:root{
  --bg:#0b0f14; --card:#121826; --text:#e7edf5; --muted:#aab6c5;
  --accent:#74c0fc; --accent2:#9bffb0; --warn:#ffd43b; --danger:#ff6b6b;
  --border:rgba(255,255,255,0.08);
}
*{box-sizing:border-box}
html,body{margin:0;padding:0;background:var(--bg);color:var(--text);font-family:system-ui,-apple-system,Segoe UI,Roboto,Ubuntu,Cantarell,Noto Sans,sans-serif}
a{color:var(--accent);text-decoration:none}
a:hover{text-decoration:underline}
.container{max-width:980px;margin:0 auto;padding:28px 18px}
.header{display:flex;gap:14px;align-items:flex-start;justify-content:space-between;flex-wrap:wrap}
.brand{display:flex;flex-direction:column;gap:4px}
.brand h1{margin:0;font-size:26px;letter-spacing:0.2px}
.brand .tag{color:var(--muted);font-size:14px}
.badge{display:inline-flex;align-items:center;gap:8px;padding:6px 10px;border:1px solid var(--border);border-radius:999px;color:var(--muted);font-size:12px}
.card{background:var(--card);border:1px solid var(--border);border-radius:16px;padding:16px;margin-top:14px}
.grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(240px,1fr));gap:12px}
.search{display:flex;gap:10px;align-items:center;flex-wrap:wrap;margin-top:14px}
.search input{flex:1;min-width:240px;background:#0f1522;border:1px solid var(--border);border-radius:12px;padding:10px 12px;color:var(--text);outline:none}
.search select{background:#0f1522;border:1px solid var(--border);border-radius:12px;padding:10px 12px;color:var(--text);outline:none}
.k{display:flex;flex-direction:column;gap:8px}
.k .title{display:flex;gap:10px;align-items:center;justify-content:space-between}
.k h3{margin:0;font-size:16px}
.meta{display:flex;gap:8px;flex-wrap:wrap}
.pill{display:inline-flex;align-items:center;padding:3px 8px;border-radius:999px;border:1px solid var(--border);font-size:12px;color:var(--muted)}
.pill.easy{color:var(--accent2)}
.pill.medium{color:var(--warn)}
.pill.hard{color:var(--danger)}
hr{border:none;border-top:1px solid var(--border);margin:14px 0}
ol,ul{margin:8px 0 0 20px}
li{margin:6px 0;color:var(--text)}
small{color:var(--muted)}
.btnrow{display:flex;gap:10px;flex-wrap:wrap;margin-top:12px}
button,.btn{background:#0f1522;color:var(--text);border:1px solid var(--border);border-radius:12px;padding:10px 12px;cursor:pointer}
button:hover,.btn:hover{border-color:rgba(116,192,252,0.6)}
.footer{margin-top:22px;color:var(--muted);font-size:12px;line-height:1.5}
.code{font-family:ui-monospace,SFMono-Regular,Menlo,Monaco,Consolas,"Liberation Mono","Courier New",monospace;font-size:12px;color:#d7e3f4}