:root {
    --primary-color: #007bff;
    --primary-hover: #0056b3;
    --secondary-color: #6c757d;
    --secondary-hover: #5a6268;
    --background-color: #f8f9fa;
    --font-color: #212529;
    --border-color: #dee2e6;
    --white-color: #fff;
    --error-color: #dc3545;
    --success-color: #28a745;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    margin: 0;
    background-color: var(--background-color);
    color: var(--font-color);
    line-height: 1.6;
}

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

header {
    border-bottom: 1px solid var(--border-color);
    margin-bottom: 2rem;
    padding-bottom: 1rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

header h1 {
    margin: 0;
    color: var(--primary-color);
}

header p {
    margin: 0;
    color: var(--secondary-color);
}

header nav {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.form-container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
}

.form-wrapper, .file-list-wrapper, .file-view {
    background: var(--white-color);
    padding: 1.5rem;
    border-radius: 8px;
    border: 1px solid var(--border-color);
    margin-bottom: 2rem;
}

h2 {
    margin-top: 0;
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 0.5rem;
    margin-bottom: 1rem;
}

.form-group {
    margin-bottom: 1rem;
}

label {
    display: block;
    margin-bottom: .5rem;
    font-weight: bold;
}

input[type="text"],
input[type="email"],
input[type="password"],
textarea {
    width: 100%;
    padding: 0.5rem;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    box-sizing: border-box;
}

textarea {
    min-height: 150px;
    resize: vertical;
}

.button, .button-secondary, .button-link {
    display: inline-block;
    padding: 0.6rem 1.2rem;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    text-decoration: none;
    font-weight: bold;
    text-align: center;
}

.button {
    background-color: var(--primary-color);
    color: var(--white-color);
}

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

.button-secondary {
    background-color: var(--secondary-color);
    color: var(--white-color);
}

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

.button-link {
    background: none;
    color: var(--primary-color);
    padding: 0;
    border: none;
    font-size: 1em;
}

.form-actions {
    display: flex;
    gap: 1rem;
}

.message {
    margin-top: 1rem;
    font-weight: bold;
}

#login-message.error, #register-message.error, #file-message.error {
    color: var(--error-color);
}

#login-message.success, #register-message.success, #file-message.success {
    color: var(--success-color);
}

#file-list {
    list-style: none;
    padding: 0;
}

#file-list li {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0.75rem;
    border-bottom: 1px solid var(--border-color);
}

#file-list li:last-child {
    border-bottom: none;
}

#file-list .file-actions button, #file-list .file-actions a {
    margin-left: 0.5rem;
}

.file-content {
    background-color: #f4f4f4;
    padding: 1rem;
    border-radius: 4px;
    white-space: pre-wrap;
    word-wrap: break-word;
    border: 1px solid var(--border-color);
}

.author {
    color: var(--secondary-color);
    margin-top: -1rem;
    margin-bottom: 1rem;
}

@media (max-width: 768px) {
    .form-container {
        grid-template-columns: 1fr;
    }
}