:root{--primary-color:#4f46e5;--accent-color:#f43f5e;--background:#f8fafc;--text-main:#1e293b;--text-muted:#64748b;--card-bg:rgba(255,255,255,.9);--shadow:0 4px 20px rgba(0,0,0,.08)}*{box-sizing:border-box;margin:0;padding:0}body{color:var(--text-main);background-color:var(--background);font-family:Inter,-apple-system,system-ui,BlinkMacSystemFont,Segoe UI,Roboto,Noto Sans,Ubuntu,Cantarell,Helvetica Neue,sans-serif;line-height:1.6}header{z-index:1000;background:#fff;padding:12px 0;position:sticky;top:0;box-shadow:0 1px 3px rgba(0,0,0,.05)}.nav-container{justify-content:space-between;align-items:center;max-width:1400px;margin:0 auto;padding:0 20px;display:flex}.logo-link{color:var(--primary-color);font-size:1.2rem;font-weight:700;text-decoration:none}.page-wrapper{max-width:1400px;margin:0 auto;padding:20px}.ad-slot{width:100%;min-height:90px;color:var(--text-muted);background:#e2e8f0;border:1px dashed #cbd5e1;border-radius:8px;justify-content:center;align-items:center;margin:20px 0;font-size:.9rem;display:flex}h1{text-align:center;background:linear-gradient(135deg, var(--primary-color), var(--accent-color));-webkit-text-fill-color:transparent;background-clip:text;margin:30px 0;font-size:2.2rem}.operation-area{width:100%;height:60vh;box-shadow:var(--shadow);background:#fff;border:1px solid #e2e8f0;border-radius:16px;position:relative;overflow:hidden}.control-panel{z-index:1000;pointer-events:none;justify-content:space-between;align-items:center;display:flex;position:absolute;top:15px;left:15px;right:15px}.controls-left,.display-right{pointer-events:auto;background:var(--card-bg);backdrop-filter:blur(4px);box-shadow:var(--shadow);border-radius:10px;padding:10px 15px}.file-btn{background:var(--primary-color);color:#fff;cursor:pointer;border-radius:6px;padding:8px 16px;font-size:.9rem;transition:transform .2s}.file-btn:hover{transform:translateY(-2px)}#angleDisplay{color:var(--primary-color);font-size:1.2rem;font-weight:700}#calculations{color:var(--text-muted);margin-top:4px;font-size:.8rem}.container{width:100%;height:100%;position:relative}.image-container{justify-content:center;align-items:center;width:100%;height:100%;display:flex}.background-image{object-fit:contain;max-width:100%;max-height:100%}.protractor{z-index:100;position:absolute;top:50%;left:50%;transform:translate(-50%,-50%)}.angle-vertex{background:var(--accent-color);cursor:move;z-index:102;border:3px solid #fff;border-radius:50%;width:24px;height:24px;position:absolute;transform:translate(-50%,-50%);box-shadow:0 4px 10px rgba(0,0,0,.2)}.angle-line{background:var(--accent-color);transform-origin:0;cursor:pointer;z-index:101;border-radius:2px;height:4px;position:absolute}.line-a,.line-b{width:300px;top:-2px}.line-handle{background:var(--primary-color);cursor:grab;border:3px solid #fff;border-radius:50%;width:18px;height:18px;position:absolute;top:-7px;right:-9px;box-shadow:0 4px 10px rgba(0,0,0,.2)}.articles-section{grid-template-columns:1fr;gap:40px;margin-top:60px;display:grid}.article-card{background:#fff;border-radius:12px;padding:30px;box-shadow:0 2px 10px rgba(0,0,0,.03)}.article-card h2{color:var(--primary-color);align-items:center;gap:10px;margin-bottom:20px;display:flex}.article-card p,.article-card li{color:var(--text-main);margin-bottom:12px}.article-card ul{list-style:none}.article-card li:before{content:"•";color:var(--accent-color);margin-right:10px;font-weight:700}.features-grid{grid-template-columns:repeat(auto-fit,minmax(200px,1fr));gap:20px;margin-top:20px;display:grid}.feature-item{background:var(--background);text-align:center;border-radius:8px;padding:15px;font-weight:600}footer{text-align:center;background:#fff;border-top:1px solid #e2e8f0;margin-top:80px;padding:40px 0}.footer-link{color:var(--text-muted);font-size:.9rem;text-decoration:none}.footer-link:hover{color:var(--primary-color)}.language-links{flex-wrap:wrap;justify-content:center;gap:15px;margin-top:20px;display:flex}.language-links a{color:var(--text-muted);font-size:.85rem;text-decoration:none;transition:color .2s}.language-links a:hover{color:var(--primary-color)}@media (max-width:768px){h1{font-size:1.6rem}.page-wrapper{padding:10px}.operation-area{height:50vh}.control-panel{pointer-events:none;flex-direction:column;align-items:stretch;gap:10px}.controls-left,.display-right{pointer-events:auto;text-align:center}.line-a,.line-b{width:150px}}#translation-strings{display:none}