/* ====================================================================
   PERSONAL ACADEMIC WEBSITE — STYLE.CSS
   ====================================================================
   Table of Contents
   ─────────────────
    1.  Custom Properties (CSS Variables)
    2.  Reset & Base
    3.  Typography
    4.  Layout Utilities
    5.  Navigation
    6.  Skip Link (Accessibility)
    7.  Home Section
    8.  Research Section
    9.  Publications Section
   10.  Projects Section
   11.  News Section
   12.  About Section
   13.  Footer
   14.  Components — Buttons
   15.  Responsive Breakpoints
   16.  Dark Mode (prefers-color-scheme)
   17.  Reduced-Motion & Accessibility
   18.  Scroll Fade-In Animation Targets
==================================================================== */


/* ====================================================================
   1. CUSTOM PROPERTIES
==================================================================== */
:root {
  /* ── Colour Palette ── */
  --clr-bg:            #ffffff;
  --clr-bg-alt:        #f8fafc;
  --clr-text:          #111827;
  --clr-text-muted:    #4b5563;
  --clr-text-light:    #9ca3af;
  --clr-accent:        #0f766e;   /* teal-700 */
  --clr-accent-hover:  #115e59;   /* teal-800 */
  --clr-accent-light:  #ccfbf1;   /* teal-100 */
  --clr-accent-dark:   #134e4a;   /* teal-900 */
  --clr-border:        #e5e7eb;
  --clr-border-light:  #f3f4f6;
  --clr-nav-bg:        rgba(255, 255, 255, 0.96);
  --clr-code-bg:       #f1f5f9;

  /* ── Typography ── */
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
               "Helvetica Neue", Arial, "Noto Sans", sans-serif,
               "Apple Color Emoji", "Segoe UI Emoji";
  --font-mono: "SFMono-Regular", "SF Mono", "Fira Code", "Fira Mono",
               "Roboto Mono", Menlo, Consolas, "Liberation Mono", monospace;

  /* Font sizes (fluid clamp where useful) */
  --fs-xs:   0.75rem;    /* 12px */
  --fs-sm:   0.875rem;   /* 14px */
  --fs-base: 1rem;       /* 16px */
  --fs-md:   1.125rem;   /* 18px */
  --fs-lg:   1.25rem;    /* 20px */
  --fs-xl:   1.5rem;     /* 24px */
  --fs-2xl:  1.875rem;   /* 30px */
  --fs-3xl:  2.25rem;    /* 36px */
  --fs-4xl:  clamp(2rem, 5vw, 3rem);

  /* Line heights */
  --lh-tight:   1.25;
  --lh-snug:    1.375;
  --lh-normal:  1.5;
  --lh-relaxed: 1.625;

  /* Font weights */
  --fw-normal:   400;
  --fw-medium:   500;
  --fw-semibold: 600;
  --fw-bold:     700;

  /* ── Spacing ── */
  --sp-1:   0.25rem;
  --sp-2:   0.5rem;
  --sp-3:   0.75rem;
  --sp-4:   1rem;
  --sp-5:   1.25rem;
  --sp-6:   1.5rem;
  --sp-8:   2rem;
  --sp-10:  2.5rem;
  --sp-12:  3rem;
  --sp-16:  4rem;
  --sp-20:  5rem;

  /* ── Layout ── */
  --max-w:       900px;
  --max-w-wide:  1100px;
  --nav-height:  60px;

  /* ── Effects ── */
  --radius-sm:   4px;
  --radius:      8px;
  --radius-lg:   12px;
  --radius-xl:   16px;
  --radius-full: 9999px;

  --shadow-sm:  0 1px 2px rgba(0,0,0,0.05);
  --shadow:     0 1px 3px rgba(0,0,0,0.1), 0 1px 2px rgba(0,0,0,0.06);
  --shadow-md:  0 4px 6px rgba(0,0,0,0.07), 0 2px 4px rgba(0,0,0,0.06);
  --shadow-lg:  0 10px 15px rgba(0,0,0,0.08), 0 4px 6px rgba(0,0,0,0.05);
  --shadow-nav: 0 1px 0 rgba(0,0,0,0.07), 0 2px 8px rgba(0,0,0,0.05);

