:root{--color-bg-main: #121212;--color-bg-surface: #1E1E1E;--color-bg-alt: #2A2A2A;--color-brand-orange: #E85D04;--color-brand-orange-hover: #F48C06;--color-text-primary: #FFFFFF;--color-text-secondary: #A0A0A0;--color-text-muted: #808080;--color-text-inverse: #121212;--color-text-accent: #E85D04;--color-text-success: #28a745;--color-text-warning: #ffc107;--color-text-error: #dc3545;--color-border: #333333;--color-overlay-dark: rgba(0, 0, 0, .8);--color-overlay-light: rgba(255, 255, 255, .1);--color-surface-subtle: rgba(255, 255, 255, .08);--color-border-subtle: rgba(255, 255, 255, .1);--color-brand-shadow: rgba(232, 93, 4, .3);--color-brand-glow: rgba(232, 93, 4, .15);--color-shadow-default: rgba(0, 0, 0, .1);--color-shadow-elevated: rgba(0, 0, 0, .2);--space-1: .25rem;--space-2: .5rem;--space-3: .75rem;--space-4: 1rem;--space-6: 1.5rem;--space-8: 2rem;--space-12: 3rem;--font-family-primary: -apple-system, BlinkMacSystemFont, "Segoe UI", "Roboto", sans-serif;--font-family-mono: "SFMono-Regular", "Monaco", "Consolas", "Liberation Mono", "Courier New", monospace;--font-size-xs: .75rem;--font-size-sm: .875rem;--font-size-base: 1rem;--font-size-md: 1.125rem;--font-size-lg: 1.25rem;--font-size-xl: 1.5rem;--font-size-2xl: 1.875rem;--font-size-3xl: 2.25rem;--font-size-4xl: 3rem;--font-weight-light: 300;--font-weight-normal: 400;--font-weight-medium: 500;--font-weight-semibold: 600;--font-weight-bold: 700;--font-weight-extrabold: 800;--line-height-tight: 1.25;--line-height-snug: 1.375;--line-height-normal: 1.5;--line-height-relaxed: 1.625;--line-height-loose: 2;--letter-spacing-tighter: -.05em;--letter-spacing-tight: -.025em;--letter-spacing-normal: 0;--letter-spacing-wide: .025em;--letter-spacing-wider: .05em;--border-radius-small: 4px;--border-radius-large: 12px;--border-radius-base: 8px;--transition-base: all .2s ease;--shadow-sm: 0 1px 3px var(--color-shadow-default);--shadow-md: 0 4px 12px var(--color-shadow-default);--shadow-lg: 0 6px 20px var(--color-shadow-elevated);--shadow-brand: 0 4px 12px var(--color-brand-shadow);--shadow-brand-lg: 0 6px 20px rgba(232, 93, 4, .4)}body{margin:0;padding:0;font-family:var(--font-family-primary);font-size:var(--font-size-base);line-height:var(--line-height-normal);color:var(--color-text-primary);background-color:var(--color-bg-main)}#root{min-height:100vh}.app{min-height:100vh;display:flex;flex-direction:column}.landing-page{padding:var(--space-4)}.detail-page-body{min-height:100vh;background-color:var(--color-bg-main);color:var(--color-text-primary)}.two-column-layout{display:grid;grid-template-columns:45% 55%;gap:var(--space-8);max-width:1400px;margin:0 auto;padding:var(--space-4)}.left-column,.right-column{display:flex;flex-direction:column;gap:var(--space-6)}.centered{text-align:center}.btn{display:flex;align-items:center;justify-content:center;padding:var(--space-2) 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transparent;background-color:transparent;white-space:nowrap;min-width:fit-content;box-sizing:border-box}.btn:disabled{opacity:.5;cursor:not-allowed;transform:none}.btn--secondary{background-color:var(--color-bg-alt);color:var(--color-text-secondary);border-color:var(--color-border)}.btn--secondary:hover:not(:disabled){color:var(--color-text-primary);background-color:var(--color-bg-surface);border-color:var(--color-border);transform:translateY(-1px)}.btn--primary{background-color:var(--color-brand-orange);color:#fff;border-color:var(--color-brand-orange)}.btn--primary:hover:not(:disabled){background-color:var(--color-brand-orange-hover);transform:translateY(-1px);box-shadow:var(--shadow-brand)}.btn--ghost{background-color:transparent;color:var(--color-text-secondary);border-color:transparent}.btn--ghost:hover:not(:disabled){color:var(--color-text-primary);background-color:var(--color-bg-alt);border-color:var(--color-border)}.btn--small{padding:var(--space-1) var(--space-3);font-size:var(--font-size-xs);height:32px}.btn--large{padding:var(--space-3) var(--space-6);font-size:var(--font-size-base);height:44px}.btn--gradient{background:linear-gradient(135deg,var(--color-brand-orange) 0%,#F48C06 50%,#FF9500 100%);color:#fff;border:none;position:relative;overflow:hidden;box-shadow:0 2px 6px #e85d0433;will-change:transform,box-shadow}.btn--gradient:before{content:"";position:absolute;top:0;left:-100%;width:100%;height:100%;background:linear-gradient(90deg,transparent,rgba(255,255,255,.1),transparent);transition:left .6s