styles.css

:root {
    --primary-color: #2196F3;
    --hover-color: #1976D2;
    --background-color: #f5f5f5;
    --text-color: #333;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background-color: var(--background-color);
    color: var(--text-color);
    line-height: 1.6;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.container {
    max-width: 800px;
    margin: 2rem auto;
    padding: 0 1rem;
}

h1 {
    text-align: center;
    margin-bottom: 2rem;
    color: var(--text-color);
}

.upload-container {
    border: 2px dashed #dee2e6;
    padding: 2rem;
    text-align: center;
    transition: border-color 0.3s ease;
    cursor: pointer;
    background: #f8f9fa;
}

.upload-container.drag-over {
    border-color: #0d6efd;
    background: #fff;
}

.upload-icon {
    width: 64px;
    height: 64px;
    margin-bottom: 1rem;
}

.file-input {
    display: none;
}

.upload-button {
    display: inline-block;
    padding: 0.5rem 1.5rem;
    background-color: var(--primary-color);
    color: white;
    border-radius: 4px;
    cursor: pointer;
    transition: background-color 0.3s ease;
}

.upload-button:hover {
    background-color: var(--hover-color);
}

.file-info {
    margin-top: 1.5rem;
    text-align: center;
}

.convert-button {
    margin-top: 1rem;
    padding: 0.5rem 1.5rem;
    background-color: var(--primary-color);
    color: white;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    transition: background-color 0.3s ease;
}

.convert-button:hover:not(:disabled) {
    background-color: var(--hover-color);
}

.convert-button:disabled {
    background-color: #ccc;
    cursor: not-allowed;
}

.hidden {
    display: none;
}

.table-responsive {
    max-height: 400px;
    overflow-y: auto;
}

.table th {
    position: sticky;
    top: 0;
    background: white;
    z-index: 1;
}

footer {
    margin-top: auto;
    font-size: 0.9rem;
}

footer .bi-github {
    font-size: 1.2rem;
    margin-right: 0.5rem;
    vertical-align: -0.2rem;
}