/* ============================================================
   MUSTAFIZUR RAHMAN — ACADEMIC PORTFOLIO
   Aesthetic: Editorial / Refined Academic
   ============================================================ */

:root {
  --bg: #fafaf8;
  --surface: #ffffff;
  --surface-alt: #f3f2ef;
  --text: #1a1a1a;
  --text-secondary: #555;
  --text-tertiary: #888;
  --border: #e2e0db;
  --accent: #192a56;
  --accent-light: #2d4a8a;
  --accent-bg: rgba(25, 42, 86, 0.04);
  --link: #1a4a8a;
  --shadow-sm: 0 1px 2px rgba(0,0,0,0.04);
  --shadow-md: 0 4px 16px rgba(0,0,0,0.06);
  --max-w: 780px;
  --max-w-wide: 1020px;
  --serif: 'Newsreader', Georgia, 'Times New Roman', serif;
  --sans: 'Outfit', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --mono: 'JetBrains Mono', 'Fira Code', monospace;
}

html[data-theme="dark"] {
  --bg: #111;
  --surface: #1a1a1a;
  --surface-alt: #222;
  --text: #e5e5e0;
  --text-secondary: #aaa;
  --text-tertiary: #777;
  --border: #333;
  --accent: #8aacdf;
  --accent-light: #a3c0e8;
  --accent-bg: rgba(138, 172, 223, 0.06);
  --link: #8aacdf;
  --shadow-sm: 0 1px 2px rgba(0,0,0,0.2);
  --shadow-md: 0 4px 16px rgba(0,0,0,0.3);
}

/* RESET */
*, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 80px; }

body {
  font-family: var(--sans);
  font-weight: 400;
  font-size: 16px;
  line-height: 1.75;
  color: var(--text);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
}

a { color: var(--link); text-decoration: none; transition: color 0.15s; }
a:hover { color: var(--accent); }
img { display: block; max-width: 100%; }
strong { font-weight: 600; }
em { font-family: var(--serif); font-style: italic; }

/* ===== HEADER ===== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border);
}

.navbar {
  max-width: var(--max-w-wide);
  margin: 0 auto;
  padding: 0 32px;
  height: 64px;
  display: flex;
  align-items: center;
  gap: 32px;
}

.brand {
  font-family: var(--serif);
  font-weight: 600;
  font-size: 1.05rem;
  color: var(--text);
  text-decoration: none;
  letter-spacing: -0.01em;
  white-space: nowrap;
}

.nav-links {
  margin-left: auto;
  list-style: none;
  display: flex;
  align-items: center;
  gap: 4px;
}

.nav-links a {
  font-size: 0.84rem;
  font-weight: 500;
  color: var(--text-secondary);
  padding: 6px 12px;
  border-radius: 6px;
  transition: color 0.15s, background 0.15s;
  text-decoration: none;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--text);
  background: var(--accent-bg);
}

.theme-toggle {
  width: 36px;
  height: 36px;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: transparent;
  color: var(--text-secondary);
  cursor: pointer;
  display: grid;
  place-items: center;
  transition: color 0.15s, border-color 0.15s;
  flex-shrink: 0;
}

.theme-toggle:hover { color: var(--text); border-color: var(--text-tertiary); }
.icon-moon { display: none; }
html[data-theme="dark"] .icon-sun { display: none; }
html[data-theme="dark"] .icon-moon { display: block; }

.menu-toggle {
  display: none;
  width: 36px;
  height: 36px;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: transparent;
  cursor: pointer;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 5px;
}

.menu-toggle span {
  display: block;
  width: 16px;
  height: 1.5px;
  background: var(--text);
  border-radius: 1px;
}

/* ===== HERO ===== */
.hero {
  border-bottom: 1px solid var(--border);
}

.hero-inner {
  max-width: var(--max-w-wide);
  margin: 0 auto;
  padding: 72px 32px 80px;
  display: grid;
  grid-template-columns: 180px 1fr;
  gap: 48px;
  align-items: start;
}

