/* ════════════════════════════════════════════════════════════════
   SHEIKH SAJJAD HOSSAIN — PORTFOLIO STYLESHEET
   ──────────────────────────────────────────────────────────────────
   TABLE OF CONTENTS
     1.  Design tokens (colors, spacing, shadows) — dark & light
     2.  Base / reset / typography
     3.  Reusable utilities (container, buttons, badges, tags, cards)
     4.  Header & navigation
     5.  Hero section
     6.  About section
     7.  Timeline (Experience + Education)
     8.  Skills
     9.  Projects
    10.  Research & publications
    11.  Sliders / carousels
    12.  Footer / contact
    13.  Floating UI (scroll progress, back-to-top)
    14.  Scroll-reveal animations
    15.  Responsive breakpoints
    16.  Accessibility & reduced motion
   ──────────────────────────────────────────────────────────────────
   THEMING: every color is a CSS variable defined in :root (dark,
   the default) and overridden in [data-theme="light"]. To re-brand
   the whole site, change --accent / --accent-2 only.
   ════════════════════════════════════════════════════════════════ */

/* ═══ 1. DESIGN TOKENS ═══════════════════════════════════════════ */
:root {
  /* Backgrounds */
  --bg: #070b14;
  --bg-alt: #0b101d;
  --surface: #101727;
  --surface-2: #16203455;

  /* Text */
  --text-strong: #f1f3f7;
  --text: #b9c0cf;
  --text-muted: #717a8e;

  /* Brand accent — change these two to re-color the entire site */
  --accent: #4f8cff;
  --accent-2: #8b5cf6;
  --accent-soft: rgba(79, 140, 255, 0.12);
  --gradient: linear-gradient(135deg, var(--accent), var(--accent-2));

  /* Lines & shadows */
  --border: #1e2940;
  --border-strong: #2c3a58;
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.25);
  --shadow-md: 0 10px 30px rgba(0, 0, 0, 0.35);
  --shadow-accent: 0 8px 24px rgba(79, 140, 255, 0.25);

  /* Glass surfaces (header) */
  --glass: rgba(10, 15, 26, 0.72);

  /* Typography */
  --font-body: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --font-heading: "Space Grotesk", var(--font-body);

  /* Layout rhythm */
  --container: 1140px;
  --radius: 14px;
  --radius-sm: 8px;
  --section-pad: clamp(4rem, 9vw, 6.5rem);

  color-scheme: dark;
}

/* Light theme — toggled by the moon/sun button (js/main.js) */
[data-theme="light"] {
  --bg: #f7f9fc;
  --bg-alt: #eef2f8;
  --surface: #ffffff;
  --surface-2: #ffffffcc;

  --text-strong: #101626;
  --text: #3c4458;
  --text-muted: #6c7589;

  --accent: #2563eb;
  --accent-2: #7c3aed;
  --accent-soft: rgba(37, 99, 235, 0.08);

  --border: #dfe5ef;
  --border-strong: #c7d0e0;
  --shadow-sm: 0 2px 8px rgba(16, 24, 40, 0.06);
  --shadow-md: 0 10px 30px rgba(16, 24, 40, 0.1);
  --shadow-accent: 0 8px 24px rgba(37, 99, 235, 0.18);

  --glass: rgba(255, 255, 255, 0.78);

  color-scheme: light;
}

/* ═══ 2. BASE / RESET / TYPOGRAPHY ═══════════════════════════════ */
*,
*::before,
*::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  /* keeps anchored sections from hiding under the sticky header */
  scroll-padding-top: 84px;
}

body {
  font-family: var(--font-body);
  background-color: var(--bg);
  color: var(--text);
  line-height: 1.7;
  font-size: 1rem;
  -webkit-font-smoothing: antialiased;
  transition: background-color 0.35s ease, color 0.35s ease;
}

h1, h2, h3, h4 {
  font-family: var(--font-heading);
  color: var(--text-strong);
  line-height: 1.25;
  font-weight: 600;
  text-wrap: balance;
}

img, video {
  max-width: 100%;
  display: block;
}

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

::selection {
  background: var(--accent);
  color: #fff;
}

/* ═══ 3. REUSABLE UTILITIES ══════════════════════════════════════ */
.container {
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: clamp(1.25rem, 4vw, 2rem);
}

.section {
  padding-block: var(--section-pad);
}

/* Alternating band background for visual rhythm between sections */
.section-alt {
  background-color: var(--bg-alt);
  border-block: 1px solid var(--border);
}

