/* ================================================================
   THERMOCEIL — STYLESHEET
   Structural assessment of historic fibrous plaster via infrared
   thermography. Visual language: petrol/navy academic tone +
   thermal-orange accent (the actual colour signature of an IR
   camera reading), set against a warm stone paper background.
   ================================================================ */


/* ----------------------------------------------------------------
   1. DESIGN TOKENS
   ---------------------------------------------------------------- */
:root {
  /* Colour: core palette */
  --color-ink:          #16232C;  /* primary text */
  --color-navy:         #1B3B5F;  /* brand / primary */
  --color-navy-dark:    #0F2436;  /* header, footer, hero background */
  --color-navy-light:   #2C577F;  /* hover states on navy */
  --color-thermal:      #E2672B;  /* accent — thermal orange (signature colour) */
  --color-thermal-soft: #F2A65A;  /* lighter thermal tone for gradients */
  --color-paper:        #F3EFE6;  /* warm stone background */
  --color-surface:      #FFFFFF;  /* card surfaces */
  --color-line:         #DED6C4;  /* hairline borders on paper */
  --color-line-dark:    rgba(255, 255, 255, 0.14); /* hairlines on navy */
  --color-muted:        #5B6670;  /* secondary text on paper */
  --color-muted-light:  #A9B7C4;  /* secondary text on navy */

  /* Typography */
  --font-display: "Fraunces", Georgia, serif;
  --font-body: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --font-mono: "IBM Plex Mono", "SFMono-Regular", Menlo, monospace;

  /* Type scale (fluid, mobile-first) */
  --text-xs:   0.8rem;
  --text-sm:   0.9rem;
  --text-base: 1rem;
  --text-md:   1.15rem;
  --text-lg:   clamp(1.4rem, 1.1rem + 1.2vw, 1.9rem);
  --text-xl:   clamp(1.9rem, 1.4rem + 2vw, 2.75rem);
  --text-hero: clamp(2.6rem, 1.8rem + 4vw, 5rem);

  /* Spacing scale */
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 1rem;
  --space-4: 1.5rem;
  --space-5: 2.5rem;
  --space-6: 4rem;
  --space-7: 6rem;
  --space-8: 8rem;

  /* Layout */
  --content-width: 1140px;
  --content-padding: clamp(1.25rem, 4vw, 3rem);
  --radius-sm: 4px;
  --radius-md: 8px;

  /* Elevation */
  --shadow-sm: 0 1px 2px rgba(15, 36, 54, 0.06), 0 1px 1px rgba(15, 36, 54, 0.04);
  --shadow-md: 0 8px 24px rgba(15, 36, 54, 0.10);

  /* Motion */
  --ease-out: cubic-bezier(0.16, 1, 0.3, 1);
  --duration-fast: 180ms;
  --duration-base: 320ms;
}


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

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  font-family: var(--font-body);
  font-size: var(--text-base);
  line-height: 1.65;
  color: var(--color-ink);
  background-color: var(--color-paper);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

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

a {
  color: inherit;
  text-decoration: none;
}

ul {
  list-style: none;
  margin: 0;
  padding: 0;
}

h1, h2, h3, h4 {
  font-family: var(--font-display);
  font-weight: 600;
  line-height: 1.15;
  margin: 0 0 var(--space-3);
  color: var(--color-navy-dark);
}

p {
  margin: 0 0 var(--space-3);
}

button {
  font-family: inherit;
  cursor: pointer;
}

/* Respect reduced-motion preferences throughout the site */
@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;
  }
}

/* Visible keyboard focus, everywhere */
a:focus-visible,
button:focus-visible {
  outline: 2px solid var(--color-thermal);
  outline-offset: 3px;
  border-radius: var(--radius-sm);
}

/* Visually hidden but available to screen readers (e.g. "opens in new tab" context) */
.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* Skip link — hidden until focused */
.skip-link {
  position: absolute;
  left: -999px;
  top: auto;
  background: var(--color-thermal);
  color: #fff;
  padding: var(--space-2) var(--space-3);
  z-index: 1000;
  border-radius: var(--radius-sm);
}
.skip-link:focus {
  left: var(--space-3);
  top: var(--space-3);
}


