/* ─── THEME TOKENS ─── */
[data-theme="light"] {
  --bg:        #ffffff;
  --bg-subtle: #f8f7f4;
  --bg-hover:  #f2f0ec;
  --ink:       #1a1916;
  --ink2:      #4a4843;
  --ink3:      #8a8680;
  --border:    #e8e5df;
  --border-md: #d0cdc6;
  --nav-bg:    rgba(255,255,255,0.92);
  --tag-bg:    #f2f0ec;
  --card-bg:   #ffffff;
  --go-bg:     rgba(0,172,215,0.07);
  --go-color:  #007a9e;
  --go-border: rgba(0,172,215,0.22);
  --py-bg:     rgba(55,118,171,0.07);
  --py-color:  #1e5a8a;
  --py-border: rgba(55,118,171,0.22);
  --green-bg:  #f0faf3;
  --green-bdr: #b8e8c4;
  --green-ink: #2d7a44;
  --wip-bg:    #fff8ed;
  --wip-bdr:   #f5d68a;
  --wip-ink:   #8a5e00;
  --toggle-track: #e0ddd7;
  --toggle-knob:  #1a1916;
}
[data-theme="dark"] {
  --bg:        #111110;
  --bg-subtle: #191817;
  --bg-hover:  #201f1e;
  --ink:       #e8e5de;
  --ink2:      #a8a5a0;
  --ink3:      #5e5c59;
  --border:    #272523;
  --border-md: #363330;
  --nav-bg:    rgba(17,17,16,0.93);
  --tag-bg:    #1c1b1a;
  --card-bg:   #151413;
  --go-bg:     rgba(0,172,215,0.09);
  --go-color:  #3ac8f2;
  --go-border: rgba(0,172,215,0.18);
  --py-bg:     rgba(55,118,171,0.09);
  --py-color:  #6baad4;
  --py-border: rgba(55,118,171,0.18);
  --green-bg:  rgba(45,122,68,0.14);
  --green-bdr: rgba(45,122,68,0.3);
  --green-ink: #5ecf82;
  --wip-bg:    rgba(138,94,0,0.14);
  --wip-bdr:   rgba(138,94,0,0.3);
  --wip-ink:   #e0b560;
  --toggle-track: #2a2826;
  --toggle-knob:  #e8e5de;
}

/* ─── RESET ─── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }
body {
  font-family: 'DM Sans', system-ui, sans-serif;
  background: var(--bg);
  color: var(--ink);
  font-size: 15px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  transition: background 0.22s, color 0.22s;
}

/* ─── NAV ─── */
nav {
  position: fixed; top: 0; left: 0; right: 0; z-index: 100;
  background: var(--nav-bg);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--border);
  padding: 0 2rem;
  height: 56px;
  display: flex; align-items: center; justify-content: space-between;
  transition: background 0.22s, border-color 0.22s;
}
.nav-left { display: flex; align-items: center; gap: 2rem; }
.nav-logo {
  font-family: 'DM Serif Display', Georgia, serif;
  font-size: 1.05rem; color: var(--ink);
  text-decoration: none; letter-spacing: -0.01em;
  transition: color 0.22s; flex-shrink: 0;
}
.nav-links { display: flex; gap: 1.6rem; list-style: none; }
.nav-links a {
  font-size: 13px; font-weight: 400;
  color: var(--ink3); text-decoration: none;
  letter-spacing: 0.01em; cursor: pointer;
  transition: color 0.15s;
}
.nav-links a:hover { color: var(--ink); }
.nav-links a.active { color: var(--ink); font-weight: 500; }
.nav-links a.nav-active { color: var(--ink); font-weight: 500; }

