/* ===== ChineseUnitTests · English site styles (light, mobile-first) ===== */
:root{
  --ink:#111827; --ink2:#374151; --muted:#6b7280; --line:#e5e7eb; --bg:#f7f8fa;
  --brand:#2563eb; --brand-d:#1d4ed8; --ok:#059669; --warn:#b45309; --warn-bg:#fffbeb;
}
*{box-sizing:border-box}
html,body{margin:0;padding:0}
body{background:var(--bg);color:var(--ink);font:16px/1.6 -apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,"Helvetica Neue",Arial,"PingFang SC","Microsoft YaHei",sans-serif;-webkit-text-size-adjust:100%}
a{color:var(--brand);text-decoration:none}
a:hover{text-decoration:underline}
h1,h2,h3{line-height:1.25;margin:0 0 12px}
h1{font-size:26px}
h2{font-size:20px}
h3{font-size:17px}
p{margin:0 0 12px}
ul{margin:0 0 12px;padding-left:20px}
img{max-width:100%;height:auto}
code{background:#f3f4f6;border:1px solid var(--line);border-radius:4px;padding:1px 5px;font-size:13px}
.wrap{max-width:1080px;margin:0 auto;padding:0 16px}
.muted{color:var(--muted)}
.small{font-size:13px}
.warn-text{color:var(--warn)}

/* header */
.site-header{background:#fff;border-bottom:1px solid var(--line);position:sticky;top:0;z-index:20}
.site-header .wrap{display:flex;align-items:center;justify-content:space-between;gap:12px;min-height:60px}
.logo{display:inline-flex;align-items:center;gap:9px;color:var(--ink);font-weight:700;font-size:19px}
.logo:hover{text-decoration:none}
.site-header nav{display:flex;gap:16px;font-size:15px;flex-wrap:wrap}
.site-header nav a{color:var(--ink2)}
@media(max-width:520px){ .site-header nav{gap:11px;font-size:14px} }

/* footer */
.site-footer{margin-top:48px;background:#fff;border-top:1px solid var(--line);padding:26px 0 34px;color:var(--muted);font-size:13.5px;text-align:center}
.site-footer p{margin:5px 0}
.foot-links a{color:var(--ink2)}

/* buttons */
.btn{display:inline-block;background:#fff;border:1px solid var(--line);color:var(--ink);padding:10px 18px;border-radius:8px;font-size:15px;font-weight:600;cursor:pointer}
.btn:hover{text-decoration:none;border-color:#cbd5e1}
.btn-buy{background:var(--brand);border-color:var(--brand);color:#fff;width:100%;text-align:center;padding:14px 20px;font-size:16px}
.btn-buy:hover{background:var(--brand-d);border-color:var(--brand-d)}
.btn-row{display:flex;gap:10px;flex-wrap:wrap}

/* hero */
.hero{background:#fff;border-bottom:1px solid var(--line);padding:32px 0 26px;text-align:center}
.hero h1{font-size:27px;margin-bottom:10px}
.hero p{color:var(--ink2);max-width:760px;margin:0 auto 14px}
.hero-steps{display:flex;gap:8px;justify-content:center;flex-wrap:wrap;color:var(--muted);font-size:14px}
.hero-steps i{font-style:normal;color:#cbd5e1}
@media(max-width:640px){ .hero h1{font-size:21px} .hero{padding:22px 0 18px} }

/* filters */
.filter-bar{background:#fff;border:1px solid var(--line);border-radius:10px;padding:12px 14px;margin:18px 0}
.f-row{display:flex;align-items:flex-start;gap:8px;padding:5px 0;flex-wrap:wrap}
.f-label{flex:0 0 78px;color:var(--muted);font-size:13px;padding-top:5px}
.chip{display:inline-block;padding:4px 11px;border:1px solid var(--line);border-radius:999px;font-size:13.5px;color:var(--ink2);background:#fff}
.chip:hover{border-color:#cbd5e1;text-decoration:none}
.chip.on{background:var(--brand);border-color:var(--brand);color:#fff}
@media(max-width:640px){ .f-label{flex:0 0 100%;padding-top:0} }

