/* ═══════════════════════════════════════════════════
   Bingxi Liu · Personal Homepage
   Dark Cyber-Theme · Shared Styles
   ═══════════════════════════════════════════════════ */

/* ─── CSS Variables ─── */
:root {
  --bg-deep:    #06060c;
  --bg-card:    #0e0e1a;
  --bg-card-hover: #141428;
  --border:     #1e1e3a;
  --border-glow: #3b3b6e;
  --text:       #c8c8d8;
  --text-dim:   #7878a0;
  --text-bright:#e8e8f8;
  --accent:     #6c5ce7;
  --accent-glow:#a29bfe;
  --accent2:    #00cec9;
  --accent2-glow:#81ecec;
  --radius:     12px;
  --font:       'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Noto Sans SC', sans-serif;
  --font-mono:  'JetBrains Mono', 'Fira Code', 'Cascadia Code', monospace;
}

/* ─── Reset ─── */
*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth;font-size:16px}
body{
  font-family:var(--font);
  background:var(--bg-deep);
  color:var(--text);
  line-height:1.7;
  overflow-x:hidden;
  -webkit-font-smoothing:antialiased;
}
a{color:var(--accent-glow);text-decoration:none;transition:color .25s}
a:hover{color:var(--accent2-glow)}

/* ─── Animated Background ─── */
.bg-stars{
  position:fixed;inset:0;z-index:-2;
  background:
    radial-gradient(ellipse at 20% 50%,rgba(108,92,231,.08) 0%,transparent 60%),
    radial-gradient(ellipse at 80% 20%,rgba(0,206,201,.06) 0%,transparent 50%),
    radial-gradient(ellipse at 50% 80%,rgba(108,92,231,.04) 0%,transparent 50%),
    var(--bg-deep);
}
.bg-grid{
  position:fixed;inset:0;z-index:-1;opacity:.025;
  background-image:
    linear-gradient(rgba(255,255,255,.03) 1px,transparent 1px),
    linear-gradient(90deg,rgba(255,255,255,.03) 1px,transparent 1px);
  background-size:60px 60px;
}

/* ─── Particles Canvas ─── */
#particles{position:fixed;inset:0;z-index:-1;pointer-events:none}

/* ─── Layout ─── */
.container{max-width:860px;margin:0 auto;padding:0 24px}
section{padding:56px 0;position:relative}
section+section{border-top:1px solid var(--border)}
.section-label{
  font-family:var(--font-mono);
  font-size:.75rem;text-transform:uppercase;letter-spacing:.15em;
  color:var(--accent-glow);
  margin-bottom:8px;
}
h2{
  font-size:1.5rem;font-weight:700;color:var(--text-bright);
  margin-bottom:24px;letter-spacing:-.01em;
  display:flex;align-items:center;gap:12px;
}
h2::after{content:'';flex:1;height:1px;background:var(--border);margin-left:4px}

/* ─── Header ─── */
header{
  padding:80px 0 64px;text-align:center;
}
.header-shield{
  display:inline-block;position:relative;
  padding:3px;border-radius:50%;
  background:linear-gradient(135deg,var(--accent),var(--accent2));
  margin-bottom:28px;
}
.profile-img{
  width:140px;height:140px;border-radius:50%;object-fit:cover;
  display:block;border:4px solid var(--bg-deep);
}
header h1{
  font-size:2.4rem;font-weight:800;letter-spacing:-.03em;
  background:linear-gradient(135deg,var(--text-bright) 0%,var(--accent-glow) 50%,var(--accent2-glow) 100%);
  -webkit-background-clip:text;-webkit-text-fill-color:transparent;
  background-clip:text;
  margin-bottom:8px;
}
header .subtitle{font-size:1.05rem;color:var(--text-dim);margin-bottom:4px}
header .affiliation{font-size:.85rem;color:var(--text-dim);line-height:1.6}
.social-links{
  margin-top:22px;display:flex;justify-content:center;gap:12px;flex-wrap:wrap;
}
.social-links a{
  display:inline-flex;align-items:center;gap:6px;
  font-size:.82rem;color:var(--text-dim);
  padding:7px 16px;border:1px solid var(--border);border-radius:24px;
  transition:all .25s;
}
.social-links a:hover{
  background:rgba(108,92,231,.12);
  border-color:var(--accent);
  color:var(--accent-glow);
}

/* ─── Lang Switcher ─── */
.lang-switch{
  position:fixed;top:20px;right:20px;z-index:100;
  display:flex;gap:4px;
  background:var(--bg-card);border:1px solid var(--border);
  border-radius:24px;padding:3px;
}
.lang-switch a{
  padding:6px 14px;border-radius:20px;font-size:.8rem;font-weight:500;
  color:var(--text-dim);transition:all .2s;
}
.lang-switch a.active{
  background:var(--accent);color:#fff;
}
.lang-switch a:hover:not(.active){color:var(--text-bright)}

