/* =============================================================================
   SENTINO AI - LUXURY / EDITORIAL DESIGN SYSTEM
   Elegant, refined, precise aesthetic
   Fonts: Playfair Display (headings) + Inter (body)
   ============================================================================= */

/* =============================================================================
   CSS VARIABLES - DESIGN TOKENS
   ============================================================================= */

:root {
  /* Core Palette */
  --bg: #F9F8F6;
  --bg-muted: #EBE5DE;
  --fg: #1A1A1A;
  --fg-muted: #6C6863;
  --accent: #F97316;
  --accent-hover: #EA580C;
  --white: #FFFFFF;

  /* Semantic Colors */
  --success: #16A34A;
  --warning: #D97706;
  --error: #DC2626;
  --info: #2563EB;

  /* Legacy Compatibility */
  --background-color: var(--bg);
  --surface-color: var(--white);
  --text-primary: var(--fg);
  --text-secondary: var(--fg-muted);
  --border-color: rgba(26, 26, 26, 0.1);
  --primary-color: var(--accent);
  --primary-hover: var(--accent-hover);

  /* Typography */
  --font-serif: 'Playfair Display', Georgia, serif;
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-mono: 'JetBrains Mono', monospace;
  --font-primary: var(--font-sans);
  --font-display: var(--font-serif);

  /* Font Sizes */
  --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: 1.875rem;
  --text-4xl: 2.5rem;

  /* Spacing */
  --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;

  /* Radius - Sharp edges for luxury */
  --radius-sm: 0;
  --radius-md: 0;
  --radius-lg: 0;
  --radius-xl: 0;
  --radius-full: 0;

  /* Shadows */
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.08);
  --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.1);

  /* Timing */
  --ease: cubic-bezier(0.25, 0.46, 0.45, 0.94);
  --duration: 500ms;
  --duration-fast: 300ms;
}

/* =============================================================================
   BASE STYLES
   ============================================================================= */

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-sans);
  font-size: var(--text-base);
  line-height: 1.6;
  color: var(--fg);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

/* =============================================================================
   APP HEADER
   ============================================================================= */

/* --- Header: sticky, sits in document flow --- */
.app-header {
  position: sticky;
  top: 0;
  z-index: var(--z-header);
  background: var(--bg);
  border-bottom: 1px solid var(--border);
  flex-shrink: 0;
}

.header-inner {
  max-width: 1600px;
  margin: 0 auto;
  padding: 0 var(--space-6);
  height: var(--header-height);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-6);
}

/* Logo */
.header-logo {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  text-decoration: none;
  color: var(--fg);
  font-family: var(--font-serif);
  font-size: 1.2rem;
  flex-shrink: 0;
}

.logo-mark {
  width: 24px;
  height: 24px;
  background: var(--accent);
  border-radius: var(--radius-sm);
}

/* Nav links */
.header-nav {
  display: flex;
  align-items: center;
  gap: var(--space-1);
  margin-left: var(--space-6);
}

.header-nav-link {
  font-size: var(--text-sm);
  font-weight: 500;
  color: var(--fg-muted);
  text-decoration: none;
  padding: 0.375rem 0.75rem;
  border-radius: var(--radius-md);
  transition: all var(--duration-fast) var(--ease);
}

.header-nav-link:hover {
  color: var(--fg);
  background: var(--bg-muted);
}

.header-nav-link.active {
  color: var(--accent);
  background: var(--accent-light);
}

/* Right-side actions */
.header-actions {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  margin-left: auto;
}

.header-auth-link {
  font-size: var(--text-sm);
  font-weight: 500;
  color: var(--fg-muted);
  text-decoration: none;
  padding: 0.375rem 0.75rem;
  border-radius: var(--radius-md);
  transition: all var(--duration-fast) var(--ease);
}

.header-auth-link:hover {
  color: var(--fg);
  background: var(--bg-muted);
}

/* Hamburger toggle (mobile only) */
.header-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: var(--space-2);
}

.header-toggle span {
  width: 18px;
  height: 1.5px;
  background: var(--fg);
  border-radius: 1px;
  transition: all var(--duration-fast) var(--ease);
}

.header-toggle.active span:first-child {
  transform: rotate(45deg) translate(3px, 3px);
}

.header-toggle.active span:last-child {
  transform: rotate(-45deg) translate(3px, -3px);
}

