:root{--space-black: #0a0e27;--deep-navy: #141b34;--panel-gray: #1a2238;--electric-cyan: #00d9ff;--scientific-green: #00ff9f;--amber-alert: #ffaa00;--soft-white: #e8f1f5;--grid-color: rgba(0, 217, 255, .15);--glow-cyan: rgba(0, 217, 255, .5);--glow-green: rgba(0, 255, 159, .4)}@keyframes scanline{0%{transform:translateY(-100%)}to{transform:translateY(100vh)}}@keyframes fadeInUp{0%{opacity:0;transform:translateY(20px)}to{opacity:1;transform:translateY(0)}}@keyframes pulse{0%,to{opacity:1}50%{opacity:.6}}@keyframes shimmer{0%{left:-100%}to{left:100%}}*{box-sizing:border-box}body{background:var(--space-black);background-image:repeating-linear-gradient(0deg,transparent,transparent 2px,var(--grid-color) 2px,var(--grid-color) 3px),repeating-linear-gradient(90deg,transparent,transparent 2px,var(--grid-color) 2px,var(--grid-color) 3px);background-size:50px 50px;min-height:100vh;font-family:IBM Plex Mono,monospace;color:var(--soft-white);position:relative;overflow-x:hidden}body:before{content:"";position:fixed;top:0;left:0;width:100%;height:3px;background:linear-gradient(90deg,transparent,var(--electric-cyan),transparent);animation:scanline 8s linear infinite;opacity:.3;pointer-events:none;z-index:1000}body.simultaneity-active:before{display:none}.main-container{padding:2rem 1rem;max-width:1400px;margin:0 auto;animation:fadeInUp .6s ease-out}canvas{filter:drop-shadow(0 0 10px rgba(0,217,255,.2))}.hide-on-mobile{display:block}.header{background:var(--deep-navy);border:2px solid var(--electric-cyan);border-radius:4px;padding:2.5rem 2rem;margin-bottom:2rem;box-shadow:0 0 30px var(--glow-cyan),inset 0 0 20px #00d9ff1a;text-align:center;position:relative;overflow:hidden}.header:before{content:"";position:absolute;top:0;left:-100%;width:100%;height:100%;background:linear-gradient(90deg,transparent,rgba(0,217,255,.1),transparent);animation:shimmer 3s infinite}.header h1{font-family:Orbitron,sans-serif;color:var(--electric-cyan);font-weight:900;margin-bottom:.5rem;font-size:3rem;letter-spacing:2px;text-transform:uppercase;text-shadow:0 0 20px var(--glow-cyan);position:relative}.github-link{position:absolute;top:1.5rem;right:1.5rem;display:flex;align-items:center;gap:.35rem;color:var(--electric-cyan);text-decoration:none;font-family:Orbitron,sans-serif;font-weight:600;font-size:.75rem;text-transform:uppercase;letter-spacing:.5px;padding:.4rem .75rem;border:1px solid var(--electric-cyan);border-radius:2px;background:#00d9ff0d;transition:all .3s ease;z-index:10;cursor:pointer}.github-link:hover{color:var(--scientific-green);border-color:var(--scientific-green);background:#00ff9f1a;box-shadow:0 0 15px var(--glow-green);transform:translateY(-2px)}.github-link svg,.github-link span{pointer-events:none}.github-link svg{width:20px;height:20px;fill:currentColor}.header .subtitle{color:var(--scientific-green);font-size:.95rem;letter-spacing:1px;font-weight:500;text-transform:uppercase}.speed-of-light{display:inline-block;background:#00d9ff1a;border:1px solid var(--electric-cyan);color:var(--electric-cyan);padding:.6rem 1.8rem;border-radius:2px;font-weight:600;margin-top:1rem;font-family:IBM Plex Mono,monospace;letter-spacing:1px;box-shadow:0 0 15px var(--glow-cyan);animation:pulse 2s infinite;position:relative}.calculator-card{background:var(--panel-gray);border:2px solid rgba(0,217,255,.3);border-radius:4px;padding:0;box-shadow:0 0 40px #00d9ff33,inset 0 0 30px #00000080;overflow:hidden}.nav-tabs{border-bottom:2px solid var(--electric-cyan);background:var(--deep-navy);padding:1rem 1rem 0;gap:.5rem}.nav-tabs .nav-link{border:1px solid rgba(0,217,255,.3);color:var(--soft-white);font-weight:600;padding:.75rem 1.5rem;border-radius:0;margin-right:0;transition:all .2s ease;background:#0000004d;font-family:Orbitron,sans-serif;font-size:.85rem;letter-spacing:.5px;text-transform:uppercase;position:relative}.nav-tabs .nav-link:hover{color:var(--electric-cyan);background:#00d9ff1a;border-color:var(--electric-cyan);box-shadow:0 0 10px