  --transition:    150ms ease;
  --transition-md: 260ms ease;
}


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

html {
  scroll-behavior: smooth;
  /* Offset anchor targets so they clear the sticky nav */
  scroll-padding-top: calc(var(--nav-height) + 1.25rem);
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-sans);
  font-size: var(--fs-base);
  line-height: var(--lh-relaxed);
  color: var(--clr-text);
  background-color: var(--clr-bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

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

a:hover {
  color: var(--clr-accent-hover);
  text-decoration: underline;
  text-underline-offset: 3px;
}

a:focus-visible {
  outline: 2px solid var(--clr-accent);
  outline-offset: 3px;
  border-radius: var(--radius-sm);
}

ul, ol {
  list-style: none;
}

button {
  cursor: pointer;
  border: none;
  background: none;
  font-family: inherit;
  font-size: inherit;
  color: inherit;
}

strong {
  font-weight: var(--fw-semibold);
}


/* ====================================================================
   3. TYPOGRAPHY
==================================================================== */
h1, h2, h3, h4, h5, h6 {
  line-height: var(--lh-tight);
  font-weight: var(--fw-bold);
  color: var(--clr-text);
}


/* ====================================================================
   4. LAYOUT UTILITIES
==================================================================== */
.container {
  width: 100%;
  max-width: var(--max-w);
  margin-inline: auto;
  padding-inline: var(--sp-6);
}

.container-wide {
  width: 100%;
  max-width: var(--max-w-wide);
  margin-inline: auto;
  padding-inline: var(--sp-6);
}

.section {
  padding-block: var(--sp-20);
}

.section-alt {
  background-color: var(--clr-bg-alt);
}

.section-home {
  padding-top: calc(var(--nav-height) + var(--sp-16));
  padding-bottom: var(--sp-20);
}

.section-title {
  font-size: var(--fs-2xl);
  letter-spacing: -0.02em;
  margin-bottom: var(--sp-3);
}

.section-subtitle {
  color: var(--clr-text-muted);
  font-size: var(--fs-md);
  line-height: var(--lh-relaxed);
  margin-bottom: var(--sp-10);
  max-width: 65ch;
}

.subsection-title {
  font-size: var(--fs-xl);
  font-weight: var(--fw-semibold);
  letter-spacing: -0.01em;
  margin-top: var(--sp-12);
  margin-bottom: var(--sp-4);
  padding-bottom: var(--sp-2);
  border-bottom: 2px solid var(--clr-border);
}


/* ====================================================================
   5. NAVIGATION
==================================================================== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  height: var(--nav-height);
  background-color: var(--clr-nav-bg);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--clr-border);
  box-shadow: var(--shadow-nav);
}

.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: var(--nav-height);
}

.nav-brand {
  font-size: var(--fs-md);
  font-weight: var(--fw-bold);
  color: var(--clr-text);
  letter-spacing: -0.02em;
  text-decoration: none;
  flex-shrink: 0;
  transition: color var(--transition);
}

.nav-brand:hover {
  color: var(--clr-accent);
  text-decoration: none;
}

.nav-menu {
  display: flex;
  align-items: center;
  gap: var(--sp-1);
  list-style: none;
}

.nav-link {
  display: inline-block;
  padding: var(--sp-2) var(--sp-3);
  font-size: var(--fs-sm);
  font-weight: var(--fw-medium);
  color: var(--clr-text-muted);
  text-decoration: none;
  border-radius: var(--radius-sm);
  transition: color var(--transition), background-color var(--transition);
  white-space: nowrap;
}

.nav-link:hover {
  color: var(--clr-text);
  background-color: var(--clr-border-light);
  text-decoration: none;
}

