/* ============================================
   TANDEM NEXUS - Premium Design System
   Built with design-ui-systems + design-brand-guardian principles
   ============================================ */

/* Design Tokens */
:root {
  /* Brand Colors - Tandem Nexus: Bold Black & White */
  --color-black: #000000;
  --color-white: #ffffff;

  /* Neutrals with warmth */
  --color-gray-50: #fafafa;
  --color-gray-100: #f5f5f5;
  --color-gray-200: #e5e5e5;
  --color-gray-300: #d4d4d4;
  --color-gray-400: #a3a3a3;
  --color-gray-500: #737373;
  --color-gray-600: #525252;
  --color-gray-700: #404040;
  --color-gray-800: #262626;
  --color-gray-900: #171717;

  /* Accent colors */
  --color-accent: #2563eb;
  --color-accent-light: #3b82f6;
  --color-success: #10b981;
  --color-warning: #f59e0b;
  --color-error: #ef4444;

  /* Typography - Premium Font Stack */
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-mono: 'SF Mono', 'Fira Code', 'Monaco', monospace;
  --font-display: 'Inter', sans-serif;

  /* Type Scale - Musical ratios */
  --text-xs: 0.75rem;
  --text-sm: 0.875rem;
  --text-base: 1rem;
  --text-lg: 1.125rem;
  --text-xl: 1.25rem;
  --text-2xl: 1.5rem;
  --text-3xl: 2rem;
  --text-4xl: 2.5rem;
  --text-5xl: 3rem;

  /* Font weights */
  --font-normal: 400;
  --font-medium: 500;
  --font-semibold: 600;
  --font-bold: 700;

  /* Spacing - 4px base unit */
  --space-0: 0;
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-5: 1.25rem;
  --space-6: 1.5rem;
  --space-8: 2rem;
  --space-10: 2.5rem;
  --space-12: 3rem;
  --space-16: 4rem;
  --space-20: 5rem;
  --space-24: 6rem;

  /* Shadows - Layered depth */
  --shadow-xs: 0 1px 2px rgba(0,0,0,0.04);
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.06), 0 1px 2px rgba(0,0,0,0.04);
  --shadow-md: 0 4px 6px -1px rgba(0,0,0,0.08), 0 2px 4px -1px rgba(0,0,0,0.04);
  --shadow-lg: 0 10px 15px -3px rgba(0,0,0,0.08), 0 4px 6px -2px rgba(0,0,0,0.04);
  --shadow-xl: 0 20px 25px -5px rgba(0,0,0,0.08), 0 10px 10px -5px rgba(0,0,0,0.03);
  --shadow-2xl: 0 25px 50px -12px rgba(0,0,0,0.15);

  /* 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);

  /* Border Radius */
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --radius-xl: 16px;
  --radius-2xl: 24px;
  --radius-full: 9999px;
}

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

html {
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
}

body {
  font-family: var(--font-sans);
  font-size: var(--text-base);
  line-height: 1.6;
  color: var(--color-gray-900);
  background: var(--color-gray-50);
}

.hidden { display: none !important; }

/* ============================================
   LOGIN SCREEN - Full immersive experience
   ============================================ */
.login {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--color-black);
  position: relative;
  overflow: hidden;
}

/* Subtle grid pattern */
.login::before {
  content: '';
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(255,255,255,0.03) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255,255,255,0.03) 1px, transparent 1px);
  background-size: 60px 60px;
  pointer-events: none;
}

.login-box {
  text-align: center;
  padding: var(--space-10);
  position: relative;
  z-index: 1;
}

.login-logo {
  width: 280px;
  height: auto;
  margin-bottom: var(--space-12);
  display: block;
}

.login-form {
  display: flex;
  max-width: 320px;
  margin: 0 auto;
  border-radius: var(--radius-md);
  overflow: hidden;
  box-shadow: var(--shadow-2xl);
}

.login-form input {
  flex: 1;
  padding: var(--space-4) var(--space-5);
  border: none;
  font-size: var(--text-base);
  font-family: var(--font-sans);
  background: var(--color-white);
  outline: none;
}

.login-form input::placeholder {
  color: var(--color-gray-400);
}

.login-form button {
  padding: var(--space-4) var(--space-8);
  background: var(--color-gray-900);
  color: var(--color-white);
  border: none;
  font-size: var(--text-sm);
  font-weight: var(--font-semibold);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  cursor: pointer;
  transition: all var(--transition-fast);
  white-space: nowrap;
}

.login-form button:hover {
  background: var(--color-gray-700);
}

.login-error {
  color: var(--color-error);
  font-size: var(--text-sm);
  margin-top: var(--space-4);
  min-height: 24px;
}

