sm);
  background: var(--bg-tertiary);
  border-radius: var(--radius-sm);
}

.task-due-date.overdue {
  color: var(--danger);
  background: rgba(220, 53, 69, 0.1);
}

.priority-pill {
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  padding: var(--spacing-sm) var(--spacing-md);
  border-radius: var(--radius-lg);
  border: 2px solid;
  letter-spacing: 0.5px;
  position: relative;
  overflow: hidden;
}

.priority-pill::before {
  content: "";
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(
    90deg,
    transparent,
    rgba(255, 255, 255, 0.3),
    transparent
  );
  transition: left var(--transition-normal);
}

.priority-pill:hover::before {
  left: 100%;
}

.priority-pill.low {
  color: var(--priority-low);
  border-color: var(--priority-low);
  background: linear-gradient(
    135deg,
    rgba(16, 185, 129, 0.1) 0%,
    rgba(5, 150, 105, 0.1) 100%
  );
  box-shadow: 0 2px 8px rgba(16, 185, 129, 0.2);
}

.priority-pill.medium {
  color: var(--priority-medium);
  border-color: var(--priority-medium);
  background: linear-gradient(
    135deg,
    rgba(245, 158, 11, 0.1) 0%,
    rgba(217, 119, 6, 0.1) 100%
  );
  box-shadow: 0 2px 8px rgba(245, 158, 11, 0.2);
}

.priority-pill.high {
  color: var(--priority-high);
  border-color: var(--priority-high);
  background: linear-gradient(
    135deg,
    rgba(239, 68, 68, 0.1) 0%,
    rgba(220, 38, 38, 0.1) 100%
  );
  box-shadow: 0 2px 8px rgba(239, 68, 68, 0.2);
}

.task-actions {
  display: flex;
  gap: var(--spacing-sm);
  flex-shrink: 0;
}

.task-actions .btn {
  padding: var(--spacing-sm);
  font-size: 0.875rem;
  border-radius: var(--radius-md);
  min-width: 36px;
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.task-actions .btn:hover {
  transform: scale(1.1);
}

.task-title-edit {
  width: 100%;
  background: transparent;
  border: 2px solid var(--border-focus);
  border-radius: var(--radius-sm);
  padding: var(--spacing-xs);
  font-size: 1rem;
  font-weight: 500;
  color: var(--text-primary);
}

.empty-state {
  text-align: center;
  padding: var(--spacing-2xl);
  color: var(--text-secondary);
  background: rgba(255, 255, 255, 0.1);
  backdrop-filter: blur(10px);
  border-radius: var(--radius-xl);
  border: 1px solid rgba(255, 255, 255, 0.2);
  box-shadow: 0 8px 32px var(--shadow-lg);
}

.empty-icon {
  font-size: 4rem;
  margin-bottom: var(--spacing-lg);
  opacity: 0.7;
  animation: float 3s ease-in-out infinite;
}

@keyframes float {
  0%,
  100% {
    transform: translateY(0px);
  }
  50% {
    transform: translateY(-10px);
  }
}

.empty-state h2 {
  font-size: 1.75rem;
  margin-bottom: var(--spacing-md);
  color: var(--text-primary);
  font-weight: 700;
}

.empty-state p {
  font-size: 1.1rem;
  opacity: 0.8;
}

.stats-footer {
  margin-top: var(--spacing-xl);
  padding: var(--spacing-lg);
  background: rgba(255, 255, 255, 0.1);
  backdrop-filter: blur(10px);
  border-radius: var(--radius-xl);
  border: 1px solid rgba(255, 255, 255, 0.2);
  box-shadow: 0 8px 32px var(--shadow-lg);
  text-align: center;
  font-size: 0.875rem;
  color: var(--text-secondary);
}

.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
  gap: var(--spacing-md);
}

.stat-item {
  display: flex;
  flex-direction: column;
  align-items: center;
}

.stat-value {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: var(--spacing-xs);
}

.stat-label {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.modal {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0, 0, 0, 0.5);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1000;
  opacity: 0;
  visibility: hidden;
  transition: all var(--transition-normal);
}