/* ----------------------------------------------------------------
   3. LAYOUT PRIMITIVES
   ---------------------------------------------------------------- */
.section {
  padding: var(--space-7) 0;
}

.section__inner {
  max-width: var(--content-width);
  margin: 0 auto;
  padding: 0 var(--content-padding);
}

.section__eyebrow {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-thermal);
  margin-bottom: var(--space-2);
}

.section__title {
  font-size: var(--text-xl);
  max-width: 32ch;
  margin-bottom: var(--space-5);
}

/* Alternate paper/surface banding between sections for gentle rhythm */
.about,
.publications {
  background-color: var(--color-surface);
}


/* ----------------------------------------------------------------
   4. BUTTONS
   ---------------------------------------------------------------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  padding: 0.85rem 1.75rem;
  font-family: var(--font-body);
  font-weight: 600;
  font-size: var(--text-sm);
  border-radius: var(--radius-sm);
  border: 1px solid transparent;
  transition: transform var(--duration-fast) var(--ease-out),
              background-color var(--duration-fast) var(--ease-out),
              border-color var(--duration-fast) var(--ease-out);
}

.btn--primary {
  background-color: var(--color-thermal);
  color: #fff;
}
.btn--primary:hover {
  background-color: #C9541D;
  transform: translateY(-2px);
}

.btn--ghost {
  background-color: transparent;
  border-color: var(--color-line-dark);
  color: #fff;
}
.btn--ghost:hover {
  border-color: var(--color-thermal-soft);
  color: var(--color-thermal-soft);
}


/* ----------------------------------------------------------------
   5. STICKY HEADER & NAVIGATION
   ---------------------------------------------------------------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background-color: rgba(15, 36, 54, 0.85);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--color-line-dark);
}

.nav {
  max-width: var(--content-width);
  margin: 0 auto;
  padding: var(--space-3) var(--content-padding);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav__brand {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 1.25rem;
  color: #fff;
  letter-spacing: 0.01em;
}

.nav__menu {
  display: flex;
  gap: var(--space-5);
}

.nav__link {
  position: relative;
  font-size: var(--text-sm);
  font-weight: 500;
  color: var(--color-muted-light);
  padding: var(--space-1) 0;
  transition: color var(--duration-fast) var(--ease-out);
}

.nav__link::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -2px;
  width: 0;
  height: 2px;
  background-color: var(--color-thermal);
  transition: width var(--duration-base) var(--ease-out);
}

.nav__link:hover,
.nav__link.active {
  color: #fff;
}
.nav__link.active::after {
  width: 100%;
}

/* Hamburger toggle — hidden on desktop */
.nav__toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 32px;
  height: 32px;
  background: transparent;
  border: none;
  padding: 0;
}

.nav__toggle-bar {
  width: 100%;
  height: 2px;
  background-color: #fff;
  transition: transform var(--duration-base) var(--ease-out),
              opacity var(--duration-fast) var(--ease-out);
}

/* Toggle → X animation when menu is open */
.nav__toggle[aria-expanded="true"] .nav__toggle-bar:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}
.nav__toggle[aria-expanded="true"] .nav__toggle-bar:nth-child(2) {
  opacity: 0;
}
.nav__toggle[aria-expanded="true"] .nav__toggle-bar:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}


/* ----------------------------------------------------------------
   6. HERO
   ---------------------------------------------------------------- */
.hero {
  position: relative;
  min-height: 92vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: var(--space-6) var(--content-padding);
  background-color: var(--color-navy-dark);
  color: #fff;
  overflow: hidden;
  isolation: isolate;
}

/* Faint blueprint-style grid, evoking structural drawings */
.hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(var(--color-line-dark) 1px, transparent 1px),
    linear-gradient(90deg, var(--color-line-dark) 1px, transparent 1px);
  background-size: 48px 48px;
  opacity: 0.35;
  z-index: -2;
}

