/* 基础回退：旧版浏览器没有 CSS 变量或 Grid 时仍可正常阅读 */
*{box-sizing:border-box}
html{font-size:100%;-ms-text-size-adjust:100%;-webkit-text-size-adjust:100%}
body{margin:0;background:#07111f;color:#edf6ff;font:16px/1.7 Arial,"Microsoft YaHei",sans-serif}
.wrap{width:1120px;max-width:calc(100% - 36px);margin:auto}
.grid,.tabs{display:block;clear:both}
.grid:after,.tabs:after{content:"";display:table;clear:both}
.grid>.card,.tabs>.mode{float:left;width:31%;margin:1%}
img,video{max-width:100%;height:auto}

:root{--bg:#07111f;--panel:#0d1d31;--panel2:#102945;--line:#294969;--ink:#edf6ff;--muted:#a9bad2;--blue:#46a9ff;--gold:#ffd36c;--red:#ff716b}
body{background:radial-gradient(900px 600px at 85% -100px,#163f70 0,transparent 70%),var(--bg);color:var(--ink);font:16px/1.7 system-ui,-apple-system,"Microsoft YaHei",sans-serif}
.wrap{width:min(1120px,calc(100% - 36px));margin:auto}
.nav{height:68px;display:flex;align-items:center;justify-content:space-between}
.brand{font-weight:900;font-size:19px}.brand i{font-style:normal;color:var(--blue)}
.nav a{color:var(--muted);text-decoration:none;margin-left:18px;font-size:14px}
.section{padding:58px 0}.section.dark{background:#091727}
.section h1{font-size:42px;line-height:1.2;margin:0 0 12px}.section h2{font-size:31px;margin:0 0 10px}
.lead,.muted,li{color:var(--muted)}
.grid,.tabs{display:grid;grid-template-columns:repeat(3,1fr);gap:16px}
.tabs{grid-template-columns:1fr 1fr}
.card,.mode,.video-box,.faq details{background:var(--panel);border:1px solid var(--line);border-radius:16px;padding:22px}
.card h3,.mode h3{margin:4px 0 8px;font-size:23px}.n{color:var(--blue);font-weight:900;font-size:13px}
.mode ol{padding-left:22px}.mode li{margin:8px 0}.red{color:var(--red);font-weight:800}
.notice{border-left:4px solid var(--gold);background:#241e10;color:#ffe6a1;padding:12px 15px;border-radius:0 9px 9px 0}
.video-box{margin-top:28px}.video-box video{width:100%;display:block;border-radius:10px;background:#000}
.btn{display:inline-block;padding:11px 18px;border-radius:9px;background:var(--blue);color:#021422;text-decoration:none;font-weight:900;margin:8px 8px 0 0}
.faq details{margin:10px 0;padding:16px}.faq summary{cursor:pointer;font-weight:800}.faq p{color:var(--muted)}
.footer{border-top:1px solid var(--line);padding:28px 0;color:#8398b4;font-size:13px}
@media(max-width:800px){.nav nav{display:none}.grid,.tabs{grid-template-columns:1fr 1fr}}
@media(max-width:520px){.grid,.checks,.sequence{grid-template-columns:1fr}}