body {
    font-family: Arial, sans-serif;
    margin: 20px;
    background-color: #f5f5f5;
}
.container {
    max-width: 900px;
    margin: auto;
    background: white;
    padding: 20px;
    border-radius: 8px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}
h1 {
    text-align: center;
    color: #333;
    margin-bottom: 20px;
}
textarea {
    width: 100%;
    height: 150px;
    margin-bottom: 10px;
    padding: 8px;
    border: 1px solid #ccc;
    border-radius: 4px;
    resize: vertical;
    font-family: inherit;
}
input[type="text"] {
    width: 100%;
    margin-bottom: 10px;
    padding: 8px;
    border: 1px solid #ccc;
    border-radius: 4px;
    box-sizing: border-box;
}
.buttons {
    margin-bottom: 10px;
    display: flex;
    flex-wrap: wrap;
    gap: 5px;
}
button {
    padding: 8px 12px;
    background-color: #4CAF50;
    color: white;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    font-size: 14px;
}
button:hover {
    background-color: #45a049;
}
#load-file-btn, #download-btn {
    background-color: #2196F3;
}
#load-file-btn:hover {
    background-color: #0b7dda;
}
#download-btn:hover {
    background-color: #0b7dda;
}
#output-text {
    background-color: #f9f9f9;
}
#message {
    margin-top: 10px;
    padding: 8px;
    border-radius: 4px;
    font-weight: bold;
}
#message.info {
    background-color: #d4edda;
    color: #155724;
    border: 1px solid #c3e6cb;
}
#message.error {
    background-color: #f8d7da;
    color: #721c24;
    border: 1px solid #f5c6cb;
}
.matrix-container {
    margin: 15px 0;
    padding: 10px;
    background-color: #f0f0f0;
    border-radius: 4px;
    overflow-x: auto;
    text-align: center;
}
.matrix-table {
    border-collapse: collapse;
    margin: 5px auto;
    font-family: monospace;
    display: inline-table;
}
.matrix-table td, .matrix-table th {
    border: 1px solid #999;
    padding: 5px 10px;
    text-align: center;
}
.matrix-table th {
    background-color: #ddd;
    font-weight: bold;
}
.matrix-info {
    font-style: italic;
    margin: 5px 0;
    color: #555;
}

#message.warning {
    background-color: #fff3cd;
    color: #856404;
    border: 1px solid #ffeeba;
}

.keystream-display {
    margin-top: 10px;
    padding: 8px;
    background-color: #f9f9f9;
    border: 1px solid #ddd;
    border-radius: 4px;
    font-family: monospace;
    font-size: 14px;
    word-break: break-all;
}