/* list */
.list-head{display:flex;align-items:center;justify-content:space-between;gap:12px;margin:22px 0 12px;flex-wrap:wrap}
.list-head h2{margin:0}
.list-head h2 small{color:var(--muted);font-size:14px;font-weight:400}
.clear{font-size:13.5px;color:var(--muted)}
.grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(250px,1fr));gap:14px}
.card{display:flex;flex-direction:column;justify-content:space-between;background:#fff;border:1px solid var(--line);border-radius:10px;padding:14px;min-height:132px;color:var(--ink);position:relative;overflow:hidden}
.card:hover{border-color:#bfdbfe;box-shadow:0 2px 10px rgba(37,99,235,.07);text-decoration:none}
.card-head{display:flex;justify-content:space-between;align-items:center;gap:6px;margin-bottom:8px}
.card-subject{display:inline-block;font-size:11.5px;font-weight:700;color:#fff;padding:3px 9px;border-radius:5px;letter-spacing:.3px}
.card-title{font-weight:600;font-size:15.5px;margin-bottom:6px}
.card-sub{color:var(--muted);font-size:13px;flex:1}
.card-foot{display:flex;align-items:center;justify-content:space-between;margin-top:10px}

/* 热卖区 + 学科色标 */
.hot-section .sec-title{margin-top:0}
.sec-title{font-size:19px;margin:26px 0 12px}
.sec-title small{color:var(--muted);font-size:13.5px;font-weight:normal}
.card-hot{border-color:#fdba74}
.card-hot:hover{border-color:#fb923c;box-shadow:0 2px 12px rgba(249,115,22,.13)}
.hot-tag{position:absolute;top:-1px;right:-1px;background:#ff6b35;color:#fff;font-size:11px;padding:2px 9px;border-radius:0 10px 0 10px;font-weight:600}
.chip .dot{display:inline-block;width:8px;height:8px;border-radius:50%;margin-right:6px;vertical-align:middle}
.chip-subject.on .dot{background:#fff!important}
.tag{font-size:12px;color:var(--muted);background:#f3f4f6;border-radius:4px;padding:2px 7px}
.price{font-weight:700;color:var(--brand)}
.empty{background:#fff;border:1px dashed var(--line);border-radius:10px;padding:28px;text-align:center;color:var(--muted)}
.pager{display:flex;align-items:center;justify-content:center;gap:14px;margin:26px 0;font-size:14.5px}
.pager .off{color:#cbd5e1}
.pager .cur{color:var(--muted)}

/* info blocks */
.info-blocks{display:grid;grid-template-columns:repeat(auto-fit,minmax(260px,1fr));gap:14px;margin:30px 0 0}
.info{background:#fff;border:1px solid var(--line);border-radius:10px;padding:16px}
.info h3{margin-bottom:6px}
.info p{margin:0;color:var(--ink2);font-size:14.5px}

/* crumbs */
.crumb{font-size:13.5px;color:var(--muted);margin:16px 0}
.crumb a{color:var(--muted)}

/* detail */
.detail-head{display:grid;grid-template-columns:1fr 320px;gap:22px;align-items:start;margin-bottom:22px}
.d-info{background:#fff;border:1px solid var(--line);border-radius:10px;padding:20px}
.d-chapter{color:var(--brand);font-weight:600;margin:-4px 0 8px}
.d-sub{color:var(--muted);margin-bottom:14px}
.d-meta{list-style:none;padding:0;margin:0;font-size:14.5px;color:var(--ink2)}
.d-meta li{padding:5px 0;border-bottom:1px dashed #f1f3f6}
.d-meta li:last-child{border-bottom:0}
.d-meta b{display:inline-block;min-width:92px;color:var(--muted);font-weight:600}
.d-orig{margin-top:10px;font-size:13px}
.d-buy{background:#fff;border:1px solid var(--line);border-radius:10px;padding:18px;position:sticky;top:78px}
.buy-price{font-size:30px;font-weight:800;letter-spacing:-1px}
.buy-perks{list-style:none;padding:0;margin:14px 0 0;font-size:13.5px;color:var(--ink2)}
.buy-perks li{padding:3px 0}
.d-note{margin:14px 0 0;font-size:12.5px;color:var(--muted);border-top:1px solid var(--line);padding-top:12px}
@media(max-width:820px){ .detail-head{grid-template-columns:1fr} .d-buy{position:static} }