/* Small colored label above each section title */
.section-eyebrow {
  font-size: 0.8125rem;
  font-weight: 700;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 0.5rem;
}

.section-title {
  font-size: clamp(1.75rem, 4vw, 2.5rem);
  font-weight: 700;
  margin-bottom: clamp(2rem, 5vw, 3rem);
  position: relative;
  padding-bottom: 0.85rem;
}

.section-title::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: 0;
  width: 64px;
  height: 4px;
  border-radius: 4px;
  background: var(--gradient);
}

.highlight {
  color: var(--accent);
  font-weight: 600;
}

.gradient-text {
  background: var(--gradient);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.inline-link {
  font-size: 0.85em;
  text-decoration: none;
  margin-left: 0.5rem;
  white-space: nowrap;
}
.inline-link:hover { text-decoration: underline; }
.inline-link i { font-size: 0.75em; }

/* ── Buttons ── */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.55rem;
  padding: 0.8rem 1.75rem;
  border-radius: 999px;
  font-weight: 600;
  font-size: 0.9375rem;
  text-decoration: none;
  cursor: pointer;
  border: 1px solid transparent;
  transition: transform 0.2s ease, box-shadow 0.2s ease,
    background-color 0.2s ease, border-color 0.2s ease;
}

.btn-primary {
  background: var(--gradient);
  color: #fff;
  box-shadow: var(--shadow-accent);
}
.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 12px 28px rgba(79, 140, 255, 0.35);
}

.btn-ghost {
  background: transparent;
  color: var(--text-strong);
  border-color: var(--border-strong);
}
.btn-ghost:hover {
  border-color: var(--accent);
  color: var(--accent);
  transform: translateY(-2px);
}

.btn-small {
  padding: 0.5rem 1.1rem;
  font-size: 0.85rem;
}

/* ── Private (non-clickable) button + hover tooltip ──
   Used for projects whose source code lives in a private repo.
   The element is a <span role="button" aria-disabled="true">, so it
   is not a link and cannot be clicked through to a 404. */
.btn-private {
  cursor: not-allowed;
  opacity: 0.7;
}
.btn-private:hover {
  /* cancel the normal ghost-button lift/recolor — it should feel inert */
  transform: none;
  border-color: var(--border-strong);
  color: var(--text-strong);
}

/* Tooltip shown on hover/focus of any element carrying [data-tooltip] */
[data-tooltip] {
  position: relative;
}
[data-tooltip]::after {
  content: attr(data-tooltip);
  position: absolute;
  bottom: calc(100% + 8px);
  left: 50%;
  transform: translateX(-50%) translateY(4px);
  white-space: nowrap;
  background: var(--text-strong);
  color: var(--bg);
  padding: 0.4rem 0.7rem;
  border-radius: var(--radius-sm);
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.01em;
  opacity: 0;
  pointer-events: none;
  box-shadow: var(--shadow-md);
  transition: opacity 0.18s ease, transform 0.18s ease;
  z-index: 30;
}
[data-tooltip]:hover::after,
[data-tooltip]:focus-visible::after {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}

/* ── Badges (status chips on cards) ── */
.badge {
  display: inline-block;
  padding: 0.3rem 0.85rem;
  border-radius: 999px;
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.04em;
}

.badge-accent {
  margin-left: 0.6rem;
  background: var(--accent-soft);
  color: var(--accent);
  border: 1px solid var(--accent);
}

.badge-soon {
  background: var(--accent-soft);
  color: var(--accent);
  border: 1px dashed var(--accent);
  margin-bottom: 0.85rem;
}

/* ── Tags (technology pills) ── */
.tag {
  background-color: var(--accent-soft);
  color: var(--text);
  padding: 0.32rem 0.85rem;
  border-radius: 999px;
  font-size: 0.8125rem;
  font-weight: 500;
  border: 1px solid var(--border);
  transition: border-color 0.2s ease, color 0.2s ease;
}
.tag:hover {
  border-color: var(--accent);
  color: var(--accent);
}

/* ── Cards ── */
.card {
  background-color: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  transition: transform 0.3s ease, border-color 0.3s ease,
    box-shadow 0.3s ease;
}
.card:hover {
  border-color: var(--accent);
  box-shadow: var(--shadow-md);
}