.nav-link.active {
  color: var(--clr-accent);
  background-color: var(--clr-accent-light);
  font-weight: var(--fw-semibold);
}

/* ── Hamburger toggle (visible on mobile) ── */
.nav-toggle {
  display: none;
  width: 40px;
  height: 40px;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius);
  transition: background-color var(--transition);
  flex-shrink: 0;
}

.nav-toggle:hover {
  background-color: var(--clr-border-light);
}

.hamburger,
.hamburger::before,
.hamburger::after {
  display: block;
  width: 20px;
  height: 2px;
  background-color: var(--clr-text);
  border-radius: 2px;
  transition: transform var(--transition-md), opacity var(--transition);
}

.hamburger {
  position: relative;
}

.hamburger::before,
.hamburger::after {
  content: '';
  position: absolute;
  left: 0;
}

.hamburger::before { top: -6px; }
.hamburger::after  { top:  6px; }

/* Open state */
.nav-toggle[aria-expanded="true"] .hamburger {
  background: transparent;
}
.nav-toggle[aria-expanded="true"] .hamburger::before {
  transform: rotate(45deg) translate(4px, 4px);
}
.nav-toggle[aria-expanded="true"] .hamburger::after {
  transform: rotate(-45deg) translate(4px, -4px);
}


/* ====================================================================
   6. SKIP LINK (Accessibility)
==================================================================== */
.skip-link {
  position: absolute;
  left: -9999px;
  top: var(--sp-3);
  z-index: 9999;
  background: var(--clr-accent);
  color: #fff;
  padding: var(--sp-2) var(--sp-5);
  border-radius: var(--radius);
  font-weight: var(--fw-semibold);
  font-size: var(--fs-sm);
  text-decoration: none;
}

.skip-link:focus {
  left: var(--sp-4);
  outline: 2px solid #fff;
  outline-offset: 2px;
}


/* ====================================================================
   7. HOME SECTION
==================================================================== */
.home-grid {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: var(--sp-12);
  align-items: start;
}

.home-name {
  font-size: var(--fs-4xl);
  letter-spacing: -0.03em;
  line-height: 1.1;
  margin-bottom: var(--sp-2);
}

.home-title {
  font-size: var(--fs-md);
  color: var(--clr-text-muted);
  font-weight: var(--fw-medium);
  margin-bottom: var(--sp-1);
}

.home-affiliation {
  font-size: var(--fs-sm);
  color: var(--clr-text-light);
  margin-bottom: var(--sp-6);
}

/* The one-line research identity */
.home-identity {
  font-size: var(--fs-lg);
  font-weight: var(--fw-semibold);
  color: var(--clr-text);
  line-height: var(--lh-snug);
  margin-bottom: var(--sp-5);
  border-left: 3px solid var(--clr-accent);
  padding-left: var(--sp-4);
  max-width: 60ch;
}

/* Credibility chips row */
.home-cred {
  display: flex;
  flex-wrap: wrap;
  gap: var(--sp-2);
  margin-bottom: var(--sp-6);
}

.cred-chip {
  display: inline-block;
  padding: 3px var(--sp-3);
  background-color: var(--clr-accent-light);
  color: var(--clr-accent-dark);
  border-radius: var(--radius-full);
  font-size: var(--fs-xs);
  font-weight: var(--fw-semibold);
  letter-spacing: 0.01em;
  line-height: 1.6;
}

/* Action buttons row */
.home-buttons {
  display: flex;
  flex-wrap: wrap;
  gap: var(--sp-3);
  margin-bottom: var(--sp-8);
}

.home-bio {
  color: var(--clr-text-muted);
  font-size: var(--fs-base);
  line-height: var(--lh-relaxed);
  max-width: 65ch;
  margin-bottom: var(--sp-3);
}

/* Profile photo area */
.home-photo-wrap {
  display: flex;
  justify-content: flex-end;
  padding-top: var(--sp-4);
}

