:root{
  --max: 1100px;
  --radius: 18px;
  --shadow: 0 18px 55px rgba(0,0,0,.35);

  --bg0:#070A12;
  --bg1:#0B1022;
  --text:#EAF0FF;
  --muted:#A8B0C7;

  --surface: rgba(255,255,255,.08);
  --surface2: rgba(255,255,255,.06);
  --border: rgba(255,255,255,.14);
  --ring: rgba(255,255,255,.22);

  --accentA: #7C3AED;   /* tím */
  --accentB: #06B6D4;   /* cyan */
  --accentC: #F59E0B;   /* amber */
  --accentD: #EC4899;   /* hồng */
}

[data-theme="light"]{
  --bg0:#F6F7FF;
  --bg1:#EEF1FF;
  --text:#101427;
  --muted:#5B6378;

  --surface: rgba(0,0,0,.05);
  --surface2: rgba(0,0,0,.04);
  --border: rgba(0,0,0,.10);
  --ring: rgba(0,0,0,.16);

  --shadow: 0 16px 45px rgba(10,10,20,.14);
}

*{ box-sizing:border-box; }
html{ scroll-behavior:smooth; }
body{
  margin:0;
  font-family: system-ui, -apple-system, Segoe UI, Roboto, Arial, sans-serif;
  color: var(--text);
  line-height: 1.55;

  background:
    radial-gradient(900px 550px at 12% -10%, rgba(124,58,237,.55), transparent 55%),
    radial-gradient(900px 550px at 88% 0%, rgba(6,182,212,.45), transparent 55%),
    radial-gradient(800px 500px at 60% 120%, rgba(236,72,153,.35), transparent 60%),
    linear-gradient(180deg, var(--bg0), var(--bg1));
}

a{ color: inherit; }
a:hover{ text-decoration: none; }

.container{
  width: min(var(--max), 100% - 32px);
  margin-inline: auto;
}

.skip-link{
  position:absolute;
  left:-999px;
  top: 8px;
  background: var(--surface);
  color: var(--text);
  padding: 10px 12px;
  border-radius: 12px;
  border: 1px solid var(--border);
  backdrop-filter: blur(10px);
}
.skip-link:focus{ left: 16px; z-index: 999; }

.site-header{
  position: sticky;
  top: 0;
  z-index: 20;
  backdrop-filter: blur(14px);
  background: linear-gradient(180deg, rgba(10,12,18,.70), rgba(10,12,18,.40));
  border-bottom: 1px solid var(--border);
}
[data-theme="light"] .site-header{
  background: linear-gradient(180deg, rgba(246,247,255,.78), rgba(246,247,255,.45));
}

.header-inner{
  padding: 14px 0;
  display:flex;
  align-items:center;
  justify-content: space-between;
  gap: 12px;
}

.brand{
  display:flex;
  align-items:center;
  gap: 12px;
  min-width: 240px;
}
.avatar{
  border-radius: 999px;
  border: 1px solid var(--border);
  box-shadow: 0 10px 30px rgba(0,0,0,.25);
}
.brand-kicker{ margin:0; color: var(--muted); font-size: 13px; }
.brand-title{ margin:0; font-size: 18px; }

.header-actions{
  display:flex;
  gap: 10px;
  align-items:center;
}

.site-nav{
  border-top: 1px solid var(--border);
}
.nav-inner{
  display:flex;
  gap: 14px;
  padding: 10px 0;
  overflow:auto;
}
.site-nav a{
  padding: 8px 10px;
  border-radius: 12px;
  border: 1px solid transparent;
  white-space: nowrap;
  color: var(--muted);
}
.site-nav a:hover{
  color: var(--text);
  border-color: var(--border);
  background: var(--surface2);
}
.site-nav a:focus-visible{
  outline: none;
  border-color: var(--ring);
  box-shadow: 0 0 0 3px var(--ring);
}

