/* Core navigation contract: book, tools, cases; independent training and LoopOS. */
.csi-core-header{display:flex;align-items:center;gap:30px;min-height:88px;padding:12px 40px;background:#141918;color:#f3f0e7;border-bottom:1px solid #333834;position:relative;z-index:30;font-family:"Avenir Next","PingFang SC","Microsoft YaHei",sans-serif}
.csi-core-brand{display:flex;align-items:center;gap:15px;flex-shrink:0;text-decoration:none;color:#f3f0e7}
.csi-core-brand img{width:68px;height:59px}.csi-core-brand strong{display:block;font-size:19px;font-weight:400;letter-spacing:3px;line-height:1.45}.csi-core-brand small{display:block;font-size:9px;letter-spacing:1.2px;color:#b3bcb0;margin-top:5px;line-height:1.5}
.csi-core-desktop{margin-left:auto;display:flex;align-items:center;gap:30px}.csi-core-primary,.csi-core-secondary{display:flex;gap:28px;align-items:center}.csi-core-primary a{position:relative;display:block;padding:12px 0;font-size:14px;color:#d5d8ce;line-height:1.5;white-space:nowrap;text-decoration:none}.csi-core-primary a[aria-current]{color:#dda17b}.csi-core-primary a[aria-current]:after{content:"";position:absolute;bottom:3px;left:0;right:0;height:2px;background:#dda17b}.csi-core-secondary{border-left:1px solid #3f4b42;padding-left:28px;gap:20px}.csi-core-secondary a{display:block;font-size:12px;color:#b3bcb0;padding:12px 0;line-height:1.5;white-space:nowrap;text-decoration:none}
.csi-core-menu{display:none;margin-left:auto}.csi-core-menu summary{display:flex;gap:16px;align-items:center;min-height:44px;padding:10px;list-style:none;cursor:pointer;font-size:13px;line-height:1.5}.csi-core-menu summary::-webkit-details-marker{display:none}.csi-core-panel{position:absolute;left:0;right:0;top:100%;padding:20px 24px 28px;background:#141918;border-top:1px solid #3f4b42;box-shadow:0 18px 24px #14191820}.csi-core-panel .csi-core-primary,.csi-core-panel .csi-core-secondary{display:grid;gap:0;border:0;padding:0}.csi-core-panel nav a{min-height:44px;border-bottom:1px solid #3f4b42}.csi-core-panel .csi-core-secondary{margin-top:24px}.csi-core-panel p{font-size:11px;color:#b3bcb0;margin:0 0 8px}.csi-core-header :focus-visible{outline:2px solid #abd0c6;outline-offset:4px}
@media(max-width:1100px){.csi-core-desktop{display:none}.csi-core-menu{display:block}.csi-core-header{padding:10px 24px}}
@media(max-width:640px){.csi-core-header{min-height:76px;padding:10px 20px;gap:16px}.csi-core-brand{gap:10px}.csi-core-brand img{width:50px;height:45px}.csi-core-brand strong{font-size:17px;letter-spacing:2px}.csi-core-brand small{font-size:8px;letter-spacing:0}}
@media print{.csi-core-header{display:none}}