:root {
    --primary-color: #2563eb;
    --secondary-color: #64748b;
    --success-color: #10b981;
    --danger-color: #ef4444;
    --warning-color: #f59e0b;
    --light-bg: #f8fafc;
    --dark-text: #1e293b;
    --border-color: #e2e8f0;
    --shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.1);
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background-color: var(--light-bg);
    color: var(--dark-text);
    line-height: 1.6;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

/* Navbar */
.navbar {
    background-color: white;
    border-bottom: 2px solid var(--primary-color);
    box-shadow: var(--shadow);
    position: sticky;
    top: 0;
    z-index: 100;
}

.navbar-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 70px;
}

.navbar-brand {
    font-size: 24px;
    font-weight: bold;
    color: var(--primary-color);
    text-decoration: none;
    transition: opacity 0.3s ease;
}

.navbar-brand:hover {
    opacity: 0.8;
}

.navbar-menu {
    display: flex;
    list-style: none;
    gap: 30px;
}

.nav-link {
    color: var(--secondary-color);
    text-decoration: none;
    font-weight: 500;
    transition: color 0.3s ease;
}

.nav-link:hover {
    color: var(--primary-color);
}

/* Main Container */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 40px 20px;
    flex-grow: 1;
}

/* Hero Section */
.hero {
    text-align: center;
    padding: 60px 20px;
    background: linear-gradient(135deg, var(--primary-color), #1e40af);
    color: white;
    border-radius: 12px;
    margin-bottom: 40px;
    box-shadow: var(--shadow-lg);
}

.hero h1 {
    font-size: 44px;
    margin-bottom: 10px;
}

.hero p {
    font-size: 18px;
    margin-bottom: 25px;
    opacity: 0.95;
}

/* Alerts */
.alert {
    padding: 15px 20px;
    margin-bottom: 20px;
    border-radius: 8px;
    border-left: 4px solid;
    animation: slideIn 0.3s ease;
}

@keyframes slideIn {
    from {
        transform: translateX(-20px);
        opacity: 0;
    }

    to {
        transform: translateX(0);
        opacity: 1;
    }
}

.alert-success {
    background-color: #ecfdf5;
    border-color: var(--success-color);
    color: #065f46;
}

.alert-danger {
    background-color: #fef2f2;
    border-color: var(--danger-color);
    color: #991b1b;
}

.alert-warning {
    background-color: #fffbeb;
    border-color: var(--warning-color);
    color: #92400e;
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 12px 24px;
    border-radius: 8px;
    border: none;
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    text-decoration: none;
    transition: all 0.3s ease;
    text-align: center;
}

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

.btn-primary:hover {
    background-color: #1d4ed8;
    box-shadow: var(--shadow-lg);
    transform: translateY(-2px);
}

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

.btn-secondary:hover {
    background-color: #475569;
}

.btn-small {
    padding: 8px 16px;
    font-size: 14px;
}

/* Forms */
.form-container {
    background: white;
    padding: 40px;
    border-radius: 12px;
    box-shadow: var(--shadow-lg);
    max-width: 600px;
    margin: 0 auto;
}

.form-subtitle {
    color: var(--secondary-color);
    font-size: 16px;
    margin-bottom: 30px;
}

.guestbook-form {
    margin-top: 30px;
}

.form-group {
    margin-bottom: 25px;
}

.form-group label {
    display: block;
    margin-bottom: 8px;
    font-weight: 600;
    color: var(--dark-text);
}

.form-control {
    width: 100%;
    padding: 12px 15px;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    font-size: 16px;
    font-family: inherit;
    transition: border-color 0.3s ease, box-shadow 0.3s ease;
}

.form-control:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.form-control:invalid {
    border-color: var(--danger-color);
}

.form-group small {
    display: block;
    margin-top: 6px;
    color: var(--secondary-color);
    font-size: 14px;
}

.character-count {
    margin-top: 10px;
    text-align: right;
    color: var(--secondary-color);
    font-size: 14px;
}