/* ============================================
   APP SHELL - Clean architecture
   ============================================ */
.app {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  background: var(--color-white);
}

/* Header - Sticky navigation */
.header {
  background: var(--color-white);
  border-bottom: 1px solid var(--color-gray-200);
  padding: var(--space-4) var(--space-8);
  display: flex;
  align-items: center;
  justify-content: space-between;
  position: sticky;
  top: 0;
  z-index: 100;
  backdrop-filter: blur(8px);
  background: rgba(255,255,255,0.95);
}

.header-logo {
  height: 36px;
  width: auto;
}

.header-nav {
  display: flex;
  gap: var(--space-1);
  background: var(--color-gray-100);
  padding: var(--space-1);
  border-radius: var(--radius-lg);
}

.nav-btn {
  padding: var(--space-2) var(--space-5);
  background: transparent;
  border: none;
  font-size: var(--text-sm);
  font-weight: var(--font-medium);
  color: var(--color-gray-600);
  cursor: pointer;
  border-radius: var(--radius-md);
  transition: all var(--transition-fast);
}

.nav-btn:hover {
  color: var(--color-gray-900);
}

.nav-btn.active {
  background: var(--color-white);
  color: var(--color-gray-900);
  box-shadow: var(--shadow-sm);
}

/* Content Container */
.content {
  flex: 1;
  padding: var(--space-10) var(--space-8);
  max-width: 1400px;
  margin: 0 auto;
  width: 100%;
}

/* Section Header */
.section-header {
  margin-bottom: var(--space-8);
  max-width: 600px;
}

.section-header h1 {
  font-size: var(--text-3xl);
  font-weight: var(--font-bold);
  color: var(--color-gray-900);
  margin-bottom: var(--space-2);
  letter-spacing: -0.02em;
}

.section-header p {
  font-size: var(--text-lg);
  color: var(--color-gray-500);
  line-height: 1.5;
}

/* Footer */
.footer {
  background: var(--color-gray-900);
  color: var(--color-white);
  padding: var(--space-4) var(--space-8);
  display: flex;
  justify-content: center;
  gap: var(--space-10);
  font-size: var(--text-sm);
}

.footer span {
  color: var(--color-gray-400);
  display: flex;
  gap: var(--space-2);
}

.footer strong {
  color: var(--color-white);
  font-weight: var(--font-semibold);
}

/* ============================================
   DISCIPLINE CARDS - Premium grid
   ============================================ */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: var(--space-5);
}

.card {
  background: var(--color-white);
  border: 1px solid var(--color-gray-200);
  border-radius: var(--radius-xl);
  padding: var(--space-6);
  transition: all var(--transition-normal);
  position: relative;
  overflow: hidden;
}

.card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: var(--color-gray-900);
  transform: scaleX(0);
  transition: transform var(--transition-normal);
  transform-origin: left;
}

.card:hover {
  border-color: var(--color-gray-300);
  box-shadow: var(--shadow-lg);
  transform: translateY(-2px);
}

.card:hover::before {
  transform: scaleX(1);
}

.card-featured {
  border: 2px solid var(--color-gray-900);
  grid-column: span 2;
  background: linear-gradient(135deg, var(--color-white) 0%, var(--color-gray-50) 100%);
}

.card-featured::before {
  height: 4px;
  background: var(--color-gray-900);
  transform: scaleX(1);
}

.card-pending {
  border-style: dashed;
  border-color: var(--color-gray-300);
  opacity: 0.7;
}

.card-pending:hover {
  transform: none;
  box-shadow: none;
}

.card-pending::before {
  display: none;
}

.btn-pending {
  background: var(--color-gray-200) !important;
  color: var(--color-gray-500) !important;
  cursor: not-allowed !important;
  font-style: italic;
}

.btn-pending:hover {
  background: var(--color-gray-200) !important;
  color: var(--color-gray-500) !important;
}

.btn-pending-inline {
  color: var(--color-gray-400) !important;
  font-style: italic;
  cursor: not-allowed !important;
}

.btn-pending-inline:hover {
  background: transparent !important;
  color: var(--color-gray-400) !important;
}

.card-icon {
  font-size: var(--text-3xl);
  display: block;
  margin-bottom: var(--space-4);
}

.card h2 {
  font-size: var(--text-lg);
  font-weight: var(--font-semibold);
  margin-bottom: var(--space-1);
  color: var(--color-gray-900);
}

.card-meta {
  font-size: var(--text-sm);
  color: var(--color-gray-400);
  margin-bottom: var(--space-5);
}