ease}.btn--gradient:hover:not(:disabled){background:linear-gradient(135deg,#f48c06,#ff9500,#ffb01f);transform:translateY(-2px);box-shadow:var(--shadow-brand-lg)}.btn--gradient:hover:before{left:100%}.btn--circular{width:48px;height:48px;padding:0;border-radius:50%;min-width:48px}.related-openings-tab{margin-top:var(--space-6)}.tab-header{display:flex;align-items:center;gap:var(--space-3);margin-bottom:var(--space-3)}.mainline-callout{background:var(--color-surface-subtle);padding:var(--space-2) var(--space-3);border-left:3px solid var(--color-brand-orange);border-radius:var(--border-radius-small);font-size:var(--font-size-sm);margin:var(--space-3) 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var(--color-border-subtle);border-radius:var(--border-radius-base);transition:var(--transition-base)}.variation-item__link{width:100%;display:flex;gap:var(--space-2);align-items:center;justify-content:flex-start;border:none;background:transparent;color:var(--color-text-primary);text-align:left;padding:var(--space-2) var(--space-3);font-size:var(--font-size-sm);cursor:pointer}.variation-item__link:hover{background:var(--color-bg-surface)}.variation-item__name{flex:1;font-weight:var(--font-weight-medium)}.variation-item__games{font-size:var(--font-size-xs);color:var(--color-text-secondary)}.related-teaser{padding:var(--space-3);border:1px solid var(--color-border-subtle);border-radius:var(--border-radius-base);background:var(--color-bg-surface)}.related-teaser__header{display:flex;align-items:baseline;justify-content:space-between;margin-bottom:var(--space-2);gap:var(--space-3)}.related-teaser__title-group{display:flex;align-items:center;gap:var(--space-2)}.related-teaser__descriptor{font-size:var(--font-size-xs);color:var(--color-text-muted);margin:0}.related-teaser__list{list-style:none;padding:0;margin:0 0 var(--space-2) 0;display:flex;flex-direction:column;gap:var(--space-2)}.related-teaser__item--mainline{border:1px solid var(--color-border-subtle);border-radius:var(--border-radius-small);background:var(--color-surface-subtle)}.related-teaser__body{position:relative}.related-teaser__body .related-teaser__list{padding-bottom:0;position:relative}.related-teaser__body.is-collapsed .related-teaser__list{max-height:188px;overflow:hidden}.related-teaser__body.is-expanded .related-teaser__list{max-height:420px;overflow:auto;padding-right:4px}.related-teaser__list{will-change:contents}.related-teaser__list>.related-teaser__item{opacity:1;transform:translateY(0);transition:opacity .32s ease,transform .36s ease}.related-teaser__toggle{transition:background-color .16s ease,color .16s ease,border-color .16s ease}.related-teaser__toggle-icon:before,.related-teaser__toggle-icon:after{transition:transform .26s cubic-bezier(.4,0,.2,1)}@media (prefers-reduced-motion: reduce){.related-teaser__list,.related-teaser__toggle-icon:before,.related-teaser__toggle-icon:after,.related-teaser__list>.related-teaser__item{transition:none!important}}.view-all-link{font-weight:var(--font-weight-medium)}.related-teaser__body.is-expanded+.related-teaser__footer .view-all-link{align-self:flex-start}@media (max-width: 720px){.related-teaser__body.is-expanded .related-teaser__list{max-height:60vh}}.related-teaser__footer{display:flex;justify-content:flex-start}.related-teaser__toggle{display:inline-flex;align-items:center;gap:6px;background:var(--color-bg-alt);border:1px solid var(--color-border-subtle);color:var(--color-text-secondary);font-size:var(--font-size-xs);padding:4px 10px;border-radius:var(--border-radius-small);cursor:pointer;transition:var(--transition-base);line-height:1}.related-teaser__toggle:hover{background:var(--color-bg-surface);color:var(--color-text-primary)}.related-teaser__toggle:focus-visible{outline:2px solid var(--color-brand-orange);outline-offset:2px}.related-teaser__toggle-icon{width:10px;height:10px;position:relative}.related-teaser__toggle-icon:before,.related-teaser__toggle-icon:after{content:"";position:absolute;left:0;top:50%;width:100%;height:2px;background:currentColor;transition:transform .25s ease;transform-origin:center}.related-teaser__toggle-icon:before{transform:translateY(-50%) rotate(45deg)}.related-teaser__toggle-icon:after{transform:translateY(-50%) rotate(-45deg)}.related-teaser__toggle[aria-expanded=true] .related-teaser__toggle-icon:before{transform:translateY(-50%) rotate(135deg)}.related-teaser__toggle[aria-expanded=true] .related-teaser__toggle-icon:after{transform:translateY(-50%) rotate(45deg)}.related-teaser__count{opacity:.85}.opening-card,.video-card{contain:layout style}.chessboard-container{contain:layout}.detail-header{background-color:var(--color-bg-surface);border-bottom:1px