/* dark toggle */
.theme-toggle {
  width: 32px; height: 32px;
  background: transparent;
  border: 1px solid transparent; cursor: pointer; border-radius: 6px;
  display: flex; align-items: center; justify-content: center;
  color: var(--ink3); transition: color 0.22s;
  flex-shrink: 0; position: relative;
}
.theme-toggle:hover { border-color: var(--border); }
.theme-toggle:active { transform: scale(0.92); }
.sun-icon { position: absolute; opacity: 1; transition: opacity 0.22s, transform 0.22s; transform: scale(1) rotate(0deg); }
.moon-icon { position: absolute; opacity: 0; transition: opacity 0.22s, transform 0.22s; transform: scale(0) rotate(-90deg); }
[data-theme="dark"] .sun-icon { opacity: 0; transform: scale(0) rotate(90deg); }
[data-theme="dark"] .moon-icon { opacity: 1; transform: scale(1) rotate(0deg); }

/* ─── PAGE SYSTEM ─── */
.page { display: none; padding-top: 56px; min-height: 100vh; animation: fadeUp 0.2s ease; }
.page.active { display: block; }
@keyframes fadeUp { from { opacity: 0; transform: translateY(7px); } to { opacity: 1; transform: none; } }

/* ─── LAYOUT ─── */
.container { max-width: 760px; margin: 0 auto; padding: 0 2rem; }
.section { padding: 4.5rem 0; }
.section + .section { border-top: 1px solid var(--border); }

/* ─── TYPOGRAPHY ─── */
h1 {
  font-family: 'DM Serif Display', Georgia, serif;
  font-size: clamp(2.1rem, 5vw, 3.1rem);
  font-weight: 400; line-height: 1.1; letter-spacing: -0.02em; color: var(--ink);
}
h2 {
  font-family: 'DM Serif Display', Georgia, serif;
  font-size: 1.65rem; font-weight: 400;
  letter-spacing: -0.015em; line-height: 1.2; color: var(--ink);
}
h3 {
  font-family: 'DM Mono', monospace;
  font-size: 10px; font-weight: 500;
  letter-spacing: 0.1em; text-transform: uppercase;
  color: var(--ink3); margin-bottom: 1.2rem;
}
p { color: var(--ink2); line-height: 1.75; }

/* ─── HERO ─── */
.hero {
  padding: 6rem 0 4.5rem;
  display: grid; grid-template-columns: 1fr auto; gap: 3rem; align-items: start;
}
.hero-eyebrow {
  font-family: 'DM Mono', monospace; font-size: 11px;
  letter-spacing: 0.1em; text-transform: uppercase;
  color: var(--ink3); margin-bottom: 1.2rem;
  display: flex; align-items: center; gap: 0.6rem;
}
.hero-eyebrow::before { content:''; display:block; width:18px; height:1px; background:var(--ink3); }
.hero h1 { margin-bottom: 1.5rem; }
.hero h1 em { font-style: italic; color: var(--ink3); }
.hero-bio { font-size: 1rem; color: var(--ink2); max-width: 490px; margin-bottom: 2rem; line-height: 1.8; }
.hero-links { display: flex; gap: 0.65rem; flex-wrap: wrap; }
.hero-avatar {
  width: 86px; height: 86px; border-radius: 50%;
  border: 1px solid var(--border);
  display: flex; align-items: center; justify-content: center;
  font-family: 'DM Serif Display', serif; font-size: 1.75rem;
  color: var(--ink2); background: var(--bg-subtle); flex-shrink: 0; margin-top: 0.5rem;
  transition: background 0.22s, border-color 0.22s;
}

/* ─── BUTTONS ─── */
.btn {
  display: inline-flex; align-items: center; gap: 0.4rem;
  font-size: 13px; font-weight: 500; font-family: 'DM Sans', sans-serif;
  padding: 0.48rem 0.95rem;
  border: 1px solid var(--border); border-radius: 5px;
  text-decoration: none; color: var(--ink); background: var(--bg);
  cursor: pointer;
  transition: background 0.15s, border-color 0.15s, transform 0.1s, color 0.22s;
}
.btn:hover { background: var(--bg-hover); border-color: var(--border-md); }
.btn:active { transform: scale(0.98); }
.btn-solid { background: var(--ink); color: var(--bg); border-color: var(--ink); }
.btn-solid:hover { opacity: 0.82; background: var(--ink); }