.hero-photo {
  width: 180px;
  height: 180px;
  border-radius: 50%;
  overflow: hidden;
  border: 3px solid var(--border);
  box-shadow: var(--shadow-md);
  flex-shrink: 0;
}

.hero-photo img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.hero-text h1 {
  font-family: var(--serif);
  font-size: 2.4rem;
  font-weight: 700;
  letter-spacing: -0.03em;
  line-height: 1.15;
  color: var(--text);
}

.hero-role {
  margin-top: 8px;
  font-size: 1.08rem;
  font-weight: 500;
  color: var(--accent);
  letter-spacing: -0.01em;
}

.hero-affiliation {
  font-size: 0.95rem;
  color: var(--text-secondary);
  margin-top: 2px;
}

.hero-summary {
  margin-top: 20px;
  max-width: 600px;
  font-size: 0.98rem;
  color: var(--text-secondary);
  line-height: 1.8;
}

.hero-links {
  margin-top: 28px;
  display: flex;
  align-items: center;
  gap: 20px;
  flex-wrap: wrap;
}

.hero-links a {
  font-size: 0.88rem;
  font-weight: 500;
  color: var(--text-secondary);
  text-decoration: none;
  transition: color 0.15s;
}

.hero-links a:hover { color: var(--text); }

.btn-primary {
  display: inline-flex;
  align-items: center;
  padding: 10px 24px;
  background: var(--accent);
  color: #fff !important;
  border-radius: 8px;
  font-weight: 600;
  font-size: 0.88rem;
  letter-spacing: 0.01em;
  transition: background 0.2s, transform 0.15s;
}

html[data-theme="dark"] .btn-primary {
  background: var(--accent-light);
  color: #111 !important;
}

.btn-primary:hover { transform: translateY(-1px); opacity: 0.92; }

/* ===== SECTIONS ===== */
.section {
  border-bottom: 1px solid var(--border);
}

.section-inner {
  max-width: var(--max-w-wide);
  margin: 0 auto;
  padding: 64px 32px;
}

.section h2 {
  font-family: var(--serif);
  font-size: 1.6rem;
  font-weight: 600;
  letter-spacing: -0.02em;
  margin-bottom: 32px;
  color: var(--text);
}

/* Prose */
.prose {
  max-width: var(--max-w);
}

.prose p {
  color: var(--text-secondary);
  font-size: 0.98rem;
  line-height: 1.85;
}

.prose p + p { margin-top: 18px; }

/* ===== NEWS ===== */
.news-list { max-width: var(--max-w); }

.news-entry {
  display: grid;
  grid-template-columns: 64px 1fr;
  gap: 16px;
  padding: 14px 0;
  align-items: baseline;
}

.news-entry + .news-entry { border-top: 1px solid var(--border); }

.news-entry time {
  font-family: var(--mono);
  font-size: 0.82rem;
  color: var(--text-tertiary);
  font-weight: 500;
}

.news-entry p {
  font-size: 0.94rem;
  color: var(--text-secondary);
  line-height: 1.65;
}

.news-entry strong { color: var(--text); }

/* ===== RESEARCH ===== */
.research-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 2px;
  background: var(--border);
  border: 1px solid var(--border);
  border-radius: 12px;
  overflow: hidden;
}

.research-item {
  background: var(--surface);
  padding: 28px 28px 32px;
}

.research-num {
  display: inline-block;
  font-family: var(--mono);
  font-size: 0.72rem;
  font-weight: 500;
  color: var(--text-tertiary);
  margin-bottom: 12px;
  letter-spacing: 0.05em;
}

.research-item h3 {
  font-family: var(--serif);
  font-size: 1.1rem;
  font-weight: 600;
  letter-spacing: -0.015em;
  line-height: 1.3;
  color: var(--text);
}

