*{margin:0;padding:0;box-sizing:border-box}
:root{--red:#cc0000;--red-d:#a30000;--ink:#1a1a1a;--muted:#5b6673;--line:#e3e8ee;--bg:#f4f6f9;--card:#fff;--blue:#0758c8;--green:#188a42}
body{font-family:'Segoe UI',system-ui,-apple-system,Roboto,Arial,sans-serif;color:var(--ink);background:var(--bg);line-height:1.6}
a{color:inherit}
.hidden{display:none!important}
.container{width:min(940px,calc(100% - 32px));margin:0 auto}

.site-bar{background:#171a20;color:#fff}
.bar-inner{width:min(940px,calc(100% - 32px));margin:0 auto;display:flex;align-items:center;justify-content:space-between;padding:12px 0}
.back{color:#ffd6d6;text-decoration:none;font-weight:700;font-size:14px}
.back:hover{color:#fff}
.bar-title{font-weight:800;font-size:13px;color:#b9c1cc;letter-spacing:.5px}

.hero{background:linear-gradient(120deg,#7a0000,#cc0000 60%,#e02424);color:#fff;padding:48px 0 54px}
.hero-inner{width:min(940px,calc(100% - 32px));margin:0 auto}
.topic-pill{display:inline-block;background:rgba(255,255,255,.16);border:1px solid rgba(255,255,255,.3);padding:5px 14px;border-radius:999px;font-size:12px;font-weight:800;letter-spacing:1.2px;margin-bottom:16px}
.hero h1{font-size:clamp(30px,5vw,44px);line-height:1.1;font-weight:900;letter-spacing:-1px}
.hero h1 span{color:#ffd9d9}
.hero p{margin:14px 0 0;max-width:680px;color:#ffe4e4;font-size:16px}
.hero-actions{display:flex;gap:10px;margin-top:22px;flex-wrap:wrap}
.btn{border:0;border-radius:9px;padding:11px 20px;font-weight:750;font-size:14px;cursor:pointer;font-family:inherit}
.btn-light{background:#fff;color:var(--red-d)}
.btn-light:hover{filter:brightness(.94)}
.btn-ghost{background:transparent;color:#fff;border:1.5px solid rgba(255,255,255,.6)}
.btn-ghost:hover{background:rgba(255,255,255,.12)}
.hero-stats{display:flex;gap:22px;margin-top:24px;flex-wrap:wrap;font-size:14px;color:#ffdede}
.hero-stats b{font-size:20px;color:#fff}

.toolbar{position:sticky;top:0;z-index:20;background:var(--bg);padding:18px 0 8px}
.search-box{background:var(--card);border:1px solid var(--line);border-radius:10px;display:flex;align-items:center;gap:9px;padding:11px 15px;box-shadow:0 3px 10px rgba(20,40,70,.05)}
.search-box input{border:0;outline:0;width:100%;font-size:15px;font-family:inherit}
.chip-row{display:flex;gap:8px;flex-wrap:wrap;margin-top:14px}
.chip{border:1px solid var(--line);background:var(--card);color:var(--muted);border-radius:999px;padding:6px 14px;font-size:13px;font-weight:700;cursor:pointer}
.chip:hover{border-color:var(--red);color:var(--red)}
.chip.active{background:var(--red);border-color:var(--red);color:#fff}
.result-line{color:var(--muted);font-size:13px;font-weight:700;margin:14px 2px 12px}

.qa-list{display:flex;flex-direction:column;gap:12px;padding-bottom:60px}
.qa-card{background:var(--card);border:1px solid var(--line);border-radius:12px;overflow:hidden;box-shadow:0 3px 12px rgba(20,40,70,.05)}
.qa-head{display:flex;gap:14px;align-items:flex-start;padding:18px 20px;cursor:pointer;user-select:none}
.qa-num{flex:0 0 34px;height:28px;border-radius:8px;background:var(--red);color:#fff;font-weight:800;font-size:13px;display:grid;place-items:center;margin-top:1px}
.qa-q{flex:1;font-weight:750;font-size:16px;line-height:1.45}
.qa-topic{display:inline-block;margin-top:7px;background:#fbeaea;color:var(--red-d);font-size:11px;font-weight:800;letter-spacing:.5px;text-transform:uppercase;padding:2px 9px;border-radius:6px}
.qa-toggle{flex:0 0 28px;height:28px;border-radius:50%;border:1px solid var(--line);display:grid;place-items:center;color:var(--muted);font-size:15px;transition:transform .2s,background .2s;margin-top:1px}
.qa-card.open .qa-toggle{transform:rotate(180deg);background:var(--red);color:#fff;border-color:var(--red)}
.qa-body{max-height:0;overflow:hidden;transition:max-height .3s ease}
.qa-card.open .qa-body{max-height:2000px}
.qa-body-inner{padding:0 20px 20px 68px;border-top:1px dashed var(--line);margin-right:0}
.ans-label{display:inline-block;margin-top:16px;font-size:12px;font-weight:850;letter-spacing:.6px;text-transform:uppercase;color:var(--green);margin-bottom:6px}
.exp-label{color:var(--blue);margin-top:16px}
.qa-answer{font-size:15px;color:#222}
.qa-explain{font-size:14px;color:var(--muted);margin-top:8px;padding:12px 14px;background:#f6f9ff;border-left:3px solid var(--blue);border-radius:0 8px 8px 0}

.no-results{text-align:center;padding:50px 20px;color:var(--muted);background:var(--card);border:1px dashed var(--line);border-radius:12px;margin-bottom:60px}

.site-foot{background:#171a20;color:#aeb7c2;padding:26px 0;font-size:13px}
.site-foot a{color:#ff8a8a;text-decoration:none}
.site-foot a:hover{text-decoration:underline}

@media(max-width:640px){
  .qa-body-inner{padding:0 16px 18px 16px}
  .qa-num{flex-basis:30px}
}