/* Dashed look for "to be added" placeholder entries.
   Remove the class once the entry has real content. */
.placeholder-card {
  border-style: dashed;
  border-color: var(--border-strong);
}
.placeholder-card .timeline-summary,
.placeholder-card .timeline-list {
  color: var(--text-muted);
}

/* ═══ 4. HEADER & NAVIGATION ═════════════════════════════════════ */
.skip-link {
  position: absolute;
  top: -48px;
  left: 1rem;
  z-index: 300;
  background: var(--accent);
  color: #fff;
  padding: 0.6rem 1.2rem;
  border-radius: 0 0 var(--radius-sm) var(--radius-sm);
  text-decoration: none;
  transition: top 0.2s ease;
}
.skip-link:focus { top: 0; }

.site-header {
  position: sticky;
  top: 0;
  z-index: 200;
  background: var(--glass);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--border);
  transition: box-shadow 0.3s ease, background-color 0.3s ease;
}
.site-header.scrolled { box-shadow: var(--shadow-sm); }

.header-inner {
  max-width: var(--container);
  margin-inline: auto;
  padding: 0.85rem clamp(1.25rem, 4vw, 2rem);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1.5rem;
}

.logo {
  display: flex;
  align-items: center;
  gap: 0.65rem;
  text-decoration: none;
  color: var(--text-strong);
  font-family: var(--font-heading);
  font-weight: 700;
}

.logo-mark {
  display: grid;
  place-items: center;
  width: 38px;
  height: 38px;
  border-radius: 10px;
  background: var(--gradient);
  color: #fff;
  font-size: 0.95rem;
  letter-spacing: 0.02em;
  flex-shrink: 0;
}

.logo-text {
  font-size: 0.95rem;
  letter-spacing: 0.01em;
}

nav {
  display: flex;
  gap: clamp(1rem, 2vw, 1.75rem);
}

.nav-link {
  position: relative;
  color: var(--text);
  text-decoration: none;
  font-size: 0.9rem;
  font-weight: 500;
  padding: 0.35rem 0;
  transition: color 0.2s ease;
}

/* animated underline on hover + active section (scroll spy) */
.nav-link::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: 0;
  width: 100%;
  height: 2px;
  border-radius: 2px;
  background: var(--gradient);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.25s ease;
}
.nav-link:hover,
.nav-link.active { color: var(--text-strong); }
.nav-link:hover::after,
.nav-link.active::after { transform: scaleX(1); }

.header-actions {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

/* Theme toggle: shows moon in dark mode, sun in light mode */
.theme-toggle {
  display: grid;
  place-items: center;
  width: 38px;
  height: 38px;
  border-radius: 10px;
  border: 1px solid var(--border-strong);
  background: transparent;
  color: var(--text-strong);
  font-size: 0.95rem;
  cursor: pointer;
  transition: border-color 0.2s ease, color 0.2s ease, transform 0.2s ease;
}
.theme-toggle:hover {
  border-color: var(--accent);
  color: var(--accent);
  transform: rotate(15deg);
}
.theme-toggle .fa-sun { display: none; }
[data-theme="light"] .theme-toggle .fa-moon { display: none; }
[data-theme="light"] .theme-toggle .fa-sun { display: block; }

/* Hamburger (mobile only) */
.menu-btn {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 38px;
  height: 38px;
  border-radius: 10px;
  border: 1px solid var(--border-strong);
  background: transparent;
  cursor: pointer;
  padding: 8px;
}
.menu-btn span {
  display: block;
  height: 2px;
  border-radius: 2px;
  background: var(--text-strong);
  transition: transform 0.25s ease, opacity 0.25s ease;
}
/* hamburger → X animation when open */
.menu-btn.open span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.menu-btn.open span:nth-child(2) { opacity: 0; }
.menu-btn.open span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* ═══ 5. HERO ════════════════════════════════════════════════════ */
.hero {
  position: relative;
  overflow: hidden;
  padding-block: clamp(4rem, 10vw, 7rem) clamp(3rem, 6vw, 4.5rem);
}

/* soft glowing blobs behind the hero — pure CSS decoration */
.hero-glow {
  position: absolute;
  border-radius: 50%;
  filter: blur(110px);
  opacity: 0.35;
  pointer-events: none;
}
.hero-glow-1 {
  width: 480px;
  height: 480px;
  background: var(--accent);
  top: -160px;
  right: -120px;
}
.hero-glow-2 {
  width: 380px;
  height: 380px;
  background: var(--accent-2);
  bottom: -140px;
  left: -120px;
  opacity: 0.22;
}

