.lch-theme-dark{--lch-bg:#0c0e14;--lch-bg-card:#141721;--lch-bg-section-border:#1e2433;--lch-bg-stat-card:#ffffff08;--lch-bg-prob-row:#141721;--lch-bg-prob-row-hover:#1a1e2b;--lch-bg-tag:#ffffff0d;--lch-bg-cta:radial-gradient(circle at center,#f973161a 0%,#0f111ce6 100%);--lch-bg-skeleton:#1e2337;--lch-text-primary:#f1f5f9;--lch-text-secondary:#94a3b8;--lch-text-muted:#64748b;--lch-text-id:#64748b;--lch-text-tag:#94a3b8;--lch-text-prob-title:#f1f5f9;--lch-text-prob-title-hover:#f97316;--lch-text-section-title:#fff;--lch-text-stat-num:#f97316;--lch-text-stat-label:#64748b;--lch-text-view-more:#f97316;--lch-text-view-more-hover:#ea580c;--lch-border:#232838;--lch-border-prob-row:#232838;--lch-border-prob-row-hover:#f97316;--lch-border-stat-card:#ffffff14;--lch-badge-bg:#f973161f;--lch-badge-border:#f973164d;--lch-badge-color:#f97316;--lch-shadow-prob-hover:0 10px 25px -5px #00000080,0 0 20px -5px #f9731626;--lch-solve-bg:#f973161f;--lch-solve-color:#f97316;--lch-solve-border:#f973164d;--lch-solve-hover-bg:#f97316;--lch-solve-hover-color:#fff;--lch-diff-easy-color:#00b8a3;--lch-diff-easy-bg:#00b8a31f;--lch-diff-easy-border:#00b8a340;--lch-diff-medium-color:#ffc01e;--lch-diff-medium-bg:#ffc01e1f;--lch-diff-medium-border:#ffc01e40;--lch-diff-hard-color:#ff375f;--lch-diff-hard-bg:#ff375f1f;--lch-diff-hard-border:#ff375f40;--lch-cta-title-color:#fff;--lch-cta-desc-color:#94a3b8;--lch-cta-border:#232838;--lch-cta-btn-bg:linear-gradient(135deg,#f97316 0%,#ea580c 100%);--lch-cta-btn-shadow:0 10px 25px -5px #f9731666;--lch-cta-btn-shadow-hover:0 15px 30px -5px #f973168c}.lch-theme-light{--lch-bg:#f8f9fb;--lch-bg-card:#fff;--lch-bg-section-border:#e2e8f0;--lch-bg-stat-card:#fff;--lch-bg-prob-row:#fff;--lch-bg-prob-row-hover:#fff7ed;--lch-bg-tag:#f1f5f9;--lch-bg-cta:linear-gradient(180deg,#fff7ed 0%,#fff 100%);--lch-bg-skeleton:#e8edf5;--lch-text-primary:#0f172a;--lch-text-secondary:#334155;--lch-text-muted:#64748b;--lch-text-id:#64748b;--lch-text-tag:#334155;--lch-text-prob-title:#0f172a;--lch-text-prob-title-hover:#ea580c;--lch-text-section-title:#0f172a;--lch-text-stat-num:#ea580c;--lch-text-stat-label:#64748b;--lch-text-view-more:#ea580c;--lch-text-view-more-hover:#c2410c;--lch-border:#e2e8f0;--lch-border-prob-row:#e2e8f0;--lch-border-prob-row-hover:#ea580c;--lch-border-stat-card:#e2e8f0;--lch-badge-bg:#fff7ed;--lch-badge-border:#fed7aa;--lch-badge-color:#ea580c;--lch-shadow-prob-hover:0 8px 20px -4px #00000014,0 0 0 1px #f9731626;--lch-solve-bg:#fff7ed;--lch-solve-color:#f97316;--lch-solve-border:#fed7aa;--lch-solve-hover-bg:#f97316;--lch-solve-hover-color:#fff;--lch-diff-easy-color:#059669;--lch-diff-easy-bg:#ecfdf5;--lch-diff-easy-border:#a7f3d0;--lch-diff-medium-color:#d97706;--lch-diff-medium-bg:#fffbeb;--lch-diff-medium-border:#fde68a;--lch-diff-hard-color:#dc2626;--lch-diff-hard-bg:#fef2f2;--lch-diff-hard-border:#fecaca;--lch-cta-title-color:#0f172a;--lch-cta-desc-color:#64748b;--lch-cta-border:#e2e8f0;--lch-cta-btn-bg:linear-gradient(135deg,#f97316 0%,#ea580c 100%);--lch-cta-btn-shadow:0 10px 25px -5px #f9731659;--lch-cta-btn-shadow-hover:0 15px 30px -5px #f9731680}.lch-wrapper{background-color:var(--lch-bg);min-height:100vh;color:var(--lch-text-primary);flex-direction:column;font-family:-apple-system,BlinkMacSystemFont,SF Pro Display,SF Pro Text,Inter,sans-serif;transition:background-color .25s,color .25s;display:flex}.lch-main{box-sizing:border-box;flex:1;width:100%;max-width:1100px;margin:0 auto;padding:3rem 1.5rem 5rem}.lch-hero{text-align:center;margin-bottom:3.5rem}.lch-hero-logo-wrap{justify-content:center;margin-bottom:1.5rem;display:flex}.lch-hero-logo{object-fit:contain;filter:drop-shadow(0 0 28px #f9731673);border-radius:12px;width:88px;height:88px;transition:transform .3s cubic-bezier(.4,0,.2,1),filter .3s}.lch-hero-logo:hover{filter:drop-shadow(0 0 45px #f97316a6);transform:scale(1.08)rotate(2deg)}.lch-badge{background:var(--lch-badge-bg);border:1px solid var(--lch-badge-border);color:var(--lch-badge-color);text-transform:uppercase;letter-spacing:1px;border-radius:9999px;align-items:center;gap:.5rem;margin-bottom:1.25rem;padding:.4rem 1rem;font-size:.78rem;font-weight:700;display:inline-flex}.lch-title{letter-spacing:-.03em;color:var(--lch-text-primary);margin:0 0 1.2rem;font-size:2.9rem;font-weight:900;line-height:1.15}.lch-title-gradient{background:linear-gradient(135deg,#f97316 0%,#fb923c 50%,#fbbf24 100%);-webkit-text-fill-color:transparent;-webkit-background-clip:text;background-clip:text}.lch-subtitle{color:var(--lch-text-secondary);max-width:650px;margin:0 auto 2rem;font-size:1.1rem;line-height:1.65}.lch-stats-row{flex-wrap:wrap;justify-content:center;gap:1.25rem;display:flex}.lch-stat-card{background:var(--lch-bg-stat-card);border:1px solid var(--lch-border-stat-card);border-radius:14px;flex-direction:column;align-items:center;padding:1rem 1.75rem;transition:border-color .2s;display:flex}.lch-stat-card:hover{border-color:#f973164d}.lch-stat-num{color:var(--lch-text-stat-num);font-size:1.55rem;font-weight:800}.lch-stat-label{color:var(--lch-text-stat-label);text-transform:uppercase;letter-spacing:.5px;margin-top:.25rem;font-size:.78rem}.lch-section-header{border-bottom:1px solid var(--lch-bg-section-border);justify-content:space-between;align-items:center;margin-bottom:1.5rem;padding-bottom:.75rem;display:flex}.lch-section-title{color:var(--lch-text-section-title);align-items:center;gap:.6rem;margin:0;font-size:1.35rem;font-weight:700;display:flex}.lch-section-title svg{color:#f97316}.lch-view-more-link{color:var(--lch-text-view-more);align-items:center;gap:.4rem;font-size:.9rem;font-weight:600;text-decoration:none;transition:all .2s;display:inline-flex}.lch-view-more-link:hover{color:var(--lch-text-view-more-hover);transform:translate(3px)}.lch-skeleton-list{flex-direction:column;gap:.85rem;margin-bottom:2.5rem;display:flex}.lch-skeleton-row{border-radius:12px;height:76px}.lch-shimmer{background:var(--lch-bg-skeleton);background-size:200% 100%;animation:1.4s infinite lch-shimmer-anim}@keyframes lch-shimmer-anim{0%{opacity:1}50%{opacity:.5}to{opacity:1}}.lch-problems-grid{flex-direction:column;gap:.75rem;margin-bottom:2.5rem;display:flex}.lch-prob-row{background:var(--lch-bg-prob-row);border:1px solid