/* ============================================================
   SECTIONS.CSS — About, Skills, Projects, Research, Contact, Footer
   ============================================================ */

/* ─── ABOUT ─── */
.about-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--sp-12);
  align-items: start;
}
.about-lead {
  font-size: clamp(var(--fs-lg), 2.5vw, var(--fs-2xl));
  font-weight: 500;
  line-height: 1.55;
  color: var(--clr-text);
  margin-bottom: var(--sp-6);
}
.about-body { color: var(--clr-text-dim); line-height: 1.85; margin-bottom: var(--sp-6); }
.about-pills { display: flex; flex-wrap: wrap; gap: var(--sp-2); }
.about-pill {
  padding: var(--sp-2) var(--sp-4);
  border: 1px solid var(--clr-border2);
  border-radius: var(--radius-full);
  font-size: var(--fs-xs);
  color: var(--clr-text-dim);
  transition: all var(--dur-fast);
}
.about-pill:hover { border-color: var(--clr-accent); color: var(--clr-accent); }

.about-card {
  background: var(--grad-card);
  border: 1px solid var(--clr-border);
  border-radius: var(--radius-xl);
  padding: var(--sp-8);
  display: flex;
  flex-direction: column;
  gap: var(--sp-6);
}
.about-stat-row { display: flex; flex-direction: column; gap: var(--sp-4); }
.about-stat { display: flex; flex-direction: column; gap: var(--sp-1); }
.about-stat-num {
  font-size: var(--fs-4xl);
  font-weight: 700;
  letter-spacing: -0.03em;
  background: var(--grad-brand);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.about-stat-lbl { font-size: var(--fs-xs); color: var(--clr-text-mute); font-family: var(--ff-mono); }

@media (max-width: 768px) {
  .about-grid { grid-template-columns: 1fr; }
}

/* ─── SKILLS ─── */
.skills-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: var(--sp-4);
}
.skill-card {
  background: var(--grad-card);
  border: 1px solid var(--clr-border);
  border-radius: var(--radius-lg);
  padding: var(--sp-6);
  display: flex;
  flex-direction: column;
  gap: var(--sp-3);
  transition: border-color var(--dur-base), transform var(--dur-base), box-shadow var(--dur-base);
  position: relative;
  overflow: hidden;
}
.skill-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 2px;
  background: var(--grad-brand);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform var(--dur-base) var(--ease-out);
}
.skill-card:hover { border-color: var(--clr-border2); transform: translateY(-4px); box-shadow: var(--shadow-md), var(--shadow-glow); }
.skill-card:hover::before { transform: scaleX(1); }

.skill-icon {
  width: 44px; height: 44px;
  background: var(--grad-subtle);
  border: 1px solid var(--clr-border);
  border-radius: var(--radius-md);
  display: grid;
  place-items: center;
  color: var(--clr-accent);
  font-size: 22px;
}
.skill-card h3 { font-size: var(--fs-base); font-weight: 600; }
.skill-card p { font-size: var(--fs-sm); color: var(--clr-text-dim); line-height: 1.7; }

/* Skill bars */
.skill-bar-group { display: flex; flex-direction: column; gap: var(--sp-3); margin-top: var(--sp-2); }
.skill-bar-item { display: flex; flex-direction: column; gap: var(--sp-1); }
.skill-bar-top { display: flex; justify-content: space-between; font-size: var(--fs-xs); color: var(--clr-text-dim); }
.skill-bar-track {
  height: 4px;
  background: rgba(255,255,255,0.06);
  border-radius: var(--radius-full);
  overflow: hidden;
}
.skill-bar-fill {
  height: 100%;
  background: var(--grad-brand);
  border-radius: var(--radius-full);
  width: 0;
  transition: width 1.2s var(--ease-out);
}
.skill-bar-fill.animated { width: var(--w); }

