/* ==========================================================================
   CSS CUSTOM VARIABLES & THEME TOKENS
   ========================================================================== */
:root {
  /* Font Families */
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  --font-serif: 'Lora', Georgia, Cambria, "Times New Roman", Times, serif;

  /* Colors (Default Light Mode) */
  --bg-primary: #f3f6f9;
  --bg-secondary: #ffffff;
  --bg-card: rgba(255, 255, 255, 0.7);
  --sidebar-bg: rgba(255, 255, 255, 0.8);
  --border-card: rgba(255, 255, 255, 0.5);
  --border-outer: rgba(218, 224, 233, 0.7);
  
  --text-main: #0f172a;
  --text-muted: #475569;
  --text-inverse: #ffffff;
  
  --accent-color: #2563eb;
  --accent-hover: #1d4ed8;
  --accent-bg-alpha: rgba(37, 99, 235, 0.08);
  
  --shadow-sm: 0 4px 6px -1px rgba(0, 0, 0, 0.05), 0 2px 4px -2px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 12px 20px -8px rgba(0, 0, 0, 0.08), 0 4px 12px -2px rgba(0, 0, 0, 0.03);
  --shadow-lg: 0 20px 25px -5px rgba(0, 0, 0, 0.05), 0 8px 10px -6px rgba(0, 0, 0, 0.05);

  --glass-blur: blur(16px);
  --transition-smooth: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 20px;
}



/* ==========================================================================
   RESET & BASE STYLES
   ========================================================================== */
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: var(--font-sans);
  color: var(--text-main);
  background-color: var(--bg-primary);
  line-height: 1.6;
  overflow-x: hidden;
  min-height: 100vh;
  position: relative;
  transition: background-color 0.4s ease, color 0.4s ease;
}

a {
  color: var(--accent-color);
  text-decoration: none;
  transition: var(--transition-smooth);
}

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

/* Decorative Background Glows */
.glow-bg {
  position: absolute;
  width: 600px;
  height: 600px;
  border-radius: 50%;
  filter: blur(150px);
  opacity: 0.4;
  z-index: -1;
  pointer-events: none;
  transition: opacity 0.5s ease;
}

.glow-1 {
  background: radial-gradient(circle, rgba(59, 130, 246, 0.25) 0%, rgba(0,0,0,0) 70%);
  top: -10%;
  left: -10%;
}

.glow-2 {
  background: radial-gradient(circle, rgba(147, 51, 234, 0.18) 0%, rgba(0,0,0,0) 70%);
  bottom: 10%;
  right: -10%;
}


/* ==========================================================================
   LAYOUT STRUCTURE
   ========================================================================== */
.container {
  max-width: 1280px;
  margin: 0 auto;
  padding: 2.5rem 1.5rem;
  display: grid;
  grid-template-columns: 320px 1fr;
  gap: 2.5rem;
  position: relative;
}

/* ==========================================================================
   SIDEBAR: PROFILE CARD
   ========================================================================== */
.sidebar {
  position: relative;
}

.profile-card {
  position: sticky;
  top: 2.5rem;
  background: var(--sidebar-bg);
  border: 1px solid var(--border-outer);
  border-top-color: var(--border-card);
  border-left-color: var(--border-card);
  box-shadow: var(--shadow-md);
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  border-radius: var(--radius-lg);
  padding: 2.25rem 1.75rem;
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  transition: var(--transition-smooth);
}

.avatar-container {
  margin-bottom: 1.5rem;
  position: relative;
}

.profile-photo {
  width: 130px;
  height: 130px;
  border-radius: 50%;
  object-fit: cover;
  border: 4px solid var(--bg-secondary);
  box-shadow: var(--shadow-md);
  transition: var(--transition-smooth);
}

.profile-photo:hover {
  transform: scale(1.04);
}

.cv-download-container {
  width: 100%;
  margin-top: 0.25rem;
}

.cv-btn {
  width: 100%;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.65rem;
  padding: 0.75rem 1rem;
  border-radius: var(--radius-md);
  background-color: var(--accent-color);
  color: #ffffff !important;
  font-size: 0.88rem;
  font-weight: 600;
  cursor: pointer;
  box-shadow: var(--shadow-sm);
  transition: var(--transition-smooth);
}

.cv-btn:hover {
  background-color: var(--accent-hover);
  box-shadow: 0 4px 10px rgba(37, 99, 235, 0.2);
  transform: translateY(-1px);
}

.cv-btn .icon {
  width: 16px;
  height: 16px;
}

.profile-name {
  font-family: var(--font-serif);
  font-size: 1.75rem;
  font-weight: 700;
  color: var(--text-main);
  margin-bottom: 0.5rem;
  letter-spacing: -0.5px;
}