.home-photo-placeholder {
  width: 150px;
  height: 150px;
  border-radius: var(--radius-xl);
  background-color: var(--clr-accent-light);
  border: 2px solid var(--clr-border);
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  flex-shrink: 0;
}

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

.home-photo-placeholder svg {
  width: 100%;
  height: 100%;
}


/* ====================================================================
   8. RESEARCH SECTION
==================================================================== */
.research-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--sp-6);
}

.research-theme {
  background: var(--clr-bg);
  border: 1px solid var(--clr-border);
  border-radius: var(--radius-lg);
  padding: var(--sp-6);
  transition: box-shadow var(--transition-md), border-color var(--transition-md);
}

.research-theme:hover {
  box-shadow: var(--shadow-md);
  border-color: #99f6e4;   /* teal-200 */
}

.theme-header {
  display: flex;
  align-items: center;
  gap: var(--sp-3);
  margin-bottom: var(--sp-3);
}

.theme-icon {
  font-size: var(--fs-xl);
  line-height: 1;
  flex-shrink: 0;
}

.theme-header h3 {
  font-size: var(--fs-md);
  font-weight: var(--fw-semibold);
  line-height: var(--lh-snug);
}

.theme-framing {
  font-size: var(--fs-sm);
  color: var(--clr-text-muted);
  font-style: italic;
  margin-bottom: var(--sp-4);
  line-height: var(--lh-relaxed);
}

.theme-bullets {
  list-style: disc;
  padding-left: var(--sp-5);
  margin-bottom: var(--sp-4);
}

.theme-bullets li {
  font-size: var(--fs-sm);
  color: var(--clr-text);
  margin-bottom: var(--sp-2);
  line-height: var(--lh-relaxed);
}

.theme-papers {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--sp-2);
  border-top: 1px solid var(--clr-border);
  padding-top: var(--sp-3);
  margin-top: auto;
}

.papers-label {
  font-size: var(--fs-xs);
  font-weight: var(--fw-semibold);
  color: var(--clr-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.paper-link {
  font-size: var(--fs-xs);
  color: var(--clr-accent);
  background: var(--clr-accent-light);
  padding: 2px var(--sp-2);
  border-radius: var(--radius-sm);
  text-decoration: none;
  transition: background-color var(--transition), color var(--transition);
  white-space: nowrap;
}

.paper-link:hover {
  background-color: var(--clr-accent);
  color: #fff;
  text-decoration: none;
}


/* ====================================================================
   9. PUBLICATIONS SECTION
==================================================================== */
.pub-list {
  list-style: none;
  padding: 0;
  border-top: 1px solid var(--clr-border);
}

.pub-entry {
  padding: var(--sp-5) 0;
  border-bottom: 1px solid var(--clr-border-light);
}

.pub-title {
  font-size: var(--fs-base);
  font-weight: var(--fw-semibold);
  color: var(--clr-text);
  line-height: var(--lh-snug);
  margin-bottom: var(--sp-1);
}

.pub-authors {
  font-size: var(--fs-sm);
  color: var(--clr-text-muted);
  margin-bottom: var(--sp-2);
  line-height: var(--lh-relaxed);
}

.pub-venue {
  margin-bottom: var(--sp-2);
}

.venue-badge {
  display: inline-block;
  padding: 2px var(--sp-2);
  background-color: var(--clr-accent);
  color: #fff;
  border-radius: var(--radius-sm);
  font-size: var(--fs-xs);
  font-weight: var(--fw-semibold);
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.preprint-badge {
  background-color: #6b7280;
}

.pub-links {
  display: flex;
  flex-wrap: wrap;
  gap: var(--sp-2);
  margin-top: var(--sp-2);
  align-items: center;
}

