:root{
  --bg:#0f1724; /* deep background for modern look */
  --surface:#0b1220;
  --muted:#7dd3fc; /* cyan-ish */
  --accent:#60a5fa; /* blue accent */
  --success:#34d399; /* green */
  --muted-foreground:#9ca3af;
  --text:#e6eef8;
  --muted-bg:rgba(255,255,255,0.03);
  --container-width:1100px;
}
/* Light theme variables when data-theme="light" on body */
body[data-theme="light"]{
  --bg:#ffffff;
  --surface:#fbfbfd;
  --muted:#0ea5a4;
  --accent:#0ea5ff;
  --success:#198754;
  --muted-foreground:#4b5563;
  --text:#0b1220;
  --muted-bg:rgba(11,18,32,0.03);
}
*{box-sizing:border-box}
body{font-family: Inter, ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial; background:var(--bg);color:var(--text);margin:0;line-height:1.5;-webkit-font-smoothing:antialiased}
.container{max-width:var(--container-width);margin:0 auto;padding:0 20px}
.navbar{background:transparent;border-bottom:1px solid rgba(255,255,255,0.04)}
.nav-inner{display:flex;align-items:center;gap:16px;padding:18px 0}
.nav-inner{position:relative}
.nav-toggle{display:none;background:transparent;border:0;font-size:20px;color:var(--text);cursor:pointer}
.nav-links{display:flex;gap:12px;flex:1;align-items:center}
.nav-links a{color:var(--muted-foreground);text-decoration:none;padding:8px 12px;border-radius:10px;transition:background .18s,color .18s;display:inline-flex;align-items:center;gap:6px;line-height:1}
.nav-links a:hover{background:var(--muted-bg);color:var(--text)}
.nav-links a.active{color:var(--accent);font-weight:700;background:linear-gradient(90deg, rgba(96,165,250,0.08), rgba(96,165,250,0.03))}
.nav-actions{display:flex;align-items:center}
.login-btn{background:transparent;border:0;color:var(--text);cursor:pointer}
.hero{display:flex;gap:28px;align-items:center;padding:72px 0}
.avatar{
  width:160px;height:160px;object-fit:cover;border-radius:50%;
  border:3px solid rgba(255,255,255,0.04);
  box-shadow:0 8px 20px rgba(2,6,23,0.12);
  transition:transform .18s ease,box-shadow .18s ease,filter .18s ease;
  display:block;
}
.avatar:hover{
  transform:scale(1.04);
  box-shadow:0 18px 30px rgba(2,6,23,0.16);
  filter:brightness(1.02);
}
.hero-text h1{color:var(--accent);margin:0 0 12px;font-size:40px;letter-spacing:0.6px}
.hero-text p{margin:0;color:var(--muted-foreground);font-size:16px}
.hero-text .muted{color:var(--muted)}
.site-footer{padding:28px 0;text-align:center;color:var(--muted-foreground);font-size:14px}
/* footer transition separator */
.site-footer{
  position:relative;
  padding:36px 0 48px;
}
.site-footer::before{
  content:"";
  position:absolute;
  left:0;right:0;top:-48px;height:48px;
  background:linear-gradient(180deg, rgba(255,255,255,0.02), rgba(255,255,255,0));
  pointer-events:none;
}
.site-footer hr{
  border:0;height:1px;margin:0 auto 18px;max-width:680px;background:linear-gradient(90deg, rgba(255,255,255,0.02), rgba(255,255,255,0.04), rgba(255,255,255,0.02));
  opacity:0.9;
}

/* main content spacing to breathe above footer */
main.container{padding-bottom:24px}

/* small lift effect so footer feels separated */
.site-footer{box-shadow:inset 0 1px 0 rgba(255,255,255,0.02)}
@media (max-width:900px){
  .hero{flex-direction:column;text-align:center;padding:40px 0}
  .nav-toggle{display:block}
  /* ensure nav items and controls are spaced at the edges */
  .nav-inner{justify-content:space-between}
  .nav-links{display:none}
  /* when mobile menu is toggled */
  .nav-links.show{display:flex;flex-direction:column;gap:8px;margin-top:10px;padding:12px;background:linear-gradient(180deg, rgba(255,255,255,0.02), rgba(255,255,255,0.01));border-radius:12px}
  /* place theme toggle in flow so flex space-between aligns it to the right */
  .theme-toggle{position:static;right:auto;top:auto;padding:8px 10px;border-radius:10px;z-index:40}
}

