/* ============================================================
   VARIABLES — edit colors, fonts, and spacing here
   ============================================================ */
:root {
  --color-bg:         #ffffff;
  --color-text:       #333333;
  --color-text-light: #666666;
  --color-accent:     #3a7bd5;
  --color-divider:    #dddddd;
  --color-hover-bg:   #f5f8ff;

  --font-mono:   'JetBrains Mono', 'Courier New', monospace;
  --font-serif:  'Source Serif 4', Georgia, serif;

  --max-width:   900px;
  --gap:         2rem;
}

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

html { font-size: 16px; }

body {
  font-family: var(--font-serif);
  background: var(--color-bg);
  color: var(--color-text);
  line-height: 1.7;
  padding: 2rem 1.5rem 4rem;
}

a {
  color: var(--color-accent);
  text-decoration: none;
}
a:hover { text-decoration: underline; }

/* ============================================================
   HEADER
   ============================================================ */
header {
  max-width: var(--max-width);
  margin: 0 auto 3rem;
}

.site-name {
  font-family: var(--font-mono);
  font-size: 1rem;
  font-weight: 500;
  letter-spacing: 0.02em;
  color: var(--color-text);
}

/* ============================================================
   MAIN WRAPPER
   ============================================================ */
main {
  max-width: var(--max-width);
  margin: 0 auto;
}

/* ============================================================
   HERO — photo + bio side by side
   ============================================================ */
.hero {
  display: flex;
  align-items: flex-start;
  gap: var(--gap);
  margin-bottom: 2.5rem;
}

/* --- Photo --- */
.hero-photo {
  flex-shrink: 0;
  position: relative;
  width: 200px;
  height: 200px;
}

.hero-photo img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  border-radius: 50%;
  display: block;
  filter: grayscale(20%);
}

/* Fallback initials circle (shown when photo fails to load) */
.photo-fallback {
  position: absolute;
  inset: 0;
  border-radius: 50%;
  background: #dce8f7;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-mono);
  font-size: 2rem;
  color: var(--color-accent);
  z-index: -1; /* sits behind the real photo when it loads */
}

/* If the img fails, show fallback in front */
.hero-photo img[data-error] + .photo-fallback {
  z-index: 1;
}

/* --- Bio text --- */
.hero-bio {
  flex: 1;
  padding-top: 0.25rem;
}

.hero-bio h1 {
  font-family: var(--font-mono);
  font-size: 2rem;
  font-weight: 400;
  color: var(--color-accent);
  margin-bottom: 0.75rem;
  letter-spacing: -0.01em;
}

.hero-bio p {
  font-size: 0.97rem;
  color: var(--color-text);
  margin-bottom: 0.6rem;
}

/* ============================================================
   CV LINK
   ============================================================ */
.cv-link {
  margin-bottom: 2rem;
}

.cv-link a {
  font-family: var(--font-mono);
  font-size: 0.95rem;
  font-style: italic;
  color: var(--color-accent);
  border-bottom: 1px solid transparent;
  padding-bottom: 2px;
  transition: border-color 0.15s;
}
.cv-link a:hover {
  text-decoration: none;
  border-bottom-color: var(--color-accent);
}

/* ============================================================
   ACCORDION SECTIONS
   ============================================================ */
.sections {
  border-top: 1px solid var(--color-divider);
}

.accordion {
  border-bottom: 1px solid var(--color-divider);
}

.accordion-header {
  width: 100%;
  display: flex;
  align-items: center;
  gap: 1rem;
  padding: 1.1rem 0;
  background: none;
  border: none;
  cursor: pointer;
  text-align: left;
  font-family: var(--font-mono);
  font-size: 1.05rem;
  font-weight: 400;
  color: var(--color-text);
  transition: color 0.15s;
}

.accordion-header:hover {
  color: var(--color-accent);
}

.toggle-icon {
  font-size: 1.2rem;
  font-weight: 300;
  color: var(--color-text-light);
  width: 1rem;
  text-align: center;
  flex-shrink: 0;
  transition: transform 0.2s;
  user-select: none;
}

/* Rotate + into × look when open (using CSS content swap) */
.accordion.open .toggle-icon {
  content: "−";
  color: var(--color-accent);
}

.accordion-body {
  padding: 0.5rem 0 1.75rem 2rem;
}

/* ============================================================
   PAPER LIST
   ============================================================ */
.paper-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 1.4rem;
}

.paper-title {
  font-weight: 400;
  font-size: 0.97rem;
  margin-bottom: 0.2rem;
}

.paper-title a {
  color: var(--color-text);
  font-style: italic;
}
.paper-title a:hover {
  color: var(--color-accent);
  text-decoration: none;
}

.paper-meta {
  font-size: 0.88rem;
  color: var(--color-text-light);
  margin-bottom: 0.4rem;
}

/* Abstract toggle button */
.abstract-toggle {
  background: none;
  border: none;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--color-accent);
  cursor: pointer;
  padding: 0;
  letter-spacing: 0.02em;
}
.abstract-toggle:hover { text-decoration: underline; }

.abstract {
  margin-top: 0.5rem;
  padding: 0.75rem 1rem;
  background: var(--color-hover-bg);
  border-left: 3px solid var(--color-accent);
  font-size: 0.9rem;
  color: var(--color-text-light);
  line-height: 1.65;
}

/* ============================================================
   RESEARCH INTERESTS
   ============================================================ */
.interests-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  font-size: 0.95rem;
}

/* ============================================================
   TEACHING
   ============================================================ */
.accordion-body h3 {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--color-text-light);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin: 1.2rem 0 0.5rem;
}
.accordion-body h3:first-child { margin-top: 0; }

.teaching-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
  font-size: 0.93rem;
}

/* ============================================================
   CONTACT & BIO
   ============================================================ */
.contact-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: calc(var(--gap) * 1.5);
}

.contact-info p,
.bio p {
  font-size: 0.93rem;
  margin-bottom: 0.5rem;
}

/* ============================================================
   FOOTER
   ============================================================ */
footer {
  max-width: var(--max-width);
  margin: 3rem auto 0;
  padding-top: 1.5rem;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--color-text-light);
}

/* ============================================================
   RESPONSIVE — single breakpoint at 620px
   ============================================================ */
@media (max-width: 620px) {
  .hero {
    flex-direction: column;
    align-items: center;
    text-align: center;
  }

  .hero-photo {
    width: 150px;
    height: 150px;
  }

  .hero-bio h1 {
    font-size: 1.5rem;
  }

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

  .accordion-body {
    padding-left: 1rem;
  }
}