/* ─── PROJECTS ─── */
.work-filters {
  display: flex;
  gap: var(--sp-2);
  flex-wrap: wrap;
  margin-bottom: var(--sp-8);
}
.chip {
  padding: var(--sp-2) var(--sp-4);
  border: 1px solid var(--clr-border);
  border-radius: var(--radius-full);
  font-size: var(--fs-sm);
  font-weight: 500;
  color: var(--clr-text-dim);
  background: transparent;
  transition: all var(--dur-fast);
  cursor: pointer;
}
.chip em { font-style: normal; font-size: var(--fs-xs); margin-left: var(--sp-1); color: var(--clr-text-mute); }
.chip:hover, .chip.active {
  border-color: var(--clr-accent);
  color: var(--clr-accent);
  background: rgba(56,189,248,0.08);
}
.chip.active em { color: var(--clr-accent); }

.work-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: var(--sp-5);
}

.work-card {
  background: var(--grad-card);
  border: 1px solid var(--clr-border);
  border-radius: var(--radius-xl);
  padding: var(--sp-6);
  display: flex;
  flex-direction: column;
  gap: var(--sp-4);
  transition: all var(--dur-base) var(--ease-out);
  text-decoration: none;
  color: inherit;
  position: relative;
  overflow: hidden;
}
.work-card::after {
  content: '';
  position: absolute;
  inset: 0;
  background: var(--grad-subtle);
  opacity: 0;
  transition: opacity var(--dur-base);
  pointer-events: none;
}
.work-card:hover { border-color: var(--clr-border2); transform: translateY(-6px); box-shadow: var(--shadow-lg), var(--shadow-glow); }
.work-card:hover::after { opacity: 1; }

.work-card-top { display: flex; justify-content: space-between; align-items: flex-start; }
.work-num {
  font-family: var(--ff-mono);
  font-size: var(--fs-xs);
  color: var(--clr-text-mute);
  border: 1px solid var(--clr-border);
  padding: 2px var(--sp-2);
  border-radius: var(--radius-sm);
}
.work-link-icon { color: var(--clr-text-mute); font-size: 18px; transition: color var(--dur-fast), transform var(--dur-fast); }
.work-card:hover .work-link-icon { color: var(--clr-accent); transform: translate(3px, -3px); }

.work-card h3 { font-size: var(--fs-base); font-weight: 600; line-height: 1.4; }
.work-card p  { font-size: var(--fs-sm); color: var(--clr-text-dim); line-height: 1.7; flex: 1; }
.work-tags { display: flex; flex-wrap: wrap; gap: var(--sp-2); margin-top: auto; }

/* Featured card */
.work-card.featured {
  grid-column: span 2;
  background: linear-gradient(135deg, rgba(56,189,248,0.06) 0%, rgba(129,140,248,0.06) 100%);
  border-color: rgba(56,189,248,0.2);
}
.work-card.featured h3 { font-size: var(--fs-xl); }
@media (max-width: 700px) { .work-card.featured { grid-column: span 1; } }

/* hidden cards for filter */
.work-card.hidden { display: none; }

/* ─── RESEARCH / PUBLICATIONS ─── */
.pub {
  background: var(--grad-card);
  border: 1px solid var(--clr-border);
  border-radius: var(--radius-xl);
  padding: var(--sp-8);
  display: flex;
  flex-direction: column;
  gap: var(--sp-4);
  transition: border-color var(--dur-base), box-shadow var(--dur-base);
  margin-bottom: var(--sp-5);
}
.pub:hover { border-color: var(--clr-border2); box-shadow: var(--shadow-md); }
.pub-meta { display: flex; gap: var(--sp-4); flex-wrap: wrap; }
.pub-meta span {
  font-family: var(--ff-mono);
  font-size: var(--fs-xs);
  color: var(--clr-text-mute);
}
.pub-meta .pub-journal { color: var(--clr-accent); }
.pub h3 { font-size: var(--fs-xl); font-weight: 600; line-height: 1.4; }
.pub-authors { font-size: var(--fs-sm); color: var(--clr-text-dim); }
.pub-body { font-size: var(--fs-sm); color: var(--clr-text-dim); line-height: 1.8; }
.pub-doi a {
  font-family: var(--ff-mono);
  font-size: var(--fs-xs);
  color: var(--clr-accent);
  transition: color var(--dur-fast);
}
.pub-doi a:hover { color: var(--clr-accent2); }
.pub-badges { display: flex; gap: var(--sp-2); flex-wrap: wrap; }

