:root {
  /* Color Palette */
  --primary-h: 215;
  --primary-s: 89%;
  --primary-l: 60%;
  --primary: hsl(var(--primary-h), var(--primary-s), var(--primary-l));
  --primary-dark: hsl(var(--primary-h), var(--primary-s), 45%);
  --primary-light: hsl(var(--primary-h), var(--primary-s), 90%);
  
  --bg-main: #f8fafc;
  --bg-sidebar: #ffffff;
  --text-main: #1e293b;
  --text-muted: #64748b;
  --border-color: #e2e8f0;
  
  --success: #22c55e;
  --warning: #f59e0b;
  --danger: #ef4444;
  
  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
  --shadow: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
  
  --radius-sm: 0.375rem;
  --radius: 0.5rem;
  --radius-lg: 1rem;
  --radius-full: 9999px;
  
  --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  -webkit-font-smoothing: antialiased;
}

body {
  font-family: 'Nanum Gothic', sans-serif;
  background-color: var(--bg-main);
  color: var(--text-main);
  line-height: 1.5;
  overflow: hidden;
}

h1, h2, h3, .logo span {
  font-family: 'Jua', sans-serif;
}

button, input, select {
  font-family: inherit;
  font-size: inherit;
  border: none;
  outline: none;
}

button {
  cursor: pointer;
  transition: var(--transition);
}

/* Layout */
.app-wrapper {
  display: flex;
  height: 100vh;
  width: 100vw;
}

/* Sidebar */
.sidebar {
  width: 280px;
  background-color: var(--bg-sidebar);
  border-right: 1px solid var(--border-color);
  display: flex;
  flex-direction: column;
  padding: 2rem 1.5rem;
  z-index: 10;
}

.sidebar-header .logo {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-size: 1.5rem;
  color: var(--primary);
  margin-bottom: 2.5rem;
}

.sidebar-nav {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  margin-bottom: 2rem;
}

.nav-item {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.75rem 1rem;
  border-radius: var(--radius);
  color: var(--text-muted);
  background: transparent;
  width: 100%;
  text-align: left;
}

.nav-item i {
  width: 20px;
  text-align: center;
}

.nav-item span {
  flex: 1;
  font-weight: 500;
}

.nav-item:hover {
  background-color: var(--primary-light);
  color: var(--primary);
}

.nav-item.active {
  background-color: var(--primary);
  color: white;
}

.badge {
  background-color: rgba(255, 255, 255, 0.2);
  padding: 2px 8px;
  border-radius: var(--radius-full);
  font-size: 0.75rem;
}

.nav-item.active .badge {
  background-color: rgba(255, 255, 255, 0.3);
}

.sidebar-section {
  margin-bottom: 2rem;
}

.section-label {
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 0.75rem;
  padding-left: 1rem;
}

.priority-high { color: var(--danger); }
.priority-medium { color: var(--warning); }
.priority-low { color: var(--success); }

.sidebar-footer {
  margin-top: auto;
}

.progress-wrap {
  background: var(--primary-light);
  padding: 1rem;
  border-radius: var(--radius-lg);
}

.progress-label {
  display: flex;
  justify-content: space-between;
  font-size: 0.875rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
  color: var(--primary-dark);
}

.progress-bar {
  height: 8px;
  background: rgba(255, 255, 255, 0.5);
  border-radius: var(--radius-full);
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  background: var(--primary);
  width: 0%;
  transition: width 0.5s ease-out;
}

/* Main Content */
.main-content {
  flex: 1;
  padding: 2rem 3rem;
  overflow-y: auto;
  background: linear-gradient(135deg, #f8fafc 0%, #f1f5f9 100%);
}

.main-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  margin-bottom: 2.5rem;
}

.header-title h1 {
  font-size: 2.25rem;
  margin-bottom: 0.25rem;
  color: var(--text-main);
}

.header-title p {
  color: var(--text-muted);
  font-size: 1.1rem;
}

.header-actions {
  display: flex;
  gap: 1rem;
}

.search-box {
  position: relative;
  display: flex;
  align-items: center;
}

.search-box i {
  position: absolute;
  left: 1rem;
  color: var(--text-muted);
}