.preview-sec{background:#fff;border:1px solid var(--line);border-radius:10px;padding:18px;margin-bottom:22px}
.preview-frame{position:relative;width:100%;height:620px;border:1px solid var(--line);border-radius:8px;overflow:hidden;background:#fafafa}
.preview-frame iframe{width:100%;height:100%;border:0}
@media(max-width:640px){ .preview-frame{height:430px} }
.related h2{margin-top:6px}

/* checkout */
.checkout h1{margin-top:20px}
.co-grid{display:grid;grid-template-columns:1fr 360px;gap:20px;align-items:start}
.co-order,.co-pay{background:#fff;border:1px solid var(--line);border-radius:10px;padding:20px}
.co-line{display:flex;justify-content:space-between;gap:12px;padding:8px 0;border-bottom:1px dashed #f1f3f6;font-size:14.5px}
.co-line span{color:var(--muted)}
.co-line.total{border-bottom:0;font-size:17px;margin-top:6px}
.co-line.total b{font-size:22px;color:var(--brand)}
.notice{background:#eff6ff;border:1px solid #bfdbfe;color:#1e40af;border-radius:8px;padding:11px 14px;font-size:14px;margin:0 0 14px}
.notice.warn{background:var(--warn-bg);border-color:#fde68a;color:var(--warn)}
.pay-error{background:#fef2f2;border:1px solid #fecaca;color:#b91c1c;border-radius:8px;padding:11px 14px;font-size:14px;margin-top:12px}
@media(max-width:820px){ .co-grid{grid-template-columns:1fr} }

/* result / download */
.result{background:#fff;border:1px solid var(--line);border-radius:12px;padding:26px;text-align:center;max-width:720px;margin:24px auto}
.result-icon{font-size:34px;margin-bottom:8px}
.result-box{background:#f9fafb;border:1px solid #eef1f5;border-radius:10px;padding:18px;margin:16px 0}
.result-box .btn-buy{margin-top:6px}
.result-notes{text-align:left;font-size:14px;color:var(--ink2);border-top:1px solid var(--line);padding-top:14px;margin-top:16px}

/* forms */
.lookup{background:#fff;border:1px solid var(--line);border-radius:12px;padding:24px;max-width:760px;margin:24px auto}
.form-inline{display:flex;gap:12px;flex-wrap:wrap;align-items:flex-end}
.form-stack{display:flex;flex-direction:column;gap:14px;max-width:520px}
label{display:block;font-size:14px;color:var(--ink2);font-weight:600}
input[type=text],input[type=email],textarea{width:100%;margin-top:5px;padding:10px 12px;border:1px solid #d1d5db;border-radius:8px;font-size:15px;font-family:inherit;background:#fff;color:var(--ink)}
input:focus,textarea:focus{outline:0;border-color:var(--brand);box-shadow:0 0 0 3px rgba(37,99,235,.12)}
.form-inline label{flex:1 1 220px}
.order-meta{list-style:none;padding:0;margin:0 0 14px;font-size:14.5px;color:var(--ink2)}
.order-meta li{padding:4px 0}
.order-meta b{display:inline-block;min-width:96px;color:var(--muted);font-weight:600}

/* legal */
.legal{background:#fff;border:1px solid var(--line);border-radius:12px;padding:26px;max-width:860px;margin:24px auto}
.legal h2{font-size:17px;margin-top:22px}
.legal p,.legal li{color:var(--ink2);font-size:15px}
.legal code{padding:1px 5px}