/* Shared style for <a> and <button> pub link elements */
.pub-link {
  font-size: var(--fs-xs);
  font-weight: var(--fw-semibold);
  color: var(--clr-text-muted);
  padding: 3px var(--sp-3);
  border: 1px solid var(--clr-border);
  border-radius: var(--radius-sm);
  text-decoration: none;
  background: transparent;
  cursor: pointer;
  transition: color var(--transition), border-color var(--transition),
              background-color var(--transition);
  line-height: 1.5;
  display: inline-block;
}

.pub-link:hover {
  color: var(--clr-accent);
  border-color: var(--clr-accent);
  background-color: var(--clr-accent-light);
  text-decoration: none;
}

/* BibTeX collapsible pre block */
.bibtex-block {
  font-family: var(--font-mono);
  font-size: var(--fs-xs);
  background: var(--clr-code-bg);
  border: 1px solid var(--clr-border);
  border-radius: var(--radius-sm);
  padding: var(--sp-4);
  margin-top: var(--sp-3);
  white-space: pre-wrap;
  word-break: break-word;
  color: var(--clr-text-muted);
  line-height: var(--lh-relaxed);
  tab-size: 2;
}

.full-list-link {
  margin-top: var(--sp-6);
  margin-bottom: var(--sp-2);
}


/* ====================================================================
   10. PROJECTS SECTION
==================================================================== */
.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(270px, 1fr));
  gap: var(--sp-6);
}

.project-card {
  background: var(--clr-bg);
  border: 1px solid var(--clr-border);
  border-radius: var(--radius-lg);
  padding: var(--sp-6);
  display: flex;
  flex-direction: column;
  gap: 0;
  transition: box-shadow var(--transition-md), border-color var(--transition-md),
              transform var(--transition-md);
}

.project-card:hover {
  box-shadow: var(--shadow-lg);
  border-color: #99f6e4;   /* teal-200 */
  transform: translateY(-3px);
}

.project-top {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: var(--sp-3);
  margin-bottom: var(--sp-3);
}

.project-name {
  font-size: var(--fs-md);
  font-weight: var(--fw-bold);
  color: var(--clr-text);
  line-height: 1.2;
}

.project-tags {
  display: flex;
  flex-wrap: wrap;
  gap: var(--sp-1);
  justify-content: flex-end;
  flex-shrink: 0;
}

.tag {
  font-size: var(--fs-xs);
  font-weight: var(--fw-medium);
  padding: 2px var(--sp-2);
  background: var(--clr-bg-alt);
  border: 1px solid var(--clr-border);
  border-radius: var(--radius-full);
  color: var(--clr-text-muted);
  white-space: nowrap;
  line-height: 1.6;
}

.project-summary {
  font-size: var(--fs-sm);
  color: var(--clr-text-muted);
  margin-bottom: var(--sp-3);
  line-height: var(--lh-relaxed);
}

.project-bullets {
  list-style: disc;
  padding-left: var(--sp-5);
  margin-bottom: var(--sp-4);
  flex: 1;
}

.project-bullets li {
  font-size: var(--fs-sm);
  color: var(--clr-text);
  margin-bottom: var(--sp-1);
  line-height: var(--lh-relaxed);
}

.project-links {
  display: flex;
  flex-wrap: wrap;
  gap: var(--sp-2);
  border-top: 1px solid var(--clr-border-light);
  padding-top: var(--sp-3);
  margin-top: auto;
}


/* ====================================================================
   11. NEWS SECTION
==================================================================== */
.news-list {
  list-style: none;
  padding: 0;
}

.news-item {
  display: grid;
  grid-template-columns: 6.5rem 1fr;
  gap: var(--sp-5);
  padding: var(--sp-3) 0;
  border-bottom: 1px solid var(--clr-border-light);
  align-items: baseline;
}

.news-date {
  font-family: var(--font-mono);
  font-size: var(--fs-xs);
  font-weight: var(--fw-semibold);
  color: var(--clr-text-light);
  text-transform: uppercase;
  letter-spacing: 0.07em;
  flex-shrink: 0;
  padding-top: 0.15em;
}

