:root{
  --bg:#f7f9fb;
  --card:#fff;
  --text:#0f1721;
  --muted:#586069;
  --accent:#1f7bd6;
  --icon-hover: rgba(31,123,214,0.12);
  --glass: rgba(255,255,255,0.6);
  --radius:10px;
  --shadow: 0 6px 22px rgba(17,24,39,0.06);
}

*{box-sizing:border-box}
html,body{height:100%}
body{
  margin:0;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial;
  background:var(--bg);
  color:var(--text);
  -webkit-font-smoothing:antialiased;
  -moz-osx-font-smoothing:grayscale;
  line-height:1.45;
}

.container{max-width:1000px;margin:28px auto;padding:0 18px}

/* Header */
.site-header{
  background:linear-gradient(90deg, rgba(31,123,214,0.08), rgba(31,123,214,0.02));
  padding:18px 0;border-bottom:1px solid rgba(15,23,33,0.04);
}
.header-grid{display:flex;align-items:center;justify-content:space-between;gap:16px}
.lab-title{margin:0;font-size:1.25rem}
.lab-title .accent{display:block;font-weight:600;color:var(--accent);font-size:0.95rem}
.subtitle{margin:6px 0 0;color:var(--muted)}

/* Cards */
.card{background:var(--card);border-radius:var(--radius);padding:18px;margin-bottom:18px;box-shadow:var(--shadow)}
h2{margin-top:0}
.muted{color:var(--muted)}

/* Accordion */
.accordion-item{margin-top:8px;border-top:1px dashed rgba(15,23,33,0.04);padding-top:8px}
.accordion-toggle{
  display:block;width:100%;text-align:left;padding:10px;border:0;background:transparent;font-weight:600;color:var(--text);
  cursor:pointer;border-radius:8px
}
.accordion-toggle:focus{outline:2px solid rgba(31,123,214,0.15)}
.accordion-panel{padding:8px 12px}
.hidden{display:none}

/* People / avatars */
.person{
  display:flex;
  gap:14px;
  align-items:flex-start;
  margin-bottom:14px;
}
.avatar{
  width:96px;
  height:96px;
  object-fit:cover;
  border-radius:12px;
  border:1px solid rgba(15,23,33,0.06);
  background:linear-gradient(180deg, rgba(0,0,0,0.03), rgba(0,0,0,0.01));
  flex-shrink:0;
}
.person-body{flex:1}

/* Students grid */
.people-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(220px,1fr));gap:12px}
.student{background:transparent;padding:8px;border-radius:8px}

/* Contact form */
.contact-grid{display:grid;grid-template-columns:1fr 320px;gap:18px}
.contact-form label{display:block;margin-top:8px;font-size:0.85rem}
.contact-form input, .contact-form textarea{
  width:100%;padding:8px;border-radius:8px;border:1px solid rgba(15,23,33,0.08);margin-top:6px;
  background:transparent
}
.form-actions{margin-top:10px;display:flex;flex-direction:column;gap:8px}
.form-actions .muted{font-size:0.8rem}

/* Footer */
.site-footer{padding:18px 0;text-align:center;color:var(--muted)}

/* Buttons */
.btn{display:inline-flex;align-items:center;gap:8px;padding:8px 12px;border-radius:8px;border:1px solid rgba(15,23,33,0.06);background:#fff;cursor:pointer}
.btn.primary{background:var(--accent);color:#fff;border:none}
.header-actions{display:flex;gap:8px}

/* Icon-only theme button */
.btn.icon{
  padding:8px;
  width:44px;
  height:44px;
  border-radius:999px;
  justify-content:center;
  background:transparent;
  border:1px solid rgba(15,23,33,0.06);
  transition:background .18s ease, transform .1s ease;
}
.btn.icon:hover{ background: var(--icon-hover); transform: translateY(-1px); }
.btn.icon:active{ transform: translateY(0); }

/* external SVG images inside the button */
.btn.icon img{
  display:block;
  width:20px;
  height:20px;
  transition:transform .28s cubic-bezier(.2,.9,.2,1), opacity .18s ease;
}

/* copy-email button: professional pill-style */
.copy-email {
  position: relative;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 10px;
  font-size: 0.9rem;
  line-height: 1;
  color: var(--text);
  background: linear-gradient(#ffffff, #f5f8fb);
  border: 1px solid rgba(15,23,33,0.06);
  border-radius: 999px;
  box-shadow: 0 3px 10px rgba(17,24,39,0.05);
  cursor: pointer;
  transition: transform .12s ease, box-shadow .12s ease, background .12s ease;
  user-select: none;
  -webkit-tap-highlight-color: transparent;
}

.copy-email .ce-icon {
  width: 16px;
  height: 16px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  color: var(--muted);
  transition: transform .18s ease, color .18s ease;
}

.copy-email .ce-text {
  display: inline-block;
  font-weight: 600;
  color: inherit;
}

.copy-email:hover,
.copy-email:focus {
  transform: translateY(-2px);
  box-shadow: 0 6px 18px rgba(17,24,39,0.08);
  outline: none;
}
.copy-email:active { transform: translateY(-1px); }

/* tooltip using title attr */
.copy-email::after{
  content: attr(title);
  position: absolute;
  left: 50%;
  transform: translateX(-50%) translateY(8px);
  bottom: 100%;
  white-space: nowrap;
  background: rgba(15,23,33,0.92);
  color: #fff;
  font-size: 12px;
  padding: 6px 8px;
  border-radius: 6px;
  opacity: 0;
  pointer-events: none;
  transition: opacity .12s ease, transform .12s ease;
  z-index: 30;
  transform-origin: center;
  box-shadow: 0 6px 18px rgba(17,24,39,0.12);
}

/* show tooltip on hover/focus */
.copy-email:hover::after,
.copy-email:focus::after {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}

/* success state: greenish */
.copy-email.success {
  background: linear-gradient(#E9FFEF, #D9F8E0);
  border-color: rgba(26, 149, 85, 0.2);
  color: #0b6a3a;
  box-shadow: 0 6px 18px rgba(6, 105, 58, 0.06);
}
.copy-email.success .ce-icon { color: #0b6a3a; transform: scale(1.05); }

/* ensure hidden helper */
.copy-email img.hidden,
.copy-email svg.hidden {
  display: none !important;
  opacity: 0 !important;
  pointer-events: none !important;
}

/* accessible focus ring */
.copy-email:focus-visible {
  box-shadow: 0 0 0 3px rgba(31,123,214,0.14), 0 6px 18px rgba(17,24,39,0.06);
}

/* responsive */
@media (max-width:880px){
  .contact-grid{grid-template-columns:1fr}
  .header-grid{flex-direction:column;align-items:flex-start}
  .person{align-items:center}
  .avatar{width:76px;height:76px}
  .copy-email { padding: 6px 8px; gap: 6px; font-size: .85rem; }
  .copy-email .ce-icon { width:14px; height:14px; }
}

/* Dark theme */
body.dark{
  --bg:#0b1220;
  --card:#0f1721;
  --text:#e6eef8;
  --muted:#9aa9bf;
  --accent:#58a6ff;
  --icon-hover: rgba(88,166,255,0.08);
  background:linear-gradient(180deg,#071124,#0b1220);
}

/* helpers */
.hidden{display:none}