.profile-title {
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--text-main);
  line-height: 1.4;
  margin-bottom: 0.25rem;
}

.profile-subtitle {
  font-size: 0.85rem;
  color: var(--text-muted);
  line-height: 1.4;
  margin-bottom: 1.25rem;
}

.divider {
  width: 100%;
  height: 1px;
  background-color: var(--border-outer);
  margin: 1.5rem 0;
}

.contact-info {
  width: 100%;
  display: flex;
  flex-direction: column;
  gap: 0.85rem;
  text-align: left;
}

.contact-item {
  display: flex;
  align-items: flex-start;
  gap: 0.75rem;
  font-size: 0.88rem;
  color: var(--text-main);
  line-height: 1.4;
}

.contact-item a {
  word-break: break-all;
  color: var(--text-main);
  text-decoration: underline;
  text-decoration-color: var(--border-outer);
}

.contact-item a:hover {
  color: var(--accent-color);
  text-decoration-color: var(--accent-color);
}

.contact-item .icon {
  width: 16px;
  height: 16px;
  color: var(--accent-color);
  flex-shrink: 0;
  margin-top: 2px;
}

.research-interests {
  width: 100%;
  text-align: left;
}

.research-interests h3 {
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 1.5px;
  color: var(--text-muted);
  margin-bottom: 0.75rem;
  font-weight: 600;
}

.interests-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.tag {
  font-size: 0.78rem;
  font-weight: 500;
  padding: 0.3rem 0.65rem;
  border-radius: var(--radius-sm);
  background-color: var(--accent-bg-alpha);
  color: var(--accent-color);
  border: 1px solid rgba(59, 130, 246, 0.1);
  transition: var(--transition-smooth);
}

.tag:hover {
  transform: translateY(-1px);
  box-shadow: 0 4px 6px -1px rgba(59, 130, 246, 0.1);
}


.hidden {
  display: none !important;
}

/* ==========================================================================
   MAIN CONTENT AREA
   ========================================================================== */
.content-area {
  display: flex;
  flex-direction: column;
  gap: 2.5rem;
}

/* Content Header (Search & Filter) */
.content-header {
  background: var(--bg-card);
  border: 1px solid var(--border-outer);
  border-top-color: var(--border-card);
  border-left-color: var(--border-card);
  box-shadow: var(--shadow-sm);
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
  transition: var(--transition-smooth);
}

.search-box {
  position: relative;
  width: 100%;
}

.search-icon {
  position: absolute;
  left: 1rem;
  top: 50%;
  transform: translateY(-50%);
  width: 18px;
  height: 18px;
  color: var(--text-muted);
}

#search-input {
  width: 100%;
  padding: 0.85rem 1rem 0.85rem 2.75rem;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-outer);
  background-color: var(--bg-primary);
  color: var(--text-main);
  font-size: 0.95rem;
  font-family: var(--font-sans);
  transition: var(--transition-smooth);
}

#search-input:focus {
  outline: none;
  border-color: var(--accent-color);
  box-shadow: 0 0 0 3px var(--accent-bg-alpha);
  background-color: var(--bg-secondary);
}

.filter-bar {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.filter-btn {
  padding: 0.55rem 1.15rem;
  border-radius: var(--radius-md);
  border: 1px solid transparent;
  background-color: transparent;
  color: var(--text-muted);
  font-size: 0.88rem;
  font-weight: 500;
  cursor: pointer;
  transition: var(--transition-smooth);
}

.filter-btn:hover {
  background-color: var(--bg-primary);
  color: var(--text-main);
}

.filter-btn.active {
  background-color: var(--bg-secondary);
  border-color: var(--border-outer);
  color: var(--accent-color);
  box-shadow: var(--shadow-sm);
}

/* Section Styling */
.papers-section {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.section-title {
  font-family: var(--font-serif);
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--text-main);
  position: relative;
  padding-bottom: 0.5rem;
}

.section-title::after {
  content: '';
  position: absolute;
  left: 0;
  bottom: 0;
  width: 45px;
  height: 3px;
  background-color: var(--accent-color);
  border-radius: 2px;
}

.papers-list {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

/* ==========================================================================
   PAPER CARD COMPONENT (Option 3 Glassmorphism + Accent Badges)
   ========================================================================== */
.paper-card {
  background: var(--bg-card);
  border: 1px solid var(--border-outer);
  border-top-color: var(--border-card);
  border-left-color: var(--border-card);
  box-shadow: var(--shadow-sm);
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  border-radius: var(--radius-md);
  padding: 1.75rem;
  position: relative;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  transition: transform 0.3s cubic-bezier(0.25, 0.46, 0.45, 0.94), 
              box-shadow 0.3s ease, 
              border-color 0.3s ease;
}