/* Radial navy glow behind the title */
.hero::after {
  content: "";
  position: absolute;
  inset: 0;
  background: radial-gradient(circle at 50% 35%, rgba(44, 87, 127, 0.55), transparent 60%);
  z-index: -2;
}

/* Signature element: a thermal-gradient scan line sweeping down the
   hero, referencing the HRIRT scanning technique the project studies. */
.hero__scan {
  position: absolute;
  left: 0;
  right: 0;
  height: 2px;
  background: linear-gradient(90deg,
    transparent,
    var(--color-navy-light) 15%,
    var(--color-thermal-soft) 50%,
    var(--color-thermal) 65%,
    transparent 100%);
  box-shadow: 0 0 24px 4px rgba(226, 103, 43, 0.45);
  animation: scan-sweep 7s ease-in-out infinite;
  z-index: -1;
}

@keyframes scan-sweep {
  0%   { top: 8%;  opacity: 0; }
  10%  { opacity: 1; }
  50%  { top: 92%; opacity: 1; }
  60%  { opacity: 0; }
  100% { top: 92%; opacity: 0; }
}

.hero__content {
  max-width: 800px;
}

.hero__kicker {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--color-thermal-soft);
  margin-bottom: var(--space-3);
}

.hero__title {
  font-size: var(--text-hero);
  color: #fff;
  margin-bottom: var(--space-3);
}

.hero__subtitle {
  font-size: var(--text-md);
  color: var(--color-muted-light);
  max-width: 60ch;
  margin: 0 auto var(--space-4);
}

.hero__meta {
  margin-bottom: var(--space-5);
}

.hero__badge {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: #fff;
  border: 1px solid var(--color-line-dark);
  border-radius: 999px;
  padding: var(--space-2) var(--space-4);
  background-color: rgba(255, 255, 255, 0.04);
}

.hero__actions {
  display: flex;
  gap: var(--space-3);
  justify-content: center;
  flex-wrap: wrap;
}

/* Animated scroll indicator */
.scroll-indicator {
  position: absolute;
  bottom: var(--space-5);
  left: 50%;
  transform: translateX(-50%);
  width: 1px;
  height: 48px;
  overflow: hidden;
}

.scroll-indicator__line {
  display: block;
  width: 100%;
  height: 100%;
  background-color: var(--color-line-dark);
  position: relative;
}

.scroll-indicator__line::after {
  content: "";
  position: absolute;
  top: -100%;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: var(--color-thermal);
  animation: scroll-drip 2.2s ease-in-out infinite;
}

@keyframes scroll-drip {
  0%   { top: -100%; }
  60%  { top: 100%; }
  100% { top: 100%; }
}


/* ----------------------------------------------------------------
   7. ABOUT
   ---------------------------------------------------------------- */
.about__grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-6);
}

.about__text h3 {
  font-size: var(--text-md);
  color: var(--color-navy);
  margin-top: var(--space-5);
}
.about__text h3:first-child {
  margin-top: 0;
}

.about__text p {
  color: var(--color-muted);
}

.about__facts {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--space-3);
  align-content: start;
}

.fact-card {
  background-color: var(--color-paper);
  border: 1px solid var(--color-line);
  border-radius: var(--radius-md);
  padding: var(--space-4);
  display: flex;
  flex-direction: column;
  gap: var(--space-1);
}

.fact-card__value {
  font-family: var(--font-display);
  font-size: var(--text-lg);
  font-weight: 600;
  color: var(--color-thermal);
}

.fact-card__label {
  font-size: var(--text-xs);
  color: var(--color-muted);
}


/* ----------------------------------------------------------------
   8. PARTICIPANTS
   ---------------------------------------------------------------- */
.person-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-4);
  margin-bottom: var(--space-6);
}

.person-card {
  background-color: var(--color-surface);
  border: 1px solid var(--color-line);
  border-radius: var(--radius-md);
  padding: var(--space-4);
  box-shadow: var(--shadow-sm);
  transition: transform var(--duration-base) var(--ease-out),
              box-shadow var(--duration-base) var(--ease-out);
}

