*{margin:0;padding:0;box-sizing:border-box}body{font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Oxygen,Ubuntu,Cantarell,Fira Sans,Droid Sans,Helvetica Neue,sans-serif;-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale;background:linear-gradient(135deg,#667eea,#764ba2);min-height:100vh;padding:20px}.container{max-width:1400px;margin:0 auto;background:#fff;border-radius:12px;box-shadow:0 20px 60px #0000004d;overflow:hidden}header{background:linear-gradient(135deg,#667eea,#764ba2);color:#fff;padding:24px 32px;text-align:center}header h1{font-size:28px;font-weight:600}.main-content{display:grid;grid-template-columns:1fr 1fr;gap:0;height:calc(100vh - 140px)}.main-content:has(.editor-panel.collapsed){grid-template-columns:60px 1fr}.main-content:has(.preview-panel.collapsed){grid-template-columns:1fr 60px}.editor-panel,.preview-panel{display:flex;flex-direction:column;overflow:hidden;transition:all .3s ease}.editor-panel.collapsed,.preview-panel.collapsed{flex:0 0 60px;width:60px;min-width:60px;max-width:60px}.editor-panel.collapsed #editor,.preview-panel.collapsed #preview,.preview-panel.collapsed #error{display:none}.editor-panel.collapsed .panel-header h2,.preview-panel.collapsed .panel-header h2{writing-mode:vertical-rl;text-orientation:mixed;margin:0;white-space:nowrap}.editor-panel{border-right:2px solid #e5e7eb}.panel-header{display:flex;justify-content:space-between;align-items:center;padding:16px 24px;background:#f9fafb;border-bottom:1px solid #e5e7eb;flex-shrink:0}.editor-panel.collapsed .panel-header,.preview-panel.collapsed .panel-header{flex-direction:column;padding:16px 8px;height:100%;justify-content:flex-start;gap:16px}.panel-header h2{font-size:18px;font-weight:600;color:#374151}#editor{flex:1;padding:20px;border:none;resize:none;font-family:Courier New,Courier,monospace;font-size:14px;line-height:1.6;outline:none;background:#fafafa}.preview-area{flex:1;padding:20px;overflow:auto;background:#fff;position:relative;cursor:grab;-webkit-user-select:none;user-select:none}.preview-area:active{cursor:grabbing}.preview-container{display:inline-block;min-width:100%;min-height:100%;transform-origin:top left;transition:transform .2s ease}.preview-container svg{display:block;pointer-events:none}.error-message{display:none;padding:16px 24px;background:#fee2e2;border-top:1px solid #fecaca;color:#991b1b;font-size:14px}.error-message.show{display:block}.btn-group{display:flex;gap:8px;flex-wrap:wrap}.editor-panel.collapsed .btn-group,.preview-panel.collapsed .btn-group{flex-direction:column;gap:8px}.btn{padding:8px 16px;border:none;border-radius:6px;font-size:14px;font-weight:500;cursor:pointer;transition:all .2s}.btn-primary{background:#667eea;color:#fff}.btn-primary:hover{background:#5568d3;transform:translateY(-1px);box-shadow:0 4px 12px #667eea66}.btn-secondary{background:#e5e7eb;color:#374151}.btn-secondary:hover{background:#d1d5db;transform:translateY(-1px)}.btn:active{transform:translateY(0)}@media (max-width: 768px){.main-content{grid-template-columns:1fr;height:auto}.editor-panel{border-right:none;border-bottom:2px solid #e5e7eb}#editor{min-height:300px}.preview-area{min-height:400px}}