/* utility helpers */
.hidden{display:none !important}

/* ensure nav-toggle is visually tappable */
.nav-toggle{padding:8px 10px;border-radius:10px}

/* theme toggle button */
.theme-toggle{background:transparent;border:1px solid rgba(255,255,255,0.04);color:var(--text);padding:6px 10px;border-radius:10px;margin-left:12px;cursor:pointer;transition:background .18s,border-color .18s,transform .12s}
.theme-toggle:hover{transform:translateY(-1px)}
.theme-toggle[aria-pressed="true"]{background:linear-gradient(90deg, rgba(96,165,250,0.12), rgba(96,165,250,0.04));border-color:rgba(96,165,250,0.16)}

/* smooth transitions for theme change */
body{transition:background .25s ease,color .25s ease}

/* screen-reader only helper */
.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}

/* 关于页面（profile）样式 */
.profile-grid{display:grid;grid-template-columns:180px 1fr;gap:24px;align-items:start;padding:28px 0}
.profile-card{
  background: transparent; /* keep card minimal */
  border: 1px solid rgba(255,255,255,0.03);
  border-radius:12px;
  padding:12px;
  transition:transform .18s ease, box-shadow .18s ease;
  display:flex;align-items:center;justify-content:center; /* center avatar */
  overflow:hidden;
}
.profile-card:hover{transform:translateY(-6px);box-shadow:0 20px 50px rgba(2,6,23,0.7)}
.profile-avatar{
  width:160px;height:160px;object-fit:cover;border-radius:50%;
  border:3px solid rgba(255,255,255,0.04);
  box-shadow:0 8px 20px rgba(2,6,23,0.12);
  transition:transform .18s ease,box-shadow .18s ease,filter .18s ease;
  display:block;
}
.profile-avatar:hover{
  transform:scale(1.04);
  box-shadow:0 18px 30px rgba(2,6,23,0.16);
  filter:brightness(1.02);
}
.profile-avatar{margin:0}
.profile-title{margin:0 0 8px;color:var(--accent);font-size:22px}
.profile-bio{color:var(--muted-foreground);line-height:1.7}
.profile-quote{margin:12px 0;padding-left:12px;border-left:3px solid rgba(255,255,255,0.03);color:var(--muted-foreground);font-style:italic}

@media (max-width:900px){
  .profile-grid{grid-template-columns:1fr;justify-items:center;text-align:center}
  .profile-avatar{width:120px;height:120px}
}

/* 全局链接样式（不影响导航链接 .nav-links a） */
a:not(.nav-links a){
  color:var(--accent);
  text-decoration:none;
  background-image:linear-gradient(90deg, var(--accent), rgba(96,165,250,0.6));
  background-repeat:no-repeat;
  background-position:0 100%;
  background-size:0% 2px;
  transition:background-size .28s cubic-bezier(.2,.9,.2,1),color .18s;
}

a:not(.nav-links a):hover{
  background-size:100% 2px;
  color:var(--text);
}

/* focus 可见性 */
a:not(.nav-links a):focus{
  outline:3px solid rgba(96,165,250,0.14);
  outline-offset:3px;
}

/* 外部链接小图标：仅限导航内的链接 */
.nav-links a[target="_blank"]:after{
  content:"\2197"; /* ↗ */
  font-size:0.85em; /* scale relative to link text */
  display:inline-block;
  margin-left:6px;
  line-height:1; /* ensure compact box */
  opacity:0.9;
}

/* Ensure nav link content (text + arrow) is vertically centered on mobile when nav becomes a column */
@media (max-width:900px){
  /* Center the mobile nav container and its items */
  .nav-links.show{display:flex;flex-direction:column;gap:8px;margin-top:10px;padding:12px;background:linear-gradient(180deg, rgba(255,255,255,0.02), rgba(255,255,255,0.01));border-radius:12px;align-items:center}

  /* Make links auto-width and center their content for horizontal centering */
  .nav-links.show a{display:inline-flex;align-items:center;justify-content:center;gap:6px;width:auto;padding:10px 20px}

  /* Hide arrow for external links on mobile for cleaner centered layout */
  .nav-links.show a[target="_blank"]:after{display:none}
}