.btn{
  border: 1px solid var(--border);
  color: var(--text);
  padding: 10px 12px;
  border-radius: 14px;
  cursor:pointer;
  display:inline-flex;
  align-items:center;
  justify-content:center;
  gap: 8px;
  text-decoration:none;
  transition: transform .10s ease, box-shadow .15s ease, background .15s ease, border-color .15s ease;
  background:
    linear-gradient(135deg, rgba(124,58,237,.22), rgba(6,182,212,.18));
  box-shadow: 0 10px 25px rgba(0,0,0,.20);
}
.btn:hover{
  transform: translateY(-1px);
  border-color: rgba(255,255,255,.22);
  box-shadow: 0 16px 38px rgba(0,0,0,.28);
}
.btn:active{ transform: translateY(0); }
.btn:focus-visible{
  outline: none;
  box-shadow: 0 0 0 3px var(--ring), 0 18px 45px rgba(0,0,0,.28);
}
.btn[disabled]{ opacity: .6; cursor: not-allowed; transform:none; }

.btn-ghost{
  background: var(--surface2);
  box-shadow: none;
}

.section{ padding: 44px 0; }
.section-head{ margin-bottom: 18px; }
.section-head h2{ margin: 0 0 6px; font-size: 26px; }
.section-head p{ margin: 0; color: var(--muted); }

.hero{ padding: 34px 0 18px; }
.hero-grid{
  display:grid;
  grid-template-columns: 1.15fr .85fr;
  gap: 18px;
  align-items: start;
}
.hero-copy h2{
  margin:0 0 10px;
  font-size: 36px;
  line-height: 1.12;
  letter-spacing: -0.02em;
}
.hero-copy p{ margin:0 0 14px; color: var(--muted); }
.hero-cta{ display:flex; gap: 10px; flex-wrap: wrap; }

.quick-facts{
  list-style: none;
  padding:0;
  margin: 12px 0 16px;
  display:grid;
  gap: 10px;
}
.quick-facts li{
  border: 1px solid var(--border);
  background: var(--surface2);
  border-radius: var(--radius);
  padding: 12px;
  backdrop-filter: blur(10px);
}
.pill{
  display:inline-block;
  padding: 2px 8px;
  border-radius: 999px;
  border: 1px solid var(--border);
  color: var(--muted);
  margin-right: 8px;
  font-size: 12px;
  background: linear-gradient(135deg, rgba(245,158,11,.20), rgba(236,72,153,.14));
}

.card{
  background: linear-gradient(180deg, rgba(255,255,255,.10), rgba(255,255,255,.05));
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px;
  box-shadow: var(--shadow);
  backdrop-filter: blur(14px);
}
[data-theme="light"] .card{
  background: linear-gradient(180deg, rgba(0,0,0,.04), rgba(0,0,0,.02));
}
.card h3{ margin: 0 0 10px; font-size: 18px; }
.muted{ color: var(--muted); }

.checklist{ margin: 0 0 14px; padding-left: 18px; }
.checklist li{ margin: 6px 0; }

.stats{
  display:grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 10px;
}
.stat{
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 10px;
  background: var(--surface2);
}
.stat-value{ margin:0; font-size: 22px; }
.stat-label{ margin:0; color: var(--muted); font-size: 13px; }

.grid-2{
  display:grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
}

.dl{ margin: 0; }
.dl > div{
  display:grid;
  grid-template-columns: 120px 1fr;
  gap: 10px;
  padding: 10px 0;
  border-bottom: 1px dashed var(--border);
}
.dl > div:last-child{ border-bottom: none; }
dt{ color: var(--muted); }
dd{ margin:0; }
.sep{ margin: 0 8px; color: var(--muted); }

.tabs .tab-list{
  display:flex;
  gap: 10px;
  flex-wrap: wrap;
  margin-bottom: 10px;
}
.tab{
  border: 1px solid var(--border);
  background: var(--surface2);
  color: var(--text);
  padding: 8px 10px;
  border-radius: 14px;
  cursor: pointer;
  transition: transform .10s ease, background .15s ease;
}
.tab:hover{ transform: translateY(-1px); }
.tab[aria-selected="true"]{
  background: linear-gradient(135deg, rgba(124,58,237,.25), rgba(6,182,212,.20));
}
.tab:focus-visible{
  outline: none;
  box-shadow: 0 0 0 3px var(--ring);
}

.bullets{ margin: 0; padding-left: 18px; }
.bullets li{ margin: 6px 0; }

.interest-grid{
  display:grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 14px;
}
.interest p{ margin:0; color: var(--muted); }

.timeline{
  margin: 0 0 16px;
  padding-left: 18px;
}
.timeline-item{ margin: 10px 0 12px; }
.timeline-item h3{ margin: 0 0 6px; }
.timeline-item p{ margin:0; color: var(--muted); }

