/* ─────────────────────────────────────────────────────────
   HAMBURGER NAV (hidden on desktop, visible on mobile)
───────────────────────────────────────────────────────── */
.nav-hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: transparent;
  border: none;
  cursor: pointer;
  padding: 4px;
  margin-left: auto;
}

.nav-hamburger span {
  display: block;
  width: 20px;
  height: 1.5px;
  background: var(--text);
  border-radius: 2px;
}

.nav-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: var(--bg);
  z-index: 999;
  padding: 2rem 1.5rem;
  flex-direction: column;
}

.nav-overlay.is-open {
  display: flex;
}

.nav-overlay-inner {
  display: flex;
  flex-direction: column;
}

.nav-overlay-top {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 2.5rem;
}

.nav-close {
  background: transparent;
  border: none;
  font-size: 18px;
  color: var(--text-secondary);
  cursor: pointer;
  padding: 4px;
}

.nav-overlay-link {
  font-family: 'DM Mono', monospace;
  font-size: 22px;
  color: var(--text);
  padding: 14px 0;
  border-bottom: 0.5px solid var(--border);
  display: block;
}

.nav-overlay-badge {
  display: inline-block;
  margin-top: 24px;
  font-family: 'DM Mono', monospace;
  font-size: 11px;
  color: var(--green-text);
  background: var(--green-bg);
  border: 0.5px solid var(--green-border);
  padding: 4px 12px;
  border-radius: var(--radius-md);
}

/* ── ABSTRACT TOGGLE ── */
.abstract-wrap {
  position: relative;
  margin-bottom: 1.5rem;
}

.abstract-toggle {
  display: none;
  background: transparent;
  border: none;
  font-family: 'DM Mono', monospace;
  font-size: 12px;
  color: var(--info);
  cursor: pointer;
  padding: 0;
  margin-top: 6px;
}

/* ── PROJECTS DOTS ── */
.projects-dots {
  display: none;
  justify-content: center;
  gap: 6px;
  margin-top: 10px;
}

.projects-dot {
  width: 5px;
  height: 5px;
  border-radius: 50%;
  background: var(--border-md);
  transition: background 0.2s;
}

.projects-dot.active {
  background: var(--text);
}

/* ─────────────────────────────────────────────────────────
   TABLET (≤ 760px)
───────────────────────────────────────────────────────── */
@media (max-width: 760px) {
  .project-card {
    min-width: calc(80vw);
    max-width: calc(80vw);
  }
}

/* ─────────────────────────────────────────────────────────
   MOBILE (≤ 640px)
───────────────────────────────────────────────────────── */
@media (max-width: 640px) {
  .container { padding: 1.25rem 1rem 0; }
  .section { margin: 2.5rem 0; }

  /* nav */
  .nav { margin-bottom: 2rem; display: grid; grid-template-columns: 1fr auto 1fr; align-items: center; gap: 0; }
  .nav-link { display: none; }
  .open-badge { display: inline-block; margin-left: 0; justify-self: center; }
  .nav-hamburger { display: flex; justify-self: end; }

  /* hero */
  .hero-role { font-size: 11px; }
  .hero-tagline { font-size: 14px; max-width: 100%; }
  .btn { font-size: 12px; padding: 7px 13px; }
  .btn-group { gap: 6px; }

  /* research title row */
  .research-title-row { grid-template-columns: 1fr; }
  .research-title-row .exp-period { display: none; }

  /* abstract collapse */
  .abstract-wrap .research-abstract {
    display: -webkit-box;
    -webkit-line-clamp: 3;
    -webkit-box-orient: vertical;
    overflow: hidden;
  }
  .abstract-wrap.is-open .research-abstract {
    display: block;
    overflow: visible;
  }
  .abstract-toggle { display: inline-block; }

  /* chart */
  #ohlcChart { height: 160px; }
  .chart-annotation { font-size: 10px; text-align: left; padding: 6px 12px 10px; }

  /* metrics: horizontal scroll */
  .metrics-row {
    display: flex;
    flex-wrap: nowrap;
    overflow-x: auto;
    gap: 8px;
    scrollbar-width: none;
    padding-bottom: 4px;
    margin-bottom: 1.25rem;
  }
  .metrics-row::-webkit-scrollbar { display: none; }
  .metric { flex-shrink: 0; min-width: 110px; }

  /* methodology: numbered vertical */
  .method-flow {
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    counter-reset: step;
    margin-bottom: 1rem;
  }
  .marrow { display: none; }
  .mstep {
    counter-increment: step;
    display: flex;
    align-items: center;
    gap: 10px;
    background: transparent;
    border: none;
    border-bottom: 0.5px solid var(--border);
    border-radius: 0;
    padding: 9px 0;
    font-size: 12px;
    color: var(--text-secondary);
  }
  .mstep:last-child { border-bottom: none; }
  .mstep::before {
    content: "0" counter(step);
    font-family: 'DM Mono', monospace;
    font-size: 10px;
    color: var(--text-tertiary);
    min-width: 18px;
    flex-shrink: 0;
  }

  /* skills */
  .skill-row { grid-template-columns: 90px 1fr; }
  .skill-cat { font-size: 10px; padding: 10px 12px; }
  .skill-items { font-size: 13px; padding: 10px 12px; }

  /* projects */
  .projects-nav { display: none; }
  .projects-dots { display: flex; }
  .project-card {
    min-width: calc(100vw - 2rem - 10px);
    max-width: calc(100vw - 2rem - 10px);
    scroll-snap-align: center;
  }

  /* experience */
  .exp-role { font-size: 14px; }
  .exp-org { font-size: 12px; }
  .exp-detail { font-size: 12px; }
  .exp-period { font-size: 10px; }

  /* credentials */
  .cred-item { font-size: 12px; padding: 4px 10px; }

  /* footer */
  .footer { flex-direction: row; justify-content: space-between; align-items: center; padding-bottom: 2rem; }
}

/* ─────────────────────────────────────────────────────────
   VERY SMALL (≤ 400px)
───────────────────────────────────────────────────────── */
@media (max-width: 400px) {
  .hero-name { font-size: 32px; }
  .research-title { font-size: 18px; }
  .badge { font-size: 10px; padding: 2px 6px; }
  .btn { font-size: 11px; padding: 6px 11px; }
  .btn-break { display: block; flex-basis: 100%; height: 0; }
  .exp-item { grid-template-columns: 1fr; }
  .exp-period { text-align: left; }
  .cred-row { grid-template-columns: 1fr; }
  .cred-row .exp-period { text-align: left; }
}