.search-box input {
  padding: 0.75rem 1rem 0.75rem 2.75rem;
  background: white;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  width: 240px;
  transition: var(--transition);
}

.search-box input:focus {
  border-color: var(--primary);
  box-shadow: 0 0 0 4px var(--primary-light);
  width: 300px;
}

.btn-add-open {
  background: var(--primary);
  color: white;
  padding: 0.75rem 1.5rem;
  border-radius: var(--radius-lg);
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-weight: 700;
  box-shadow: 0 4px 12px rgba(var(--primary-h), var(--primary-s), 40%, 0.3);
}

.btn-add-open:hover {
  background: var(--primary-dark);
  transform: translateY(-2px);
  box-shadow: 0 6px 16px rgba(var(--primary-h), var(--primary-s), 40%, 0.4);
}

/* Stats Row */
.stats-row {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1.5rem;
  margin-bottom: 2.5rem;
}

.stat-card {
  background: white;
  padding: 1.25rem;
  border-radius: var(--radius-lg);
  display: flex;
  align-items: center;
  gap: 1rem;
  box-shadow: var(--shadow);
  transition: var(--transition);
}

.stat-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
}

.stat-icon {
  width: 48px;
  height: 48px;
  border-radius: var(--radius);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.25rem;
}

.stat-info {
  display: flex;
  flex-direction: column;
}

.stat-value {
  font-size: 1.5rem;
  font-weight: 800;
  line-height: 1;
}

.stat-label {
  font-size: 0.875rem;
  color: var(--text-muted);
  font-weight: 500;
}

/* Todo List Section */
.todo-toolbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 1.5rem;
}

.sort-wrap {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  color: var(--text-muted);
}

.sort-wrap select {
  background: transparent;
  font-weight: 600;
  color: var(--text-main);
  cursor: pointer;
}

.btn-clear-done {
  background: transparent;
  color: var(--danger);
  font-weight: 600;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.5rem 1rem;
  border-radius: var(--radius);
}

.btn-clear-done:hover {
  background: #fef2f2;
}

.todo-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.todo-item {
  background: white;
  padding: 1rem 1.25rem;
  border-radius: var(--radius-lg);
  display: flex;
  align-items: center;
  gap: 1rem;
  box-shadow: var(--shadow-sm);
  transition: var(--transition);
  animation: slideIn 0.3s ease-out;
  border-left: 4px solid transparent;
}

@keyframes slideIn {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: translateY(0); }
}

.todo-item:hover {
  box-shadow: var(--shadow);
  transform: translateX(4px);
}

.todo-item.high { border-left-color: var(--danger); }
.todo-item.medium { border-left-color: var(--warning); }
.todo-item.low { border-left-color: var(--success); }

.todo-item.completed {
  opacity: 0.6;
}

.todo-checkbox {
  width: 24px;
  height: 24px;
  border-radius: 6px;
  border: 2px solid var(--border-color);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: var(--transition);
  flex-shrink: 0;
}

.todo-item.completed .todo-checkbox {
  background: var(--success);
  border-color: var(--success);
  color: white;
}

.todo-content {
  flex: 1;
}

.todo-title {
  font-weight: 600;
  margin-bottom: 0.25rem;
  transition: var(--transition);
}

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

.todo-meta {
  display: flex;
  gap: 1rem;
  font-size: 0.75rem;
  color: var(--text-muted);
}

.meta-item {
  display: flex;
  align-items: center;
  gap: 0.25rem;
}

.category-tag {
  background: var(--primary-light);
  color: var(--primary-dark);
  padding: 2px 8px;
  border-radius: 4px;
  font-weight: 700;
}

.todo-actions {
  display: flex;
  gap: 0.5rem;
  opacity: 0;
  transition: var(--transition);
}