/* User menu */
.user-menu {
  position: relative;
}

.user-trigger {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  background: none;
  border: 1px solid var(--border);
  border-radius: var(--radius-full);
  cursor: pointer;
  padding: 0.25rem 0.625rem 0.25rem 0.25rem;
  color: var(--fg);
  font-family: var(--font-sans);
  transition: all var(--duration-fast) var(--ease);
}

.user-trigger:hover {
  border-color: var(--border-hover);
  background: var(--bg-muted);
}

.user-avatar {
  width: 28px;
  height: 28px;
  background: var(--accent);
  color: var(--white);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.7rem;
  font-weight: 600;
}

.user-avatar-img {
  width: 28px;
  height: 28px;
  border-radius: 50%;
  object-fit: cover;
}

.user-name {
  font-size: var(--text-sm);
  font-weight: 500;
}

.user-dropdown {
  position: absolute;
  top: calc(100% + 6px);
  right: 0;
  min-width: 180px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  padding: var(--space-1) 0;
  opacity: 0;
  visibility: hidden;
  transform: translateY(4px);
  transition: all var(--duration-fast) var(--ease);
}

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

.user-dropdown a {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  padding: 0.5rem 1rem;
  font-size: var(--text-sm);
  color: var(--fg);
  text-decoration: none;
  transition: all var(--duration-fast) var(--ease);
}

.user-dropdown a:hover {
  background: var(--bg-muted);
  color: var(--accent);
}

.dropdown-divider {
  height: 1px;
  background: var(--border);
  margin: var(--space-1) 0;
}

.dropdown-logout {
  color: var(--error) !important;
}

/* Mobile nav overlay */
.mobile-nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: var(--bg);
  z-index: calc(var(--z-header) - 1);
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  visibility: hidden;
  transition: all var(--duration) var(--ease);
}

.mobile-nav.active {
  opacity: 1;
  visibility: visible;
}

.mobile-nav-inner {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-6);
}

.mobile-nav-inner a {
  font-family: var(--font-serif);
  font-size: 1.5rem;
  color: var(--fg);
  text-decoration: none;
  transition: color var(--duration) var(--ease);
}

.mobile-nav-inner a:hover {
  color: var(--accent);
}

.mobile-nav-divider {
  width: 48px;
  height: 1px;
  background: var(--border);
}

/* =============================================================================
   BUTTONS
   ============================================================================= */

.btn {
  position: relative;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  height: 48px;
  padding: 0 var(--space-8);
  font-family: var(--font-sans);
  font-size: 0.75rem;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.15em;
  text-decoration: none;
  border: 1px solid transparent;
  cursor: pointer;
  overflow: hidden;
  transition: all var(--duration) var(--ease);
}

.btn-primary {
  background: var(--fg);
  color: var(--white);
  border-color: var(--fg);
}

.btn-primary .btn-bg {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: var(--accent);
  transform: translateX(-101%);
  transition: transform var(--duration) var(--ease);
}

.btn-primary:hover .btn-bg {
  transform: translateX(0);
}

.btn-primary .btn-text {
  position: relative;
  z-index: 1;
}

.btn-secondary {
  background: transparent;
  color: var(--fg);
  border-color: var(--fg);
}

.btn-secondary:hover {
  background: var(--fg);
  color: var(--white);
}

.btn-sm {
  height: 40px;
  padding: 0 var(--space-6);
  font-size: 0.7rem;
}

.btn-lg {
  height: 56px;
  padding: 0 var(--space-12);
}

/* =============================================================================
   FORMS
   ============================================================================= */

.form-group {
  margin-bottom: var(--space-6);
}

label, .form-label {
  display: block;
  font-size: 0.7rem;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.15em;
  color: var(--fg-muted);
  margin-bottom: var(--space-2);
}

input, textarea, select {
  width: 100%;
  padding: var(--space-3) 0;
  font-family: var(--font-sans);
  font-size: 1rem;
  color: var(--fg);
  background: transparent;
  border: none;
  border-bottom: 1px solid var(--fg);
  outline: none;
  transition: border-color var(--duration) var(--ease);
}

input:focus, textarea:focus, select:focus {
  border-color: var(--accent);
}

input::placeholder, textarea::placeholder {
  font-family: var(--font-serif);
  font-style: italic;
  color: var(--fg-muted);
}

textarea {
  min-height: 120px;
  resize: vertical;
}

select {
  cursor: pointer;
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%231A1A1A' d='M3 5l3 3 3-3'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 0 center;
}