.hero-content {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: clamp(2rem, 6vw, 4.5rem);
  position: relative;
}

.hero-text { max-width: 640px; }

.hero-badge {
  display: inline-flex;
  align-items: center;
  flex-wrap: wrap;
  justify-content: center;
  max-width: 100%;
  gap: 0.6rem;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-strong);
  background: var(--accent-soft);
  border: 1px solid var(--border-strong);
  padding: 0.45rem 1.1rem;
  border-radius: 999px;
  margin-bottom: 1.5rem;
}

/* blinking green dot inside the availability badge */
.pulse-dot {
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: #22c55e;
  box-shadow: 0 0 0 0 rgba(34, 197, 94, 0.6);
  animation: pulse 2s infinite;
}
@keyframes pulse {
  70% { box-shadow: 0 0 0 9px rgba(34, 197, 94, 0); }
  100% { box-shadow: 0 0 0 0 rgba(34, 197, 94, 0); }
}

.hero-title {
  font-size: clamp(2.1rem, 5.5vw, 3.4rem);
  font-weight: 700;
  margin-bottom: 0.85rem;
}

/* typed roles line */
.hero-roles {
  font-family: var(--font-heading);
  font-size: clamp(1.05rem, 2.5vw, 1.35rem);
  font-weight: 600;
  color: var(--accent);
  margin-bottom: 1.4rem;
  min-height: 1.6em; /* prevents layout shift while typing */
}
.typed-cursor {
  animation: blink 0.9s step-end infinite;
  font-weight: 400;
}
@keyframes blink { 50% { opacity: 0; } }

.hero-summary {
  font-size: 1.05rem;
  line-height: 1.85;
  margin-bottom: 2rem;
}

.hero-cta {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  margin-bottom: 1.75rem;
}

.hero-socials {
  display: flex;
  gap: 0.9rem;
}
.hero-socials a {
  display: grid;
  place-items: center;
  width: 42px;
  height: 42px;
  border-radius: 12px;
  border: 1px solid var(--border-strong);
  color: var(--text);
  font-size: 1.1rem;
  text-decoration: none;
  transition: all 0.2s ease;
}
.hero-socials a:hover {
  border-color: var(--accent);
  color: var(--accent);
  transform: translateY(-3px);
}

/* portrait with rotating gradient ring */
.hero-image { flex-shrink: 0; }

.profile-ring {
  position: relative;
  padding: 6px;
  border-radius: 50%;
  background: var(--gradient);
}

.profile-img {
  width: clamp(220px, 26vw, 320px);
  height: clamp(220px, 26vw, 320px);
  border-radius: 50%;
  object-fit: cover;
  border: 5px solid var(--bg);
}

/* stats strip under the hero */
.hero-stats {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  gap: 1rem;
  margin-top: clamp(2.5rem, 6vw, 4rem);
  position: relative;
}

.stat {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.4rem 1rem;
  text-align: center;
  transition: transform 0.25s ease, border-color 0.25s ease;
}
.stat:hover {
  transform: translateY(-4px);
  border-color: var(--accent);
}

.stat-number {
  display: block;
  font-family: var(--font-heading);
  font-size: 2rem;
  font-weight: 700;
  background: var(--gradient);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.stat-label {
  font-size: 0.85rem;
  color: var(--text-muted);
  font-weight: 500;
}

/* ═══ 6. ABOUT ═══════════════════════════════════════════════════ */
.about-grid {
  display: grid;
  grid-template-columns: 1.6fr 1fr;
  gap: clamp(2rem, 5vw, 4rem);
  align-items: start;
}

.about-text p {
  margin-bottom: 1.4rem;
  line-height: 1.85;
}

.about-media video {
  width: 100%;
  border-radius: var(--radius);
  box-shadow: var(--shadow-md);
  margin-top: 1rem;
}

.about-facts {
  display: grid;
  gap: 1rem;
}

.fact-card {
  display: flex;
  align-items: center;
  gap: 1rem;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.1rem 1.25rem;
  transition: transform 0.25s ease, border-color 0.25s ease;
}
.fact-card:hover {
  transform: translateX(6px);
  border-color: var(--accent);
}
.fact-card i {
  font-size: 1.25rem;
  color: var(--accent);
  width: 40px;
  height: 40px;
  display: grid;
  place-items: center;
  background: var(--accent-soft);
  border-radius: 10px;
  flex-shrink: 0;
}
.fact-card strong {
  display: block;
  color: var(--text-strong);
  font-size: 0.95rem;
}
.fact-card span {
  font-size: 0.85rem;
  color: var(--text-muted);
}