.form-actions {
    display: flex;
    gap: 15px;
    margin-top: 40px;
}

.form-actions button,
.form-actions a {
    flex: 1;
}

/* Messages */
.messages-section {
    margin-top: 40px;
}

.messages-section h2 {
    margin-bottom: 30px;
    font-size: 28px;
    color: var(--dark-text);
}

.message-card {
    background: white;
    padding: 25px;
    margin-bottom: 20px;
    border-radius: 12px;
    border-left: 4px solid var(--primary-color);
    box-shadow: var(--shadow);
    transition: all 0.3s ease;
}

.message-card:hover {
    box-shadow: var(--shadow-lg);
    transform: translateY(-2px);
}

.message-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 15px;
    gap: 15px;
}

.message-left {
    flex: 1;
}

.message-author {
    font-size: 18px;
    color: var(--primary-color);
    margin: 0;
}

.message-author a {
    color: var(--primary-color);
    text-decoration: none;
    transition: opacity 0.3s ease;
}

.message-author a:hover {
    opacity: 0.7;
    text-decoration: underline;
}

.message-date {
    color: var(--secondary-color);
    font-size: 14px;
    font-weight: 500;
}

.message-email {
    color: var(--secondary-color);
    font-size: 14px;
    margin-bottom: 12px;
}

.message-text {
    color: var(--dark-text);
    font-size: 16px;
    line-height: 1.7;
    word-wrap: break-word;
}

/* User Header */
.user-header {
    background: white;
    padding: 30px;
    border-radius: 12px;
    box-shadow: var(--shadow);
    margin-bottom: 40px;
}

.user-header h1 {
    margin-bottom: 10px;
}

.user-email {
    color: var(--primary-color);
    font-weight: 500;
    margin-bottom: 5px;
}

.user-joined {
    color: var(--secondary-color);
    font-size: 14px;
    margin-bottom: 20px;
}

/* No Messages */
.no-messages {
    text-align: center;
    padding: 60px 20px;
    background: white;
    border-radius: 12px;
    box-shadow: var(--shadow);
}

.no-messages p {
    color: var(--secondary-color);
    font-size: 18px;
    margin-bottom: 25px;
}

/* Pagination */
.pagination {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 15px;
    margin-top: 40px;
    padding: 20px;
}

.pagination-info {
    color: var(--secondary-color);
    font-weight: 500;
}

/* Footer */
.footer {
    background-color: var(--dark-text);
    color: white;
    text-align: center;
    padding: 20px;
    margin-top: auto;
}

.footer p {
    margin: 0;
}

/* Responsive Design */
@media (max-width: 768px) {
    .navbar-container {
        flex-direction: column;
        height: auto;
        padding: 15px 20px;
        gap: 15px;
    }

    .navbar-menu {
        gap: 15px;
    }

    .container {
        padding: 20px;
    }

    .hero {
        padding: 40px 20px;
    }

    .hero h1 {
        font-size: 32px;
    }

    .hero p {
        font-size: 16px;
    }

    .form-container {
        padding: 20px;
    }

    .message-header {
        flex-direction: column;
        gap: 10px;
    }

    .form-actions {
        flex-direction: column;
    }

    .form-actions button,
    .form-actions a {
        flex: unset;
        width: 100%;
    }

    .pagination {
        flex-wrap: wrap;
    }
}

.btn-delete {
    background-color: var(--danger-color);
    color: white;
    border: none;
    padding: 8px 14px;
    border-radius: 6px;
    cursor: pointer;
    font-size: 14px;
    font-weight: 500;
    transition: all 0.3s ease;
    white-space: nowrap;
}

.btn-delete:hover {
    background-color: #dc2626;
    transform: scale(1.05);
}

.btn-delete:active {
    transform: scale(0.95);
}

@media (max-width: 480px) {
    .navbar-brand {
        font-size: 20px;
    }

    .hero h1 {
        font-size: 24px;
    }

    .hero p {
        font-size: 14px;
    }

    .btn {
        padding: 10px 16px;
        font-size: 14px;
    }
}