:root {
  --muted: #aab4c2;
  --accent: #4cc9f0;
  --grad-start: #0f1020;
  --grad-end: #1a1a2e;
}
* { box-sizing: border-box; }
html, body { height: 100%; margin: 0; font-family: Inter, system-ui, Arial; background: linear-gradient(135deg, var(--grad-start) 0%, var(--grad-end) 100%); color: #e8ecf1; }
body { display: flex; min-height: 100vh; flex-direction: column; }
.site-header { padding: 28px 20px; text-align: center; }
.brand { font-size: 2rem; font-weight: 800; letter-spacing: .5px; background: linear-gradient(90deg, #fff, var(--accent)); -webkit-background-clip: text; background-clip: text; color: transparent; }
.subtitle { margin: 6px 0 0; color: var(--muted); font-weight: 400; }
.tabbar { display: flex; justify-content: center; gap: 8px; padding: 8px; background: rgba(255,255,255,0.04); border-bottom: 1px solid rgba(255,255,255,0.08); position: sticky; top: 0; z-index: 2; flex-wrap: wrap; }
.tab { background: rgba(255,255,255,0.08); color: #fff; border: 0; padding: 12px 16px; border-radius: 8px; cursor: pointer; font-weight: 600; transition: transform .1s ease, background .2s ease; }
.tab.active { background: #1f1f2a; box-shadow: inset 0 0 0 1px rgba(255,255,255,.15); }
.tab:hover { transform: translateY(-1px); }
.content { flex: 1; padding: 16px; max-width: 1100px; width: 100%; margin: 0 auto; }
.frame-wrap { width: 100%; height: calc(70vh); border-radius: 12px; overflow: hidden; border: 1px solid rgba(255,255,255,.15); box-shadow: 0 8px 40px rgba(0,0,0,.25); }
.frame-wrap iframe { width: 100%; height: 100%; border: 0; display: block; }
.frame-wrap.hidden { display: none; }
.footer { text-align: center; padding: 16px; color: var(--muted); font-size: 0.9rem; }


a { color: var(--accent); text-decoration: none; }
a:hover { color: var(--accent); text-decoration: underline; }
a:focus { outline: 2px solid var(--accent); outline-offset: 2px; border-radius: 4px; }

@media (max-width: 900px) {
  .frame-wrap { height: 60vh; }
  .brand { font-size: 1.4rem; }
}
@media (max-width: 600px) {
  .tabbar { flex-direction: column; align-items: stretch; }
  .tab { width: 100%; text-align: center; }
}