.news-text {
  font-size: var(--fs-base);
  color: var(--clr-text);
  line-height: var(--lh-relaxed);
}

#news-toggle {
  margin-top: var(--sp-5);
}


/* ====================================================================
   12. ABOUT SECTION
==================================================================== */
.about-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--sp-12);
  align-items: start;
}

.about-bio p {
  color: var(--clr-text-muted);
  line-height: var(--lh-relaxed);
  margin-bottom: var(--sp-4);
}

.about-cv-btn {
  margin-top: var(--sp-2);
}

.about-lists {
  display: flex;
  flex-direction: column;
  gap: var(--sp-6);
}

.about-list-block h3 {
  font-size: var(--fs-base);
  font-weight: var(--fw-semibold);
  margin-bottom: var(--sp-3);
  color: var(--clr-text);
}

.about-list-block ul {
  list-style: disc;
  padding-left: var(--sp-5);
}

.about-list-block li {
  font-size: var(--fs-sm);
  color: var(--clr-text-muted);
  margin-bottom: var(--sp-2);
  line-height: var(--lh-relaxed);
}

.about-list-block a {
  color: var(--clr-accent);
}


/* ====================================================================
   13. FOOTER
==================================================================== */

/* ── ClustrMaps visitor map strip ── */
.clustrmap-wrap {
  background-color: var(--clr-bg-alt);
  border-top: 1px solid var(--clr-border);
  padding: var(--sp-8) 0;
}

.clustrmap-inner {
  display: flex;
  justify-content: center;
  align-items: center;
}

/* Ensure the injected iframe/canvas is centred and capped in width */
.clustrmap-inner > * {
  max-width: 320px;
}

.site-footer {
  background-color: var(--clr-bg-alt);
  border-top: 1px solid var(--clr-border);
  padding: var(--sp-8) 0;
}

.footer-inner {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--sp-2);
  text-align: center;
}

.footer-inner p {
  font-size: var(--fs-sm);
  color: var(--clr-text-muted);
  line-height: var(--lh-relaxed);
}

.footer-links a {
  color: var(--clr-text-muted);
  font-size: var(--fs-sm);
  transition: color var(--transition);
}

.footer-links a:hover {
  color: var(--clr-accent);
  text-decoration: none;
}


/* ====================================================================
   14. COMPONENTS — BUTTONS
==================================================================== */
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--sp-2);
  padding: 0.5rem var(--sp-5);
  border-radius: var(--radius);
  font-size: var(--fs-sm);
  font-weight: var(--fw-semibold);
  text-decoration: none;
  line-height: 1.5;
  border: 2px solid transparent;
  cursor: pointer;
  transition: background-color var(--transition), color var(--transition),
              border-color var(--transition), box-shadow var(--transition);
  white-space: nowrap;
  font-family: var(--font-sans);
}

.btn:focus-visible {
  outline: 2px solid var(--clr-accent);
  outline-offset: 3px;
}

/* Primary — filled accent */
.btn-primary {
  background-color: var(--clr-accent);
  color: #fff;
  border-color: var(--clr-accent);
}

.btn-primary:hover {
  background-color: var(--clr-accent-hover);
  border-color: var(--clr-accent-hover);
  color: #fff;
  text-decoration: none;
  box-shadow: var(--shadow-md);
}

/* Secondary — outlined */
.btn-secondary {
  background-color: transparent;
  color: var(--clr-text);
  border-color: var(--clr-border);
}

.btn-secondary:hover {
  background-color: var(--clr-bg-alt);
  border-color: var(--clr-text-muted);
  color: var(--clr-text);
  text-decoration: none;
}

/* Ghost — text-only */
.btn-ghost {
  background-color: transparent;
  color: var(--clr-accent);
  border: none;
  padding: var(--sp-2) 0;
  font-size: var(--fs-sm);
  font-weight: var(--fw-semibold);
}

