/* hx-site.css — shared site chrome for helixstreet.com / .io / .ai / .foundation / .xyz:
   the responsive header (.hx-nav) and the click-to-play YouTube facade (.hx-yt).
   Self-contained; dark by default, .hx-nav--light for helixstreet.foundation.
   Single source: contact-form/site/hx-site.css; each site folder carries an identical copy.
   Markup: <nav id="nav" class="hx-nav"> … (see any index.html). Behaviour: hx-site.js. */

:root { --hx-nav-h: 64px; }

nav.hx-nav {
    position: fixed; top: 0; left: 0; right: 0; z-index: 100;
    margin: 0; padding: 0; display: block;
    background: var(--hx-nav-bg, rgba(0,0,0,0.55));
    backdrop-filter: blur(20px) saturate(1.6); -webkit-backdrop-filter: blur(20px) saturate(1.6);
    border-bottom: 1px solid var(--hx-nav-border, rgba(255,255,255,0.08));
    color: var(--hx-nav-text, #F1F5F9);
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    transition: background 0.3s, top 0.4s cubic-bezier(0.16, 1, 0.3, 1);
}
nav.hx-nav.scrolled { padding: 0; background: var(--hx-nav-bg-scrolled, rgba(0,0,0,0.85)); }
nav.hx-nav.hx-nav--sticky { position: sticky; top: 0; }

.hx-nav__inner {
    max-width: 1200px; margin: 0 auto; padding: 0 1.5rem; height: var(--hx-nav-h);
    display: flex; align-items: center; gap: 1.25rem;
}
.hx-nav__brand { display: flex; align-items: center; gap: 0.6rem; min-width: 0; text-decoration: none; color: inherit; }
.hx-nav__mark {
    width: 28px; height: 28px; border-radius: 50%; flex-shrink: 0; position: relative; overflow: hidden;
    background: radial-gradient(circle at 30% 30%, #14a58c, #0a6b5b 70%);
}
.hx-nav__mark::after {
    content: ""; position: absolute; inset: 5px; border-radius: 50%;
    background: repeating-linear-gradient(45deg, transparent 0 3px, rgba(255,255,255,0.35) 3px 4px);
}
.hx-nav__logo {
    font-family: 'Space Grotesk', 'Inter', sans-serif; font-weight: 700; font-size: 1.15rem; letter-spacing: -0.02em; white-space: nowrap;
    background: var(--hx-nav-logo, linear-gradient(135deg, #8B5CF6, #06D6A0));
    -webkit-background-clip: text; background-clip: text; -webkit-text-fill-color: transparent;
}
.hx-nav__logo b { font-weight: 700; }
.hx-nav__tagline { font-size: 0.72rem; color: var(--hx-nav-dim, #94A3B8); white-space: nowrap; overflow: hidden; text-overflow: ellipsis; letter-spacing: 0.02em; }
.hx-nav__badge {
    font-family: 'JetBrains Mono', ui-monospace, monospace; font-size: 0.66rem; font-weight: 600; letter-spacing: 0.06em; text-transform: uppercase;
    padding: 0.2rem 0.5rem; border-radius: 6px; color: var(--hx-nav-badge, #22D3EE);
    background: rgba(34, 211, 238, 0.12); border: 1px solid rgba(34, 211, 238, 0.4); white-space: nowrap;
}

.hx-nav__links { margin-left: auto; display: flex; align-items: center; gap: 1.6rem; }
.hx-nav__links a {
    color: var(--hx-nav-dim, #94A3B8); text-decoration: none; font-size: 0.86rem; font-weight: 400;
    white-space: nowrap; position: relative; transition: color 0.25s;
}
.hx-nav__links a::after {
    content: ""; position: absolute; left: 0; bottom: -4px; width: 0; height: 1.5px;
    background: var(--hx-nav-underline, linear-gradient(135deg, #8B5CF6, #06D6A0));
    transition: width 0.35s cubic-bezier(0.16, 1, 0.3, 1);
}
.hx-nav__links a:hover, .hx-nav__links a[aria-current] { color: var(--hx-nav-text, #F1F5F9); }
.hx-nav__links a:hover::after, .hx-nav__links a[aria-current]::after { width: 100%; }
.hx-nav__links a.hx-nav__cta {
    display: inline-flex; align-items: center; gap: 0.35rem; padding: 0.5rem 1rem; border-radius: 999px;
    font-weight: 600; font-size: 0.82rem; color: var(--hx-nav-cta-text, #06060E);
    background: var(--hx-nav-cta, linear-gradient(135deg, #8B5CF6, #06D6A0));
    transition: transform 0.25s, box-shadow 0.25s;
}
.hx-nav__links a.hx-nav__cta::after { display: none; }
.hx-nav__links a.hx-nav__cta:hover { transform: translateY(-1px); box-shadow: 0 8px 24px rgba(6, 214, 160, 0.25); color: var(--hx-nav-cta-text, #06060E); }
.hx-nav a:focus-visible { outline: 2px solid #06D6A0; outline-offset: 3px; }

