/* =====================================================================
   Quantum Nexus Lab — stylesheet
   All colors, fonts and spacing are defined as variables in :root below.
   To re-theme the whole site, edit the variables here — nothing else.
   ===================================================================== */

:root {
  /* ---- Colors ---- */
  --color-bg:            #fbfaf7;
  --color-bg-alt:        #f2f0ea;
  --color-surface:       #ffffff;
  --color-text:          #202329;
  --color-text-muted:    #5c6470;
  --color-border:        #e3e0d8;
  --color-accent:        #1f3a5f;   /* deep navy — primary accent */
  --color-accent-dark:   #14263f;
  --color-accent-soft:   #eef2f6;   /* pale accent background */
  --color-link:          #1f3a5f;
  --color-link-hover:    #0d1e33;

  /* ---- Type ---- */
  --font-heading: "Source Serif 4", Georgia, "Times New Roman", serif;
  --font-body: -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;

  /* ---- Layout ---- */
  --max-width: 960px;
  --radius: 4px;
  --border-width: 1px;
}

/* ---------------------------------------------------------------- */
/* Reset / base                                                      */
/* ---------------------------------------------------------------- */
* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: var(--font-body);
  font-size: 17px;
  line-height: 1.65;
  color: var(--color-text);
  background: var(--color-bg);
}

h1, h2, h3, h4 {
  font-family: var(--font-heading);
  font-weight: 600;
  line-height: 1.25;
  color: var(--color-text);
  margin: 0 0 0.6em 0;
}

h1 { font-size: 2.1rem; }
h2 { font-size: 1.5rem; margin-top: 2.4em; }
h3 { font-size: 1.15rem; margin-top: 1.6em; }

p { margin: 0 0 1em 0; }

a {
  color: var(--color-link);
  text-decoration: none;
  border-bottom: 1px solid transparent;
}
a:hover {
  border-bottom-color: currentColor;
}

ul, ol { margin: 0 0 1em 0; padding-left: 1.3em; }
li { margin-bottom: 0.4em; }

img { max-width: 100%; }

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* ---------------------------------------------------------------- */
/* Header / navigation                                                */
/* ---------------------------------------------------------------- */
.site-header {
  border-bottom: var(--border-width) solid var(--color-border);
  background: var(--color-bg);
  position: sticky;
  top: 0;
  z-index: 20;
}

.site-header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 1.1rem;
  padding-bottom: 1.1rem;
}

.brand {
  display: flex;
  flex-direction: column;
  line-height: 1.2;
}

.brand-name {
  font-family: var(--font-heading);
  font-weight: 600;
  font-size: 1.15rem;
  color: var(--color-text);
  border-bottom: none;
}
.brand-name:hover { border-bottom: none; color: var(--color-accent); }

.brand-sub {
  font-size: 0.72rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--color-text-muted);
}

.nav-links {
  display: flex;
  gap: 1.6rem;
  font-size: 0.94rem;
}

.nav-links a {
  color: var(--color-text-muted);
  border-bottom: 1px solid transparent;
  padding-bottom: 2px;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--color-accent);
  border-bottom-color: var(--color-accent);
}

.nav-toggle {
  display: none;
  background: none;
  border: var(--border-width) solid var(--color-border);
  border-radius: var(--radius);
  font-size: 1rem;
  padding: 0.35rem 0.6rem;
  cursor: pointer;
  color: var(--color-text);
}

@media (max-width: 720px) {
  .nav-links {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--color-bg);
    border-bottom: var(--border-width) solid var(--color-border);
    flex-direction: column;
    gap: 0;
    display: none;
  }
  .nav-links.open { display: flex; }
  .nav-links a {
    padding: 0.85rem 1.5rem;
    border-bottom: var(--border-width) solid var(--color-border);
  }
  .nav-links a.active, .nav-links a:hover { border-bottom-color: var(--color-border); }
  .nav-toggle { display: inline-block; }
}

/* ---------------------------------------------------------------- */
/* Hero                                                               */
/* ---------------------------------------------------------------- */
.hero {
  padding: 3.6rem 0 2.6rem;
  border-bottom: var(--border-width) solid var(--color-border);
}

.hero-eyebrow {
  font-size: 0.78rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--color-text-muted);
  margin-bottom: 0.8rem;
}

.hero h1 {
  font-size: 2.4rem;
  max-width: 30ch;
}

.hero p.lede {
  font-size: 1.1rem;
  color: var(--color-text-muted);
  max-width: 55ch;
}

.hero-actions {
  margin-top: 1.4rem;
  display: flex;
  gap: 0.9rem;
  flex-wrap: wrap;
}

/* ---------------------------------------------------------------- */
/* Buttons                                                            */
/* ---------------------------------------------------------------- */
.btn {
  display: inline-block;
  font-size: 0.92rem;
  padding: 0.55rem 1.1rem;
  border-radius: var(--radius);
  border: var(--border-width) solid var(--color-accent);
  color: var(--color-accent);
  background: transparent;
}
.btn:hover {
  background: var(--color-accent);
  color: #fff;
  border-bottom: var(--border-width) solid var(--color-accent);
}

.btn-primary {
  background: var(--color-accent);
  color: #fff;
}
.btn-primary:hover {
  background: var(--color-accent-dark);
  border-color: var(--color-accent-dark);
  color: #fff;
}

/* ---------------------------------------------------------------- */
/* Sections / cards                                                   */
/* ---------------------------------------------------------------- */
.section {
  padding: 2.6rem 0;
}
.section + .section {
  border-top: var(--border-width) solid var(--color-border);
}