.card-actions {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
}

.card-actions button {
  padding: var(--space-2) var(--space-4);
  background: var(--color-gray-100);
  border: none;
  border-radius: var(--radius-md);
  font-size: var(--text-sm);
  font-weight: var(--font-medium);
  color: var(--color-gray-700);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.card-actions button:hover {
  background: var(--color-gray-900);
  color: var(--color-white);
}

/* ============================================
   DOCUMENTS VIEW - Organized grid
   ============================================ */
.doc-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: var(--space-6);
}

.doc-group {
  background: var(--color-white);
  border: 1px solid var(--color-gray-200);
  border-radius: var(--radius-xl);
  padding: var(--space-6);
  transition: all var(--transition-normal);
}

.doc-group:hover {
  border-color: var(--color-gray-300);
  box-shadow: var(--shadow-md);
}

.doc-group h3 {
  font-size: var(--text-xs);
  font-weight: var(--font-bold);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--color-gray-400);
  margin-bottom: var(--space-4);
  padding-bottom: var(--space-3);
  border-bottom: 1px solid var(--color-gray-100);
}

.doc-group ul {
  list-style: none;
}

.doc-group li {
  margin-bottom: var(--space-1);
}

.doc-group button {
  width: 100%;
  text-align: left;
  padding: var(--space-3) var(--space-4);
  background: transparent;
  border: none;
  border-radius: var(--radius-md);
  font-size: var(--text-sm);
  color: var(--color-gray-700);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.doc-group button:hover {
  background: var(--color-gray-100);
  color: var(--color-gray-900);
}

.folder-buttons {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--space-2);
}

.folder-buttons button {
  text-align: center;
  background: var(--color-gray-50);
  font-weight: var(--font-medium);
  border: 1px solid var(--color-gray-100);
}

.folder-buttons button:hover {
  background: var(--color-gray-900);
  color: var(--color-white);
  border-color: var(--color-gray-900);
}

/* ============================================
   MODAL - Immersive document viewer
   ============================================ */
.modal {
  position: fixed;
  inset: 0;
  z-index: 1000;
  display: flex;
  align-items: flex-start;
  justify-content: center;
  padding: var(--space-8);
  overflow-y: auto;
}

.modal-backdrop {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.7);
  backdrop-filter: blur(4px);
}

.modal-window {
  position: relative;
  background: var(--color-white);
  border-radius: var(--radius-xl);
  max-width: 900px;
  width: 100%;
  box-shadow: var(--shadow-2xl);
  max-height: calc(100vh - var(--space-16));
  display: flex;
  flex-direction: column;
  animation: modalIn 0.3s ease;
}

@keyframes modalIn {
  from {
    opacity: 0;
    transform: translateY(20px) scale(0.98);
  }
  to {
    opacity: 1;
    transform: translateY(0) scale(1);
  }
}

.modal-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: var(--space-4) var(--space-6);
  border-bottom: 1px solid var(--color-gray-100);
  flex-shrink: 0;
}

#modal-title {
  font-size: var(--text-sm);
  font-family: var(--font-mono);
  color: var(--color-gray-400);
}

.modal-close {
  width: 36px;
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--color-gray-100);
  border: none;
  border-radius: var(--radius-md);
  font-size: var(--text-xl);
  color: var(--color-gray-500);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.modal-close:hover {
  background: var(--color-gray-900);
  color: var(--color-white);
}

.modal-content {
  padding: var(--space-8);
  overflow-y: auto;
  flex: 1;
}

/* Typography in Modal */
.modal-content h1 {
  font-size: var(--text-3xl);
  font-weight: var(--font-bold);
  margin-bottom: var(--space-4);
  padding-bottom: var(--space-4);
  border-bottom: 2px solid var(--color-gray-900);
  letter-spacing: -0.02em;
}

.modal-content h2 {
  font-size: var(--text-2xl);
  font-weight: var(--font-bold);
  margin-top: var(--space-10);
  margin-bottom: var(--space-4);
  color: var(--color-gray-900);
  letter-spacing: -0.01em;
}

.modal-content h3 {
  font-size: var(--text-xl);
  font-weight: var(--font-semibold);
  margin-top: var(--space-8);
  margin-bottom: var(--space-3);
  color: var(--color-gray-800);
}

.modal-content h4 {
  font-size: var(--text-lg);
  font-weight: var(--font-semibold);
  margin-top: var(--space-6);
  margin-bottom: var(--space-2);
  color: var(--color-gray-800);
}

.modal-content p {
  margin-bottom: var(--space-4);
  line-height: 1.75;
  color: var(--color-gray-700);
}

.modal-content ul, .modal-content ol {
  margin-bottom: var(--space-4);
  padding-left: var(--space-6);
}

