/* ==========================================================================
   Md Samiul Islam Sagar (msis.io) — Single-Page Responsive Research Stylesheet
   Mobile-First | Fluid Grids | Animations | Anti-Download Media Shield
   ========================================================================== */

:root {
  --bg-primary: #0a0f1d;
  --bg-secondary: #111827;
  --bg-card: rgba(22, 31, 51, 0.84);
  --bg-card-hover: rgba(30, 42, 68, 0.96);
  --bg-glass: rgba(10, 15, 29, 0.85);
  --text-primary: #f8fafc;
  --text-secondary: #cbd5e1;
  --text-muted: #94a3b8;
  --accent-cyan: #38bdf8;
  --accent-teal: #2dd4bf;
  --accent-crimson: #f43f5e;
  --accent-amber: #fbbf24;
  --border-subtle: rgba(148, 163, 184, 0.16);
  --border-highlight: rgba(56, 189, 248, 0.45);
  --shadow-lg: 0 20px 40px -15px rgba(2, 6, 23, 0.75);
  --radius-md: 12px;
  --radius-lg: 18px;
  --max-width: 1200px;
  --header-height: 68px;
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', Consolas, monospace;
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--header-height) + 1.25rem);
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-sans);
  background-color: var(--bg-primary);
  background-image:
    radial-gradient(circle at 12% 15%, rgba(56, 189, 248, 0.09), transparent 35%),
    radial-gradient(circle at 88% 10%, rgba(244, 63, 94, 0.08), transparent 35%),
    radial-gradient(circle at 50% 85%, rgba(45, 212, 191, 0.06), transparent 40%);
  color: var(--text-primary);
  line-height: 1.65;
  min-height: 100vh;
  overflow-x: hidden;
  display: flex;
  flex-direction: column;
}

a {
  color: var(--accent-cyan);
  text-decoration: none;
  transition: all 0.2s ease;
}

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

/* --- Sticky Responsive Navigation --- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 1000;
  height: var(--header-height);
  background: var(--bg-glass);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--border-subtle);
}

.nav-container {
  max-width: var(--max-width);
  height: 100%;
  margin: 0 auto;
  padding: 0 1.25rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.65rem;
  font-weight: 800;
  font-size: clamp(1rem, 2.5vw, 1.18rem);
  color: var(--text-primary);
  white-space: nowrap;
}

.brand-badge {
  background: linear-gradient(135deg, var(--accent-cyan), var(--accent-teal));
  color: #06121e;
  font-family: var(--font-mono);
  font-weight: 800;
  font-size: 0.78rem;
  padding: 0.22rem 0.5rem;
  border-radius: 6px;
}

.nav-toggle-checkbox {
  display: none;
}

.nav-toggle-label {
  display: none;
  cursor: pointer;
  padding: 0.45rem 0.8rem;
  border: 1px solid var(--border-subtle);
  border-radius: 8px;
  color: var(--text-primary);
  font-size: 0.9rem;
  font-weight: 600;
  background: rgba(255, 255, 255, 0.04);
  user-select: none;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 0.3rem;
  list-style: none;
}

.nav-links a {
  color: var(--text-secondary);
  font-size: 0.88rem;
  font-weight: 500;
  padding: 0.45rem 0.75rem;
  border-radius: 8px;
  white-space: nowrap;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--accent-cyan);
  background: rgba(56, 189, 248, 0.12);
}

/* --- Main Container & Sections --- */
main {
  flex: 1;
  max-width: var(--max-width);
  width: 100%;
  margin: 0 auto;
  padding: clamp(1.25rem, 3vw, 2.5rem) clamp(1rem, 3vw, 1.5rem) 4rem;
}

.scroll-section {
  padding-top: 0.5rem;
}

.section-divider {
  border: 0;
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--border-subtle), transparent);
  margin: clamp(2.5rem, 5vw, 4rem) 0;
}

.section-header {
  margin-bottom: 1.75rem;
}

.eyebrow {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.74rem;
  text-transform: uppercase;
  letter-spacing: 0.11em;
  color: var(--accent-cyan);
  background: rgba(56, 189, 248, 0.1);
  border: 1px solid rgba(56, 189, 248, 0.28);
  padding: 0.25rem 0.7rem;
  border-radius: 999px;
  margin-bottom: 0.65rem;
}

.section-title {
  font-size: clamp(1.5rem, 3.5vw, 2.2rem);
  font-weight: 800;
  letter-spacing: -0.025em;
  line-height: 1.2;
}

.section-subtitle {
  color: var(--text-secondary);
  max-width: 780px;
  margin-top: 0.45rem;
  font-size: clamp(0.92rem, 1.8vw, 1.02rem);
}