.todo-item:hover .todo-actions {
  opacity: 1;
}

.btn-action {
  width: 32px;
  height: 32px;
  border-radius: var(--radius);
  display: flex;
  align-items: center;
  justify-content: center;
  background: #f1f5f9;
  color: var(--text-muted);
}

.btn-action:hover {
  background: var(--primary-light);
  color: var(--primary);
}

.btn-action.delete:hover {
  background: #fee2e2;
  color: var(--danger);
}

/* Empty & Loading States */
.empty-state, .loading-state {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 5rem 0;
  color: var(--text-muted);
  text-align: center;
}

.empty-state i, .loading-state i {
  font-size: 4rem;
  margin-bottom: 1.5rem;
  opacity: 0.2;
}

.empty-state p {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-main);
  margin-bottom: 0.5rem;
}

/* Modals */
.modal-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(15, 23, 42, 0.6);
  backdrop-filter: blur(4px);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 100;
  animation: fadeIn 0.2s ease-out;
}

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

.modal {
  background: white;
  width: 100%;
  max-width: 500px;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  overflow: hidden;
  animation: modalPop 0.3s cubic-bezier(0.34, 1.56, 0.64, 1);
}

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

.modal-sm {
  max-width: 400px;
}

.modal-header {
  padding: 1.5rem;
  border-bottom: 1px solid var(--border-color);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.modal-close {
  background: transparent;
  font-size: 1.25rem;
  color: var(--text-muted);
}

.modal-body {
  padding: 1.5rem;
}

.form-group {
  margin-bottom: 1.5rem;
}

.form-group label {
  display: block;
  font-weight: 700;
  margin-bottom: 0.5rem;
  font-size: 0.875rem;
}

.required { color: var(--danger); }

.form-group input[type="text"],
.form-group select,
.form-group input[type="date"] {
  width: 100%;
  padding: 0.75rem 1rem;
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  transition: var(--transition);
}

.form-group input:focus, .form-group select:focus {
  border-color: var(--primary);
  box-shadow: 0 0 0 3px var(--primary-light);
}

.form-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
}

.char-count {
  display: block;
  text-align: right;
  font-size: 0.75rem;
  color: var(--text-muted);
  margin-top: 0.25rem;
}

.category-chips {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.chip {
  background: #f1f5f9;
  padding: 0.5rem 1rem;
  border-radius: var(--radius-full);
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--text-muted);
}

.chip.active {
  background: var(--primary);
  color: white;
}

.modal-footer {
  padding: 1.5rem;
  background: #f8fafc;
  display: flex;
  justify-content: flex-end;
  gap: 0.75rem;
}

.btn-cancel {
  background: transparent;
  padding: 0.75rem 1.5rem;
  border-radius: var(--radius);
  font-weight: 700;
  color: var(--text-muted);
}

.btn-submit {
  background: var(--primary);
  color: white;
  padding: 0.75rem 1.5rem;
  border-radius: var(--radius);
  font-weight: 700;
}

.btn-delete {
  background: var(--danger);
  color: white;
  padding: 0.75rem 1.5rem;
  border-radius: var(--radius);
  font-weight: 700;
}

/* Toasts */
.toast-container {
  position: fixed;
  bottom: 2rem;
  right: 2rem;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  z-index: 1000;
}

.toast {
  background: white;
  padding: 1rem 1.5rem;
  border-radius: var(--radius);
  box-shadow: var(--shadow-lg);
  display: flex;
  align-items: center;
  gap: 0.75rem;
  animation: slideInRight 0.3s ease-out;
  border-left: 4px solid var(--primary);
}

@keyframes slideInRight {
  from { transform: translateX(100%); opacity: 0; }
  to { transform: translateX(0); opacity: 1; }
}

.toast.success { border-left-color: var(--success); }
.toast.error { border-left-color: var(--danger); }

/* Custom Scrollbar */
::-webkit-scrollbar {
  width: 8px;
}

::-webkit-scrollbar-track {
  background: transparent;
}

::-webkit-scrollbar-thumb {
  background: #cbd5e1;
  border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
  background: #94a3b8;
}

[hidden] {
  display: none !important;
}