.btn-ghost:hover {
  color: var(--clr-accent-hover);
  text-decoration: none;
}

.btn-icon {
  width: 1em;
  height: 1em;
  flex-shrink: 0;
}

/* Icon-only social link buttons */
.btn-social {
  width: 38px;
  height: 38px;
  padding: 0;
  justify-content: center;
  background: transparent;
  color: var(--clr-text-muted);
  border-color: var(--clr-border);
}

.btn-social svg {
  width: 18px;
  height: 18px;
  flex-shrink: 0;
}

.btn-social:hover {
  background-color: var(--clr-accent-light);
  border-color: var(--clr-accent);
  color: var(--clr-accent);
  text-decoration: none;
  box-shadow: none;
}


/* ====================================================================
   15. RESPONSIVE BREAKPOINTS
==================================================================== */

/* ── Tablet / small desktop (≤ 900px) ── */
@media (max-width: 900px) {
  .research-grid {
    grid-template-columns: 1fr;
  }

  .about-grid {
    grid-template-columns: 1fr;
    gap: var(--sp-8);
  }
}

/* ── Mobile (≤ 768px) ── */
@media (max-width: 768px) {
  /* Mobile nav */
  .nav-toggle {
    display: flex;
  }

  .nav-menu {
    position: fixed;
    top: var(--nav-height);
    left: 0;
    right: 0;
    background: var(--clr-bg);
    border-bottom: 1px solid var(--clr-border);
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    padding: var(--sp-3) var(--sp-4) var(--sp-5);
    box-shadow: var(--shadow-md);
    display: none;
  }

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

  .nav-link {
    padding: var(--sp-3) var(--sp-4);
    font-size: var(--fs-base);
  }

  /* Home layout: stack vertically, photo comes first */
  .home-grid {
    grid-template-columns: 1fr;
    gap: var(--sp-8);
  }

  .home-photo-wrap {
    order: -1;
    justify-content: flex-start;
  }

  .home-photo-placeholder {
    width: 120px;
    height: 120px;
  }

  /* Projects: single column */
  .projects-grid {
    grid-template-columns: 1fr;
  }

  /* News: collapse date to its own line */
  .news-item {
    grid-template-columns: 1fr;
    gap: var(--sp-1);
  }

  /* General spacing */
  .section {
    padding-block: var(--sp-16);
  }

  .container,
  .container-wide {
    padding-inline: var(--sp-4);
  }
}

/* ── Small mobile (≤ 480px) ── */
@media (max-width: 480px) {
  .home-buttons {
    flex-direction: column;
    align-items: flex-start;
  }

  .home-cred {
    flex-direction: column;
    align-items: flex-start;
  }

  .home-name {
    font-size: var(--fs-2xl);
  }

  .section-title {
    font-size: var(--fs-xl);
  }

  .projects-grid {
    grid-template-columns: 1fr;
  }

  .exp-item {
    grid-template-columns: 1fr;
    gap: var(--sp-2) 0;
  }
}


/* ====================================================================
   10b. EXPERIENCE TIMELINE
==================================================================== */
.experience-timeline {
  display: flex;
  flex-direction: column;
  gap: var(--sp-3);
  margin-bottom: var(--sp-8);
}

.exp-item {
  display: grid;
  grid-template-columns: 170px 1fr;
  gap: 0 var(--sp-6);
  padding: var(--sp-4) var(--sp-5);
  background: var(--clr-bg);
  border: 1px solid var(--clr-border);
  border-left: 3px solid var(--clr-accent);
  border-radius: var(--radius);
  transition: box-shadow var(--transition-md), border-color var(--transition-md);
}

.exp-item:hover {
  box-shadow: var(--shadow-md);
  border-left-color: var(--clr-accent-hover);
}

.exp-meta {
  display: flex;
  flex-direction: column;
  gap: var(--sp-2);
  align-items: flex-start;
  padding-top: 2px;
}