/* ═══ 7. TIMELINE (Experience + Education) ═══════════════════════ */
.timeline {
  position: relative;
  padding-left: 2rem;
}

/* the vertical gradient line */
.timeline::before {
  content: "";
  position: absolute;
  left: 7px;
  top: 6px;
  bottom: 6px;
  width: 2px;
  background: linear-gradient(180deg, var(--accent), var(--accent-2));
  opacity: 0.45;
}

.timeline-item {
  position: relative;
  margin-bottom: 2rem;
}
.timeline-item:last-child { margin-bottom: 0; }

.timeline-dot {
  position: absolute;
  left: -2rem;
  top: 26px;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: var(--bg);
  border: 3px solid var(--accent);
  box-shadow: 0 0 0 4px var(--accent-soft);
}

.timeline-card { padding: 1.75rem 2rem; }

.timeline-role {
  font-size: 1.2rem;
  margin-bottom: 0.35rem;
}

.timeline-company {
  color: var(--accent);
  font-weight: 600;
}

.timeline-meta {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.45rem;
  color: var(--text-muted);
  font-size: 0.9rem;
  margin-bottom: 1rem;
}
.timeline-meta i { font-size: 0.85em; }

.timeline-summary { margin-bottom: 0.85rem; }

.timeline-list {
  padding-left: 1.2rem;
  display: grid;
  gap: 0.45rem;
}
.timeline-list li::marker { color: var(--accent); }

/* education-specific: logo beside the degree title */
.edu-header {
  display: flex;
  align-items: center;
  gap: 1.25rem;
  margin-bottom: 1rem;
}
.edu-logo {
  width: 64px;
  height: 64px;
  object-fit: contain;
  border-radius: var(--radius-sm);
  background: #fff;
  padding: 6px;
  flex-shrink: 0;
}

/* ═══ 8. SKILLS ══════════════════════════════════════════════════ */
.skills-category { margin-bottom: 2.5rem; }
.skills-category:last-child { margin-bottom: 0; }

.skills-heading {
  font-size: 1.05rem;
  color: var(--text-strong);
  margin-bottom: 1.1rem;
  display: flex;
  align-items: center;
  gap: 0.6rem;
}
.skills-heading i { color: var(--accent); }

.skills-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(130px, 1fr));
  gap: 1rem;
}

.skill-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.4rem 0.9rem;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.8rem;
  transition: transform 0.25s ease, border-color 0.25s ease,
    box-shadow 0.25s ease;
}
.skill-card:hover {
  border-color: var(--accent);
  transform: translateY(-5px);
  box-shadow: var(--shadow-accent);
}
.skill-card i {
  font-size: 2.1rem;
  background: var(--gradient);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.skill-card span {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-strong);
  text-align: center;
}

/* ═══ 9. PROJECTS ════════════════════════════════════════════════ */
.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(340px, 100%), 1fr));
  gap: 2rem;
}

.project-card {
  display: flex;
  flex-direction: column;
  overflow: hidden; /* clips media corners to the card radius */
}
.project-card:hover { transform: translateY(-6px); }

.project-media {
  position: relative;
  background: var(--bg-alt);
  border-bottom: 1px solid var(--border);
}
.project-media img,
.project-media video {
  width: 100%;
  aspect-ratio: 16 / 10;
  object-fit: cover;
}

.project-body {
  padding: 1.75rem;
  display: flex;
  flex-direction: column;
  flex: 1;
}

.project-meta {
  font-size: 0.8rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 0.5rem;
}

.project-title {
  font-size: 1.25rem;
  margin-bottom: 0.85rem;
  display: flex;
  align-items: center;
  gap: 0.6rem;
}
.project-title i { color: var(--accent); font-size: 1.05rem; }

.project-description { margin-bottom: 0.75rem; }

.project-subheading {
  font-size: 0.95rem;
  margin: 0.5rem 0 0.5rem;
}

.project-list {
  padding-left: 1.2rem;
  display: grid;
  gap: 0.4rem;
  margin-bottom: 1rem;
}
.project-list li::marker { color: var(--accent); }

.project-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-top: auto; /* pins tags to the card bottom for equal heights */
  padding-top: 0.75rem;
}

