:root {
    --primary-color: #0052cc;
    --secondary-color: #f0f6ff;
    --text-color: #333;
    --light-gray: #f8f9fa;
    --border-color: #dee2e6;
    --success-color: #28a745;
    --error-color: #dc3545;
    --white: #fff;
    --shadow: 0 10px 30px rgba(0, 82, 204, 0.1);
}

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

body {
    font-family: 'Poppins', sans-serif;
    background-color: var(--light-gray);
    color: var(--text-color);
    line-height: 1.6;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

.container {
    max-width: 960px;
    margin: 40px auto;
    padding: 20px;
    flex: 1;
}

.header {
    text-align: center;
    margin-bottom: 40px;
}

.header h1 {
    font-size: 2.8rem;
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: 10px;
}

.header p {
    font-size: 1.1rem;
    color: #6c757d;
    max-width: 700px;
    margin: 0 auto;
}

.card {
    background-color: var(--white);
    border-radius: 12px;
    padding: 40px;
    margin-bottom: 30px;
    box-shadow: var(--shadow);
    border: 1px solid var(--border-color);
}

.instructions h2 {
    text-align: center;
    font-size: 1.8rem;
    margin-bottom: 30px;
    color: var(--primary-color);
}

.instructions ul {
    list-style: none;
    display: flex;
    justify-content: space-around;
    gap: 20px;
}

.instructions li {
    text-align: center;
    max-width: 220px;
}

.instructions .icon {
    background-color: var(--secondary-color);
    border-radius: 50%;
    width: 80px;
    height: 80px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 20px;
    color: var(--primary-color);
    font-size: 2.5rem;
}

.instructions strong {
    display: block;
    font-weight: 600;
    margin-bottom: 5px;
}

.instructions span {
    font-size: 0.9rem;
    color: #6c757d;
}

.upload-area {
    border: 2px dashed var(--border-color);
    border-radius: 12px;
    padding: 50px;
    text-align: center;
    cursor: pointer;
    transition: all 0.3s ease;
}

.upload-area:hover, .upload-area.dragover {
    border-color: var(--primary-color);
    background-color: var(--secondary-color);
}

.upload-icon {
    font-size: 4rem;
    color: var(--primary-color);
    margin-bottom: 20px;
}

.upload-text {
    font-size: 1.2rem;
    font-weight: 600;
    margin-bottom: 10px;
}

.upload-subtext {
    color: #6c757d;
}

#fileInput {
    display: none;
}

.btn {
    background-color: var(--primary-color);
    color: var(--white);
    border: none;
    padding: 15px 35px;
    border-radius: 8px;
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    display: block;
    margin: 30px auto 0;
}

.btn:hover {
    background-color: #0041a3;
    transform: translateY(-2px);
}

.btn:disabled {
    background-color: #adb5bd;
    cursor: not-allowed;
    transform: none;
}

.files-preview, .progress-container {
    display: none;
}

.files-preview h3, .progress-container h3 {
    font-size: 1.5rem;
    margin-bottom: 20px;
    color: var(--primary-color);
}

.file-item {
    display: flex;
    align-items: center;
    padding: 15px;
    margin-bottom: 10px;
    background-color: var(--light-gray);
    border-radius: 8px;
    border-left: 4px solid var(--primary-color);
}

.file-icon {
    font-size: 1.5rem;
    color: var(--primary-color);
    margin-right: 15px;
}

.progress-bar {
    width: 100%;
    height: 10px;
    background-color: var(--light-gray);
    border-radius: 10px;
    overflow: hidden;
    margin-bottom: 20px;
}

.progress-fill {
    height: 100%;
    background-color: var(--primary-color);
    width: 0%;
    transition: width 0.4s ease;
}

.spinner {
    border: 4px solid var(--light-gray);
    border-top: 4px solid var(--primary-color);
    border-radius: 50%;
    width: 30px;
    height: 30px;
    animation: spin 1s linear infinite;
    margin: 20px auto 0;
}

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

.status-message {
    text-align: center;
    padding: 15px;
    border-radius: 8px;
    margin-top: 20px;
    font-weight: 500;
}

.success {
    background-color: #d4edda;
    color: #155724;
    border: 1px solid #c3e6cb;
}

.error {
    background-color: #f8d7da;
    color: #721c24;
    border: 1px solid #f5c6cb;
}

.info {
    background-color: var(--secondary-color);
    color: var(--primary-color);
    border: 1px solid rgba(0, 82, 204, 0.2);
}

.footer {
    text-align: center;
    padding: 20px;
    color: #6c757d;
    font-size: 0.9rem;
    background-color: var(--white);
    border-top: 1px solid var(--border-color);
}

.footer a {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 600;
}

.footer a:hover {
    text-decoration: underline;
}

@media (max-width: 768px) {
    .instructions ul {
        flex-direction: column;
        align-items: center;
    }
}