:root{--primary:#1769e0;--text:#172033;--muted:#667085;--border:#e5e7eb;--bg:#f7f9fc;--card:#fff;--shadow:0 10px 30px rgba(15,23,42,.07)}
*{box-sizing:border-box}html,body{margin:0;padding:0;overflow-x:hidden;font-family:Arial,Helvetica,sans-serif;color:var(--text);background:var(--bg)}
a{text-decoration:none;color:inherit}.container{width:min(1120px,92%);margin:auto}
.site-header{background:#fff;border-bottom:1px solid var(--border);position:sticky;top:0;z-index:20}
.nav-wrap{min-height:72px;display:flex;align-items:center;gap:28px}.brand{font-size:1.2rem;font-weight:800;white-space:nowrap}.brand span{color:var(--primary)}
.nav-links{margin-left:auto;display:flex;align-items:center;gap:22px}.nav-links>a{font-weight:600;font-size:.92rem}.nav-links>a:hover,.nav-drop-btn:hover{color:var(--primary)}
.nav-dropdown{position:relative}.nav-drop-btn{border:0;background:transparent;color:var(--text);font:inherit;font-weight:600;cursor:pointer;padding:0}
.nav-dropdown-menu{position:absolute;top:calc(100% + 18px);left:50%;transform:translateX(-50%);min-width:235px;padding:8px;background:#fff;border:1px solid var(--border);border-radius:12px;box-shadow:var(--shadow);opacity:0;visibility:hidden;pointer-events:none}
.nav-dropdown-menu a{display:block;padding:9px 12px;border-radius:8px;font-size:.9rem}.nav-dropdown-menu a:hover{background:#edf3ff;color:var(--primary)}
.nav-dropdown:hover .nav-dropdown-menu,.nav-dropdown:focus-within .nav-dropdown-menu{opacity:1;visibility:visible;pointer-events:auto}
.menu-toggle{display:none;border:0;background:none;font-size:1.5rem}
.hero{padding:62px 0 42px;background:linear-gradient(180deg,#eef5ff,#f7f9fc)}
.hero h1{font-size:2.5rem;margin:0 0 12px}.hero p{max-width:760px;color:var(--muted);font-size:1.05rem;line-height:1.7}
.search{margin:24px 0 36px}.search input{width:100%;padding:15px 17px;border:1px solid var(--border);border-radius:12px;font-size:1rem;outline:none}.search input:focus{border-color:var(--primary)}
.section{padding:42px 0}.section h2{font-size:1.55rem;margin:0 0 8px}.section-intro{color:var(--muted);margin:0 0 24px}
.grid{display:grid;grid-template-columns:repeat(3,1fr);gap:18px}.card{background:var(--card);border:1px solid var(--border);border-radius:15px;padding:22px;box-shadow:var(--shadow)}
.card h3{margin:0 0 9px;font-size:1.08rem}.card p{color:var(--muted);line-height:1.6;font-size:.93rem}.card a.more{color:var(--primary);font-weight:700;font-size:.9rem}
.problem-list{display:grid;grid-template-columns:repeat(2,1fr);gap:12px;margin-top:22px}.problem{background:#fff;border:1px solid var(--border);border-radius:11px;padding:15px 16px;color:#263247}.problem:hover{border-color:#b9cdf5;color:var(--primary)}
.ad{margin:28px 0;padding:28px;text-align:center;border:1px dashed #cfd6e2;color:#98a2b3;background:#fff;font-size:.75rem;letter-spacing:1.4px}
.site-footer{margin-top:35px;background:#111827;color:#cbd5e1;padding:40px 0}.footer-grid{display:grid;grid-template-columns:2fr 1fr 1fr 1fr;gap:30px}.site-footer h3{color:#fff;margin-top:0}.site-footer a{display:block;margin:8px 0;color:#cbd5e1;font-size:.9rem}.site-footer a:hover{color:#fff}.copyright{border-top:1px solid #2c3545;margin-top:28px;padding-top:18px;font-size:.85rem;color:#94a3b8}
@media(max-width:900px){
 .nav-wrap{min-height:64px}.menu-toggle{display:block;margin-left:auto}.nav-links{display:none;position:absolute;top:64px;left:0;right:0;background:#fff;padding:18px;flex-direction:column;gap:14px;border-bottom:1px solid var(--border);box-shadow:var(--shadow)}
 .nav-links.mobile-open{display:flex}.nav-dropdown{width:100%;text-align:center}.nav-drop-btn{padding:5px 0}.nav-dropdown-menu{position:static;transform:none;display:none;opacity:1;visibility:visible;pointer-events:auto;box-shadow:none;border:0;padding:4px 0 8px}.nav-dropdown-menu.open{display:block}
 .grid{grid-template-columns:repeat(2,1fr)}.footer-grid{grid-template-columns:repeat(2,1fr)}
}
@media(max-width:600px){.hero{padding:45px 0 30px}.hero h1{font-size:2rem}.grid,.problem-list,.footer-grid{grid-template-columns:1fr}}