/* ─── TECH STRIP ─── */
.tech-strip {
  padding: 1.75rem 0;
  border-top: 1px solid var(--border); border-bottom: 1px solid var(--border);
}
.tech-row { display: flex; flex-wrap: wrap; gap: 0.38rem; align-items: center; }
.tech-tag {
  font-family: 'DM Mono', monospace; font-size: 11px;
  padding: 0.25rem 0.6rem; border: 1px solid var(--border);
  border-radius: 3px; color: var(--ink2); background: var(--tag-bg); white-space: nowrap;
  transition: border-color 0.15s, color 0.15s, background 0.22s;
}
.tech-tag:hover { border-color: var(--border-md); color: var(--ink); background: var(--bg-hover); }
.tech-tag.go { border-color: var(--go-border); color: var(--go-color); background: var(--go-bg); }
.tech-tag.py { border-color: var(--py-border); color: var(--py-color); background: var(--py-bg); }

/* ─── SECTION HEADER ─── */
.section-header { margin-bottom: 2.25rem; }
.section-header h2 { margin-bottom: 0.5rem; }
.section-header p { font-size: 13.5px; color: var(--ink3); margin-top: 0.3rem; }

/* ─── PROJECT GRID ─── */
.projects-grid {
  display: grid; grid-template-columns: 1fr 1fr;
  border: 1px solid var(--border); border-radius: 7px; overflow: hidden;
  transition: border-color 0.22s;
}
.project-card {
  padding: 1.5rem; background: var(--card-bg);
  border-right: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
  text-decoration: none; color: inherit;
  display: flex; flex-direction: column; gap: 0.6rem;
  position: relative;
  transition: background 0.15s, border-color 0.22s;
}
.project-card:hover { background: var(--bg-hover); border-color: var(--border-md); }
.project-card:hover .project-name svg { opacity: 1; transform: rotate(45deg); transition: opacity 0.2s, transform 0.2s; }
.project-card:nth-child(2n) { border-right: none; }
.project-card:nth-last-child(-n+2) { border-bottom: none; }
.project-card.solo { grid-column: 1/-1; border-right: none; }
.project-name {
  font-size: 0.875rem; font-weight: 500; color: var(--ink);
  display: flex; align-items: center; gap: 0.4rem;
}
.project-name svg { opacity: 0.28; flex-shrink: 0; }
.project-desc { font-size: 13px; color: var(--ink2); line-height: 1.65; flex: 1; }
.project-footer { display: flex; align-items: flex-end; justify-content: space-between; margin-top: auto; gap: 0.5rem; }
.project-tags { display: flex; flex-wrap: wrap; gap: 0.28rem; }
.tag {
  font-family: 'DM Mono', monospace; font-size: 10.5px;
  padding: 0.16rem 0.48rem; background: var(--tag-bg);
  border: 1px solid var(--border); border-radius: 2px; color: var(--ink3);
  transition: background 0.22s, border-color 0.22s;
}
.badge-wip {
  font-family: 'DM Mono', monospace; font-size: 10px;
  padding: 0.16rem 0.5rem; border-radius: 2px; white-space: nowrap;
  background: var(--wip-bg); border: 1px solid var(--wip-bdr); color: var(--wip-ink);
  transition: background 0.22s, border-color 0.22s, color 0.22s;
}
.lang-chip {
  display: flex; align-items: center; gap: 0.28rem;
  font-family: 'DM Mono', monospace; font-size: 10.5px; color: var(--ink3);
  flex-shrink: 0;
}
.lang-dot { width: 7px; height: 7px; border-radius: 50%; display: inline-block; }
.arrow-link {
  position: absolute; top: 1.35rem; right: 1.35rem;
  font-size: 12px; color: var(--ink3); opacity: 0;
  text-decoration: none; transition: opacity 0.2s, transform 0.2s;
  transform: translate(0, 0);
}
.project-card:hover .arrow-link { opacity: 1; transform: translate(3px, -3px); }

