.site-header-wrap { position: sticky; top: 0; z-index: 60; padding: clamp(.85rem, 2vw, 1.1rem) clamp(1rem, 4vw, 2.5rem) 0; }
.site-header { max-width: var(--container); margin: 0 auto; background: rgba(255,255,255,.9); backdrop-filter: blur(10px); -webkit-backdrop-filter: blur(10px); border-radius: var(--radius-pill); box-shadow: var(--shadow-float); padding: .55rem .6rem .55rem 1.15rem; display: flex; align-items: center; justify-content: space-between; gap: 1.5rem; transition: background .3s var(--ease); }
[data-theme="dark"] .site-header { background: rgba(15,24,48,.85); }
.brand { display: flex; align-items: center; gap: .6rem; }
.brand-mark { width: 22px; height: 22px; flex-shrink: 0; }
.brand-mark svg { width: 100%; height: 100%; }
.brand-text { display: flex; flex-direction: column; line-height: 1.1; }
.brand-name { font-weight: 800; font-size: .98rem; color: var(--color-ink); letter-spacing: -.01em; }
.brand-sub { font-size: .58rem; font-weight: 600; letter-spacing: .07em; text-transform: uppercase; color: var(--color-graphite); margin-top: .2em; }

.header-actions { display: flex; align-items: center; gap: .5rem; flex-shrink: 0; }

.theme-toggle, .nav-toggle { display: flex; flex-direction: column; justify-content: center; align-items: center; gap: 5px; width: 38px; height: 38px; background: var(--color-page); border-radius: 50%; border: none; cursor: pointer; padding: 0; flex-shrink: 0; transition: background .2s var(--ease); color: var(--color-ink); }
.theme-toggle:hover, .nav-toggle:hover { background: var(--color-hairline); }
.theme-toggle svg { width: 18px; height: 18px; }
.theme-toggle .icon-moon { display: none; }
[data-theme="dark"] .theme-toggle .icon-sun { display: none; }
[data-theme="dark"] .theme-toggle .icon-moon { display: block; }

.nav-toggle span { display: block; width: 15px; height: 1.5px; background: var(--color-ink); transition: transform .3s var(--ease), opacity .3s var(--ease); }
.nav-toggle.is-active span:nth-child(1) { transform: translateY(6.5px) rotate(45deg); }
.nav-toggle.is-active span:nth-child(2) { opacity: 0; }
.nav-toggle.is-active span:nth-child(3) { transform: translateY(-6.5px) rotate(-45deg); }

.sheet-backdrop { position: fixed; inset: 0; background: rgba(16,26,48,.4); opacity: 0; pointer-events: none; transition: opacity .3s var(--ease); z-index: 70; }
.sheet-backdrop.is-open { opacity: 1; pointer-events: auto; }
.mobile-sheet { position: fixed; left: 0; right: 0; bottom: 0; max-height: min(80vh, 640px); overflow-y: auto; background: var(--color-surface); border-radius: 24px 24px 0 0; padding: .8rem 1.5rem calc(1.75rem + env(safe-area-inset-bottom)); transform: translateY(calc(100% + var(--drag-y, 0px))); transition: transform .4s var(--ease); z-index: 71; box-shadow: 0 -10px 34px rgba(16,26,48,.14); }
.mobile-sheet.is-open { transform: translateY(var(--drag-y, 0px)); }
.mobile-sheet.is-dragging { transition: none; }
.sheet-handle { width: 36px; height: 4px; border-radius: var(--radius-pill); background: var(--color-hairline); margin: 0 auto 1.25rem; flex-shrink: 0; touch-action: none; cursor: grab; }
.sheet-handle:active { cursor: grabbing; }

.sheet-cta { margin-bottom: 1.4rem; }
.sheet-cta .btn { width: 100%; }
.sheet-group + .sheet-group { margin-top: 1.4rem; }
.sheet-group-label { font-size: .72rem; font-weight: 700; letter-spacing: .08em; text-transform: uppercase; color: var(--color-accent-deep); margin-bottom: .35rem; display: block; }
.sheet-nav a { display: block; padding: .8rem 0; border-bottom: 1px solid var(--color-hairline); font-size: 1rem; font-weight: 600; color: var(--color-ink); transition: color .2s var(--ease); }
.sheet-group:last-child .sheet-nav a:last-child { border-bottom: none; }
.sheet-nav a:hover { color: var(--color-accent-deep); }

@media (min-width: 640px) {
  .mobile-sheet { left: 50%; right: auto; bottom: clamp(1rem, 3vw, 1.5rem); transform: translate(-50%, calc(130% + var(--drag-y, 0px))); width: 100%; max-width: 420px; border-radius: 24px; }
  .mobile-sheet.is-open { transform: translate(-50%, var(--drag-y, 0px)); }
}