/* --- Hero Section --- */
.hero {
  display: grid;
  grid-template-columns: 1.35fr 0.85fr;
  gap: clamp(1.5rem, 3vw, 2.5rem);
  align-items: center;
  padding: clamp(1.35rem, 3.5vw, 2.5rem);
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  margin-bottom: 2rem;
  position: relative;
  overflow: hidden;
}

.hero h1 {
  font-size: clamp(1.85rem, 4.5vw, 3rem);
  line-height: 1.15;
  font-weight: 800;
  letter-spacing: -0.03em;
  margin-bottom: 0.65rem;
}

.gradient-text {
  background: linear-gradient(95deg, #38bdf8, #2dd4bf, #f43f5e);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero-role {
  font-size: clamp(0.95rem, 2vw, 1.1rem);
  color: var(--text-secondary);
  margin-bottom: 0.9rem;
  font-weight: 500;
}

.hero-bio {
  color: var(--text-muted);
  font-size: clamp(0.9rem, 1.6vw, 0.98rem);
  margin-bottom: 1.4rem;
}

.btn-group {
  display: flex;
  flex-wrap: wrap;
  gap: 0.7rem;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.45rem;
  padding: 0.68rem 1.2rem;
  border-radius: 10px;
  font-weight: 600;
  font-size: 0.9rem;
  transition: transform 0.18s ease, box-shadow 0.18s ease;
}

.btn-primary {
  background: linear-gradient(135deg, var(--accent-cyan), var(--accent-teal));
  color: #06121e;
}

.btn-primary:hover {
  color: #06121e;
  transform: translateY(-2px);
  box-shadow: 0 10px 24px -6px rgba(56, 189, 248, 0.5);
}

.btn-outline {
  background: rgba(255, 255, 255, 0.03);
  color: var(--text-primary);
  border: 1px solid var(--border-subtle);
}

.btn-outline:hover {
  border-color: var(--accent-cyan);
  color: var(--accent-cyan);
  transform: translateY(-2px);
}

/* --- Universal Fluid Grids (Zero Overflow on Small Phones) --- */
.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 190px), 1fr));
  gap: 1rem;
  margin-bottom: 2rem;
}

.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 310px), 1fr));
  gap: 1.25rem;
}

.card-grid-2 {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 420px), 1fr));
  gap: 1.35rem;
}

.stat-card,
.card {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: clamp(1.15rem, 2.5vw, 1.6rem);
  position: relative;
  overflow: hidden;
  transition: border-color 0.2s ease, transform 0.2s ease;
}

.card {
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.stat-card:hover,
.card:hover {
  border-color: var(--border-highlight);
}

.stat-number {
  font-size: clamp(1.65rem, 3vw, 2.05rem);
  font-weight: 800;
  color: var(--accent-cyan);
  line-height: 1.1;
  margin-bottom: 0.3rem;
}

.stat-label {
  font-size: 0.88rem;
  color: var(--text-secondary);
  font-weight: 600;
}

.stat-sub {
  font-size: 0.78rem;
  color: var(--text-muted);
  margin-top: 0.2rem;
}

.card h3 {
  font-size: 1.14rem;
  margin: 0.6rem 0 0.5rem;
  color: var(--text-primary);
}

.card p,
.card ul {
  color: var(--text-secondary);
  font-size: 0.92rem;
  margin-bottom: 0.9rem;
}

.card ul {
  padding-left: 1.15rem;
}

.card ul li {
  margin-bottom: 0.4rem;
}

/* --- Media Frames (for Subfolder Photos & Videos) --- */
.media-frame {
  background: linear-gradient(160deg, rgba(15, 23, 42, 0.95), rgba(30, 41, 59, 0.85));
  border: 1px dashed rgba(56, 189, 248, 0.38);
  border-radius: var(--radius-md);
  padding: 0.85rem;
  text-align: center;
  position: relative;
  overflow: hidden;
}

.media-frame img,
.media-frame video {
  width: 100%;
  max-height: 310px;
  object-fit: cover;
  border-radius: 8px;
  display: block;
  margin-bottom: 0.55rem;
  background: #090d16;
}

.media-caption {
  font-size: 0.78rem;
  color: var(--text-muted);
  font-family: var(--font-mono);
  word-break: break-all;
}

.media-path-tag {
  display: inline-block;
  margin-top: 0.25rem;
  padding: 0.15rem 0.5rem;
  border-radius: 5px;
  background: rgba(56, 189, 248, 0.12);
  color: var(--accent-cyan);
  font-family: var(--font-mono);
  font-size: 0.72rem;
}

/* --- Tags --- */
.tag-list {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  margin-top: 0.5rem;
}

.tag {
  font-family: var(--font-mono);
  font-size: 0.73rem;
  padding: 0.22rem 0.6rem;
  border-radius: 6px;
  background: rgba(148, 163, 184, 0.12);
  color: var(--text-secondary);
  border: 1px solid rgba(148, 163, 184, 0.2);
}