var(--glow-cyan)}.nav-tabs .nav-link.active{color:var(--space-black);background:var(--electric-cyan);border-color:var(--electric-cyan);box-shadow:0 0 20px var(--glow-cyan)}.nav-tabs .nav-link.active:after{content:"";position:absolute;bottom:-2px;left:0;right:0;height:2px;background:var(--electric-cyan)}.tab-content{padding:2rem;background:var(--panel-gray)}.calc-section{margin-bottom:2rem;padding:1.5rem;background:#0000004d;border-radius:0;border:1px solid rgba(0,217,255,.3);border-left:3px solid var(--scientific-green);box-shadow:inset 0 0 15px #00000080}.calc-section:last-child{margin-bottom:0}.calc-label{font-weight:600;color:var(--scientific-green);margin-bottom:1rem;font-size:1rem;display:flex;align-items:center;font-family:Orbitron,sans-serif;letter-spacing:1px;text-transform:uppercase}.calc-label:before{content:"▸";display:inline-block;color:var(--electric-cyan);font-size:1.2rem;margin-right:.5rem}.input-group-custom{display:flex;gap:.75rem;align-items:flex-end;flex-wrap:wrap}.form-control{border:1px solid rgba(0,217,255,.4);border-radius:0;padding:.75rem 1rem;font-size:1rem;line-height:1.5;height:calc(1.5em + 1.5rem + 2px);transition:all .2s ease;background:#00000080;color:var(--soft-white);font-family:IBM Plex Mono,monospace;font-weight:500}.form-control::placeholder{color:#e8f1f566}.form-control:focus{border-color:var(--electric-cyan);box-shadow:0 0 15px var(--glow-cyan);outline:none;background:#000000b3;color:var(--soft-white)}.btn-calculate{background:var(--electric-cyan);border:1px solid var(--electric-cyan);color:var(--space-black);padding:.75rem 2rem;border-radius:0;font-weight:700;font-size:1rem;line-height:1.5;height:calc(1.5em + 1.5rem + 2px);transition:all .2s ease;box-shadow:0 0 20px var(--glow-cyan);font-family:Orbitron,sans-serif;text-transform:uppercase;letter-spacing:1px;cursor:pointer}.btn-calculate:hover{background:var(--scientific-green);border-color:var(--scientific-green);box-shadow:0 0 25px var(--glow-green);transform:translateY(-1px)}.btn-calculate:active{transform:translateY(0)}.chart-time-mode-toggle{display:inline-flex;margin-left:1rem;border:1px solid rgba(0,217,255,.3);background:#00000080;border-radius:3px;overflow:hidden}.chart-time-mode-btn{background:transparent;border:none;color:var(--soft-white);padding:.35rem .75rem;font-weight:600;font-size:.65rem;font-family:IBM Plex Mono,monospace;text-transform:uppercase;letter-spacing:.3px;cursor:pointer;transition:all .15s ease;border-right:1px solid rgba(0,217,255,.2)}.chart-time-mode-btn:last-child{border-right:none}.chart-time-mode-btn:hover:not(.active){background:#00d9ff1a;color:var(--electric-cyan)}.chart-time-mode-btn.active{background:var(--electric-cyan);color:var(--space-black);box-shadow:0 0 10px var(--glow-cyan)}.result-box{background:#0009;padding:.75rem 1rem;border-radius:0;border:1px solid var(--amber-alert);display:flex;align-items:center;font-weight:600;color:var(--amber-alert);flex:1;font-family:IBM Plex Mono,monospace;font-size:1rem;line-height:1.5;height:calc(1.5em + 1.5rem + 2px);box-shadow:0 0 15px #ffaa004d,inset 0 0 10px #00000080}.result-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(200px,1fr));gap:1rem;margin-top:1rem}.result-item{background:#0009;padding:1rem;border-radius:0;border:1px solid rgba(0,217,255,.4);box-shadow:inset 0 0 10px #00000080;transition:all .2s ease}.result-item:hover{border-color:var(--electric-cyan);box-shadow:0 0 15px var(--glow-cyan),inset 0 0 10px #00000080}.result-item-label{font-size:.75rem;color:var(--electric-cyan);font-weight:600;margin-bottom:.5rem;text-transform:uppercase;letter-spacing:1px;font-family:Orbitron,sans-serif}.result-item-value{color:var(--soft-white);font-weight:600;font-size:1.1rem;word-wrap:break-word;font-family:IBM Plex Mono,monospace}.notebook-link{display:inline-flex;align-items:center;gap:.35rem;margin-left:.75rem;color:var(--scientific-green);font-size:.7rem;text-decoration:none;font-weight:500;transition:all .2s