.accordion{ margin-top: 14px; }
.acc-item{
  border-top: 1px solid var(--border);
  padding-top: 10px;
  margin-top: 10px;
}
.acc-trigger{
  width: 100%;
  text-align: left;
  border: 1px solid var(--border);
  background: var(--surface2);
  color: var(--text);
  padding: 10px 12px;
  border-radius: 14px;
  cursor: pointer;
  transition: transform .10s ease;
}
.acc-trigger:hover{ transform: translateY(-1px); }
.acc-trigger:focus-visible{
  outline: none;
  box-shadow: 0 0 0 3px var(--ring);
}
.acc-panel{ padding: 10px 12px 0; color: var(--muted); }

.project-toolbar{
  display:grid;
  grid-template-columns: 1.2fr .8fr auto;
  gap: 12px;
  align-items: end;
  margin-bottom: 14px;
}
.field{ display:grid; gap: 6px; }
label, .label-like{ color: var(--muted); font-size: 13px; }

input, select, textarea{
  width: 100%;
  border: 1px solid var(--border);
  background: var(--surface2);
  color: var(--text);
  padding: 10px 12px;
  border-radius: 14px;
}
input:focus, select:focus, textarea:focus{
  outline: none;
  box-shadow: 0 0 0 3px var(--ring);
}
textarea{ resize: vertical; min-height: 120px; }

.project-grid{
  display:grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 14px;
}
.project{ display:flex; flex-direction: column; gap: 10px; }
.project .meta{
  display:flex;
  justify-content: space-between;
  gap: 10px;
  align-items: center;
}
.tag-row{ display:flex; flex-wrap: wrap; gap: 8px; }

.tag{
  font-size: 12px;
  color: rgba(255,255,255,.90);
  border: 1px solid rgba(255,255,255,.16);
  padding: 3px 10px;
  border-radius: 999px;
  background: linear-gradient(135deg, rgba(236,72,153,.26), rgba(245,158,11,.20));
}
[data-theme="light"] .tag{
  color: rgba(0,0,0,.78);
  border-color: rgba(0,0,0,.12);
}

.project p{ margin:0; color: var(--muted); }
.project-actions{ display:flex; gap: 10px; margin-top: auto; }

.error{
  margin: 0;
  min-height: 18px;
  color: #ffb4b4;
}
[data-theme="light"] .error{ color: #b00020; }

.form-actions{
  display:flex;
  gap: 10px;
  flex-wrap: wrap;
  margin-top: 10px;
}
.form-hint{ margin: 10px 0 0; color: var(--muted); }

.site-footer{
  border-top: 1px solid var(--border);
  padding: 18px 0;
}
.footer-inner{
  display:flex;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
  color: var(--muted);
}
.to-top{
  padding: 8px 10px;
  border-radius: 12px;
  border: 1px solid var(--border);
  background: var(--surface2);
  text-decoration:none;
}

.modal{
  width: min(720px, 92vw);
  border: 1px solid var(--border);
  border-radius: 18px;
  background: linear-gradient(180deg, rgba(255,255,255,.10), rgba(255,255,255,.06));
  color: var(--text);
  padding: 14px;
  box-shadow: var(--shadow);
  backdrop-filter: blur(14px);
}
.modal::backdrop{ background: rgba(0,0,0,.60); }
.modal-head{
  display:flex;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
  padding-bottom: 10px;
  border-bottom: 1px solid var(--border);
}
.modal-body{ padding-top: 10px; color: var(--muted); }

/* tablet */
@media (max-width: 900px){
  .hero-grid{ grid-template-columns: 1fr; }
  .grid-2{ grid-template-columns: 1fr; }
  .interest-grid{ grid-template-columns: repeat(2, 1fr); }
  .project-grid{ grid-template-columns: repeat(2, 1fr); }
  .project-toolbar{ grid-template-columns: 1fr 1fr; }
  .project-toolbar .field:last-child{ grid-column: 1 / -1; }
}

/* mobile */
@media (max-width: 520px){
  .section{ padding: 34px 0; }
  .hero-copy h2{ font-size: 30px; }
  .stats{ grid-template-columns: 1fr; }
  .interest-grid{ grid-template-columns: 1fr; }
  .project-grid{ grid-template-columns: 1fr; }
  .dl > div{ grid-template-columns: 1fr; }
}