/* ─── INTERESTS ─── */
.interests-grid { display: grid; grid-template-columns: repeat(3,1fr); gap: 1.1rem; margin-top: 1.5rem; }
.interest-card {
  padding: 1.25rem; border: 1px solid var(--border); border-radius: 6px; background: var(--card-bg);
  transition: background 0.22s, border-color 0.22s;
}
.interest-icon { font-size: 1.1rem; margin-bottom: 0.55rem; }
.interest-title { font-weight: 500; font-size: 0.875rem; margin-bottom: 0.3rem; color: var(--ink); }
.interest-desc { font-size: 12.5px; color: var(--ink3); line-height: 1.6; }

/* ─── TIMELINE ─── */
.timeline { display: flex; flex-direction: column; }
.timeline-item {
  display: grid; grid-template-columns: 106px 1fr; gap: 2rem; padding: 2.25rem 0;
  border-bottom: 1px solid var(--border);
}
.timeline-item:last-child { border-bottom: none; }
.timeline-date { font-family: 'DM Mono', monospace; font-size: 10.5px; color: var(--ink3); padding-top: 2px; line-height: 1.55; }
.timeline-role { font-size: 0.95rem; font-weight: 500; color: var(--ink); margin-bottom: 0.18rem; }
.timeline-co {
  font-size: 13px; color: var(--ink3); margin-bottom: 0.9rem;
  display: flex; align-items: center; gap: 0.45rem; flex-wrap: wrap;
}
.dot { width: 3px; height: 3px; border-radius: 50%; background: var(--border-md); flex-shrink: 0; }
.current-badge {
  display: inline-flex; align-items: center; gap: 0.3rem;
  font-family: 'DM Mono', monospace; font-size: 10px; letter-spacing: 0.04em;
  padding: 0.16rem 0.5rem; border-radius: 2px;
  background: var(--green-bg); border: 1px solid var(--green-bdr); color: var(--green-ink);
  transition: background 0.22s, border-color 0.22s, color 0.22s;
}
.current-badge::before {
  content: ''; width: 5px; height: 5px; border-radius: 50%; background: var(--green-ink);
  animation: pulse 2s ease-in-out infinite;
}
@keyframes pulse { 0%,100%{opacity:1} 50%{opacity:0.3} }
.tl-bullets { list-style: none; display: flex; flex-direction: column; gap: 0.5rem; }
.tl-bullets li {
  font-size: 13.5px; color: var(--ink2); line-height: 1.65; padding-left: 1rem; position: relative;
}
.tl-bullets li::before { content: '–'; position: absolute; left: 0; color: var(--ink3); }
.chip-row { display: flex; flex-wrap: wrap; gap: 0.3rem; margin-top: 0.8rem; }

/* ─── CERT CARDS ─── */
.cert-grid { display: flex; flex-wrap: wrap; gap: 0.75rem; }
.cert-card {
  padding: 0.85rem 1.05rem; border: 1px solid var(--border); border-radius: 5px;
  background: var(--card-bg); transition: background 0.22s, border-color 0.22s;
}
.cert-card .cert-name { font-weight: 500; font-size: 13.5px; color: var(--ink); margin-bottom: 0.18rem; }
.cert-card .cert-sub { font-family: 'DM Mono', monospace; font-size: 11px; color: var(--ink3); }

/* ─── RESUME CTA ─── */
.resume-cta {
  display: flex; align-items: center; justify-content: space-between;
  padding: 1.35rem 1.65rem; border: 1px solid var(--border); border-radius: 6px;
  background: var(--bg-subtle); margin-top: 3rem; flex-wrap: wrap; gap: 1rem;
  transition: background 0.22s, border-color 0.22s;
}
.resume-cta-label { font-weight: 500; font-size: 0.9rem; color: var(--ink); margin-bottom: 0.18rem; }
.resume-cta-sub { font-size: 12.5px; color: var(--ink3); }

