:root {
    --color-primary: #4a90e2;
    --color-text-primary: #2c3e50;
    --color-text-secondary: #7f8c8d;
    --color-text-muted: #6c757d;
    --color-background: #f8f9fa;
    --color-background-hover: #e9ecef;
    --color-border: #dee2e6;
    --color-white: white;
    --color-error: #dc3545;
    --color-spinner-border: #f3f3f3;
    --gradient-background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
    
    --shadow-default: 0 10px 30px rgba(0,0,0,0.1);
    --border-radius-lg: 20px;
    --border-radius-md: 12px;
    --border-radius-sm: 8px;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body {
    background: var(--gradient-background);
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
}

.container {
    width: 100%;
    max-width: 600px;
    padding: 20px;
}

.upload-box {
    background: var(--color-white);
    border-radius: var(--border-radius-lg);
    padding: 40px;
    box-shadow: var(--shadow-default);
}

h1 {
    color: var(--color-text-primary);
    text-align: center;
    margin-bottom: 10px;
    font-size: 28px;
}

.upload-description {
    text-align: center;
    color: var(--color-text-secondary);
    margin-bottom: 30px;
}

.file-upload {
    position: relative;
    margin: 25px 0;
}

.file-upload input[type="file"] {
    display: none;
}

.file-upload-label {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 40px 20px;
    background: var(--color-background);
    border: 2px dashed var(--color-border);
    border-radius: var(--border-radius-md);
    cursor: pointer;
    transition: all 0.3s ease;
}

.file-upload-label:hover {
    background: var(--color-background-hover);
    border-color: var(--color-primary);
}

.file-upload-label:hover .file-icon {
    color: var(--color-primary);

}

.upload-icon {
    font-size: 48px;
    margin-bottom: 15px;
}

.upload-text {
    text-align: center;
    color: var(--color-text-muted);
    font-size: 16px;
    line-height: 1.5;
}

.file-name {
    margin-top: 15px;
    padding: 10px;
    background: var(--color-background-hover);
    border-radius: var(--border-radius-sm);
    color: var(--color-primary);
    text-align: center;
    display: none;
}

.file-error {
    color: var(--color-error);
    text-align: center;
    margin-top: 10px;
    display: none;
}

.upload-info {
    margin-top: 30px;
    padding: 20px;
    background: var(--color-background);
    border-radius: var(--border-radius-md);
}

.info-item {
    display: flex;
    align-items: center;
    margin: 10px 0;
    color: var(--color-text-muted);
}

.info-icon {
    margin-right: 10px;
    font-size: 18px;
}

.file-upload-label.dragover {
    background: var(--color-background-hover);
    border-color: var(--color-primary);
    transform: scale(1.02);
}

.spinner-container {
    text-align: center;
    margin-top: 20px;
}

.spinner {
    width: 40px;
    height: 40px;
    border: 4px solid var(--color-spinner-border);
    border-top: 4px solid var(--color-primary);
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin: 0 auto;
}

.spinner-text {
    margin-top: 10px;
    color: var(--color-text-muted);
}

.file-icon {
    font-size: 40px;
    text-align: center;
    color: var(--color-text-muted);
    transition: all 0.3s ease;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

@media (max-width: 480px) {
    .upload-box {
        padding: 20px;
    }
    
    h1 {
        font-size: 24px;
    }
    
    .upload-icon {
        font-size: 36px;
    }
    
    .upload-text {
        font-size: 14px;
    }
}