/* Search Input Styling */
.search-input, .search-bar input {
  width: 100%;
  padding: var(--space-4);
  font-family: var(--font-sans);
  font-size: 1rem;
  color: var(--fg);
  background: var(--white);
  border: 1px solid var(--border-color);
  transition: all var(--duration) var(--ease);
}

.search-input:focus, .search-bar input:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(249, 115, 22, 0.1);
}

/* =============================================================================
   CARDS
   ============================================================================= */

.card {
  background: var(--white);
  border: 1px solid var(--border-color);
  padding: var(--space-6);
  transition: all var(--duration) var(--ease);
}

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

/* =============================================================================
   ALERTS
   ============================================================================= */

.alert {
  padding: var(--space-4) var(--space-6);
  border-left: 3px solid var(--fg);
  background: var(--bg-muted);
  margin-bottom: var(--space-6);
  font-size: 0.9rem;
}

.alert-error {
  border-color: var(--error);
  background: rgba(220, 38, 38, 0.05);
  color: var(--error);
}

.alert-success {
  border-color: var(--success);
  background: rgba(22, 163, 74, 0.05);
  color: var(--success);
}

.alert-warning {
  border-color: var(--warning);
  background: rgba(217, 119, 6, 0.05);
  color: var(--warning);
}

/* =============================================================================
   APP CONTAINER
   ============================================================================= */

.app-container {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.main-content {
  flex: 1;
  padding-top: 80px;
}

/* =============================================================================
   SEARCH SECTION
   ============================================================================= */

.search-section {
  padding: var(--space-12) var(--space-6);
  max-width: 800px;
  margin: 0 auto;
}

.search-hero h2 {
  font-family: var(--font-serif);
  font-size: clamp(1.75rem, 4vw, 2.5rem);
  font-weight: 400;
  text-align: center;
  margin-bottom: var(--space-2);
}

.search-subtitle {
  text-align: center;
  color: var(--fg-muted);
  margin-bottom: var(--space-8);
}

.search-form {
  margin-bottom: var(--space-8);
}

.search-bar {
  display: flex;
  gap: var(--space-4);
  margin-bottom: var(--space-4);
}

.search-bar input {
  flex: 1;
}

.search-btn {
  padding: 0 var(--space-8);
  background: var(--fg);
  color: var(--white);
  border: none;
  font-size: 0.8rem;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  cursor: pointer;
  transition: background var(--duration) var(--ease);
}

.search-btn:hover {
  background: var(--accent);
}

.search-meta {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: var(--space-4);
}

.filters-toggle {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  background: none;
  border: 1px solid var(--border-color);
  padding: var(--space-2) var(--space-4);
  font-size: 0.8rem;
  color: var(--fg-muted);
  cursor: pointer;
  transition: all var(--duration) var(--ease);
}

.filters-toggle:hover {
  border-color: var(--fg);
  color: var(--fg);
}

.active-sources {
  display: flex;
  gap: var(--space-2);
  flex-wrap: wrap;
}

.source-tag {
  font-size: 0.7rem;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--fg-muted);
  padding: var(--space-1) var(--space-3);
  background: var(--bg-muted);
}

.search-filters {
  display: none;
  padding: var(--space-6);
  background: var(--white);
  border: 1px solid var(--border-color);
  margin-top: var(--space-4);
}

.search-filters.active {
  display: block;
}

.filters-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  gap: var(--space-6);
  margin-bottom: var(--space-6);
}

.filter-group label {
  display: block;
  margin-bottom: var(--space-2);
}

.filter-group select {
  width: 100%;
  padding: var(--space-3);
  background: var(--bg);
  border: 1px solid var(--border-color);
}

.source-chips {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
}

.source-chip {
  display: flex;
  align-items: center;
  padding: var(--space-2) var(--space-4);
  border: 1px solid var(--border-color);
  cursor: pointer;
  transition: all var(--duration) var(--ease);
}

.source-chip input {
  display: none;
}

.source-chip span {
  font-size: 0.8rem;
}

.source-chip.active, .source-chip:has(input:checked) {
  background: var(--fg);
  color: var(--white);
  border-color: var(--fg);
}

.sci-hub-toggle {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  cursor: pointer;
  margin-top: var(--space-4);
}

.sci-hub-toggle input {
  width: auto;
}

.sci-hub-toggle span {
  font-size: 0.9rem;
}

/* =============================================================================
   TRENDING SECTION
   ============================================================================= */

.trending-section {
  padding: 0 var(--space-6) var(--space-12);
  max-width: 800px;
  margin: 0 auto;
}

