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

:root {
  /* Color Variables */
  --primary: #6366f1;
  --primary-dark: #4f46e5;
  --primary-light: #818cf8;
  --secondary: #64748b;
  --success: #22c55e;
  --danger: #ef4444;
  --warning: #f59e0b;
  --info: #3b82f6;
  
  /* Background Colors */
  --bg-primary: #0a0a0f;
  --bg-secondary: #13131f;
  --bg-tertiary: #1c1c2a;
  --bg-modal: rgb(13 13 19 / 26%);
  --bg-hover: rgba(255, 255, 255, 0.05);
  
  /* Text Colors */
  --text-primary: #f8fafc;
  --text-secondary: #cbd5e1;
  --text-muted: #64748b;
  --text-bright: #ffffff;
  
  /* Border Colors */
  --border-dim: rgba(255, 255, 255, 0.1);
  --border-bright: rgba(255, 255, 255, 0.2);
  
  /* Spacing */
  --spacing-xs: 0.25rem;
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --spacing-lg: 1.5rem;
  --spacing-xl: 2rem;
  
  /* Border Radius */
  --radius-sm: 0.175rem;
  --radius-md: 0.2rem;
  --radius-lg: 0.275rem;
  --radius-xl: 0.35rem;
  --radius-full: 9999px;
  
  /* Transitions */
  --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-normal: 250ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 350ms cubic-bezier(0.4, 0, 0.2, 1);
  
  /* Shadows */
  --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.5);
  --shadow-glow: 0 0 20px rgba(99, 102, 241, 0.3);
  
  /* Font Family */
  --font-sans: 'Inter', system-ui, -apple-system, sans-serif;
  --font-mono: 'JetBrains Mono', monospace;
}

/* Base Styles */
body {
  font-family: var(--font-sans);
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.5;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
}

body * {
  font-family: var(--font-sans);
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
  font-weight: 600;
  line-height: 1.25;
  margin-bottom: var(--spacing-md);
}

h1 { font-size: 2rem; }
h2 { font-size: 1.75rem; }
h3 { font-size: 1.5rem; }
h4 { font-size: 1.25rem; }
h5 { font-size: 1.125rem; }
h6 { font-size: 1rem; }

/* Grid System */
.container {
  width: 100%;
  margin-right: auto;
  margin-left: auto;
  padding-right: var(--spacing-md);
  padding-left: var(--spacing-md);
  max-width: 1280px;
}

.grid {
  display: grid;
  gap: var(--spacing-md);
}

/* Flexbox Utilities */
.flex { display: flex; }
.flex-col { flex-direction: column; }
.items-center { align-items: center; }
.justify-between { justify-content: space-between; }
.gap-2 { gap: var(--spacing-sm); }
.gap-4 { gap: var(--spacing-md); }

/* Button Styles */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.625rem 1.25rem;
  font-size: 0.875rem;
  font-weight: 500;
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: all var(--transition-fast);
  border: 1px solid transparent;
  gap: var(--spacing-sm);
  letter-spacing: 0.025em;
  height: 2.5rem;
  user-select: none;
}

.btn-primary {
  background-color: var(--primary);
  color: var(--text-bright);
  box-shadow: var(--shadow-glow);
}

.btn-primary:hover {
  background-color: var(--primary-dark);
  transform: translateY(-1px);
  box-shadow: var(--shadow-glow), var(--shadow-md);
}

.btn-secondary {
  background-color: var(--bg-tertiary);
  color: var(--text-primary);
  border: 1px solid var(--border-dim);
}

.btn-secondary:hover {
  background-color: var(--bg-hover);
  border-color: var(--border-bright);
}

.btn-danger {
  background-color: var(--danger);
  color: var(--text-bright);
}

.btn-danger:hover {
  filter: brightness(110%);
}

.btn-icon {
  padding: var(--spacing-sm);
  border-radius: var(--radius-md);
}

/* Form Elements */
.form-group {
  margin-bottom: var(--spacing-md);
}

.input {
  width: 100%;
  padding: 0.625rem 1rem;
  font-size: 0.875rem;
  line-height: 1.5;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-dim);
  background-color: var(--bg-tertiary);
  color: var(--text-primary);
  transition: all var(--transition-fast);
}

.input:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 2px rgba(99, 102, 241, 0.2);
}

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

textarea.input {
  min-height: 80px;
  resize: vertical;
}

/* Modal Component */
.modal-overlay {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background-color: var(--bg-modal);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 100000;
  opacity: 0;
  visibility: hidden;
  transition: all var(--transition-normal);
  backdrop-filter: blur(4px);
}

