:root {
    --bg-color: #f8f9fa;
    --text-color: #212529;
    --accent-color: #0d6efd;
    --btn-hover: #0b5ed7;
    --card-bg: #ffffff;
    --card-shadow: rgba(0, 0, 0, 0.05);
    --meta-text: #6c757d;
}
@media (prefers-color-scheme: dark) {
    :root {
        --bg-color: #121212;
        --text-color: #e0e0e0;
        --accent-color: #3b82f6;
        --btn-hover: #2563eb;
        --card-bg: #1e1e1e;
        --card-shadow: rgba(0, 0, 0, 0.3);
        --meta-text: #9ca3af;
    }
}
body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    margin: 0;
    padding: 0;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    transition: background-color 0.3s, color 0.3s;
}
.container {
    text-align: center;
    background-color: var(--card-bg);
    padding: 2.5rem;
    border-radius: 12px;
    box-shadow: 0 4px 20px var(--card-shadow);
    max-width: 90%;
    width: 450px;
    transition: background-color 0.3s, box-shadow 0.3s;
}
h1 {
    color: var(--accent-color);
    margin-top: 0;
    margin-bottom: 1rem;
    font-size: 2.2rem;
    letter-spacing: -0.5px;
}
p {
    margin: 0;
    font-size: 1.1rem;
    line-height: 1.5;
}
.btn-admin {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    background-color: var(--accent-color);
    color: #ffffff;
    text-decoration: none;
    padding: 0.75rem 1.5rem 0.55rem 1.4rem; /* 0.75rem 1.5rem */
    border-radius: 6px;
    font-weight: 600;
    font-size: 1rem;
    line-height: 1.2; /* 1 */
    transition: background-color 0.2s ease, transform 0.1s ease;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
    margin-top: 1.2rem;
}
.btn-admin:hover {
    background-color: var(--btn-hover);
}
.btn-admin:active {
    transform: scale(0.98);
}
.security-note {
    display: block;
    margin-top: 1.2rem;
    font-size: 0.85rem;
    color: var(--meta-text);
}