.research-item p {
  margin-top: 8px;
  font-size: 0.88rem;
  color: var(--text-secondary);
  line-height: 1.7;
}

/* ===== PUBLICATIONS ===== */
.pub-list {
  list-style: none;
  max-width: var(--max-w);
}

.pub-entry {
  display: grid;
  grid-template-columns: 56px 1fr;
  gap: 20px;
  padding: 24px 0;
}

.pub-entry + .pub-entry { border-top: 1px solid var(--border); }

.pub-meta time {
  font-family: var(--mono);
  font-size: 0.82rem;
  color: var(--text-tertiary);
  font-weight: 500;
}

.pub-body h3 {
  font-family: var(--serif);
  font-size: 1.05rem;
  font-weight: 600;
  line-height: 1.35;
  letter-spacing: -0.01em;
  color: var(--text);
}

.pub-authors {
  margin-top: 6px;
  font-size: 0.88rem;
  color: var(--text-secondary);
}

.pub-venue {
  margin-top: 3px;
  font-size: 0.88rem;
  color: var(--text-tertiary);
}

.pub-desc {
  margin-top: 10px;
  font-size: 0.88rem;
  color: var(--text-secondary);
  line-height: 1.7;
}

.pub-links {
  margin-top: 12px;
  display: flex;
  gap: 16px;
}

.pub-links a {
  font-size: 0.84rem;
  font-weight: 600;
  color: var(--link);
}

/* ===== TEACHING ===== */
.teaching-list { max-width: var(--max-w); }

.teaching-entry {
  padding: 24px 0;
}

.teaching-meta {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 10px;
}

.teaching-badge {
  font-family: var(--mono);
  font-size: 0.72rem;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--accent);
  background: var(--accent-bg);
  padding: 3px 10px;
  border-radius: 4px;
}

.teaching-meta time {
  font-family: var(--mono);
  font-size: 0.82rem;
  color: var(--text-tertiary);
}

.teaching-entry h3 {
  font-family: var(--serif);
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--text);
}

.teaching-entry p {
  margin-top: 6px;
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.75;
}

/* ===== PROJECTS ===== */
.project-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 2px;
  background: var(--border);
  border: 1px solid var(--border);
  border-radius: 12px;
  overflow: hidden;
}

.project-entry {
  background: var(--surface);
  padding: 28px;
  display: flex;
  flex-direction: column;
  min-height: 220px;
}

.project-tags {
  display: flex;
  gap: 6px;
  margin-bottom: 14px;
}

.project-tags span {
  font-family: var(--mono);
  font-size: 0.7rem;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-tertiary);
  background: var(--surface-alt);
  padding: 3px 8px;
  border-radius: 4px;
}

.project-entry h3 {
  font-family: var(--serif);
  font-size: 1.05rem;
  font-weight: 600;
  letter-spacing: -0.01em;
  line-height: 1.3;
  color: var(--text);
}

.project-entry p {
  margin-top: 8px;
  font-size: 0.88rem;
  color: var(--text-secondary);
  line-height: 1.7;
}

.project-link {
  margin-top: auto;
  padding-top: 16px;
  font-size: 0.84rem;
  font-weight: 600;
  color: var(--link);
}

/* ===== EDUCATION ===== */
.edu-list { max-width: var(--max-w); }

.edu-entry {
  display: grid;
  grid-template-columns: 130px 1fr;
  gap: 20px;
  padding: 18px 0;
}

.edu-entry + .edu-entry { border-top: 1px solid var(--border); }

.edu-entry time {
  font-family: var(--mono);
  font-size: 0.82rem;
  color: var(--text-tertiary);
  font-weight: 500;
}

.edu-entry h3 {
  font-family: var(--serif);
  font-size: 1.02rem;
  font-weight: 600;
  color: var(--text);
}

.edu-entry p {
  margin-top: 2px;
  font-size: 0.88rem;
  color: var(--text-secondary);
}