/* ─── EDUCATION ─── */
.edu-timeline { display: flex; flex-direction: column; gap: 0; }
.edu-item {
  display: grid;
  grid-template-columns: 160px 1fr;
  gap: var(--sp-8);
  padding-block: var(--sp-8);
  border-bottom: 1px solid var(--clr-border);
  position: relative;
}
.edu-item:last-child { border-bottom: none; }
.edu-when { font-family: var(--ff-mono); font-size: var(--fs-xs); color: var(--clr-text-mute); padding-top: 4px; }
.edu-what h3 { font-size: var(--fs-xl); font-weight: 600; margin-bottom: var(--sp-2); }
.edu-what h3 span { font-weight: 400; color: var(--clr-text-dim); }
.edu-deg { color: var(--clr-accent); font-size: var(--fs-sm); margin-bottom: var(--sp-3); }
.edu-desc { color: var(--clr-text-dim); font-size: var(--fs-sm); line-height: 1.8; }
@media (max-width: 640px) { .edu-item { grid-template-columns: 1fr; gap: var(--sp-2); } }

/* ─── EXPERIENCE ─── */
.exp-card {
  background: var(--grad-card);
  border: 1px solid var(--clr-border);
  border-radius: var(--radius-xl);
  padding: var(--sp-8);
  display: flex;
  gap: var(--sp-6);
  transition: border-color var(--dur-base), box-shadow var(--dur-base);
  margin-bottom: var(--sp-5);
}
.exp-card:hover { border-color: var(--clr-border2); box-shadow: var(--shadow-md); }
.exp-logo {
  width: 52px; height: 52px;
  background: var(--grad-subtle);
  border: 1px solid var(--clr-border);
  border-radius: var(--radius-md);
  display: grid;
  place-items: center;
  color: var(--clr-accent);
  font-size: 24px;
  flex-shrink: 0;
}
.exp-content { flex: 1; }
.exp-content h3 { font-size: var(--fs-lg); font-weight: 600; margin-bottom: var(--sp-1); }
.exp-org { color: var(--clr-accent); font-size: var(--fs-sm); font-weight: 500; }
.exp-period { font-family: var(--ff-mono); font-size: var(--fs-xs); color: var(--clr-text-mute); margin-bottom: var(--sp-3); }
.exp-desc { font-size: var(--fs-sm); color: var(--clr-text-dim); line-height: 1.8; }
@media (max-width: 480px) { .exp-card { flex-direction: column; } }

/* ─── CONTACT ─── */
.contact-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--sp-12);
  align-items: start;
}
.contact-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: var(--sp-2);
  font-size: var(--fs-xs);
  font-family: var(--ff-mono);
  color: var(--clr-text-mute);
  margin-bottom: var(--sp-6);
}
.contact-eyebrow .dot { width: 7px; height: 7px; border-radius: 50%; background: var(--clr-green); animation: pulse-dot 2s infinite; }
.contact-title {
  font-size: clamp(var(--fs-4xl), 5vw, var(--fs-6xl));
  font-weight: 700;
  letter-spacing: -0.03em;
  line-height: 1.1;
  margin-bottom: var(--sp-5);
}
.contact-title em { font-style: normal; background: var(--grad-brand); -webkit-background-clip: text; -webkit-text-fill-color: transparent; background-clip: text; }
.contact-desc { color: var(--clr-text-dim); font-size: var(--fs-base); line-height: 1.8; margin-bottom: var(--sp-8); }
.contact-links { display: flex; flex-direction: column; gap: var(--sp-3); }
.contact-link {
  display: flex;
  align-items: center;
  gap: var(--sp-3);
  padding: var(--sp-3) var(--sp-4);
  border-radius: var(--radius-md);
  border: 1px solid var(--clr-border);
  transition: all var(--dur-fast);
  color: var(--clr-text-dim);
  font-size: var(--fs-sm);
}
.contact-link:hover { border-color: var(--clr-accent); color: var(--clr-text); background: rgba(56,189,248,0.05); }
.contact-link .material-symbols-outlined { color: var(--clr-accent); font-size: 20px; }