ease;text-transform:none;letter-spacing:.5px;opacity:.8}.notebook-link:hover{color:var(--electric-cyan);opacity:1;text-shadow:0 0 8px var(--glow-green)}.notebook-link:before{content:"📖";font-size:.9rem}.input-label{font-size:.75rem;color:var(--electric-cyan);font-weight:600;margin-bottom:.25rem;text-transform:uppercase;letter-spacing:.5px}input[type=range]{-webkit-appearance:none;appearance:none;height:4px;background:#00d9ff66;border-radius:2px;border:1px solid rgba(0,217,255,.3);cursor:pointer;outline:none;vertical-align:middle}input[type=range]::-webkit-slider-track{background:transparent;height:4px;border:none;border-radius:2px}input[type=range]::-moz-range-track{background:transparent;height:4px;border:none;border-radius:2px}input[type=range]::-webkit-slider-thumb{-webkit-appearance:none;appearance:none;width:14px;height:14px;background:var(--electric-cyan);border-radius:50%;cursor:pointer;box-shadow:0 0 8px #00d9ff80;transition:all .15s ease}input[type=range]::-moz-range-thumb{width:14px;height:14px;background:var(--electric-cyan);border:none;border-radius:50%;cursor:pointer;box-shadow:0 0 8px #00d9ff80;transition:all .15s ease}input[type=range]:hover::-webkit-slider-thumb{background:var(--scientific-green);box-shadow:0 0 12px #00ff9f99;transform:scale(1.05)}input[type=range]:hover::-moz-range-thumb{background:var(--scientific-green);box-shadow:0 0 12px #00ff9f99;transform:scale(1.05)}input[type=range]:active::-webkit-slider-thumb{transform:scale(.95)}input[type=range]:active::-moz-range-thumb{transform:scale(.95)}.help-btn{display:inline-flex;align-items:center;justify-content:center;width:24px;height:24px;min-width:24px;min-height:24px;margin-left:.75rem;background:transparent;border:2px solid var(--electric-cyan);border-radius:50%;color:var(--electric-cyan);font-family:IBM Plex Mono,monospace;font-size:.85rem;font-weight:700;cursor:pointer;transition:all .2s ease;padding:0;line-height:1;flex-shrink:0}.help-btn:hover{background:var(--electric-cyan);color:var(--space-black);box-shadow:0 0 15px var(--glow-cyan);transform:scale(1.1)}.help-btn:active{transform:scale(.95)}.help-modal{background:var(--panel-gray);border:2px solid var(--electric-cyan);border-radius:0;box-shadow:0 0 40px #00d9ff66}.help-modal .modal-header{background:#00000080;border-bottom:2px solid var(--electric-cyan);padding:1.5rem}.help-modal .modal-title{color:var(--electric-cyan);font-family:Orbitron,sans-serif;font-size:1.25rem;font-weight:700;text-transform:uppercase;letter-spacing:1.5px}.help-modal .btn-close{filter:invert(1);opacity:.7;transition:opacity .2s ease}.help-modal .btn-close:hover{opacity:1}.help-modal .modal-body{background:var(--panel-gray);color:var(--soft-white);font-family:IBM Plex Mono,monospace;font-size:.95rem;line-height:1.7;padding:2rem}.help-modal .modal-body h3{color:var(--scientific-green);font-family:Orbitron,sans-serif;font-size:1rem;font-weight:600;text-transform:uppercase;letter-spacing:1px;margin-top:1.5rem;margin-bottom:.75rem}.help-modal .modal-body h3:first-child{margin-top:0}.help-modal .modal-body p{margin-bottom:1rem}.help-modal .modal-body ul{margin-left:1.5rem;margin-bottom:1rem}.help-modal .modal-body li{margin-bottom:.5rem;color:var(--soft-white)}.help-modal .modal-body strong{color:var(--electric-cyan);font-weight:600}.help-modal .modal-body em{color:var(--scientific-green);font-style:italic}.modal-backdrop.show{opacity:.7;background-color:#001428e6}@media(max-width:768px){.main-container{padding:1rem .75rem}.header{padding:1.5rem 1rem;margin-bottom:1rem}.github-link{position:static;margin:0 auto 1rem;font-size:.75rem;padding:.4rem .75rem}.github-link svg{width:18px;height:18px}.header h1{font-size:1.5rem;letter-spacing:1px}.header .subtitle{font-size:.8rem}.speed-of-light{padding:.4rem 1rem;font-size:.85rem;margin-top:.75rem}.nav-tabs{padding:.5rem .5rem 0;flex-wrap:nowrap;overflow-x:auto;overflow-y:hidden;-webkit-overflow-scrolling:touch;scrollbar-width:none;-ms-overflow-style:none}.nav-tabs::-webkit-scrollbar{display:none}.nav-tabs .nav-link{padding:.6rem 1rem;font-size:.65rem;white-space:nowrap;flex-shrink:0}.tab-content{padding:1rem}.calc-section{padding:1rem;margin-bottom:1rem}.calc-label{font-size:.85rem;margin-bottom:.75rem}.input-group-custom{flex-direction:row;flex-wrap:wrap;gap:.75rem}.input-group-custom>div{min-width:calc(50% - .375rem)!important;max-width:calc(50% - .375rem);flex:0 0 calc(50% - .375rem)}.btn-calculate{padding:.875rem 1.5rem;font-size:.9rem}.input-group-custom .btn-calculate{min-width:calc(50% - .375rem);max-width:calc(50% - .375rem);flex:0 0 calc(50% - .375rem)}.result-box{width:100%;min-height:calc(1.5em + 1.5rem + 2px);height:auto}.result-grid{grid-template-columns:1fr 1fr;gap:.75rem}.result-item{padding:.75rem}.result-item-label{font-size:.65rem}.result-item-value{font-size:.95rem;word-break:break-all}canvas{max-height:250px}.simultaneity-controls{position:static!important;transform:none!important;margin:1rem auto 0!important;width:100%!important}.simultaneity-time-display,.simultaneity-space-display{position:static!important;margin:.75rem auto!important;width:calc(100% - 2rem)!important;max-width:100%!important}#simultaneityContainer{padding-bottom:0!important}.simultaneity-controls input[type=range]{width:150px!important}#twinsMinkowskiContainer{display:flex!important;flex-direction:column!important}#twinsMinkowskiContainer>svg{order:1}.minkowski-velocity-slider{position:static!important;margin:1rem auto 0!important;width:100%!important;justify-content:center!important;order:2}.minkowski-velocity-slider .velocity-slider-input{width:150px!important}.minkowski-controls{position:static!important;transform:none!important;margin:1rem auto 0!important;width:100%!important;order:3}.twins-legend{order:4}}@media(max-width:480px){.main-container{padding:.5rem}.header{padding:1rem .75rem;margin-bottom:.75rem}.github-link{font-size:.7rem;padding:.35rem .65rem}.github-link svg{width:16px;height:16px}.header h1{font-size:1.1rem;letter-spacing:.5px}.header .subtitle{font-size:.7rem;margin-bottom:.25rem}.speed-of-light{padding:.3rem .8rem;font-size:.75rem;margin-top:.5rem}.nav-tabs .nav-link{padding:.5rem .75rem;font-size:.6rem}.tab-content{padding:.75rem}.calc-section{padding:.75rem;margin-bottom:.75rem}.calc-label{font-size:.75rem}.calc-label:before{font-size:1rem;margin-right:.35rem}.input-label{font-size:.65rem}.form-control{padding:.6rem .75rem;font-size:.9rem}.btn-calculate{padding:.75rem 1rem;font-size:.8rem}.result-grid{grid-template-columns:1fr;gap:.5rem}.result-item{padding:.6rem}.result-item-label{font-size:.6rem;margin-bottom:.35rem}.result-item-value{font-size:.85rem}.hide-on-mobile{display:none}canvas{max-height:200px}[style*="padding: 1rem"]{padding:.5rem!important}.simultaneity-controls{gap:6px!important}.simultaneity-controls>div{padding:6px 10px!important;font-size:10px!important}.simultaneity-controls label,.simultaneity-controls span{font-size:10px!important}.simultaneity-controls input[type=range]{width:120px!important}.simultaneity-toggle-button{padding:6px 12px!important;font-size:11px!important}.simultaneity-time-display,.simultaneity-space-display{font-size:10px!important;padding:6px 10px!important;min-width:0!important}.minkowski-velocity-slider{gap:6px!important;padding:6px 10px!important}.minkowski-velocity-slider span,.minkowski-velocity-slider label{font-size:10px!important}.minkowski-velocity-slider .velocity-slider-input{width:120px!important}.minkowski-toggle-button{padding:6px 12px!important;font-size:11px!important}.chart-time-mode-toggle{display:flex;margin-left:0;margin-top:.5rem;width:100%}.chart-time-mode-btn{flex:1;font-size:.6rem;padding:.4rem .5rem}}@media(max-width:360px){.header h1{font-size:.95rem}.header .subtitle{font-size:.6rem}.speed-of-light{font-size:.65rem;padding:.25rem .6rem}.nav-tabs .nav-link{padding:.4rem .6rem;font-size:.55rem}.calc-label{font-size:.7rem}.form-control{font-size:.85rem}.btn-calculate{font-size:.75rem}}