:root{--bg:#fafaf9;--card-bg:#fff;--text:#1e1e1e;--text-secondary:#6b7280;--text-muted:#9ca3af;--mint:#4a9e8e;--mint-dark:#3b8b7d;--mint-light:#e8f5f1;--navy:#2c3e5c;--border:#eeedeb;--shadow-xs:0 1px 2px #00000008;--shadow-sm:0 1px 3px #0000000d, 0 1px 2px #00000008;--shadow-md:0 4px 12px #0000000f;--radius-sm:8px;--radius:12px;--radius-lg:16px;--font:-apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;--max-width:1040px}*,:before,:after{box-sizing:border-box;margin:0;padding:0}html{-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale;font-size:16px}body{font-family:var(--font);color:var(--text);background:var(--bg);flex-direction:column;min-height:100vh;line-height:1.65;display:flex}.container{max-width:var(--max-width);margin:0 auto;padding:0 24px}.hero{text-align:center;padding:64px 24px 48px}.hero-title{color:var(--navy);letter-spacing:1.5px;margin-bottom:12px;font-size:2rem;font-weight:800}.hero-question{color:var(--text-secondary);font-size:1.15rem;font-weight:400}.hero-safety{color:var(--text-muted);max-width:520px;margin-top:18px;margin-left:auto;margin-right:auto;font-size:.82rem;line-height:1.6}.loading-text{text-align:center;color:var(--text-muted);padding:80px 0;font-size:.95rem}.section-title{color:var(--navy);border-bottom:2px solid var(--border);align-items:center;gap:8px;margin-bottom:16px;padding-bottom:10px;font-size:1.1rem;font-weight:700;display:flex}.core-section{margin-bottom:40px}.core-cards{grid-template-columns:1fr 1fr;gap:20px;display:grid}.core-card{background:var(--card-bg);border-radius:var(--radius-lg);border:1px solid var(--border);box-shadow:var(--shadow-sm);cursor:default;padding:28px;transition:transform .2s,box-shadow .2s}.core-card:hover{box-shadow:var(--shadow-md);transform:translateY(-2px)}.core-card-header{align-items:center;gap:12px;margin-bottom:14px;display:flex}.core-card-icon{font-size:2.4rem;line-height:1}.core-card-title{color:var(--navy);font-size:1.25rem;font-weight:700}.core-card-desc{color:var(--text-secondary);margin-bottom:18px;font-size:.9rem;line-height:1.5}.core-card-tags{flex-wrap:wrap;gap:8px;display:flex}.core-tag{background:var(--mint-light);color:var(--mint-dark);cursor:pointer;font-size:.85rem;font-weight:500;font-family:var(--font);border:none;border-radius:20px;padding:8px 16px;transition:background .15s,color .15s;display:inline-block}.core-tag:hover{background:var(--mint);color:#fff}.grid-section{margin-bottom:40px}.category-grid{grid-template-columns:repeat(3,1fr);gap:16px;display:grid}.grid-card{background:var(--card-bg);border-radius:var(--radius);border:1px solid var(--border);box-shadow:var(--shadow-xs);padding:22px;transition:transform .2s,box-shadow .2s}.grid-card:hover{box-shadow:var(--shadow-sm);transform:translateY(-2px)}.grid-card-header{align-items:center;gap:10px;margin-bottom:8px;display:flex}.grid-card-icon{font-size:1.8rem;line-height:1}.grid-card-title{color:var(--navy);font-size:1.05rem;font-weight:700}.grid-card-desc{color:var(--text-secondary);margin-bottom:14px;font-size:.84rem;line-height:1.5}.grid-card-videos{flex-direction:column;gap:6px;display:flex}.grid-video-item{border-radius:var(--radius-sm);cursor:pointer;color:var(--text);font-size:.88rem;font-family:var(--font);text-align:left;background:0 0;border:none;align-items:center;gap:8px;width:100%;padding:8px 10px;transition:background .12s;display:flex}.grid-video-item:hover{background:var(--mint-light)}.grid-video-dot{background:var(--mint);border-radius:50%;flex-shrink:0;width:6px;height:6px}.grid-video-title{white-space:nowrap;text-overflow:ellipsis;flex:1;overflow:hidden}.grid-video-duration{color:var(--text-muted);flex-shrink:0;font-size:.78rem}.compact-section{margin-bottom:60px}.compact-list{grid-template-columns:repeat(3,1fr);gap:16px;display:grid}.compact-card{background:var(--card-bg);border-radius:var(--radius);border:1px solid var(--border);padding:20px;transition:transform .2s,box-shadow .2s}.compact-card:hover{box-shadow:var(--shadow-sm);transform:translateY(-1px)}.compact-card-header{align-items:center;gap:8px;margin-bottom:6px;display:flex}.compact-card-icon{font-size:1.3rem;line-height:1}.compact-card-title{color:var(--navy);font-size:.95rem;font-weight:700}.compact-card-desc{color:var(--text-secondary);margin-bottom:12px;font-size:.8rem;line-height:1.5}.compact-video-list{flex-direction:column;gap:4px;display:flex}.compact-video-item{cursor:pointer;color:var(--text);font-size:.82rem;font-family:var(--font);text-align:left;background:0 0;border:none;border-radius:6px;align-items:center;gap:6px;width:100%;padding:5px 8px;transition:background .12s;display:flex}.compact-video-item:hover{background:var(--mint-light)}.compact-video-dot{background:var(--mint);opacity:.6;border-radius:50%;flex-shrink:0;width:5px;height:5px}.compact-video-title{white-space:nowrap;text-overflow:ellipsis;flex:1;overflow:hidden}.compact-video-duration{color:var(--text-muted);flex-shrink:0;font-size:.75rem}.welcome-overlay{z-index:200;-webkit-backdrop-filter:blur(4px);backdrop-filter:blur(4px);background:#00000080;justify-content:center;align-items:center;padding:20px;display:flex;position:fixed;inset:0}.welcome-overlay.hidden{display:none}.welcome-card{border-radius:var(--radius-lg);text-align:center;background:#fff;width:100%;max-width:420px;padding:36px 32px 28px;box-shadow:0 20px 60px #0000002e}.welcome-icon{margin-bottom:12px;font-size:3rem;display:block}.welcome-card h2{color:var(--navy);margin-bottom:16px;font-size:1.25rem;font-weight:700}.welcome-card p{color:var(--text-secondary);text-align:left;margin-bottom:8px;font-size:.9rem;line-height:1.7}.welcome-card p strong{color:var(--navy)}.welcome-muted{color:var(--text-muted)!important;margin-top:4px!important;margin-bottom:20px!important;font-size:.8rem!important}.welcome-btn{background:var(--mint);color:#fff;font-size:.95rem;font-weight:600;font-family:var(--font);cursor:pointer;border:none;border-radius:50px;padding:12px 32px;transition:background .15s,transform .1s;display:inline-block}.welcome-btn:hover{background:var(--mint-dark);transform:translateY(-1px)}.modal{z-index:100;justify-content:center;align-items:center;display:none;position:fixed;inset:0}.modal.active{display:flex}.modal-backdrop{-webkit-backdrop-filter:blur(2px);backdrop-filter:blur(2px);background:#00000073;position:absolute;inset:0}.modal-panel{background:var(--card-bg);border-radius:var(--radius-lg);z-index:1;width:90%;max-width:800px;position:relative;overflow:hidden;box-shadow:0 20px 60px #00000026}.modal-close{z-index:2;color:#fff;cursor:pointer;background:#00000080;border:none;border-radius:50%;justify-content:center;align-items:center;width:36px;height:36px;font-size:1.4rem;line-height:1;transition:background .15s;display:flex;position:absolute;top:12px;right:16px}.modal-close:hover{background:#000000b3}.video-wrapper{background:#000}.video-wrapper iframe{aspect-ratio:16/9;border:none;width:100%;height:auto;display:block}.modal-info{padding:18px 24px 22px}.modal-info h3{color:var(--navy);margin-bottom:4px;font-size:1.05rem;font-weight:700}.modal-info p{color:var(--text-secondary);font-size:.88rem;line-height:1.5}.footer{text-align:center;border-top:1px solid var(--border);color:var(--text-muted);margin-top:auto;padding:28px 24px;font-size:.82rem}.footer .container{flex-direction:column;gap:6px;display:flex}.footer-brand{color:var(--text-secondary);font-size:.92rem}.footer-brand strong{color:var(--navy)}.footer-note{color:var(--text-muted);font-size:.78rem}.footer-copy{font-size:.76rem}@media (width<=900px){.core-cards{grid-template-columns:1fr;gap:14px}.category-grid,.compact-list{grid-template-columns:repeat(2,1fr)}}@media (width<=600px){.hero{padding:40px 16px 32px}.hero-title{font-size:1.55rem}.hero-question{font-size:1rem}.container{padding:0 16px}.core-card{padding:22px 20px}.core-card-icon{font-size:2rem}.core-card-title{font-size:1.1rem}.category-grid{grid-template-columns:1fr;gap:12px}.compact-list{grid-template-columns:1fr;gap:10px}.modal-panel{border-radius:var(--radius);width:95%}.modal-info{padding:14px 16px 18px}.section-title{font-size:1rem}}