.trending-header {
  margin-bottom: var(--space-4);
}

.trending-label {
  font-size: 0.7rem;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.15em;
  color: var(--fg-muted);
}

.trending-chips {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-3);
}

.trending-chip {
  padding: var(--space-2) var(--space-4);
  background: transparent;
  border: 1px solid var(--border-color);
  font-size: 0.85rem;
  color: var(--fg);
  cursor: pointer;
  transition: all var(--duration) var(--ease);
}

.trending-chip:hover {
  background: var(--fg);
  color: var(--white);
  border-color: var(--fg);
}

/* =============================================================================
   RESULTS SECTION
   ============================================================================= */

.results-section {
  padding: var(--space-8) var(--space-6);
  max-width: 1200px;
  margin: 0 auto;
}

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

.results-count {
  font-size: 0.9rem;
  color: var(--fg-muted);
}

.paper-card {
  padding: var(--space-6);
  border-top: 1px solid var(--border-color);
  transition: all var(--duration) var(--ease);
}

.paper-card:hover {
  background: var(--bg-muted);
}

.paper-title {
  font-family: var(--font-serif);
  font-size: 1.25rem;
  font-weight: 400;
  margin-bottom: var(--space-2);
  color: var(--fg);
}

.paper-title a {
  color: inherit;
  text-decoration: none;
}

.paper-title a:hover {
  color: var(--accent);
}

.paper-authors {
  font-size: 0.9rem;
  color: var(--fg-muted);
  margin-bottom: var(--space-3);
}

.paper-abstract {
  font-size: 0.9rem;
  color: var(--fg-muted);
  line-height: 1.7;
  margin-bottom: var(--space-4);
}

.paper-meta {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-4);
  font-size: 0.8rem;
  color: var(--fg-muted);
}

.paper-actions {
  display: flex;
  gap: var(--space-3);
  margin-top: var(--space-4);
}

/* =============================================================================
   HISTORY SECTION
   ============================================================================= */

.history-section {
  padding: var(--space-8) var(--space-6);
  max-width: 1200px;
  margin: 0 auto;
}

.history-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: var(--space-6);
}

.history-header h3 {
  font-family: var(--font-serif);
  font-size: 1.25rem;
  font-weight: 400;
}

.history-list {
  display: grid;
  gap: var(--space-4);
}

.history-item {
  padding: var(--space-4);
  border: 1px solid var(--border-color);
  cursor: pointer;
  transition: all var(--duration) var(--ease);
}

.history-item:hover {
  border-color: var(--accent);
}

/* =============================================================================
   LOADING STATES
   ============================================================================= */

.loading {
  text-align: center;
  padding: var(--space-12);
  color: var(--fg-muted);
}

.spinner {
  width: 32px;
  height: 32px;
  border: 2px solid var(--border-color);
  border-top-color: var(--accent);
  border-radius: 50%;
  animation: spin 1s linear infinite;
  margin: 0 auto var(--space-4);
}

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

/* =============================================================================
   PAGE LAYOUT (from base.html)
   ============================================= */

.page-main {
  flex: 1;
  min-height: 0;
}

/* =============================================================================
   FOOTER
   ============================================= */

.app-footer {
  padding: var(--space-8) var(--space-6);
  border-top: 1px solid var(--border-color);
  margin-top: auto;
}

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

.footer-brand {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  font-family: var(--font-serif);
}

.footer-brand .logo-mark {
  width: 20px;
  height: 20px;
}

.footer-links {
  display: flex;
  gap: var(--space-6);
}

.footer-links a {
  font-size: 0.75rem;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--fg-muted);
  text-decoration: none;
}

.footer-links a:hover {
  color: var(--accent);
}

/* =============================================================================
   RESPONSIVE
   ============================================= */

@media (max-width: 768px) {
  .header-nav {
    display: none;
  }

  .header-toggle {
    display: flex;
  }

  .header-actions .header-auth-link,
  .header-actions .btn {
    display: none;
  }

  .user-name,
  .user-trigger svg {
    display: none;
  }

  .user-trigger {
    padding: 0.25rem;
    border: none;
  }

  .search-bar {
    flex-direction: column;
  }

  .search-btn {
    width: 100%;
    padding: var(--space-4);
  }

  .footer-inner {
    flex-direction: column;
    gap: var(--space-4);
    text-align: center;
  }
}

/* =============================================================================
   REDUCED MOTION
   ============================================= */

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