/* ─── Cards ─── */
.card{
  background:var(--bg-card);border:1px solid var(--border);
  border-radius:var(--radius);padding:24px 28px;margin-bottom:14px;
  transition:all .3s;position:relative;overflow:hidden;
}
.card::before{
  content:'';position:absolute;inset:0;border-radius:var(--radius);
  padding:1px;background:linear-gradient(135deg,transparent 40%,var(--border-glow));
  -webkit-mask:linear-gradient(#fff 0 0) content-box,linear-gradient(#fff 0 0);
  mask:linear-gradient(#fff 0 0) content-box,linear-gradient(#fff 0 0);
  -webkit-mask-composite:xor;mask-composite:exclude;
  opacity:0;transition:opacity .3s;
}
.card:hover{background:var(--bg-card-hover);transform:translateY(-2px)}
.card:hover::before{opacity:1}
.card h3{font-size:1rem;font-weight:600;color:var(--text-bright);margin-bottom:5px}
.card .authors{font-size:.85rem;color:var(--text-dim);margin-bottom:3px}
.card .authors .me{color:var(--accent-glow);font-weight:600}
.card .venue{font-size:.8rem;color:var(--text-dim);margin-bottom:8px}
.card .venue em{font-style:normal;color:var(--accent2);font-weight:500}
.card-links{display:flex;gap:12px;flex-wrap:wrap}
.card-links a{font-size:.8rem;font-weight:500}

/* ─── Tags ─── */
.tag-grid{display:flex;flex-wrap:wrap;gap:8px}
.tag{
  display:inline-block;padding:7px 16px;
  background:rgba(108,92,231,.08);color:var(--accent-glow);
  border:1px solid rgba(108,92,231,.2);border-radius:24px;
  font-size:.82rem;font-weight:500;transition:all .25s;
}
.tag:hover{background:rgba(108,92,231,.16);border-color:var(--accent)}

/* ─── Project Grid ─── */
.project-grid{
  display:grid;
  grid-template-columns:repeat(auto-fill,minmax(240px,1fr));
  gap:14px;
}
.project-card{
  display:block;padding:20px 22px;
  background:var(--bg-card);border:1px solid var(--border);
  border-radius:var(--radius);transition:all .3s;
}
.project-card:hover{
  background:var(--bg-card-hover);transform:translateY(-2px);
  border-color:var(--border-glow);
}
.project-card h3{font-size:.95rem;font-weight:600;color:var(--text-bright)}
.project-card p{font-size:.8rem;color:var(--text-dim);margin:4px 0 8px;line-height:1.5}
.project-card .meta{font-size:.75rem;color:var(--border-glow);font-family:var(--font-mono)}
.project-card .stars{color:var(--accent2-glow)}

/* ─── Timeline ─── */
.timeline-item{display:flex;gap:16px;margin-bottom:20px}
.timeline-dot{
  width:10px;height:10px;margin-top:8px;flex-shrink:0;
  border-radius:50%;background:var(--accent);
  box-shadow:0 0 12px var(--accent-glow);
}
.timeline-body h3{font-size:.95rem;font-weight:600;color:var(--text-bright)}
.timeline-body .where{font-size:.85rem;color:var(--text-dim)}
.timeline-body .when{font-size:.78rem;color:var(--border-glow)}

/* ─── Footer ─── */
footer{
  text-align:center;padding:48px 0 36px;
  font-size:.8rem;color:var(--border-glow);
  border-top:1px solid var(--border);
}
footer a{color:var(--text-dim)}
footer a:hover{color:var(--accent-glow)}

/* ─── Entry Page ─── */
.entry{
  display:flex;flex-direction:column;align-items:center;justify-content:center;
  min-height:100vh;text-align:center;gap:32px;
}
.entry h1{font-size:3rem}
.entry .lang-choices{display:flex;gap:16px}
.entry .lang-choices a{
  padding:14px 40px;border:1px solid var(--border);border-radius:var(--radius);
  font-size:1.1rem;font-weight:600;transition:all .3s;
  background:var(--bg-card);
}
.entry .lang-choices a:hover{
  background:var(--accent);color:#fff;border-color:var(--accent);
  box-shadow:0 0 40px rgba(108,92,231,.3);
}

/* ─── Responsive ─── */
@media(max-width:640px){
  header{padding:48px 0 36px}
  header h1{font-size:1.6rem}
  .profile-img{width:100px;height:100px}
  section{padding:36px 0}
  .project-grid{grid-template-columns:1fr}
  .social-links a{font-size:.75rem;padding:5px 12px}
}