.person-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-md);
}

.person-card__photo--placeholder {
  width: 64px;
  height: 64px;
  border-radius: 50%;
  background-color: var(--color-navy);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  font-weight: 500;
  margin-bottom: var(--space-3);
}

.person-card__name {
  font-size: var(--text-md);
  margin-bottom: var(--space-1);
}

.person-card__role {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--color-thermal);
  text-transform: uppercase;
  letter-spacing: 0.04em;
  margin-bottom: var(--space-2);
}

.person-card__affiliation {
  font-size: var(--text-sm);
  color: var(--color-muted);
  margin-bottom: var(--space-2);
}

.person-card__bio {
  font-size: var(--text-sm);
  color: var(--color-muted);
  margin-bottom: var(--space-3);
}

.person-card__links a {
  font-size: var(--text-xs);
  font-weight: 600;
  color: var(--color-navy);
  border-bottom: 1px solid var(--color-navy);
}
.person-card__links a:hover {
  color: var(--color-thermal);
  border-color: var(--color-thermal);
}

/* Partner organisation strip */
.partners__label {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--color-muted);
  margin-bottom: var(--space-3);
}

.partners__list {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
}

.partners__list li {
  font-size: var(--text-sm);
  padding: var(--space-2) var(--space-3);
  border: 1px solid var(--color-line);
  border-radius: 999px;
  color: var(--color-navy);
  background-color: var(--color-surface);
}


/* ----------------------------------------------------------------
   9. CARD GRID — NEWS
   ---------------------------------------------------------------- */
.card-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-4);
}

.card {
  background-color: var(--color-surface);
  border: 1px solid var(--color-line);
  border-radius: var(--radius-md);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
}

.card__image {
  aspect-ratio: 16 / 9;
  background-color: var(--color-paper);
}

.card__image--placeholder {
  background-image: repeating-linear-gradient(
    135deg,
    var(--color-line) 0,
    var(--color-line) 1px,
    transparent 1px,
    transparent 12px
  );
}

.card__body {
  padding: var(--space-4);
}

.card__date {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--color-thermal);
  text-transform: uppercase;
  letter-spacing: 0.04em;
  margin-bottom: var(--space-2);
}

.card__title {
  font-size: var(--text-md);
  margin-bottom: var(--space-2);
}

.card__summary {
  font-size: var(--text-sm);
  color: var(--color-muted);
  margin-bottom: 0;
}

.card--placeholder {
  border-style: dashed;
}


/* ----------------------------------------------------------------
   10. PUBLICATIONS LIST
   ---------------------------------------------------------------- */
.pub-list {
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
}

.pub-card {
  background-color: var(--color-paper);
  border: 1px solid var(--color-line);
  border-left: 3px solid var(--color-navy);
  border-radius: var(--radius-sm);
  padding: var(--space-4);
}

.pub-card--placeholder {
  border-left-color: var(--color-line);
  border-style: dashed;
}

.pub-card__title {
  font-size: var(--text-md);
  margin-bottom: var(--space-1);
}

.pub-card__meta {
  font-size: var(--text-sm);
  color: var(--color-muted);
  margin-bottom: 0;
}

.pub-card__authors {
  font-size: var(--text-sm);
  color: var(--color-ink);
  margin-bottom: var(--space-1);
}

.pub-card__links {
  margin-top: var(--space-2);
  display: flex;
  gap: var(--space-3);
}

.pub-card__links a {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  font-weight: 500;
  color: var(--color-navy);
  border-bottom: 1px solid var(--color-navy);
}


/* ----------------------------------------------------------------
   11. CONTACT
   ---------------------------------------------------------------- */
.contact__grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-5);
  align-items: start;
}

.contact__details h3 {
  font-size: var(--text-md);
}

.contact__details p {
  color: var(--color-muted);
}

.contact__details a[href^="mailto:"] {
  color: var(--color-thermal);
  font-weight: 600;
}