/* ─── PAPERSHELF ─── */
.filter-row { display: flex; gap: 0.38rem; flex-wrap: wrap; margin-bottom: 2rem; }
.filter-btn {
  font-family: 'DM Mono', monospace; font-size: 11px;
  padding: 0.26rem 0.65rem; border-radius: 3px;
  border: 1px solid var(--border); background: var(--bg);
  color: var(--ink3); cursor: pointer;
  transition: background 0.15s, border-color 0.15s, color 0.15s;
}
.filter-btn:hover { border-color: var(--border-md); color: var(--ink); }
.filter-btn.active { background: var(--ink); border-color: var(--ink); color: var(--bg); }

.papers-list { display: flex; flex-direction: column; gap: 1rem; }
.paper-row {
  padding: 0; display: flex; align-items: center; justify-content: space-between; gap: 1rem;
  cursor: pointer; transition: none;
}
.paper-row:hover { background: none; }
.paper-row:hover .paper-title { color: var(--ink2); }
.paper-title {
  font-family: 'DM Sans', sans-serif;
  font-size: 0.95rem; font-weight: 400; color: var(--ink2);
  line-height: 1.4; transition: color 0.15s; flex: 1;
}
.paper-link {
  font-family: 'DM Mono', monospace; font-size: 11px;
  color: var(--ink3); text-decoration: none; white-space: nowrap;
  transition: color 0.2s, transform 0.2s;
  flex-shrink: 0; position: relative;
  padding-bottom: 2px; border-bottom: 1px solid transparent;
}
.paper-link::after {
  content: ''; position: absolute; bottom: 0; left: 0; width: 0; height: 1px;
  background: var(--ink3); transition: width 0.25s ease;
}
.paper-link:hover { color: var(--ink); transform: translateX(4px); }
.paper-link:hover::after { width: 100%; background: var(--ink); }
.paper-meta { display: flex; align-items: center; gap: 0.55rem; flex-wrap: wrap; margin-bottom: 0.5rem; }
.paper-year { font-family: 'DM Mono', monospace; font-size: 10.5px; color: var(--ink3); }
.paper-cat {
  font-family: 'DM Mono', monospace; font-size: 10.5px;
  padding: 0.1rem 0.42rem; background: var(--tag-bg);
  border: 1px solid var(--border); border-radius: 2px; color: var(--ink3);
  transition: background 0.22s, border-color 0.22s;
}
.paper-blurb { font-size: 13px; color: var(--ink3); line-height: 1.6; max-width: 560px; }
.paper-chevron { color: var(--ink3); font-size: 12px; opacity: 0.38; padding-top: 3px; transition: opacity 0.15s; }
.paper-row:hover .paper-chevron { opacity: 1; }

/* paper detail */
.detail-back {
  display: inline-flex; align-items: center; gap: 0.38rem;
  font-size: 13px; color: var(--ink3); cursor: pointer;
  margin-bottom: 1.75rem; transition: color 0.15s;
  border: none; background: none; font-family: 'DM Sans', sans-serif; padding: 0;
}
.detail-back:hover { color: var(--ink); }
.detail-header { padding: 3.75rem 0 2rem; border-bottom: 1px solid var(--border); }
.detail-body { padding: 2.5rem 0; }
.detail-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 3rem; }
.sub-label {
  font-family: 'DM Mono', monospace; font-size: 10px;
  letter-spacing: 0.08em; text-transform: uppercase;
  color: var(--ink3); margin-bottom: 0.75rem;
}
.notes-box {
  background: var(--bg-subtle); border: 1px solid var(--border); border-radius: 5px;
  padding: 1.25rem; font-size: 13.5px; color: var(--ink2); line-height: 1.8;
  transition: background 0.22s, border-color 0.22s;
}
.idea-list { list-style: none; display: flex; flex-direction: column; gap: 0.5rem; }
.idea-list li { font-size: 13.5px; color: var(--ink2); padding-left: 1rem; position: relative; line-height: 1.65; }
.idea-list li::before { content: '–'; position: absolute; left: 0; color: var(--ink3); }

