/* ============ Upload Panel ============ */
#upload-panel {
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.9);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    z-index: 1000;
}

#upload-panel.hidden {
    display: none;
}

.upload-box {
    background: #16213e;
    padding: 30px;
    border-radius: 10px;
    margin: 15px;
    text-align: center;
    border: 2px dashed #4a5568;
    cursor: pointer;
    transition: all 0.3s;
    min-width: 300px;
}

.upload-box:hover {
    border-color: #63b3ed;
    background: #1a2a4a;
}

.upload-box.loaded {
    border-color: #48bb78;
    background: #1a3a2a;
}

.upload-box h3 {
    margin-bottom: 10px;
    color: #63b3ed;
}

.upload-box p {
    color: #a0aec0;
    font-size: 14px;
}

.upload-box.loaded p {
    color: #48bb78;
}

#start-btn {
    margin-top: 20px;
    padding: 15px 40px;
    font-size: 18px;
    background: #4299e1;
    color: white;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.3s;
}

#start-btn:hover:not(:disabled) {
    background: #3182ce;
}

#start-btn:disabled {
    background: #4a5568;
    cursor: not-allowed;
}