solid var(--color-border);padding:var(--space-3) 0;box-shadow:0 2px 12px #0000001a;-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px);position:sticky;top:0;z-index:100;transition:transform .3s ease-in-out}.detail-header.mobile-hidden{transform:translateY(-100%)}.detail-header-container{display:flex;align-items:center;justify-content:space-between;max-width:1400px;margin:0 auto;padding:0 var(--space-4);min-height:52px;position:relative}.mobile-menu-toggle,.back-text-mobile{display:none}.back-text-desktop{display:inline}.floating-back-btn{position:fixed;top:var(--space-4);left:var(--space-4);background:#000c;color:#fff;border:none;border-radius:50%;width:48px;height:48px;display:none;align-items:center;justify-content:center;font-size:var(--font-size-lg);cursor:pointer;z-index:1000;-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px);box-shadow:0 4px 12px #0000004d;transition:all .2s ease}.header-left{display:flex;align-items:center;justify-content:flex-start;flex:0 0 auto}.header-center{position:absolute;left:50%;top:50%;transform:translate(-50%,-50%);z-index:1}.header-right{display:flex;align-items:center;justify-content:flex-end;gap:var(--space-3);flex:0 1 auto;min-width:0}.back-button{color:var(--color-text-secondary);text-decoration:none;transition:all .2s ease;font-size:var(--font-size-sm);font-weight:var(--font-weight-medium);padding:var(--space-2) var(--space-4);border-radius:var(--border-radius-base);border:1px solid transparent;background-color:transparent;display:flex;align-items:center;gap:var(--space-2);white-space:nowrap}.back-button:hover{color:var(--color-text-primary);background-color:var(--color-bg-alt);border-color:var(--color-border);transform:translate(-2px)}.site-title{color:var(--color-text-primary);text-decoration:none;font-size:var(--font-size-xl);font-weight:var(--font-weight-semibold);line-height:var(--line-height-tight);letter-spacing:var(--letter-spacing-tight);transition:all .2s ease;position:relative}.site-title:after{content:"";position:absolute;bottom:-2px;left:50%;width:0;height:2px;background:linear-gradient(90deg,var(--color-brand-orange),#F48C06);transition:all .3s ease;transform:translate(-50%);border-radius:1px}.site-title:hover{color:var(--color-brand-orange);transform:translateY(-1px)}.site-title:hover:after{width:100%}.page-title-area{padding:var(--space-6) var(--space-4) var(--space-8) var(--space-4);background:linear-gradient(145deg,var(--color-bg-surface) 0%,rgba(30,30,30,.95) 100%);border-bottom:1px solid rgba(232,93,4,.2);position:relative}.page-title-area:before{content:"";position:absolute;top:0;left:50%;transform:translate(-50%);width:60px;height:2px;background:linear-gradient(90deg,var(--color-brand-orange) 0%,rgba(232,93,4,.3) 100%);border-radius:1px}.opening-name{font-size:var(--font-size-3xl);font-weight:var(--font-weight-bold);line-height:var(--line-height-tight);margin:0 0 var(--space-6) 0;color:var(--color-text-primary);letter-spacing:var(--letter-spacing-tight);text-align:center;position:relative}.complexity-and-tags{display:flex;justify-content:center;align-items:center;gap:var(--space-3);flex-wrap:wrap;margin-top:var(--space-2)}.eco-pill,.style-pill,.complexity-tag,.style-tag{display:inline-flex;align-items:center;padding:var(--space-1) var(--space-3);border-radius:var(--border-radius-base);font-size:var(--font-size-xs);font-weight:var(--font-weight-medium);letter-spacing:.2px;text-transform:capitalize;border:1px solid transparent;transition:all .2s ease;line-height:1}.eco-pill{background-color:#50505033;color:#ffffffb3;border-color:#5050504d;font-family:var(--font-family-mono);text-transform:uppercase;font-weight:var(--font-weight-semibold);letter-spacing:.5px}.style-pill,.style-tag{background-color:#ffffff14;color:var(--color-text-muted);border-color:#ffffff1a}.chessboard-section{background-color:var(--color-bg-surface);border-radius:var(--border-radius-large);padding:var(--space-6);border:1px solid rgba(255,255,255,.1);box-shadow:0 6px 20px #0003}.chessboard-container{display:flex;justify-content:center;margin-bottom:var(--space-4);position:relative}.chessboard-fen-utilities{border-top:1px solid rgba(255,255,255,.1);padding-top:var(--space-4);margin-top:var(--space-2)}.chessboard-fen-utilities .fen-utilities-label{color:var(--color-text-secondary);font-size:var(--font-size-xs);font-weight:var(--font-weight-semibold);margin-bottom:var(--space-3);display:block;text-transform:uppercase;letter-spacing:.5px}.chessboard-fen-utilities .fen-display{display:flex;gap:var(--space-2);align-items:center}.chessboard-fen-utilities .fen-input{flex:1;background-color:var(--color-bg-alt);color:var(--color-text-secondary);border:1px solid var(--color-border);border-radius:var(--border-radius-base);padding:0 var(--space-3);font-size:var(--font-size-xs);font-family:var(--font-family-mono);line-height:1;height:32px;box-sizing:border-box}.chessboard-fen-utilities .copy-btn,.chessboard-fen-utilities .analyze-btn{background-color:#e85d0426;color:var(--color-text-secondary);border:1px solid rgba(232,93,4,.25);border-radius:var(--border-radius-base);padding:0 var(--space-3);cursor:pointer;transition:var(--transition-base);text-decoration:none;font-size:var(--font-size-xs);font-weight:var(--font-weight-normal);white-space:nowrap;height:32px;display:flex;align-items:center;justify-content:center;box-sizing:border-box}.chessboard-fen-utilities .copy-btn:hover,.chessboard-fen-utilities .analyze-btn:hover{background-color:#e85d0440;color:var(--color-brand-orange);border-color:#e85d0466;transform:translateY(-1px)}.chessboard-navigation{display:flex;justify-content:center;gap:var(--space-2);margin-top:var(--space-4);padding-top:var(--space-4);border-top:1px solid rgba(255,255,255,.1)}.chessboard-nav-btn{background-color:var(--color-bg-alt);color:var(--color-text-secondary);border:1px solid var(--color-border);border-radius:var(--border-radius-base);padding:var(--space-2) var(--space-3);cursor:pointer;transition:var(--transition-base);font-size:var(--font-size-sm);font-weight:var(--font-weight-semibold);min-width:44px;height:36px;display:flex;align-items:center;justify-content:center;box-shadow:0 1px 3px #0000001a}.chessboard-nav-btn:hover:not(:disabled){background-color:var(--color-brand-orange);color:#fff;border-color:var(--color-brand-orange);transform:translateY(-1px);box-shadow:0 2px 6px #e85d044d}.chessboard-nav-btn:disabled{opacity:.3;cursor:not-allowed;color:var(--color-text-muted)}.opening-moves-list{background-color:var(--color-bg-surface);border-radius:var(--border-radius-large);padding:var(--space-4) var(--space-6);margin-top:var(--space-4);border:1px solid rgba(255,255,255,.08);box-shadow:0 2px 8px #0000001a}.opening-moves-list .title-subsection{margin:0 0 var(--space-4) 0;color:var(--color-text-primary);font-size:var(--font-size-lg);font-weight:var(--font-weight-semibold);letter-spacing:var(--letter-spacing-tight)}.moves-notation{display:flex;flex-wrap:wrap;gap:var(--space-2);align-items:start;max-height:120px;overflow-y:auto;padding:var(--space-2) 0;line-height:1.4}.move-pair{display:flex;align-items:center;gap:var(--space-1);flex-shrink:0;margin-right:var(--space-2)}.move-number{color:var(--color-text-secondary);font-weight:var(--font-weight-medium);font-size:var(--font-size-xs);min-width:20px;text-align:right;margin-right:var(--space-1);flex-shrink:0}.move-btn{background-color:var(--color-bg-alt);color:var(--color-text-primary);border:1px solid var(--color-border);border-radius:var(--border-radius-small);padding:var(--space-1) var(--space-2);cursor:pointer;transition:var(--transition-base);font-family:var(--font-family-mono);font-size:var(--font-size-xs);font-weight:var(--font-weight-medium);min-width:48px;text-align:center;white-space:nowrap;height:28px;display:flex;align-items:center;justify-content:center}.move-btn:hover{background-color:var(--color-brand-orange);border-color:var(--color-brand-orange);color:#fff;transform:translateY(-1px);box-shadow:0 2px 4px #e85d044d}.move-btn.active{background-color:var(--color-brand-orange);border-color:var(--color-brand-orange);color:#fff;font-weight:var(--font-weight-semibold);box-shadow:0 2px 6px #e85d0466}.moves-notation::-webkit-scrollbar{width:4px;height:4px}.moves-notation::-webkit-scrollbar-track{background:var(--color-bg-alt);border-radius:2px}.moves-notation::-webkit-scrollbar-thumb{background:var(--color-border);border-radius:2px}.moves-notation::-webkit-scrollbar-thumb:hover{background:var(--color-text-secondary)}.statistics-component{background-color:var(--color-bg-surface);border-radius:var(--border-radius-large);padding:var(--space-6);margin-bottom:var(--space-6);border:1px solid rgba(255,255,255,.1);box-shadow:0 4px 16px #0000001f}.statistics-component .title-subsection{margin:0 0 var(--space-6) 0;font-size:var(--font-size-xl);font-weight:var(--font-weight-semibold);color:var(--color-text-primary);letter-spacing:var(--letter-spacing-tight)}.statistics-bars{display:flex;flex-direction:column;gap:var(--space-4);margin-bottom:var(--space-6)}.stat-bar{display:flex;align-items:center;gap:var(--space-3);padding:var(--space-1) 