/* ─── CV JOURNEY ─── */
.journal-intro {
  background: var(--bg-subtle); border: 1px solid var(--border);
  border-radius: 6px; padding: 1.4rem 1.65rem; margin-bottom: 2.5rem;
  transition: background 0.22s, border-color 0.22s;
}
.journal-intro p { font-size: 14px; line-height: 1.8; }

.roadmap-list { display: flex; flex-direction: column; gap: 0.55rem; margin-top: 0.85rem; margin-bottom: 3rem; }
.roadmap-item { display: flex; align-items: flex-start; gap: 0.7rem; font-size: 13.5px; color: var(--ink2); line-height: 1.65; }
.roadmap-dot {
  width: 8px; height: 8px; border-radius: 50%;
  border: 1.5px solid var(--border-md); flex-shrink: 0; margin-top: 6px;
  transition: border-color 0.22s, background 0.22s;
}
.roadmap-dot.done { background: var(--green-ink); border-color: var(--green-ink); }
.roadmap-dot.now  { border-color: var(--wip-ink); background: var(--wip-bg); }

.journal-entry {
  padding: 1.85rem 0; border-bottom: 1px solid var(--border);
  display: grid; grid-template-columns: 100px 1fr; gap: 2rem;
}
.journal-entry:first-of-type { border-top: 1px solid var(--border); }
.entry-date { font-family: 'DM Mono', monospace; font-size: 10.5px; color: var(--ink3); padding-top: 3px; line-height: 1.5; }
.entry-title { font-size: 0.9rem; font-weight: 500; color: var(--ink); margin-bottom: 0.38rem; }
.entry-body { font-size: 13.5px; color: var(--ink2); line-height: 1.75; margin-bottom: 0.7rem; }
.resource-link {
  font-size: 12px; font-family: 'DM Mono', monospace; color: var(--ink3);
  text-decoration: none; border-bottom: 1px solid var(--border); padding-bottom: 1px;
  transition: color 0.15s, border-color 0.15s;
}
.resource-link:hover { color: var(--ink); border-color: var(--ink3); }

.cv-proj-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; margin-top: 1.5rem; }
.cv-proj-card {
  padding: 1.25rem; border: 1px solid var(--border); border-radius: 6px;
  background: var(--card-bg); text-decoration: none;
  transition: background 0.15s, border-color 0.22s;
}
.cv-proj-card:hover { background: var(--bg-hover); border-color: var(--border-md); }
.cv-proj-name { font-size: 0.875rem; font-weight: 500; color: var(--ink); margin-bottom: 0.35rem; }
.cv-proj-desc { font-size: 12.5px; color: var(--ink3); line-height: 1.6; }

/* ─── FOOTER ─── */
footer {
  border-top: 1px solid var(--border); padding: 2.25rem 0;
  display: flex; align-items: center; justify-content: space-between;
  flex-wrap: wrap; gap: 1rem; transition: border-color 0.22s;
}
footer p { font-size: 12px; color: var(--ink3); }
.footer-links { display: flex; gap: 1.4rem; }
.footer-links a { font-size: 12px; color: var(--ink3); text-decoration: none; transition: color 0.15s; }
.footer-links a:hover { color: var(--ink); }

/* ─── RESPONSIVE ─── */
@media (max-width: 600px) {
  .hero { grid-template-columns: 1fr; }
  .hero-avatar { display: none; }
  .projects-grid, .cv-proj-grid { grid-template-columns: 1fr; }
  .project-card { border-right: none !important; }
  .project-card:nth-last-child(-n+2) { border-bottom: 1px solid var(--border) !important; }
  .project-card:last-child { border-bottom: none !important; }
  .detail-grid { grid-template-columns: 1fr; }
  .timeline-item, .journal-entry { grid-template-columns: 1fr; gap: 0.35rem; }
  .interests-grid { grid-template-columns: 1fr; }
  nav { padding: 0 1rem; }
  .nav-links { gap: 1rem; }
  .container { padding: 0 1.25rem; }
}