/* ===== CONTACT ===== */
.contact-body { max-width: var(--max-w); }

.contact-intro {
  font-size: 0.98rem;
  color: var(--text-secondary);
  line-height: 1.8;
  margin-bottom: 28px;
}

.contact-details {
  display: grid;
  gap: 0;
}

.contact-details > div {
  display: grid;
  grid-template-columns: 100px 1fr;
  gap: 16px;
  padding: 14px 0;
}

.contact-details > div + div { border-top: 1px solid var(--border); }

.contact-details dt {
  font-family: var(--mono);
  font-size: 0.78rem;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-tertiary);
}

.contact-details dd {
  font-size: 0.94rem;
  color: var(--text-secondary);
}

.contact-details a { color: var(--link); }

/* ===== EXPERIENCE ===== */
.exp-list { max-width: var(--max-w); }

.exp-entry {
  padding: 24px 0;
}

.exp-entry + .exp-entry { border-top: 1px solid var(--border); }

.exp-meta {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 10px;
}

.exp-entry h3 {
  font-family: var(--serif);
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--text);
}

.exp-entry p {
  margin-top: 6px;
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.75;
}

/* ===== CERTIFICATIONS ===== */
.cert-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 2px;
  background: var(--border);
  border: 1px solid var(--border);
  border-radius: 12px;
  overflow: hidden;
}

.cert-entry {
  background: var(--surface);
  padding: 22px 24px;
}

.cert-entry h3 {
  font-family: var(--serif);
  font-size: 0.95rem;
  font-weight: 600;
  line-height: 1.3;
  color: var(--text);
}

.cert-entry p {
  margin-top: 4px;
  font-size: 0.82rem;
  color: var(--text-tertiary);
}

/* ===== EDUCATION DETAIL ===== */
.edu-detail {
  margin-top: 4px;
  font-size: 0.86rem !important;
  color: var(--text-tertiary) !important;
  line-height: 1.65;
}

/* ===== FOOTER ===== */
.site-footer {
  padding: 32px 0;
  text-align: center;
  color: var(--text-tertiary);
  font-size: 0.82rem;
}

/* ===== SCROLL REVEAL ===== */
.section-inner,
.hero-inner {
  animation: reveal 0.5s ease both;
}

@keyframes reveal {
  from { opacity: 0; transform: translateY(16px); }
  to { opacity: 1; transform: translateY(0); }
}

/* ===== RESPONSIVE ===== */
@media (max-width: 860px) {
  .navbar { padding: 0 20px; }

  .menu-toggle {
    display: flex;
    margin-left: auto;
  }

  .nav-links {
    position: absolute;
    top: 64px;
    left: 16px;
    right: 16px;
    display: none;
    flex-direction: column;
    padding: 8px;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 10px;
    box-shadow: var(--shadow-md);
  }

  .nav-links.open { display: flex; }

  .nav-links a {
    display: block;
    padding: 10px 14px;
  }

  .hero-inner {
    grid-template-columns: 1fr;
    padding: 48px 20px 56px;
    gap: 24px;
    text-align: center;
  }

  .hero-photo {
    width: 140px;
    height: 140px;
    margin: 0 auto;
  }

  .hero-links { justify-content: center; }

  .hero-text h1 { font-size: 2rem; }

  .hero-summary { margin-left: auto; margin-right: auto; }

  .section-inner { padding: 48px 20px; }

  .research-grid,
  .project-grid,
  .cert-grid {
    grid-template-columns: 1fr;
  }

  .pub-entry,
  .edu-entry,
  .news-entry {
    grid-template-columns: 1fr;
    gap: 4px;
  }

  .contact-details > div {
    grid-template-columns: 1fr;
    gap: 2px;
  }
}

@media (max-width: 520px) {
  .brand { font-size: 0.95rem; }
  .hero-text h1 { font-size: 1.7rem; }
}