.section-head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 1rem;
  flex-wrap: wrap;
}

.grid {
  display: grid;
  gap: 1.2rem;
}
.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }

@media (max-width: 760px) {
  .grid-2, .grid-3, .grid-4 { grid-template-columns: 1fr; }
}

.card {
  background: var(--color-surface);
  border: var(--border-width) solid var(--color-border);
  border-radius: var(--radius);
  padding: 1.3rem 1.4rem;
}

.card h3 {
  margin-top: 0;
  font-size: 1.05rem;
}

.card p {
  color: var(--color-text-muted);
  font-size: 0.95rem;
  margin-bottom: 0;
}

.tag {
  display: inline-block;
  font-size: 0.72rem;
  letter-spacing: 0.02em;
  text-transform: uppercase;
  color: var(--color-accent);
  background: var(--color-accent-soft);
  border-radius: var(--radius);
  padding: 0.15rem 0.5rem;
}

/* ---------------------------------------------------------------- */
/* People / team                                                      */
/* ---------------------------------------------------------------- */
.person {
  display: flex;
  gap: 1.2rem;
  align-items: flex-start;
}

.person-photo {
  width: 176px;
  height: 176px;
  border-radius: var(--radius);
  object-fit: cover;
  border: var(--border-width) solid var(--color-border);
  flex-shrink: 0;
}

.person-photo-placeholder {
  width: 176px;
  height: 176px;
  border-radius: var(--radius);
  border: var(--border-width) dashed var(--color-border);
  flex-shrink: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-text-muted);
  font-size: 0.8rem;
  text-align: center;
  background: var(--color-bg-alt);
}

.person-role {
  color: var(--color-accent);
  font-size: 0.9rem;
  margin-bottom: 0.3rem;
}

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

/* ---------------------------------------------------------------- */
/* Publications list                                                   */
/* ---------------------------------------------------------------- */
.pub-year {
  display: flex;
  gap: 1.4rem;
  padding: 1.1rem 0;
  border-top: var(--border-width) solid var(--color-border);
}
.pub-year:first-of-type { border-top: none; }

.pub-year-label {
  font-family: var(--font-heading);
  font-size: 1.2rem;
  color: var(--color-accent);
  width: 4.5rem;
  flex-shrink: 0;
}

.pub-list p {
  margin-bottom: 0.9rem;
  font-size: 0.96rem;
}
.pub-list p:last-child { margin-bottom: 0; }

.pub-links a {
  font-size: 0.85rem;
  margin-right: 0.7rem;
}

/* ---------------------------------------------------------------- */
/* Projects list                                                     */
/* ---------------------------------------------------------------- */
.project-item {
  display: flex;
  gap: 1.4rem;
  padding: 1.1rem 0;
  border-top: var(--border-width) solid var(--color-border);
}
.project-item:first-of-type { border-top: none; }

.project-duration {
  font-family: var(--font-heading);
  font-size: 0.95rem;
  color: var(--color-accent);
  width: 9.5rem;
  flex-shrink: 0;
}

.project-item h3 {
  margin: 0 0 0.25rem;
  font-size: 1.08rem;
}

.project-item p {
  margin: 0;
  font-size: 0.92rem;
  color: var(--color-text-muted);
}

/* ---------------------------------------------------------------- */
/* Contact                                                            */
/* ---------------------------------------------------------------- */
.contact-grid {
  display: grid;
  grid-template-columns: 1.1fr 1fr;
  gap: 2.5rem;
}
@media (max-width: 760px) {
  .contact-grid { grid-template-columns: 1fr; }
}

.def-list dt {
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--color-text-muted);
  margin-top: 1rem;
}
.def-list dt:first-child { margin-top: 0; }
.def-list dd {
  margin: 0.2rem 0 0 0;
  font-size: 1rem;
}

/* ---------------------------------------------------------------- */
/* Footer                                                             */
/* ---------------------------------------------------------------- */
.site-footer {
  background: var(--color-accent-dark);
  color: #c7d1de;
  padding: 3rem 0 2.4rem;
  margin-top: 2rem;
}

.footer-inner {
  text-align: center;
}

.footer-brand {
  font-family: var(--font-heading);
  font-weight: 600;
  font-size: 1.2rem;
  color: #fbfaf7;
  margin-bottom: 0.3rem;
}

.footer-tagline {
  font-size: 0.92rem;
  color: #9aa8bb;
  margin-bottom: 1.4rem;
}

.footer-meta {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 0.5rem 0.9rem;
  font-size: 0.78rem;
  color: #8593a8;
  padding-bottom: 1.2rem;
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
  margin: 0 auto 1.2rem;
  max-width: 40rem;
}

.footer-meta span + span::before {
  content: "\00b7";
  margin-right: 0.9rem;
  color: #55647a;
}

.footer-links {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 0 1.4rem;
  font-size: 0.86rem;
}

.footer-links a {
  color: #c7d1de;
  border-bottom-color: transparent;
}
.footer-links a:hover {
  color: #fff;
  border-bottom-color: currentColor;
}

/* ---------------------------------------------------------------- */
/* Misc                                                               */
/* ---------------------------------------------------------------- */
.text-muted { color: var(--color-text-muted); }
.small { font-size: 0.88rem; }
.mt-0 { margin-top: 0; }
.callout {
  background: var(--color-bg-alt);
  border: var(--border-width) solid var(--color-border);
  border-radius: var(--radius);
  padding: 1.2rem 1.4rem;
}