.tag-cyan { background: rgba(56, 189, 248, 0.12); color: var(--accent-cyan); border-color: rgba(56, 189, 248, 0.3); }
.tag-teal { background: rgba(45, 212, 191, 0.12); color: var(--accent-teal); border-color: rgba(45, 212, 191, 0.3); }
.tag-crimson { background: rgba(244, 63, 94, 0.14); color: #fda4af; border-color: rgba(244, 63, 94, 0.35); }
.tag-amber { background: rgba(251, 191, 36, 0.14); color: var(--accent-amber); border-color: rgba(251, 191, 36, 0.35); }

/* --- Experience Timeline --- */
.timeline {
  position: relative;
  border-left: 2px solid rgba(56, 189, 248, 0.35);
  margin-left: 0.5rem;
  padding-left: clamp(1.1rem, 3vw, 1.8rem);
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.timeline-item {
  position: relative;
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: clamp(1.1rem, 2.5vw, 1.5rem);
}

.timeline-item::before {
  content: "";
  position: absolute;
  left: calc(-1 * clamp(1.1rem, 3vw, 1.8rem) - 8px);
  top: 1.4rem;
  width: 14px;
  height: 14px;
  border-radius: 50%;
  background: var(--accent-cyan);
  border: 3px solid var(--bg-primary);
}

.timeline-meta {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: baseline;
  gap: 0.4rem;
  margin-bottom: 0.35rem;
}

.timeline-date {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--accent-cyan);
}

.timeline-org {
  font-weight: 600;
  color: var(--accent-teal);
  font-size: 0.92rem;
  margin-bottom: 0.65rem;
}

.timeline-item ul {
  padding-left: 1.15rem;
  color: var(--text-secondary);
  font-size: 0.92rem;
}

.timeline-item ul li {
  margin-bottom: 0.4rem;
}

/* --- Publications Filter & List --- */
.pub-filter-controls {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 1.4rem;
}

.pub-radio {
  display: none;
}

.pub-filter-label {
  cursor: pointer;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  padding: 0.45rem 0.9rem;
  border-radius: 999px;
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  color: var(--text-secondary);
  transition: all 0.2s ease;
}

#filter-all:checked ~ .pub-filter-controls label[for="filter-all"],
#filter-review:checked ~ .pub-filter-controls label[for="filter-review"],
#filter-journal:checked ~ .pub-filter-controls label[for="filter-journal"],
#filter-conf:checked ~ .pub-filter-controls label[for="filter-conf"],
#filter-pres:checked ~ .pub-filter-controls label[for="filter-pres"] {
  background: var(--accent-cyan);
  color: #06121e;
  border-color: var(--accent-cyan);
  font-weight: 700;
}

#filter-review:checked ~ .pub-list .pub-item:not(.cat-review),
#filter-journal:checked ~ .pub-list .pub-item:not(.cat-journal),
#filter-conf:checked ~ .pub-list .pub-item:not(.cat-conf),
#filter-pres:checked ~ .pub-list .pub-item:not(.cat-pres) {
  display: none;
}

.pub-list {
  display: flex;
  flex-direction: column;
  gap: 0.9rem;
}

.pub-item {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-left: 4px solid var(--accent-cyan);
  border-radius: var(--radius-md);
  padding: 1.15rem 1.35rem;
}

.pub-title {
  font-size: 0.98rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 0.3rem;
}

.pub-authors {
  font-size: 0.88rem;
  color: var(--text-secondary);
  margin-bottom: 0.25rem;
}

.pub-authors strong {
  color: var(--accent-cyan);
}

.pub-venue {
  font-size: 0.84rem;
  color: var(--text-muted);
  font-style: italic;
}

/* --- Interactive JS Animations & UI Widgets --- */
.scroll-progress-bar {
  position: fixed;
  top: 0;
  left: 0;
  height: 3px;
  width: 0%;
  background: linear-gradient(90deg, var(--accent-cyan), var(--accent-teal), var(--accent-crimson));
  z-index: 2000;
}

.back-to-top-btn {
  position: fixed;
  bottom: 1.25rem;
  right: 1.25rem;
  width: 44px;
  height: 44px;
  border-radius: 50%;
  border: 1px solid var(--border-highlight);
  background: rgba(15, 23, 42, 0.92);
  color: var(--accent-cyan);
  font-size: 1.2rem;
  font-weight: 800;
  cursor: pointer;
  z-index: 1500;
  opacity: 0;
  visibility: hidden;
  transform: translateY(12px);
  transition: all 0.25s ease;
}

.back-to-top-btn.visible {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.reveal-on-scroll {
  opacity: 0;
  transform: translateY(22px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.reveal-on-scroll.is-visible {
  opacity: 1;
  transform: translateY(0);
}