.modal.show {
  opacity: 1;
  visibility: visible;
}

.modal-content {
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(20px);
  border-radius: var(--radius-xl);
  padding: var(--spacing-2xl);
  max-width: 450px;
  width: 90%;
  box-shadow: 0 25px 50px rgba(0, 0, 0, 0.3);
  border: 1px solid rgba(255, 255, 255, 0.3);
  transform: scale(0.9);
  transition: transform var(--transition-normal);
}

.modal.show .modal-content {
  transform: scale(1);
}

.modal-content h2 {
  margin-bottom: var(--spacing-md);
  color: var(--text-primary);
}

.modal-content p {
  margin-bottom: var(--spacing-lg);
  color: var(--text-secondary);
}

.modal-actions {
  display: flex;
  gap: var(--spacing-sm);
  justify-content: flex-end;
}

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

*:focus {
  outline: 2px solid var(--border-focus);
  outline-offset: 2px;
}

.task-item.drag-over {
  border-color: var(--border-focus);
  background: rgba(13, 110, 253, 0.05);
}

@keyframes slideIn {
  from {
    opacity: 0;
    transform: translateY(-20px) scale(0.95);
  }
  to {
    opacity: 1;
    transform: translateY(0) scale(1);
  }
}

.task-item {
  animation: slideIn var(--transition-normal);
}

@keyframes fadeIn {
  from {
    opacity: 0;
    transform: scale(0.9);
  }
  to {
    opacity: 1;
    transform: scale(1);
  }
}

.modal {
  animation: fadeIn var(--transition-normal);
}

@keyframes pulse {
  0%,
  100% {
    transform: scale(1);
  }
  50% {
    transform: scale(1.05);
  }
}

.btn-primary:active {
  animation: pulse 0.2s ease;
}

@media (max-width: 480px) {
  .container {
    padding: var(--spacing-md);
  }

  .app-title {
    font-size: 2rem;
  }

  .input-group {
    flex-direction: column;
  }

  .input-group input,
  .input-group select {
    width: 100%;
  }

  .task-content {
    flex-direction: column;
    align-items: flex-start;
    gap: var(--spacing-sm);
  }

  .task-actions {
    align-self: flex-end;
  }

  .modal-content {
    padding: var(--spacing-lg);
  }

  .modal-actions {
    flex-direction: column;
  }
}

@media (prefers-contrast: high) {
  :root {
    --border-color: #000000;
    --text-secondary: #000000;
  }

  [data-theme="dark"] {
    --border-color: #ffffff;
    --text-secondary: #ffffff;
  }
}

@media (prefers-reduced-motion: reduce) {
  * {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }

  .task-item:hover {
    transform: none;
  }

  .btn:hover:not(:disabled) {
    transform: none;
  }
}

.developer-footer {
  margin-top: var(--spacing-lg);
  padding: var(--spacing-lg);
  background: rgba(255, 255, 255, 0.1);
  backdrop-filter: blur(10px);
  border-radius: var(--radius-xl);
  border: 1px solid rgba(255, 255, 255, 0.2);
  box-shadow: 0 8px 32px var(--shadow-lg);
  text-align: center;
}

.developer-info p {
  margin-bottom: var(--spacing-md);
  color: var(--text-primary);
  font-size: 1rem;
  font-weight: 500;
}

.social-links {
  display: flex;
  gap: var(--spacing-lg);
  justify-content: center;
  align-items: center;
}

.social-links a {
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-sm);
  padding: var(--spacing-sm) var(--spacing-md);
  background: rgba(255, 255, 255, 0.1);
  backdrop-filter: blur(10px);
  border: 1px solid rgba(255, 255, 255, 0.3);
  border-radius: var(--radius-lg);
  color: var(--text-primary);
  text-decoration: none;
  font-weight: 500;
  transition: all var(--transition-fast);
}

.social-links a:hover {
  background: rgba(255, 255, 255, 0.2);
  border-color: rgba(255, 255, 255, 0.4);
  transform: translateY(-2px);
  box-shadow: 0 4px 15px var(--shadow-lg);
}

.social-icon {
  font-size: 1.2rem;
}

@media (max-width: 480px) {
  .social-links {
    flex-direction: column;
    gap: var(--spacing-sm);
  }

  .social-links a {
    width: 100%;
    justify-content: center;
  }
}