.project-links {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-top: 1.25rem;
}

/* ═══ 10. RESEARCH & PUBLICATIONS ════════════════════════════════ */
.publications-grid {
  display: grid;
  gap: 1.5rem;
}

.publication-card { padding: 2rem; }

.publication-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 1rem;
  margin-bottom: 1rem;
}

.publication-title {
  font-size: 1.15rem;
  flex: 1;
}

.publication-status {
  padding: 0.35rem 0.9rem;
  border-radius: 999px;
  font-size: 0.75rem;
  font-weight: 700;
  white-space: nowrap;
}
.status-conference {
  background: rgba(79, 140, 255, 0.14);
  color: var(--accent);
  border: 1px solid rgba(79, 140, 255, 0.35);
}
.status-under-review {
  background: rgba(245, 158, 11, 0.14);
  color: #f59e0b;
  border: 1px solid rgba(245, 158, 11, 0.35);
}
.status-accepted {
  background: rgba(16, 185, 129, 0.14);
  color: #10b981;
  border: 1px solid rgba(16, 185, 129, 0.35);
}

.publication-description { margin-bottom: 1.1rem; }

.publication-keywords {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.publication-links {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-top: 1.25rem;
}

.publication-people {
  margin-top: 1rem;
  font-size: 0.9rem;
  color: var(--text-muted);
}
.publication-people i { color: var(--accent); margin-right: 0.4rem; }

/* ═══ 11. SLIDERS / CAROUSELS ════════════════════════════════════
   Markup: .slider-container[data-slider] > .slider > (img | figure)*
   Arrows and dot indicators are injected by js/main.js.           */
.slider-container {
  position: relative;
  overflow: hidden;
}

.slider {
  display: flex;
  transition: transform 0.5s cubic-bezier(0.4, 0, 0.2, 1);
}

.slider > img,
.slider > figure {
  width: 100%;
  flex-shrink: 0;
  margin: 0;
}

.slider figcaption {
  text-align: center;
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text-strong);
  padding: 0.85rem 1rem;
  background: var(--surface);
}

.certificates-slider {
  max-width: 860px;
  margin-inline: auto;
}
.certificates-slider .slider-container {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow-md);
}
.certificates-slider .slider img {
  aspect-ratio: 4 / 3;
  object-fit: contain;
  background: #fff;
}

/* arrow buttons (injected by JS) */
.slider-btn {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  z-index: 2;
  display: grid;
  place-items: center;
  width: 38px;
  height: 38px;
  border-radius: 50%;
  border: none;
  background: rgba(7, 11, 20, 0.55);
  color: #fff;
  font-size: 1rem;
  cursor: pointer;
  backdrop-filter: blur(4px);
  transition: background-color 0.2s ease, transform 0.2s ease;
}
.slider-btn:hover {
  background: var(--accent);
  transform: translateY(-50%) scale(1.08);
}
.slider-btn.prev { left: 0.8rem; }
.slider-btn.next { right: 0.8rem; }

/* dot indicators (injected by JS) */
.slider-dots {
  position: absolute;
  bottom: 0.8rem;
  left: 50%;
  transform: translateX(-50%);
  z-index: 2;
  display: flex;
  gap: 0.45rem;
}
.slider-dots button {
  width: 9px;
  height: 9px;
  border-radius: 50%;
  border: none;
  background: rgba(255, 255, 255, 0.45);
  cursor: pointer;
  padding: 0;
  transition: background-color 0.2s ease, transform 0.2s ease;
}
.slider-dots button.active {
  background: var(--accent);
  transform: scale(1.25);
}
/* keep dots above captions on the certificate slider */
.certificates-slider .slider-dots { bottom: 3.4rem; }

/* ═══ 12. FOOTER / CONTACT ═══════════════════════════════════════ */
.site-footer {
  background: var(--bg-alt);
  border-top: 1px solid var(--border);
  padding-top: clamp(3.5rem, 8vw, 5.5rem);
}

.footer-cta {
  text-align: center;
  max-width: 620px;
  margin: 0 auto clamp(3rem, 7vw, 4.5rem);
}

.footer-headline {
  font-size: clamp(1.6rem, 4vw, 2.4rem);
  font-weight: 700;
  margin-bottom: 0.85rem;
}

.footer-tagline {
  color: var(--text-muted);
  margin-bottom: 1.75rem;
}

.footer-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 2.5rem;
  padding-bottom: 3rem;
}