/* Contact Form */
.contact-form {
  background: var(--grad-card);
  border: 1px solid var(--clr-border);
  border-radius: var(--radius-xl);
  padding: var(--sp-8);
  display: flex;
  flex-direction: column;
  gap: var(--sp-5);
}
.form-row { display: grid; grid-template-columns: 1fr 1fr; gap: var(--sp-4); }
.form-group { display: flex; flex-direction: column; gap: var(--sp-2); }
.form-group label { font-size: var(--fs-xs); font-weight: 500; color: var(--clr-text-dim); letter-spacing: 0.05em; text-transform: uppercase; }
.form-group input,
.form-group textarea {
  background: rgba(255,255,255,0.03);
  border: 1px solid var(--clr-border);
  border-radius: var(--radius-md);
  padding: var(--sp-3) var(--sp-4);
  font-family: var(--ff-sans);
  font-size: var(--fs-sm);
  color: var(--clr-text);
  outline: none;
  transition: border-color var(--dur-fast), box-shadow var(--dur-fast);
  resize: none;
}
.form-group input:focus,
.form-group textarea:focus {
  border-color: var(--clr-accent);
  box-shadow: 0 0 0 3px rgba(56,189,248,0.12);
}
.form-group textarea { min-height: 120px; }
.form-submit {
  background: var(--grad-brand);
  color: #fff;
  padding: var(--sp-4) var(--sp-6);
  border-radius: var(--radius-full);
  font-size: var(--fs-base);
  font-weight: 600;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--sp-2);
  transition: transform var(--dur-fast), box-shadow var(--dur-fast);
  box-shadow: 0 0 24px rgba(56,189,248,0.25);
}
.form-submit:hover { transform: translateY(-2px); box-shadow: 0 0 36px rgba(56,189,248,0.4); }
.form-status { text-align: center; font-size: var(--fs-sm); color: var(--clr-green); display: none; }
.form-status.visible { display: block; }

@media (max-width: 768px) {
  .contact-grid { grid-template-columns: 1fr; }
  .form-row { grid-template-columns: 1fr; }
}

/* ─── FOOTER ─── */
.footer {
  border-top: 1px solid var(--clr-border);
  padding-block: var(--sp-8);
}
.footer-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: var(--sp-4);
}
.footer-copy { font-size: var(--fs-sm); color: var(--clr-text-mute); }
.footer-copy span { color: var(--clr-accent); }
.footer-links { display: flex; gap: var(--sp-5); }
.footer-links a { font-size: var(--fs-sm); color: var(--clr-text-mute); transition: color var(--dur-fast); }
.footer-links a:hover { color: var(--clr-text); }

/* ─── BACK TO TOP ─── */
.back-top {
  position: fixed;
  bottom: var(--sp-8);
  right: var(--sp-8);
  width: 44px; height: 44px;
  background: var(--grad-brand);
  color: #fff;
  border-radius: var(--radius-full);
  display: grid;
  place-items: center;
  box-shadow: var(--shadow-md);
  opacity: 0;
  transform: translateY(20px);
  pointer-events: none;
  transition: opacity var(--dur-base), transform var(--dur-base);
  z-index: 50;
}
.back-top.visible { opacity: 1; transform: translateY(0); pointer-events: auto; }
.back-top:hover { transform: translateY(-4px); }

/* ─── PAGE HEADER (inner pages) ─── */
.page-hero {
  padding-top: calc(var(--nav-h) + var(--sp-16));
  padding-bottom: var(--sp-16);
  text-align: center;
  position: relative;
  overflow: hidden;
}
.page-hero::before {
  content: '';
  position: absolute;
  inset: 0;
  background: radial-gradient(ellipse at center top, rgba(56,189,248,0.08) 0%, transparent 70%);
  pointer-events: none;
}
.page-hero-tag {
  display: inline-flex;
  align-items: center;
  gap: var(--sp-2);
  font-family: var(--ff-mono);
  font-size: var(--fs-xs);
  color: var(--clr-accent);
  margin-bottom: var(--sp-4);
  letter-spacing: 0.1em;
  text-transform: uppercase;
}
.page-hero h1 {
  font-size: clamp(var(--fs-4xl), 6vw, var(--fs-6xl));
  font-weight: 700;
  letter-spacing: -0.03em;
  line-height: 1.1;
  margin-bottom: var(--sp-5);
}
.page-hero p { font-size: var(--fs-lg); color: var(--clr-text-dim); max-width: 560px; margin-inline: auto; }