0}.stat-label{font-size:var(--font-size-sm);color:var(--color-text-secondary);font-weight:var(--font-weight-medium);min-width:100px;flex-shrink:0}.bar-container{flex:1;height:14px;background:var(--color-bg-alt);border-radius:var(--border-radius-base);overflow:hidden;box-shadow:inset 0 1px 3px #0003}.bar-track{width:100%;height:100%;overflow:hidden}.bar-fill{height:100%;border-radius:var(--border-radius-base);transition:width .8s ease-out}.bar-fill.white-bar{background-color:#4ecdc4}.bar-fill.draw-bar{background-color:#ffa726}.bar-fill.black-bar{background-color:#ff7043}.game-results-bar{margin-top:var(--space-2)}.results-label-row{display:flex;justify-content:space-between;margin-bottom:var(--space-2);font-size:var(--font-size-xs)}.result-label{font-weight:var(--font-weight-medium);font-size:var(--font-size-xs)}.result-label.white-label{color:#4ecdc4}.result-label.draw-label{color:#ffa726}.result-label.black-label{color:#ff7043}.segmented-bar{display:flex;height:8px;background-color:var(--color-bg-alt);border-radius:var(--border-radius-small);overflow:hidden}.bar-segment{height:100%;transition:width .8s 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#e85d044d}.category-count{margin-left:var(--space-1);opacity:.8}.empty-state{text-align:center;padding:var(--space-12);color:var(--color-text-secondary)}.empty-state p{margin-bottom:var(--space-4);font-size:var(--font-size-lg)}.reset-filter-btn{background-color:var(--color-brand-orange);color:#fff;border:none;border-radius:var(--border-radius-base);padding:var(--space-3) var(--space-6);cursor:pointer;transition:var(--transition-base);font-weight:var(--font-weight-medium)}.reset-filter-btn:hover{background-color:var(--color-brand-orange-hover);transform:translateY(-1px)}.load-more-section{text-align:center;margin-top:var(--space-6);padding:var(--space-4)}.load-more-btn{background-color:var(--color-brand-blue);color:#fff;border:none;border-radius:var(--border-radius-base);padding:var(--space-3) var(--space-6);cursor:pointer;transition:var(--transition-base);font-weight:var(--font-weight-medium);font-size:var(--font-size-base)}.load-more-btn:hover{background-color:var(--color-brand-blue-dark);transform:translateY(-1px)}.view-all-cta{text-align:center;padding:var(--space-8) var(--space-4);max-width:1200px;margin:0 auto}.view-all-btn{background:linear-gradient(135deg,var(--color-bg-surface) 0%,var(--color-bg-alt) 100%);color:var(--color-text-primary);border:2px solid var(--color-border);border-radius:var(--border-radius-large);padding:var(--space-4) var(--space-8);cursor:pointer;transition:all .3s ease;font-weight:var(--font-weight-semibold);font-size:var(--font-size-md);text-decoration:none;display:inline-flex;align-items:center;gap:var(--space-2)}.view-all-btn:hover{border-color:var(--color-brand-orange);background:linear-gradient(135deg,var(--color-brand-orange) 0%,var(--color-brand-orange-hover) 100%);color:#fff;transform:translateY(-2px);box-shadow:0 8px 25px #e85d044d}.layout{min-height:100vh;display:flex;flex-direction:column}.main-nav{background-color:var(--color-bg-surface);border-bottom:1px solid var(--color-border);padding:var(--space-4) 0}.nav-container{max-width:1280px;margin:0 auto;padding:0 var(--space-4);display:flex;justify-content:space-between;align-items:center}.nav-logo h1{margin:0;color:var(--color-text-primary);font-size:var(--font-size-h3);font-weight:var(--font-weight-bold)}.nav-logo{text-decoration:none}.nav-links{display:flex;gap:var(--space-6)}.nav-link{color:var(--color-text-secondary);text-decoration:none;font-weight:var(--font-weight-medium);transition:var(--transition-base);padding:var(--space-2) var(--space-3);border-radius:var(--border-radius-base)}.nav-link:hover,.nav-link.active{color:var(--color-text-primary);background-color:var(--color-bg-alt)}.animate-on-hover{will-change:transform;transition:transform .2s ease}.animate-on-hover:hover{transform:translateY(-2px)}.animate-fade-in{will-change:opacity,transform;animation:fadeIn .6s ease-out}.animate-slide-in{will-change:opacity,transform;animation:cardSlideIn .5s ease-out forwards}.animate-skeleton{will-change:background-position;animation:skeleton-loading 1.5s infinite}.surface{background-color:var(--color-bg-surface);border-radius:var(--border-radius-large);border:1px solid var(--color-border-subtle);box-shadow:var(--shadow-md)}.surface--compact{padding:var(--space-4)}.surface--comfortable{padding:var(--space-6)}.interactive{transition:var(--transition-base);cursor:pointer;will-change:transform,box-shadow}.interactive:hover{transform:translateY(-2px);box-shadow:0 