:root { --bg:#0b0f14; --card:#131a22; --card-border:#243142; --text:#e8eef6; --muted:#90a3b3; --accent:#6aa9ff; }
*{box-sizing:border-box} html,body{height:100%}
body{margin:0;font-family:Inter,system-ui,-apple-system,Segoe UI,Roboto,Helvetica,Arial,sans-serif;color:var(--text);background:radial-gradient(1200px 800px at 20% -10%,#132136 0,#0b0f14 60%)}
.site-header{padding:24px 20px 8px;text-align:center}
.site-header h1{margin:0 0 6px;font-size:28px;letter-spacing:.2px}
.site-header p{margin:0;color:var(--muted)}
.controls{display:flex;gap:10px;padding:14px 20px;justify-content:center;flex-wrap:wrap}
.controls input[type="search"]{min-width:260px;padding:10px 12px;border-radius:10px;border:1px solid var(--card-border);background:var(--card);color:var(--text)}
.controls button{padding:10px 14px;border:1px solid var(--card-border);background:#182232;color:var(--text);border-radius:10px;cursor:pointer}
.controls button:hover{border-color:var(--accent)}
.grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(260px,1fr));gap:16px;padding:16px 20px 60px}
.card{perspective:1200px;height:220px}
.card-inner{position:relative;width:100%;height:100%;transform-style:preserve-3d;transition:transform .5s ease}
.card.flipped .card-inner{transform:rotateY(180deg)}
.card-face{position:absolute;inset:0;border-radius:14px;border:1px solid var(--card-border);background:linear-gradient(180deg,#121a24,#0f151d);padding:14px;display:flex;align-items:center;justify-content:center;text-align:center;backface-visibility:hidden}
.card-face.back{transform:rotateY(180deg)}
.term{font-weight:700;font-size:18px;letter-spacing:.2px}
.definition{font-size:14px;color:var(--muted);line-height:1.45}
.eq{font-size:18px}
.site-footer{text-align:center;color:var(--muted);padding:28px 0;border-top:1px solid #122032;background:#0b0f14}

/* Reserve space for top ad even before load */
.ad-top{min-height:90px}
@media (max-width:600px){.ad-top{min-height:50px}}