/* Riverxo V4 — refined UX, theme toggle, mobile nav, reveals */
:root{
  color-scheme: dark;
  --bg:#0a0f14; --bg-2:#0d131a;
  --fg:#e6f4ff; --muted:#a9bed0;
  --accent:#00e7ff; --accent-2:#6d5aff;
  --card:#0f1722; --radius:18px;
  --shadow:0 12px 50px rgba(0,0,0,.35);
  --ring: 0 0 0 3px rgba(0,231,255,.25);
}
:root.light{
  color-scheme: light;
  --bg:#f7fbff; --bg-2:#eef5ff;
  --fg:#0c1a24; --muted:#405b6a;
  --accent:#0066ff; --accent-2:#6d3dff;
  --card:#ffffff; --shadow:0 8px 38px rgba(0,20,40,.10);
  --ring: 0 0 0 3px rgba(0,102,255,.18);
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;font:16px/1.6 ui-sans-serif, -apple-system, Segoe UI, Inter, Roboto, Helvetica, Arial;
  color:var(--fg);
  background: radial-gradient(1200px 800px at 20% -10%, var(--bg-2) 0, var(--bg) 60%), var(--bg);
  -webkit-font-smoothing:antialiased; text-rendering:optimizeLegibility;
  opacity:0; transition:opacity .25s ease;}
body.ready{opacity:1}
a{color:inherit; text-decoration:none}
a:focus-visible, button:focus-visible{outline:none; box-shadow:var(--ring)}
/* Buttons */
.btn{display:inline-flex; align-items:center; gap:.55rem; padding:.85rem 1.1rem; border-radius:14px; font-weight:700; transition:transform .08s ease, filter .2s}
.btn:active{transform:translateY(1px)}
.btn.primary{background:linear-gradient(135deg,var(--accent),var(--accent-2)); color:#001018}
.btn.ghost{border:1px solid color-mix(in oklab, var(--fg) 12%, transparent); background:color-mix(in oklab, var(--fg) 3%, transparent)}
/* Header */
.header{position:sticky; top:0; z-index:50; background:color-mix(in oklab, var(--bg) 70%, transparent); backdrop-filter: blur(8px);
  border-bottom:1px solid color-mix(in oklab, var(--fg) 8%, transparent)}
.header-inner{max-width:1120px; margin:0 auto; padding:12px 18px; display:flex; align-items:center; justify-content:space-between}
.brand{display:flex; align-items:center; gap:12px; font-weight:800; letter-spacing:.3px}
.brand img{width:28px; height:28px}
nav{display:flex; gap:10px; align-items:center}
/* Mobile nav */
.menu-btn{display:none}
@media (max-width:900px){
  nav{display:none}
  .menu-btn{display:inline-flex}
  .drawer{position:fixed; inset:0; background:color-mix(in oklab, var(--bg) 90%, black); display:none; padding:20px}
  .drawer.open{display:flex; flex-direction:column; gap:10px}
  .drawer a{padding:12px 14px; border-radius:12px}
}
/* Layout */
.container{max-width:1120px; margin:0 auto; padding:0 18px}
.hero{display:grid; grid-template-columns:1.2fr .8fr; gap:28px; align-items:center; margin:62px auto 40px}
.card{background:linear-gradient(180deg,color-mix(in oklab, var(--fg) 4%, transparent),transparent);
  border:1px solid color-mix(in oklab, var(--fg) 10%, transparent); border-radius:var(--radius); padding:28px; box-shadow:var(--shadow)}
h1{font-size:clamp(34px,5vw,56px); line-height:1.1; margin:0 0 18px}
p.lead{font-size:clamp(18px,2.4vw,22px); color:var(--muted); margin:0 0 22px}
.grid{display:grid; gap:18px}
.grid.cols-3{grid-template-columns:repeat(3,1fr)}
.tile{background:var(--card); border:1px solid color-mix(in oklab, var(--fg) 8%, transparent); border-radius:var(--radius); padding:22px; transform:translateY(8px); opacity:.001; transition:transform .5s ease, opacity .5s ease}
.tile.in{transform:translateY(0); opacity:1}
.tile h3{margin:0 0 8px; font-size:18px}
.tile p{margin:0; color:var(--muted)}
/* Timeline */
.timeline{position:relative; margin:20px 0 0; padding-left:22px}
.timeline:before{content:""; position:absolute; left:8px; top:0; bottom:0; width:2px; background:color-mix(in oklab, var(--fg) 12%, transparent)}
.event{margin:0 0 18px; padding-left:10px}
.event strong{display:block}
/* Footer */
.footer{padding:34px 18px 60px; margin-top:30px; display:flex; justify-content:space-between; align-items:center; border-top:1px solid color-mix(in oklab, var(--fg) 8%, transparent)}
.small{color:var(--muted); font-size:14px}
@media (max-width:900px){
  .hero{grid-template-columns:1fr}
  .grid.cols-3{grid-template-columns:1fr}
}
@media (prefers-reduced-motion: reduce){
  html{scroll-behavior:auto}
  .tile{transition:none}
  body{transition:none}
}