/* ============================================
   2. SIGN-IN PROMPT — top banner
   ============================================ */
.signin-banner {
  position: fixed;
  top: 16px;
  left: 50%;
  transform: translateX(-50%) translateY(-140%);
  width: calc(100% - 32px);
  max-width: 560px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 14px 16px;
  z-index: 340;
  opacity: 0;
  transition: transform 0.4s cubic-bezier(0.175,0.885,0.32,1.275), opacity 0.3s ease;
  overflow: hidden;
}
.signin-banner.open {
  transform: translateX(-50%) translateY(0);
  opacity: 1;
}
/* Animated gradient border accent */
.signin-banner::before {
  content: '';
  position: absolute;
  inset: -1px;
  border-radius: 17px;
  padding: 1px;
  background: linear-gradient(90deg,
    rgba(123,47,255,0.7), rgba(255,60,172,0.8),
    rgba(0,245,212,0.6), rgba(123,47,255,0.7));
  background-size: 200% 100%;
  animation: borderSpin 4s linear infinite;
  -webkit-mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
  -webkit-mask-composite: destination-out;
          mask-composite: exclude;
  pointer-events: none;
  opacity: 0.6;
}
.signin-inner {
  display: flex; align-items: center; gap: 12px; position: relative;
}
.signin-avatar {
  width: 40px; height: 40px;
  background: linear-gradient(135deg, var(--accent2), var(--accent));
  border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  font-size: 1.1rem;
  flex-shrink: 0;
  box-shadow: 0 0 0 1px rgba(255,255,255,0.05), 0 0 16px rgba(123,47,255,0.4);
}
.signin-text { flex: 1; min-width: 0; }
.signin-title {
  font-family: 'Syne', sans-serif;
  font-weight: 700;
  font-size: 0.84rem;
  letter-spacing: 0.01em;
}
.signin-title .gem {
  color: var(--gold);
  font-family: 'Syne', sans-serif;
  font-weight: 800;
}
.signin-sub {
  font-size: 0.65rem;
  color: var(--muted);
  margin-top: 2px;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.btn-signin {
  padding: 9px 16px;
  background: linear-gradient(135deg, var(--accent2), var(--accent));
  border: none;
  border-radius: 10px;
  color: white;
  font-family: 'Syne', sans-serif;
  font-weight: 700;
  font-size: 0.75rem;
  cursor: pointer;
  transition: all 0.2s;
  white-space: nowrap;
  flex-shrink: 0;
  letter-spacing: 0.03em;
}
.btn-signin:hover { transform: translateY(-1px); box-shadow: 0 4px 14px rgba(123,47,255,0.4); }
.signin-close {
  width: 26px; height: 26px;
  background: var(--surface2);
  border: 1px solid var(--border);
  border-radius: 7px;
  cursor: pointer;
  display: flex; align-items: center; justify-content: center;
  font-size: 0.75rem;
  color: var(--muted);
  transition: all 0.15s;
  flex-shrink: 0;
}
.signin-close:hover { color: var(--accent); border-color: var(--accent); }