.contact__social {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2) var(--space-4);
  margin-top: var(--space-4);
  padding-top: var(--space-4);
  border-top: 1px solid var(--color-line);
}

.contact__social a {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--color-navy);
  border-bottom: 1px solid transparent;
}
.contact__social a:hover {
  border-bottom-color: var(--color-thermal);
  color: var(--color-thermal);
}

.contact__map-placeholder {
  aspect-ratio: 4 / 3;
  border-radius: var(--radius-md);
  background-color: var(--color-navy-dark);
  background-image:
    linear-gradient(var(--color-line-dark) 1px, transparent 1px),
    linear-gradient(90deg, var(--color-line-dark) 1px, transparent 1px);
  background-size: 32px 32px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-muted-light);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
}


/* ----------------------------------------------------------------
   12. FOOTER
   ---------------------------------------------------------------- */
.site-footer {
  background-color: var(--color-navy-dark);
  color: var(--color-muted-light);
}

.site-footer__inner {
  max-width: var(--content-width);
  margin: 0 auto;
  padding: var(--space-5) var(--content-padding);
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
  font-size: var(--text-xs);
}

.site-footer__funding {
  color: var(--color-muted-light);
}

.site-footer__back {
  color: var(--color-thermal-soft);
  font-family: var(--font-mono);
  margin-top: var(--space-2);
}
.site-footer__back:hover {
  text-decoration: underline;
}


/* ----------------------------------------------------------------
   13. BACK TO TOP BUTTON
   ---------------------------------------------------------------- */
.back-to-top {
  position: fixed;
  right: var(--space-4);
  bottom: var(--space-4);
  width: 44px;
  height: 44px;
  border-radius: 50%;
  border: none;
  background-color: var(--color-navy);
  color: #fff;
  font-size: var(--text-md);
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: var(--shadow-md);
  opacity: 0;
  visibility: hidden;
  transform: translateY(8px);
  transition: opacity var(--duration-base) var(--ease-out),
              transform var(--duration-base) var(--ease-out),
              background-color var(--duration-fast) var(--ease-out);
  z-index: 90;
}

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

.back-to-top:hover {
  background-color: var(--color-thermal);
}


/* ----------------------------------------------------------------
   14. SCROLL-REVEAL ANIMATION (paired with script.js IntersectionObserver)
   ---------------------------------------------------------------- */
.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.7s var(--ease-out), transform 0.7s var(--ease-out);
}

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


/* ----------------------------------------------------------------
   15. RESPONSIVE BREAKPOINTS
   ---------------------------------------------------------------- */

/* Tablet — 600px+ */
@media (min-width: 600px) {
  .person-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .card-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .contact__grid {
    grid-template-columns: 1.2fr 1fr;
  }
}

/* Small desktop — 900px+ */
@media (min-width: 900px) {
  .about__grid {
    grid-template-columns: 1.4fr 1fr;
  }

  .person-grid {
    grid-template-columns: repeat(3, 1fr);
  }

  .card-grid {
    grid-template-columns: repeat(3, 1fr);
  }
}

/* Mobile navigation — below 900px, collapse into hamburger menu */
@media (max-width: 899px) {
  .nav__toggle {
    display: flex;
  }

  .nav__menu {
    position: fixed;
    top: 0;
    right: 0;
    height: 100vh;
    width: min(78vw, 320px);
    background-color: var(--color-navy-dark);
    flex-direction: column;
    align-items: flex-start;
    gap: var(--space-4);
    padding: calc(var(--space-6) + var(--space-3)) var(--space-4) var(--space-4);
    transform: translateX(100%);
    transition: transform var(--duration-base) var(--ease-out);
    box-shadow: -8px 0 24px rgba(0, 0, 0, 0.25);
  }

  .nav__menu.is-open {
    transform: translateX(0);
  }

  .nav__link {
    font-size: var(--text-md);
  }
}

/* Large desktop — 1200px+ */
@media (min-width: 1200px) {
  .about__facts {
    grid-template-columns: repeat(2, 1fr);
  }
}