.app{min-height:100vh;padding:20px;display:flex;justify-content:center;align-items:center}.container{background:#fff;border-radius:20px;box-shadow:0 20px 60px #0000004d;width:100%;max-width:900px;overflow:hidden}.header{background:linear-gradient(135deg,#667eea,#764ba2);color:#fff;padding:40px;text-align:center}.header h1{font-size:2.5rem;margin-bottom:10px}.header p{font-size:1.1rem;opacity:.9}.tabs{display:flex;background:#f7f7f7;border-bottom:2px solid #e0e0e0}.tab{flex:1;padding:20px;border:none;background:transparent;font-size:1.1rem;cursor:pointer;transition:all .3s ease;border-bottom:3px solid transparent}.tab:hover{background:#eee}.tab.active{background:#fff;border-bottom:3px solid #667eea;font-weight:600;color:#667eea}.content{padding:40px}.stego-section{display:flex;flex-direction:column;gap:30px}.mode-selector{display:flex;gap:15px;margin-bottom:20px}.mode-btn{flex:1;padding:15px;border:2px solid #667eea;background:#fff;border-radius:10px;cursor:pointer;font-size:1rem;transition:all .3s ease;font-weight:500}.mode-btn:hover{background:#f0f0ff}.mode-btn.active{background:#667eea;color:#fff}.card{background:#f9f9f9;border-radius:15px;padding:25px;border:2px dashed #ddd}.form-group{margin-bottom:20px}.form-group label{display:block;margin-bottom:8px;font-weight:600;color:#333}.file-input-wrapper{position:relative;overflow:hidden;display:inline-block;width:100%}.file-input-wrapper input[type=file]{position:absolute;left:-9999px}.file-label{display:block;padding:15px;background:#fff;border:2px dashed #667eea;border-radius:10px;text-align:center;cursor:pointer;transition:all .3s ease}.file-label:hover{background:#f0f0ff;border-color:#764ba2}.file-selected{margin-top:10px;padding:10px;background:#e8f5e9;border-radius:5px;color:#2e7d32;font-size:.9rem}input[type=text],textarea{width:100%;padding:12px;border:2px solid #ddd;border-radius:8px;font-size:1rem;font-family:inherit;transition:border-color .3s ease}input[type=text]:focus,textarea:focus{outline:none;border-color:#667eea}textarea{resize:vertical;min-height:120px}.btn{padding:15px 30px;border:none;border-radius:10px;font-size:1rem;font-weight:600;cursor:pointer;transition:all .3s ease;width:100%}.btn-primary{background:linear-gradient(135deg,#667eea,#764ba2);color:#fff}.btn-primary:hover{transform:translateY(-2px);box-shadow:0 10px 20px #667eea4d}.btn-primary:disabled{background:#ccc;cursor:not-allowed;transform:none}.result{margin-top:25px;padding:20px;background:#fff;border-radius:10px;border-left:4px solid #667eea}.result h3{margin-bottom:10px;color:#667eea}.result-message{padding:15px;background:#f0f0ff;border-radius:8px;word-wrap:break-word;font-family:monospace}.error{margin-top:15px;padding:15px;background:#ffebee;border-left:4px solid #f44336;border-radius:5px;color:#c62828}.success{margin-top:15px;padding:15px;background:#e8f5e9;border-left:4px solid #4caf50;border-radius:5px;color:#2e7d32}.download-link{display:inline-block;margin-top:15px;padding:10px 20px;background:#4caf50;color:#fff;text-decoration:none;border-radius:8px;transition:all .3s ease}.download-link:hover{background:#45a049;transform:translateY(-2px)}.loading{text-align:center;padding:20px;color:#667eea;font-weight:600}.footer{display:flex;justify-content:space-between;align-items:center;padding:20px 40px;background:linear-gradient(135deg,#667eea,#764ba2);color:#fff;font-size:.9rem;flex-wrap:wrap;gap:15px}.footer-left,.footer-right{display:flex;align-items:center}.footer-left p{margin:0}.footer-link{color:#fff;text-decoration:none;font-weight:600;transition:all .3s ease;opacity:.95}.footer-link:hover{opacity:1;text-decoration:underline}.github-link{display:flex;align-items:center;gap:8px;padding:8px 16px;background:#ffffff1a;border-radius:8px;transition:all .3s ease}.github-link:hover{background:#fff3;text-decoration:none;transform:translateY(-2px)}.github-icon{display:inline-block;vertical-align:middle}@media (max-width: 768px){.header h1{font-size:1.8rem}.content{padding:20px}.tab{font-size:.9rem;padding:15px 10px}.footer{flex-direction:column;text-align:center;padding:20px;gap:10px}.footer-left,.footer-right{width:100%;justify-content:center}}