.exp-period {
  font-size: var(--fs-sm);
  color: var(--clr-text-muted);
  line-height: 1.4;
}

.exp-badge {
  display: inline-block;
  font-size: 0.7rem;
  font-weight: var(--fw-bold);
  letter-spacing: 0.05em;
  text-transform: uppercase;
  padding: 2px 8px;
  border-radius: var(--radius-full);
  background: var(--clr-accent-light);
  color: var(--clr-accent-dark);
}

.exp-badge-work {
  background: #fef9c3;
  color: #713f12;
}

.exp-body {
  display: flex;
  flex-direction: column;
  gap: var(--sp-1);
}

.exp-role {
  font-size: var(--fs-base);
  font-weight: var(--fw-semibold);
  color: var(--clr-text);
  line-height: var(--lh-snug);
}

.exp-org {
  font-size: var(--fs-sm);
  color: var(--clr-text-muted);
  margin-top: 1px;
}

.exp-details {
  margin: var(--sp-2) 0 0;
  padding-left: 1.2em;
  font-size: var(--fs-sm);
  color: var(--clr-text);
  display: flex;
  flex-direction: column;
  gap: 3px;
}

.exp-details li {
  line-height: var(--lh-relaxed);
}


/* ====================================================================
   16. DARK MODE (prefers-color-scheme: dark)
==================================================================== */
@media (prefers-color-scheme: dark) {
  :root {
    --clr-bg:            #0f172a;
    --clr-bg-alt:        #1e293b;
    --clr-text:          #f1f5f9;
    --clr-text-muted:    #94a3b8;
    --clr-text-light:    #64748b;
    --clr-accent:        #2dd4bf;   /* teal-300 */
    --clr-accent-hover:  #5eead4;   /* teal-200 */
    --clr-accent-light:  #0d3b38;   /* dark teal surface */
    --clr-accent-dark:   #99f6e4;   /* teal-200 */
    --clr-border:        #334155;
    --clr-border-light:  #1e293b;
    --clr-nav-bg:        rgba(15, 23, 42, 0.96);
    --clr-code-bg:       #1e293b;
  }

  /* Adjust badge backgrounds for dark mode */
  .venue-badge {
    background-color: #0f766e;   /* teal-700 */
  }

  .preprint-badge {
    background-color: #475569;
  }

  /* Research / project cards: don't wash out on hover */
  .research-theme:hover,
  .project-card:hover {
    border-color: #134e4a;   /* dark teal */
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.4);
  }

  .project-card {
    background: var(--clr-bg);
  }

  .research-theme {
    background: var(--clr-bg);
  }

  /* Experience timeline */
  .exp-item {
    background: var(--clr-bg);
  }

  .exp-item:hover {
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.4);
  }

  .exp-badge-work {
    background: #422006;
    color: #fef9c3;
  }

  /* Scrollbar */
  ::-webkit-scrollbar-track { background: var(--clr-bg); }
  ::-webkit-scrollbar-thumb { background: var(--clr-border); }
  ::-webkit-scrollbar-thumb:hover { background: var(--clr-text-muted); }
}


/* ====================================================================
   17. REDUCED MOTION & ACCESSIBILITY
==================================================================== */
@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;
  }
}

/* Scrollbar (webkit — non-standard, optional) */
::-webkit-scrollbar          { width: 8px; }
::-webkit-scrollbar-track    { background: var(--clr-bg); }
::-webkit-scrollbar-thumb    { background: var(--clr-border); border-radius: var(--radius-full); }
::-webkit-scrollbar-thumb:hover { background: var(--clr-text-muted); }


/* ====================================================================
   18. SCROLL FADE-IN ANIMATION TARGETS
       These initial states are set by main.js (JS guards for
       prefers-reduced-motion). Listed here for documentation.
       .research-theme, .project-card, .pub-entry, .news-item
       start at opacity:0 / translateY(12px) and animate in
       via IntersectionObserver.
==================================================================== */