.modal-overlay.active {
  opacity: 1;
  visibility: visible;
}

.modal-content {
  background-color: var(--bg-secondary);
  border-radius: var(--radius-lg);
  padding: var(--spacing-xl);
  max-width: 500px;
  width: 90%;
  position: relative;
  transform: translateY(-20px) scale(0.95);
  transition: all var(--transition-normal);
  border: 1px solid var(--border-bright);
  box-shadow: var(--shadow-lg);
}

.modal-overlay.active .modal-content {
  transform: translateY(0) scale(1);
}

.modal-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: var(--spacing-lg);
}

.modal-title {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--text-bright);
}

.modal-close {
  position: absolute;
  top: var(--spacing-md);
  right: var(--spacing-md);
  background: none;
  border: none;
  color: var(--text-muted);
  cursor: pointer;
  padding: var(--spacing-sm);
  border-radius: var(--radius-full);
  transition: all var(--transition-fast);
}

.modal-close:hover {
  background-color: var(--bg-hover);
  color: var(--text-bright);
}

/* Mobile Modal Styles */
@media (max-width: 768px) {
  .modal-content {
    width: 100%;
    height: 100%;
    max-width: none;
    border-radius: 0;
    padding: var(--spacing-lg);
    display: flex;
    flex-direction: column;
    overflow-y: auto;
  }
  
  .modal-content .task-form {
    flex: 1;
    padding-right: var(--spacing-sm);
  }
  
  .modal-header {
    margin-bottom: var(--spacing-md);
    flex-shrink: 0;
  }
  
  .modal-header h2 {
    font-size: 1.5rem;
  }
}

/* Card Component */
.card {
  background-color: var(--bg-secondary);
  border-radius: var(--radius-lg);
  padding: var(--spacing-lg);
  border: 1px solid var(--border-dim);
  transition: all var(--transition-fast);
}

.card:hover {
  border-color: var(--border-bright);
  box-shadow: var(--shadow-md);
}

/* Notification Component */
.notification {
  position: fixed;
  bottom: var(--spacing-lg);
  right: var(--spacing-lg);
  padding: var(--spacing-md) var(--spacing-lg);
  border-radius: var(--radius-md);
  background-color: var(--bg-secondary);
  color: var(--text-primary);
  box-shadow: var(--shadow-lg);
  transform: translateX(120%);
  transition: transform var(--transition-normal);
  z-index: 10000;
  border: 1px solid var(--border-dim);
  min-width: 300px;
}

.notification.show {
  transform: translateX(0);
}

.notification.success {
  background-color: var(--success);
  color: var(--text-bright);
}

.notification.error {
  background-color: var(--danger);
  color: var(--text-bright);
}

/* Dropdown Component */
.dropdown {
  position: relative;
  display: inline-block;
}

.dropdown-content {
  position: absolute;
  top: 100%;
  right: 0;
  min-width: 200px;
  background-color: var(--bg-secondary);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-lg);
  padding: var(--spacing-sm) 0;
  opacity: 0;
  visibility: hidden;
  transform: translateY(-10px);
  transition: all var(--transition-normal);
  z-index: 30;
  border: 1px solid var(--border-dim);
}

.dropdown.active .dropdown-content {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.dropdown-item {
  padding: var(--spacing-sm) var(--spacing-md);
  color: var(--text-primary);
  text-decoration: none;
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  transition: background-color var(--transition-fast);
}

.dropdown-item:hover {
  background-color: var(--bg-hover);
}

/* Toolbar Component */
.toolbar {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  padding: var(--spacing-sm);
  background-color: var(--bg-secondary);
  border-radius: var(--radius-md);
  border: 1px solid var(--border-dim);
}

/* Side Panel Component */
.side-panel {
  position: fixed;
  top: 0;
  right: 0;
  bottom: 0;
  width: 300px;
  background-color: var(--bg-secondary);
  box-shadow: var(--shadow-lg);
  transform: translateX(100%);
  transition: transform var(--transition-normal);
  z-index: 40;
  overflow-y: auto;
  border-left: 1px solid var(--border-dim);
}

.side-panel.open {
  transform: translateX(0);
}

/* Loading Spinner */
.spinner {
  width: 24px;
  height: 24px;
  border: 2px solid var(--border-dim);
  border-top-color: var(--primary);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

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

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

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

.slide-in {
  animation: slideIn var(--transition-normal);
}

/* Responsive Utilities */
@media (min-width: 640px) {
  .sm\:flex { display: flex; }
  .sm\:hidden { display: none; }
}

@media (min-width: 768px) {
  .md\:grid-cols-2 { grid-template-columns: repeat(2, 1fr); }
  .md\:flex { display: flex; }
  .md\:hidden { display: none; }
}

@media (min-width: 1024px) {
  .lg\:grid-cols-3 { grid-template-columns: repeat(3, 1fr); }
  .lg\:flex { display: flex; }
  .lg\:hidden { display: none; }
}