.hx-nav__burger {
    display: none; margin-left: auto; width: 44px; height: 44px; padding: 0; border: 0; background: none; cursor: pointer;
    flex-direction: column; justify-content: center; align-items: center; gap: 5px; border-radius: 8px;
}
.hx-nav__burger span { display: block; width: 22px; height: 2px; border-radius: 2px; background: var(--hx-nav-text, #F1F5F9); transition: transform 0.25s, opacity 0.25s; }
.hx-nav__burger[aria-expanded="true"] span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.hx-nav__burger[aria-expanded="true"] span:nth-child(2) { opacity: 0; }
.hx-nav__burger[aria-expanded="true"] span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }
.hx-nav__burger:focus-visible { outline: 2px solid #06D6A0; }

@media (max-width: 1280px) { .hx-nav__tagline { display: none; } }
@media (max-width: 820px) {
    .hx-nav__inner { padding: 0 1rem; }
    .hx-nav__badge { display: none; }
    .hx-nav__links { display: none; }
    .hx-nav__burger { display: flex; }
    .hx-nav__links.is-open {
        display: flex; flex-direction: column; align-items: flex-start; gap: 1.3rem;
        position: absolute; left: 0; right: 0; top: 100%; margin: 0;
        max-height: calc(100vh - var(--hx-nav-h)); overflow-y: auto;
        padding: 1.6rem 1.25rem 2rem;
        background: var(--hx-nav-menu-bg, rgba(0,0,0,0.96));
        border-bottom: 1px solid var(--hx-nav-border, rgba(255,255,255,0.08));
    }
    .hx-nav__links.is-open a { font-size: 1.15rem; }
    .hx-nav__links.is-open a.hx-nav__cta { margin-top: 0.4rem; font-size: 0.95rem; }
}

/* Light theme (helixstreet.foundation) */
nav.hx-nav.hx-nav--light {
    --hx-nav-bg: rgba(247,246,242,0.92); --hx-nav-bg-scrolled: rgba(247,246,242,0.96); --hx-nav-border: #e5e1d8;
    --hx-nav-text: #0e1a24; --hx-nav-dim: #5a6672; --hx-nav-logo: #0e1a24; --hx-nav-underline: #0a6b5b;
    --hx-nav-cta: #0e1a24; --hx-nav-cta-text: #ffffff; --hx-nav-menu-bg: rgba(247,246,242,0.98);
}
nav.hx-nav.hx-nav--light .hx-nav__logo { background: none; -webkit-text-fill-color: currentColor; color: var(--hx-nav-text); }
nav.hx-nav.hx-nav--light .hx-nav__logo b { color: #0a6b5b; }
/* Overlay variant: transparent over a dark hero until scrolled past it (hx-site.js, data-scroll-after="hero") */
nav.hx-nav.hx-nav--overlay:not(.scrolled) {
    --hx-nav-bg: rgba(10,21,32,0.35); --hx-nav-border: rgba(255,255,255,0.08);
    --hx-nav-text: #ffffff; --hx-nav-dim: rgba(255,255,255,0.72); --hx-nav-underline: #14a58c;
    --hx-nav-cta: rgba(255,255,255,0.12); --hx-nav-cta-text: #ffffff; --hx-nav-menu-bg: rgba(10,21,32,0.97);
}
nav.hx-nav.hx-nav--overlay:not(.scrolled) .hx-nav__logo { color: #ffffff; }
nav.hx-nav.hx-nav--overlay:not(.scrolled) .hx-nav__logo b { color: #14a58c; }
nav.hx-nav.hx-nav--overlay:not(.scrolled) .hx-nav__links a.hx-nav__cta { border: 1px solid rgba(255,255,255,0.25); }

/* YouTube facade: a poster + play button, the iframe is created on click (hx-site.js) */
.hx-yt { position: absolute; inset: 0; width: 100%; height: 100%; cursor: pointer; background: #000; overflow: hidden; }
.hx-yt img { width: 100%; height: 100%; object-fit: cover; display: block; opacity: 0.85; transition: opacity 0.3s, transform 0.5s; }
.hx-yt:hover img { opacity: 1; transform: scale(1.02); }
.hx-yt__play {
    position: absolute; left: 50%; top: 50%; transform: translate(-50%, -50%);
    width: 72px; height: 50px; border: 0; border-radius: 14px; cursor: pointer;
    background: rgba(255, 0, 0, 0.9); color: #fff; display: flex; align-items: center; justify-content: center;
    box-shadow: 0 10px 30px rgba(0,0,0,0.5); transition: transform 0.25s, background 0.25s;
}
.hx-yt:hover .hx-yt__play { transform: translate(-50%, -50%) scale(1.08); background: #ff0000; }
.hx-yt__play svg { width: 28px; height: 28px; fill: currentColor; }
.hx-yt__play:focus-visible { outline: 3px solid #fff; }
.hx-yt iframe { position: absolute; inset: 0; width: 100%; height: 100%; border: 0; }
@media (prefers-reduced-motion: reduce) { nav.hx-nav, .hx-yt img, .hx-yt__play, .hx-nav__links a::after { transition: none; } }