var(--lch-border-prob-row);color:inherit;border-radius:13px;justify-content:space-between;align-items:center;gap:1rem;padding:1rem 1.5rem;text-decoration:none;transition:all .2s cubic-bezier(.4,0,.2,1);display:flex}.lch-prob-row:hover{background:var(--lch-bg-prob-row-hover);border-color:var(--lch-border-prob-row-hover);box-shadow:var(--lch-shadow-prob-hover);transform:translateY(-2px)}.lch-prob-left{flex:1;align-items:center;gap:1.25rem;min-width:0;display:flex}.lch-prob-id{color:var(--lch-text-id);text-align:right;flex-shrink:0;width:32px;font-family:SF Mono,monospace;font-size:.95rem;font-weight:700}.lch-prob-info{flex-direction:column;gap:.35rem;min-width:0;display:flex}.lch-prob-title{color:var(--lch-text-prob-title);text-overflow:ellipsis;white-space:nowrap;margin:0;font-size:1rem;font-weight:600;transition:color .15s;overflow:hidden}.lch-prob-row:hover .lch-prob-title{color:var(--lch-text-prob-title-hover)}.lch-prob-tags{flex-wrap:wrap;gap:.4rem;display:flex}.lch-prob-tag{background:var(--lch-bg-tag);color:var(--lch-text-tag);border-radius:5px;padding:.15rem .5rem;font-size:.7rem;font-weight:500}.lch-prob-right{flex-shrink:0;align-items:center;gap:1rem;display:flex}.lch-diff-badge{border-radius:9999px;padding:.25rem .7rem;font-size:.73rem;font-weight:700;display:inline-block}.lch-diff-easy{color:var(--lch-diff-easy-color);background:var(--lch-diff-easy-bg);border:1px solid var(--lch-diff-easy-border)}.lch-diff-medium{color:var(--lch-diff-medium-color);background:var(--lch-diff-medium-bg);border:1px solid var(--lch-diff-medium-border)}.lch-diff-hard{color:var(--lch-diff-hard-color);background:var(--lch-diff-hard-bg);border:1px solid var(--lch-diff-hard-border)}.lch-solve-btn{background:var(--lch-solve-bg);color:var(--lch-solve-color);border:1px solid var(--lch-solve-border);border-radius:9px;align-items:center;gap:.4rem;padding:.42rem .9rem;font-size:.83rem;font-weight:600;transition:all .2s;display:inline-flex}.lch-prob-row:hover .lch-solve-btn{background:var(--lch-solve-hover-bg);color:var(--lch-solve-hover-color);border-color:#0000}.lch-view-all-cta{text-align:center;background:var(--lch-bg-cta);border:1px solid var(--lch-cta-border);border-radius:18px;padding:2.5rem}.lch-cta-title{color:var(--lch-cta-title-color);margin:0 0 .5rem;font-size:1.25rem;font-weight:700}.lch-cta-desc{color:var(--lch-cta-desc-color);margin:0 0 1.5rem;font-size:.95rem}.lch-cta-btn{background:var(--lch-cta-btn-bg);color:#fff;box-shadow:var(--lch-cta-btn-shadow);border-radius:12px;align-items:center;gap:.6rem;padding:.85rem 2rem;font-size:1rem;font-weight:700;text-decoration:none;transition:all .2s;display:inline-flex}.lch-cta-btn:hover{box-shadow:var(--lch-cta-btn-shadow-hover);transform:translateY(-2px)}@media (max-width:768px){.lch-main{padding:2rem 1rem 5rem}.lch-title{font-size:2.1rem}.lch-stats-row{gap:.75rem}.lch-stat-card{padding:.8rem 1.25rem}.lch-prob-row{flex-direction:column;align-items:flex-start}.lch-prob-right{border-top:1px solid var(--lch-bg-section-border);justify-content:space-between;width:100%;margin-top:.5rem;padding-top:.6rem}.lch-section-header{flex-direction:column;align-items:flex-start;gap:.5rem}}