.card::after,
.stat-card::after {
  content: "";
  position: absolute;
  inset: 0;
  border-radius: inherit;
  background: radial-gradient(
    400px circle at var(--mouse-x, -500px) var(--mouse-y, -500px),
    rgba(56, 189, 248, 0.1),
    transparent 45%
  );
  pointer-events: none;
  z-index: 0;
}

.card > *,
.stat-card > * {
  position: relative;
  z-index: 1;
}

.hero-neural-canvas {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
  z-index: 0;
}

.hero-rotator {
  display: inline-flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.4rem;
  font-family: var(--font-mono);
  font-size: clamp(0.78rem, 1.8vw, 0.86rem);
  background: rgba(56, 189, 248, 0.08);
  border: 1px solid rgba(56, 189, 248, 0.25);
  padding: 0.4rem 0.75rem;
  border-radius: 8px;
  margin-bottom: 1rem;
}

.rotator-prefix { color: var(--accent-teal); font-weight: 700; }
.rotator-text { color: var(--text-primary); }
.rotator-cursor { color: var(--accent-cyan); font-weight: 800; animation: blinkCursor 0.85s infinite; }

@keyframes blinkCursor {
  0%, 100% { opacity: 1; }
  50% { opacity: 0; }
}

.pub-search-wrapper { margin-bottom: 0.9rem; }

.pub-search-input {
  width: 100%;
  padding: 0.75rem 1rem;
  border-radius: 10px;
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  color: var(--text-primary);
  font-family: var(--font-sans);
  font-size: 0.92rem;
  outline: none;
}

.pub-search-input:focus {
  border-color: var(--accent-cyan);
  box-shadow: 0 0 0 3px rgba(56, 189, 248, 0.18);
}

.pub-pop-in { animation: pubFadeIn 0.3s ease forwards; }

@keyframes pubFadeIn {
  from { opacity: 0; transform: translateY(6px); }
  to { opacity: 1; transform: translateY(0); }
}

/* --- Anti-Download Media Protection --- */
img,
video,
.media-frame {
  -webkit-user-drag: none;
  user-drag: none;
  -webkit-user-select: none;
  user-select: none;
  -webkit-touch-callout: none;
}

.media-frame img { pointer-events: none; }

.media-frame::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: 2;
  background: transparent;
  pointer-events: none;
}

.security-toast {
  position: fixed;
  bottom: 1.25rem;
  left: 50%;
  transform: translateX(-50%) translateY(20px);
  background: rgba(15, 23, 42, 0.96);
  border: 1px solid var(--accent-crimson);
  color: var(--text-primary);
  font-family: var(--font-mono);
  font-size: 0.78rem;
  padding: 0.6rem 1rem;
  border-radius: 999px;
  z-index: 3000;
  opacity: 0;
  visibility: hidden;
  transition: all 0.25s ease;
  text-align: center;
  max-width: 90vw;
}

.security-toast.show {
  opacity: 1;
  visibility: visible;
  transform: translateX(-50%) translateY(0);
}

/* --- Footer --- */
.site-footer {
  border-top: 1px solid var(--border-subtle);
  background: rgba(10, 15, 29, 0.95);
  padding: 2rem 1.25rem;
  margin-top: auto;
}

.footer-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: center;
  gap: 0.85rem;
  color: var(--text-muted);
  font-size: 0.85rem;
}

/* ==========================================================================
   Responsive Media Queries (Tablets & Mobile Phones)
   ========================================================================== */
@media (max-width: 960px) {
  .hero {
    grid-template-columns: 1fr;
  }
  .nav-toggle-label {
    display: inline-flex;
    align-items: center;
    gap: 0.35rem;
  }
  .nav-links {
    display: none;
    position: absolute;
    top: var(--header-height);
    left: 0;
    right: 0;
    background: rgba(15, 23, 42, 0.98);
    border-bottom: 1px solid var(--border-subtle);
    flex-direction: column;
    padding: 0.85rem 1.25rem;
    align-items: stretch;
    box-shadow: var(--shadow-lg);
  }
  .nav-links a {
    padding: 0.75rem 1rem;
    font-size: 0.96rem;
  }
  .nav-toggle-checkbox:checked ~ .nav-links {
    display: flex;
  }
}

@media (max-width: 560px) {
  .brand-name {
    font-size: 0.95rem;
  }
  .btn-group {
    flex-direction: column;
  }
  .btn-group .btn {
    width: 100%;
  }
  .pub-filter-controls {
    overflow-x: auto;
    flex-wrap: nowrap;
    padding-bottom: 0.4rem;
  }
  .pub-filter-label {
    white-space: nowrap;
  }
}

@media (prefers-reduced-motion: reduce) {
  .reveal-on-scroll {
    opacity: 1;
    transform: none;
    transition: none;
  }
}