/* 폰트 로딩 최적화를 위한 CSS */
        @import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;700&family=Noto+Sans+KR:wght@400;700&family=Noto+Serif+KR:wght@700&family=Black+Han+Sans&family=Gaegu:wght@700&family=Nanum+Pen+Script&family=Nanum+Gothic+Coding:wght@700&family=Do+Hyeon&family=Song+Myung&display=swap');
        
            .div-container {
        margin-left: auto;
        margin-right: auto;
            background: #2c3e50;
            border: 4px solid #3f8fef;
        padding: 30px;
        border-radius: 12px;
        box-shadow: 0 4px 12px rgba(0,0,0,0.1);
        width: 100%;
        max-width: 800px;
        text-align: center;
        font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    }

        .transparent-grid {
            background-image: linear-gradient(45deg, #eee 25%, transparent 25%), 
                              linear-gradient(-45deg, #eee 25%, transparent 25%), 
                              linear-gradient(45deg, transparent 75%, #eee 75%), 
                              linear-gradient(-45deg, transparent 75%, #eee 75%);
            background-size: 10px 10px;
            background-position: 0 0, 0 5px, 5px -5px, -5px 0px;
        }

        .canvas-container {
            background-image: radial-gradient(#e5e7eb 1px, transparent 1px);
            background-size: 20px 20px;
        }

        .loading-spinner {
            border: 2px solid #f3f3f3;
            border-top: 2px solid #3b82f6;
            border-radius: 50%;
            width: 14px;
            height: 14px;
            animation: spin 1s linear infinite;
        }
        @keyframes spin { 0% { transform: rotate(0deg); } 100% { transform: rotate(360deg); } }