.modal-content li {
  margin-bottom: var(--space-2);
  line-height: 1.7;
  color: var(--color-gray-700);
}

.modal-content strong {
  font-weight: var(--font-semibold);
  color: var(--color-gray-900);
}

.modal-content code {
  background: var(--color-gray-100);
  padding: 2px 8px;
  border-radius: var(--radius-sm);
  font-family: var(--font-mono);
  font-size: 0.9em;
  color: var(--color-gray-800);
}

.modal-content pre {
  background: var(--color-gray-900);
  color: var(--color-gray-100);
  padding: var(--space-5);
  border-radius: var(--radius-lg);
  overflow-x: auto;
  margin-bottom: var(--space-4);
  font-size: var(--text-sm);
}

.modal-content pre code {
  background: none;
  padding: 0;
  color: inherit;
}

.modal-content table {
  width: 100%;
  border-collapse: collapse;
  margin-bottom: var(--space-6);
  font-size: var(--text-sm);
}

.modal-content th, .modal-content td {
  border: 1px solid var(--color-gray-200);
  padding: var(--space-3) var(--space-4);
  text-align: left;
}

.modal-content th {
  background: var(--color-gray-50);
  font-weight: var(--font-semibold);
  color: var(--color-gray-900);
}

.modal-content blockquote {
  border-left: 4px solid var(--color-gray-900);
  padding-left: var(--space-5);
  margin: var(--space-6) 0;
  color: var(--color-gray-600);
  font-style: italic;
}

.modal-content hr {
  border: none;
  border-top: 1px solid var(--color-gray-200);
  margin: var(--space-10) 0;
}

.modal-content a {
  color: var(--color-accent);
  text-decoration: none;
  font-weight: var(--font-medium);
}

.modal-content a:hover {
  text-decoration: underline;
}

/* File List in Modal */
.file-list {
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
}

.file-item {
  display: flex;
  align-items: center;
  gap: var(--space-4);
  padding: var(--space-4) var(--space-5);
  background: var(--color-gray-50);
  border-radius: var(--radius-lg);
  cursor: pointer;
  transition: all var(--transition-fast);
  border: 1px solid transparent;
}

.file-item:hover {
  background: var(--color-gray-900);
  color: var(--color-white);
  border-color: var(--color-gray-900);
  transform: translateX(4px);
}

/* Folder Type Labels */
.folder-type-label {
  font-size: var(--text-sm);
  font-weight: var(--font-semibold);
  color: var(--color-gray-500);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: var(--space-4);
  padding-bottom: var(--space-2);
  border-bottom: 1px solid var(--color-gray-200);
}

.task-folder-heading {
  font-size: var(--text-base);
  font-weight: var(--font-semibold);
  color: var(--color-gray-700);
  margin: var(--space-6) 0 var(--space-3) 0;
  padding-left: var(--space-2);
}

.task-folder-heading:first-of-type {
  margin-top: 0;
}

/* Document group description */
.doc-group-desc {
  font-size: var(--text-sm);
  color: var(--color-gray-500);
  margin: var(--space-1) 0 var(--space-3) 0;
}

/* ============================================
   RESPONSIVE DESIGN
   ============================================ */
@media (max-width: 1024px) {
  .card-featured {
    grid-column: span 1;
  }
}

@media (max-width: 768px) {
  .header {
    padding: var(--space-4);
  }

  .header-logo {
    height: 28px;
  }

  .nav-btn {
    padding: var(--space-2) var(--space-3);
    font-size: var(--text-xs);
  }

  .content {
    padding: var(--space-6) var(--space-4);
  }

  .section-header h1 {
    font-size: var(--text-2xl);
  }

  .card-grid {
    grid-template-columns: 1fr;
    gap: var(--space-4);
  }

  .doc-grid {
    grid-template-columns: 1fr;
  }

  .footer {
    flex-wrap: wrap;
    gap: var(--space-4);
    justify-content: center;
    padding: var(--space-4);
  }

  .modal {
    padding: var(--space-4);
  }

  .modal-content {
    padding: var(--space-5);
  }

  .modal-content h1 {
    font-size: var(--text-2xl);
  }

  .modal-content h2 {
    font-size: var(--text-xl);
  }
}

@media (max-width: 480px) {
  .login-logo {
    width: 200px;
  }

  .login-form {
    flex-direction: column;
  }

  .login-form button {
    padding: var(--space-4);
  }

  .folder-buttons {
    grid-template-columns: 1fr;
  }
}

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

/* Focus states */
button:focus-visible,
input:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
}

/* High contrast support */
@media (prefers-contrast: high) {
  .card {
    border-width: 2px;
  }

  .nav-btn.active {
    border: 2px solid var(--color-gray-900);
  }
}