8px 24px var(--color-shadow-elevated)}.scrollable{overflow-y:auto}.scrollable::-webkit-scrollbar{width:6px;height:6px}.scrollable::-webkit-scrollbar-track{background:var(--color-bg-alt);border-radius:3px}.scrollable::-webkit-scrollbar-thumb{background:var(--color-border);border-radius:3px}.scrollable::-webkit-scrollbar-thumb:hover{background:var(--color-text-secondary)}.loading-state,.error-state{display:flex;flex-direction:column;align-items:center;justify-content:center;min-height:400px;text-align:center;color:var(--color-text-secondary)}.skeleton{background:linear-gradient(90deg,var(--color-bg-alt) 25%,var(--color-bg-surface) 50%,var(--color-bg-alt) 75%);background-size:200% 100%;animation:skeleton-loading 1.5s infinite;will-change:background-position}@keyframes skeleton-loading{0%{background-position:200% 0}to{background-position:-200% 0}}.skeleton-card{background-color:var(--color-bg-surface);border:1px solid var(--color-border);border-radius:var(--border-radius-large);padding:var(--space-6);margin-bottom:var(--space-6)}.skeleton-title{height:24px;border-radius:var(--border-radius-base);margin-bottom:var(--space-4);width:70%}.skeleton-text{height:14px;border-radius:var(--border-radius-base);margin-bottom:var(--space-2)}.skeleton-text.short{width:40%}.skeleton-text.medium{width:60%}.skeleton-text.long{width:80%}.skeleton-bar{height:8px;border-radius:var(--border-radius-small);margin-top:var(--space-2);width:100%}.back-link{color:var(--color-brand-orange);text-decoration:none;margin-top:var(--space-4)}.back-link:hover{color:var(--color-brand-orange-hover)}.loading-spinner{display:inline-block;width:2rem;height:2rem;border:3px solid var(--color-border);border-radius:50%;border-top-color:var(--color-brand-orange);animation:spin 1s ease-in-out infinite}@keyframes spin{to{transform:rotate(360deg)}}.btn-hover-lift{will-change:transform}.btn-hover-lift:hover{transform:translateY(-1px)}.card-interactive{will-change:transform,box-shadow;transition:transform .2s ease,box-shadow .2s ease}.card-interactive:hover{transform:translateY(-2px);box-shadow:var(--shadow-lg)}@media (prefers-reduced-motion: reduce){.animate-fade-in,.animate-slide-in,.animate-skeleton,.animate-on-hover,.interactive,.btn,.opening-card{animation:none;transition:none;will-change:auto}}@media (max-width: 1024px){.two-column-layout{grid-template-columns:1fr;gap:var(--space-6);padding:var(--space-3)}.openings-grid{grid-template-columns:repeat(auto-fit,minmax(300px,1fr));gap:var(--space-4);padding:var(--space-6) var(--space-3)}.hero-section{padding:var(--space-8) var(--space-4);min-height:40vh}.video-card{flex:0 0 280px;max-width:280px}.video-carousel{gap:var(--space-4)}}@media (max-width: 768px){:root{--font-size-4xl: var(--font-size-3xl);--font-size-3xl: var(--font-size-2xl);--font-size-2xl: var(--font-size-xl);--font-size-xl: var(--font-size-lg)}.detail-header{position:sticky;top:0;z-index:100;padding:var(--space-2) 0;background-color:#141414fa;-webkit-backdrop-filter:blur(16px);backdrop-filter:blur(16px);border-bottom:1px solid rgba(232,93,4,.15);box-shadow:0 2px 20px #0000004d}.detail-header-container{display:grid;grid-template-columns:60px 1fr 60px;grid-template-areas:"left center right";align-items:center;padding:0 var(--space-3);min-height:60px;max-width:100vw;margin:0 auto;justify-content:initial;flex-direction:initial}.detail-header-container .header-left{grid-area:left;display:flex;justify-content:flex-start;position:static;flex:initial}.detail-header-container .header-left .back-button{display:flex;align-items:center;justify-content:center;width:48px;height:48px;padding:0;border-radius:var(--border-radius-large);background:#ffffff14;color:var(--color-text-primary);text-decoration:none;transition:all .2s cubic-bezier(.4,0,.2,1);border:1px solid rgba(255,255,255,.12);box-shadow:0 2px 8px #00000026;min-width:48px;white-space:normal;gap:0;font-size:18px;font-weight:300;line-height:1;position:relative;overflow:hidden}.detail-header-container .header-left .back-button:before{content:"";position:absolute;top:50%;left:50%;width:0;height:0;background:#ffffff1a;border-radius:50%;transition:width .3s ease,height .3s ease;transform:translate(-50%,-50%);z-index:0}.detail-header-container .header-left .back-button:active:before{width:48px;height:48px}.detail-header-container .header-left .back-button:active{transform:scale(.95);background:#fff3}.detail-header-container .header-left .back-button:hover{background:#ffffff26;transform:translateY(-1px) scale(1.02);box-shadow:0 4px 12px #00000040;border-color:#fff3}.detail-header-container .back-text-desktop{display:none}.detail-header-container .back-text-mobile{display:inline-flex;align-items:center;justify-content:center;font-size:18px;font-weight:300;line-height:1;height:100%;width:100%;position:relative;z-index:1}.detail-header-container .header-center{grid-area:center;display:flex;justify-content:center;align-items:center;position:static;left:auto;top:auto;transform:none;z-index:auto}.detail-header-container .header-center .site-title{font-size:var(--font-size-lg);font-weight:var(--font-weight-bold);color:var(--color-text-primary);text-decoration:none;white-space:nowrap;text-align:center;letter-spacing:-.01em;position:relative;transition:color .2s ease}.detail-header-container .header-center .site-title:after{content:"";position:absolute;bottom:-2px;left:50%;width:20px;height:2px;background:linear-gradient(90deg,var(--color-brand-orange),rgba(232,93,4,.6));border-radius:1px;transform:translate(-50%);opacity:.8}.detail-header-container .header-right{grid-area:right;display:flex;justify-content:flex-end;align-items:center;flex:initial;gap:0;min-width:auto}.detail-header-container .header-right .header-search,.detail-header-container .header-right .surprise-btn{display:none}.detail-header-container .header-right .mobile-menu-toggle{display:flex;align-items:center;justify-content:center;width:48px;height:48px;padding:0;border:1px solid rgba(255,255,255,.12);background:#ffffff14;color:var(--color-text-primary);border-radius:var(--border-radius-large);cursor:pointer;transition:all .2s cubic-bezier(.4,0,.2,1);box-shadow:0 2px 8px #00000026;min-width:48px;white-space:normal;position:relative;overflow:hidden}.detail-header-container .header-right .mobile-menu-toggle svg{width:18px;height:18px;opacity:.9;transition:opacity .2s ease}.detail-header-container .header-right .mobile-menu-toggle:before{content:"";position:absolute;top:50%;left:50%;width:0;height:0;background:#ffffff1a;border-radius:50%;transition:width .3s ease,height .3s ease;transform:translate(-50%,-50%);z-index:0}.detail-header-container .header-right .mobile-menu-toggle:active:before{width:48px;height:48px}.detail-header-container .header-right .mobile-menu-toggle:active{transform:scale(.95);background:#fff3}.detail-header-container .header-right .mobile-menu-toggle:hover{background:#ffffff26;transform:translateY(-1px) scale(1.02);box-shadow:0 4px 12px #00000040;border-color:#fff3}.detail-header-container .header-right .mobile-menu-toggle:hover svg{opacity:1}.floating-back-btn{display:none!important}.floating-back-btn{display:none}.mobile-search-overlay{position:fixed;top:0;left:0;right:0;bottom:0;background:#000000e6;-webkit-backdrop-filter:blur(8px);backdrop-filter:blur(8px);z-index:1100;display:none;flex-direction:column;padding:var(--space-4) var(--space-3);opacity:0;transition:opacity .3s ease}.mobile-search-overlay.active{display:flex;opacity:1}.mobile-search-header{display:flex;justify-content:space-between;align-items:center;margin-bottom:var(--space-6);padding:0 var(--space-2)}.mobile-search-title{color:var(--color-text-primary);font-size:var(--font-size-xl);font-weight:var(--font-weight-semibold)}.mobile-search-close{background:none;border:none;color:var(--color-text-primary);font-size:var(--font-size-xl);cursor:pointer;padding:0;border-radius:var(--border-radius-large);transition:all .2s cubic-bezier(.4,0,.2,1);width:48px;height:48px;display:flex;align-items:center;justify-content:center;background:#ffffff14;border:1px solid rgba(255,255,255,.12)}.mobile-search-close:hover{background:#ffffff26;transform:scale(1.02)}.mobile-search-content{flex:1;display:flex;flex-direction:column;gap:var(--space-4);max-width:100%;padding:0 var(--space-2)}.mobile-search-overlay .search-bar-container{width:100%;max-width:100%}.mobile-search-overlay .search-input-field{width:100%;max-width:100%;padding:var(--space-4);font-size:var(--font-size-lg);border-radius:var(--border-radius-large);box-sizing:border-box}.mobile-search-overlay .surprise-btn{width:100%;max-width:100%;padding:var(--space-4);font-size:var(--font-size-base);border-radius:var(--border-radius-large);margin-top:var(--space-4);box-sizing:border-box}.search-bar-container.header{width:100%;max-width:none}.search-bar-container.header .search-input-field{width:100%;min-width:auto;max-width:none;padding:var(--space-3) var(--space-4);font-size:var(--font-size-base)}.surprise-btn{width:100%;max-width:200px;margin:0 auto;padding:var(--space-3) var(--space-4)}.two-column-layout{grid-template-columns:1fr;gap:var(--space-4);padding:var(--space-2)}.header-left,.header-right{justify-content:center}.search-input-field{min-width:250px}.search-bar-container.header .search-input-field{min-width:200px;max-width:100%}.openings-grid{grid-template-columns:1fr;gap:var(--space-4);padding:var(--space-4) var(--space-2)}.opening-card{padding:var(--space-4);min-height:240px}.hero-section{min-height:35vh;padding:var(--space-6) var(--space-2)}.search-bar-container.landing .search-input-field{padding:var(--space-4) var(--space-6);font-size:var(--font-size-base)}.search-surprise-btn{padding:var(--space-3) var(--space-6);font-size:var(--font-size-sm)}.chessboard-container{width:100%;max-width:400px;margin:0 auto}.suggestion-item .opening-name{font-size:var(--font-size-sm);margin:0 var(--space-3) 0 var(--space-3)}.suggestion-item .eco-code{margin-right:var(--space-3);font-size:var(--font-size-xs)}}@media (max-width: 480px){:root{--font-size-3xl: var(--font-size-2xl);--font-size-2xl: var(--font-size-xl);--font-size-xl: var(--font-size-lg);--font-size-lg: var(--font-size-base)}.detail-header-container{padding:0 var(--space-3);min-height:48px}.site-title{font-size:var(--font-size-lg)}.back-button{padding:var(--space-2) var(--space-3);font-size:var(--font-size-xs)}.search-bar-container.header .search-input-field{min-width:160px;max-width:200px;font-size:var(--font-size-xs);min-height:32px;padding:var(--space-2) var(--space-3)}.surprise-btn{padding:var(--space-2) var(--space-4);font-size:var(--font-size-xs);height:32px;min-width:90px}.header-right{gap:var(--space-2)}}.video-gallery{width:100%;overflow:hidden;max-width:100%;box-sizing:border-box}.video-gallery-title{font-size:var(--font-size-lg);font-weight:var(--font-weight-bold);color:var(--color-text-primary);margin-bottom:var(--space-4)}.video-carousel{display:flex;gap:var(--space-5);overflow-x:auto;overflow-y:hidden;padding-bottom:var(--space-2);scroll-behavior:smooth;width:100%;max-width:100%;margin:0;box-sizing:border-box;scroll-snap-type:x 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.video-thumbnail{transform:scale(1.05);filter:brightness(1.1)}.video-duration{position:absolute;bottom:var(--space-2);right:var(--space-2);background:#000000e6;color:var(--color-text-primary);font-size:var(--font-size-sm);font-weight:var(--font-weight-bold);padding:var(--space-1) var(--space-2);border-radius:var(--border-radius-sm);text-shadow:0 1px 2px rgba(0,0,0,.8)}.video-info{padding:var(--space-4)}.video-title{font-size:var(--font-size-base);font-weight:var(--font-weight-medium);color:#fff;margin-bottom:var(--space-2);line-height:1.4;display:-webkit-box;-webkit-line-clamp:2;line-clamp:2;-webkit-box-orient:vertical;overflow:hidden}.video-channel{font-size:var(--font-size-sm);color:#e0e0e0;margin-bottom:var(--space-2);font-weight:var(--font-weight-bold)}.video-meta{display:flex;align-items:center;font-size:var(--font-size-xs);color:#aaa;gap:var(--space-2)}.video-meta-separator{font-weight:var(--font-weight-bold)}@media (max-width: 768px){.video-carousel{flex-direction:column;overflow-x:visible;overflow-y:visible;gap:var(--space-5);padding-bottom:0}.video-card{flex:none;width:100%;max-width:none;display:flex;background:var(--color-bg-surface);border-radius:8px;overflow:hidden;border:1px solid rgba(255,255,255,.1);transition:transform .2s ease,box-shadow .2s ease;box-shadow:0 2px 8px #00000026}.video-card:active{transform:scale(.98);box-shadow:0 2px 8px #0000004d}.video-link{display:flex;width:100%}.video-thumbnail-container{flex:0 0 140px;width:140px;aspect-ratio:16 / 9;position:relative;background:var(--color-bg-alt)}.video-thumbnail{transition:opacity .3s ease}.video-thumbnail:not([src]){opacity:0}.video-duration{bottom:var(--space-1);right:var(--space-1);font-size:var(--font-size-xs);padding:var(--space-1)}.video-info{flex:1;padding:var(--space-3);display:flex;flex-direction:column;justify-content:space-between;min-height:90px}.video-title{font-size:var(--font-size-sm);line-height:1.4;-webkit-line-clamp:2;line-clamp:2;display:-webkit-box;-webkit-box-orient:vertical;overflow:hidden;margin-bottom:var(--space-2);font-weight:var(--font-weight-medium);color:var(--color-text-primary)}.video-channel{font-size:var(--font-size-xs);margin-bottom:var(--space-1);color:var(--color-text-secondary);font-weight:var(--font-weight-medium)}.video-meta{font-size:var(--font-size-xs);color:var(--color-text-muted)}.tab-content-panel{padding:var(--space-4) var(--space-3)}}@media (max-width: 480px){.video-carousel{gap:var(--space-3)}.video-thumbnail-container{flex:0 0 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