/* Modern Light Theme */
:root {
    --primary-color: #4a90e2;
    /* Soft Blue */
    --background-color: #f5f7fa;
    /* Light Grey-Blue */
    --card-bg: #ffffff;
    --text-color: #333333;
    --text-secondary: #666666;
    --border-radius: 16px;
    --shadow: 0 10px 30px rgba(0, 0, 0, 0.08);
}

body {
    background-color: var(--background-color);
    margin: 0;
    padding: 40px 20px;
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    color: var(--text-color);
    display: flex;
    flex-direction: column;
    align-items: center;
    min-height: 100vh;
}

.ac-age-calculator {
    width: 100%;
    max-width: 480px;
    padding: 20px;
}

.ac-return-btn {
    display: inline-flex;
    align-items: center;
    margin-bottom: 25px;
    text-decoration: none;
    color: var(--text-secondary);
    font-weight: 500;
    font-size: 0.95rem;
    transition: color 0.2s ease;
}

.ac-return-btn:hover {
    color: var(--primary-color);
}

.ac-adsense {
    margin-bottom: 25px;
    text-align: center;
    border-radius: var(--border-radius);
    overflow: hidden;
}

.ac-title {
    font-size: 1.75rem;
    margin-bottom: 25px;
    text-align: center;
    color: var(--text-color);
    font-weight: 700;
    letter-spacing: -0.5px;
}

.ac-card {
    background: var(--card-bg);
    border-radius: var(--border-radius);
    padding: 35px;
    box-shadow: var(--shadow);
    border: 1px solid rgba(255, 255, 255, 0.5);
}

.ac-input-group {
    margin-bottom: 20px;
}

.ac-label {
    display: block;
    margin-bottom: 10px;
    color: var(--text-secondary);
    font-size: 0.95rem;
    font-weight: 500;
}

.ac-input {
    width: 100%;
    padding: 14px 16px;
    background: #f8f9fb;
    border: 2px solid #eef0f5;
    border-radius: 12px;
    font-size: 1rem;
    color: var(--text-color);
    outline: none;
    box-sizing: border-box;
    transition: all 0.2s ease;
    font-family: inherit;
}

.ac-input:focus {
    border-color: var(--primary-color);
    background: #fff;
    box-shadow: 0 0 0 4px rgba(74, 144, 226, 0.1);
}

.ac-note {
    font-size: 0.85rem;
    color: #999;
    margin-top: 20px;
    text-align: center;
}

.ac-result {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--primary-color);
    text-align: center;
    margin-top: 30px;
    padding-top: 25px;
    border-top: 1px solid #f0f0f0;
    line-height: 1.5;
}

/* Make the result span stand out if I assume the JS output structure needs it, 
   though currently JS outputs plain text. I'll stick to clean typography. */

/* Responsive */
@media (max-width: 500px) {
    .ac-card {
        padding: 25px;
    }

    .ac-title {
        font-size: 1.5rem;
    }
}

/* SEO Content Section */
.ac-seo-content {
    max-width: 800px;
    margin: 60px auto;
    padding: 0 20px;
    color: var(--text-color);
    line-height: 1.8;
}

.ac-seo-content h2 {
    color: var(--primary-color);
    font-size: 1.8rem;
    margin-top: 40px;
    margin-bottom: 20px;
}

.ac-seo-content h3 {
    color: var(--text-color);
    font-size: 1.4rem;
    margin-top: 30px;
    margin-bottom: 15px;
}

.ac-seo-content p {
    margin-bottom: 20px;
    font-size: 1.05rem;
}

.ac-seo-content ul,
.ac-seo-content ol {
    margin-bottom: 20px;
    padding-left: 25px;
}

.ac-seo-content li {
    margin-bottom: 10px;
}

.ac-seo-content img {
    max-width: 100%;
    height: auto;
    border-radius: 12px;
    box-shadow: var(--shadow);
    margin: 20px 0;
    display: block;
}

.aligncenter {
    margin-left: auto;
    margin-right: auto;
}