.footer-section h3 {
  font-size: 1.05rem;
  margin-bottom: 1rem;
}

.footer-section p {
  margin-bottom: 0.5rem;
  font-size: 0.95rem;
}
.footer-section p i { color: var(--accent); margin-right: 0.4rem; }

.contact-links {
  display: flex;
  flex-direction: column;
  gap: 0.8rem;
}

.contact-link {
  display: flex;
  align-items: center;
  gap: 0.8rem;
  color: var(--text);
  text-decoration: none;
  font-size: 0.95rem;
  transition: color 0.2s ease, transform 0.2s ease;
}
.contact-link:hover {
  color: var(--accent);
  transform: translateX(4px);
}
.contact-link i {
  display: grid;
  place-items: center;
  width: 34px;
  height: 34px;
  border-radius: 9px;
  background: var(--accent-soft);
  color: var(--accent);
  font-size: 0.95rem;
  flex-shrink: 0;
}

.site-footer iframe {
  width: 100%;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  margin-top: 0.75rem;
}

.footer-bottom {
  border-top: 1px solid var(--border);
  padding-block: 1.5rem;
  text-align: center;
  font-size: 0.875rem;
  color: var(--text-muted);
}

/* ═══ 13. FLOATING UI ════════════════════════════════════════════ */
/* gradient scroll-progress bar pinned to the top edge */
.scroll-progress {
  position: fixed;
  top: 0;
  left: 0;
  height: 3px;
  width: 0%;
  background: var(--gradient);
  z-index: 300;
}

.back-to-top {
  position: fixed;
  bottom: 1.5rem;
  right: 1.5rem;
  z-index: 150;
  display: grid;
  place-items: center;
  width: 44px;
  height: 44px;
  border-radius: 50%;
  border: none;
  background: var(--gradient);
  color: #fff;
  font-size: 1rem;
  cursor: pointer;
  box-shadow: var(--shadow-accent);
  opacity: 0;
  visibility: hidden;
  transform: translateY(12px);
  transition: opacity 0.3s ease, transform 0.3s ease, visibility 0.3s;
}
.back-to-top.visible {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}
.back-to-top:hover { transform: translateY(-3px); }

/* ═══ 14. SCROLL-REVEAL ANIMATIONS ═══════════════════════════════
   Elements with .reveal start hidden and fade/slide in when they
   enter the viewport (IntersectionObserver in js/main.js adds
   .visible). Siblings get a small stagger via transition-delay.   */
.reveal {
  opacity: 0;
  transform: translateY(26px);
  transition: opacity 0.7s ease, transform 0.7s ease;
}
.reveal.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ═══ 15. RESPONSIVE BREAKPOINTS ═════════════════════════════════ */
@media (max-width: 900px) {
  .about-grid { grid-template-columns: 1fr; }

  .hero-content {
    flex-direction: column-reverse;
    text-align: center;
  }
  .hero-text { max-width: 100%; }
  .hero-cta, .hero-socials { justify-content: center; }
}

@media (max-width: 768px) {
  /* mobile nav: slide-down panel under the header */
  nav {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    flex-direction: column;
    gap: 0;
    background: var(--glass);
    backdrop-filter: blur(14px);
    -webkit-backdrop-filter: blur(14px);
    border-bottom: 1px solid var(--border);
    padding: 0.5rem 1.5rem 1rem;
    display: none;
  }
  nav.open { display: flex; }
  .nav-link { padding: 0.7rem 0; }
  .nav-link::after { display: none; }

  .menu-btn { display: flex; }
  .logo-text { display: none; } /* logo mark only on small screens */

  .timeline { padding-left: 1.6rem; }
  .timeline-dot { left: -1.6rem; }
  .timeline-card { padding: 1.4rem 1.4rem; }

  .edu-header {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.85rem;
  }

  .publication-header { flex-direction: column; }
}

@media (max-width: 480px) {
  .hero-stats { grid-template-columns: repeat(2, 1fr); }
  .btn { width: 100%; justify-content: center; }
  .project-links .btn, .publication-links .btn { width: auto; }
  .hero-cta { flex-direction: column; }
}

/* ═══ 16. ACCESSIBILITY & REDUCED MOTION ═════════════════════════ */
:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
  border-radius: 4px;
}

/* Respect users who prefer minimal motion: disable all animation */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
  .reveal {
    opacity: 1;
    transform: none;
  }
}