.paper-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
  border-color: rgba(59, 130, 246, 0.2);
}

.year-label {
  position: absolute;
  right: 1.75rem;
  top: 1.75rem;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-muted);
  background-color: var(--bg-primary);
  padding: 0.25rem 0.65rem;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-outer);
}

.journal-badge {
  display: inline-block;
  align-self: flex-start;
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.8px;
  padding: 0.25rem 0.65rem;
  border-radius: var(--radius-sm);
  margin-bottom: 0.25rem;
}

/* Soft Color Badges for Journals */
.badge-eer {
  background-color: rgba(37, 99, 235, 0.1);
  color: #2563eb;
  border: 1px solid rgba(37, 99, 235, 0.15);
}

.badge-ms {
  background-color: rgba(13, 148, 136, 0.1);
  color: #0d9488;
  border: 1px solid rgba(13, 148, 136, 0.15);
}

.badge-pnas {
  background-color: rgba(147, 51, 234, 0.1);
  color: #9333ea;
  border: 1px solid rgba(147, 51, 234, 0.15);
}

.badge-jde {
  background-color: rgba(219, 39, 119, 0.1);
  color: #db2777;
  border: 1px solid rgba(219, 39, 119, 0.15);
}

.badge-wp {
  background-color: rgba(217, 119, 6, 0.1);
  color: #d97706;
  border: 1px solid rgba(217, 119, 6, 0.15);
}

.badge-wip {
  background-color: rgba(100, 116, 139, 0.1);
  color: #64748b;
  border: 1px solid rgba(100, 116, 139, 0.15);
}

.badge-default {
  background-color: rgba(79, 70, 229, 0.1);
  color: #4f46e5;
  border: 1px solid rgba(79, 70, 229, 0.15);
}

.paper-title {
  font-family: var(--font-serif);
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-main);
  line-height: 1.35;
  padding-right: 4.5rem; /* prevent title overlap with year label */
}

.paper-authors {
  font-size: 0.88rem;
  color: var(--text-muted);
}

.paper-details {
  font-size: 0.88rem;
  color: var(--text-main);
  font-style: italic;
}

.paper-links {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.5rem;
  margin-top: 0.5rem;
}

.link-btn {
  font-size: 0.78rem;
  font-weight: 600;
  padding: 0.4rem 0.85rem;
  border-radius: var(--radius-sm);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  transition: var(--transition-smooth);
}

.link-btn.primary {
  background-color: var(--accent-color);
  color: #ffffff;
}

.link-btn.primary:hover {
  background-color: var(--accent-hover);
  box-shadow: 0 4px 10px rgba(37, 99, 235, 0.2);
}

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

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

.link-btn.info {
  background-color: var(--accent-bg-alpha);
  color: var(--accent-color);
  border: 1px solid rgba(59, 130, 246, 0.05);
}

.link-btn.info:hover {
  background-color: var(--accent-color);
  color: #ffffff;
}

.paper-note {
  font-size: 0.78rem;
  color: var(--text-muted);
  margin-left: auto;
}

/* ==========================================================================
   FOOTER SECTION
   ========================================================================== */
.site-footer {
  text-align: center;
  padding: 2rem 0;
  border-top: 1px solid var(--border-outer);
  margin-top: 2rem;
  color: var(--text-muted);
  font-size: 0.85rem;
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
}

.footer-sub {
  font-size: 0.75rem;
  opacity: 0.8;
}

/* ==========================================================================
   RESPONSIVE LAYOUT (MOBILE OPTIMIZATIONS)
   ========================================================================== */
@media (max-width: 992px) {
  .container {
    grid-template-columns: 1fr;
    padding: 1.5rem 1rem;
    gap: 1.75rem;
  }
  
  .profile-card {
    position: relative;
    top: 0;
  }
}

@media (max-width: 600px) {
  .paper-card {
    padding: 1.25rem;
    gap: 0.65rem;
  }
  
  .year-label {
    position: relative;
    right: auto;
    top: auto;
    align-self: flex-start;
    margin-top: 0.25rem;
  }
  
  .paper-title {
    padding-right: 0;
    font-size: 1.15rem;
  }
  
  .paper-links {
    flex-direction: column;
    align-items: stretch;
  }
  
  .link-btn {
    width: 100%;
  }
  
  .paper-note {
    margin-left: 0;
    margin-top: 0.25rem;
    text-align: center;
  }
  
  .filter-bar {
    justify-content: center;
  }
  
  .filter-btn {
    flex-grow: 1;
    text-align: center;
  }
}