/* --- Global Styles & Variables --- */
:root {
    --bg-main: #ffffff;
    --bg-surface: #f9f9f9;
    --text-main: #1a1a1a;
    --text-secondary: #555555;
    --accent-color: #005A9C; /* A sophisticated blue */
    --accent-hover: #003D6B;
    --border-color: #e0e0e0;
    --font-heading: 'Poppins', 'Noto Sans JP', sans-serif;
    --font-body: 'Noto Sans JP', sans-serif;
}

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

html {
    scroll-behavior: smooth;
}

body {
    background-color: var(--bg-main);
    color: var(--text-main);
    font-family: var(--font-body);
    line-height: 1.8;
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

a {
    color: var(--accent-color);
    text-decoration: none;
    transition: color 0.2s ease-in-out;
}

a:hover {
    color: var(--accent-hover);
    text-decoration: underline;
}

h1, h2, h3 {
    font-family: var(--font-heading);
    line-height: 1.3;
    margin-bottom: 1.5rem;
    font-weight: 700;
}

h1 { font-size: 3rem; }
h2 { font-size: 2.25rem; }
h3 { font-size: 1.5rem; }
p { margin-bottom: 1.5rem; color: var(--text-secondary);}
p a { font-weight: 700; text-decoration: underline; }

/* --- Header & Navigation --- */
.site-header {
    background-color: var(--bg-main);
    border-bottom: 1px solid var(--border-color);
    padding: 1.5rem 0;
}

.site-header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.site-title a {
    font-family: var(--font-heading);
    font-size: 1.75rem;
    font-weight: 700;
    color: var(--text-main);
    text-decoration: none;
    letter-spacing: 1px;
}
.site-title a:hover {
    text-decoration: none;
}

.main-nav ul {
    display: flex;
    list-style-type: none;
}

.main-nav li {
    margin-left: 35px;
}

.main-nav a {
    color: var(--text-secondary);
    text-decoration: none;
    padding-bottom: 5px;
    font-size: 1rem;
    font-family: var(--font-heading);
    font-weight: 600;
    transition: color 0.2s ease-in-out;
    border-bottom: 2px solid transparent;
}
.main-nav a:hover {
    color: var(--text-main);
    border-bottom-color: var(--accent-color);
    text-decoration: none;
}
.main-nav a.active {
    color: var(--accent-color);
    font-weight: 700;
}

/* --- Main Content Layout --- */
main.container {
    padding-top: 60px;
    padding-bottom: 60px;
    display: grid;
    grid-template-columns: 1fr;
    gap: 60px;
}

@media (min-width: 992px) {
    main.container {
        grid-template-columns: 2.5fr 1fr;
    }
}

.main-content-full {
    grid-column: 1 / -1;
}

/* --- Homepage Specific --- */
.hero-section {
    padding-bottom: 2rem;
    margin-bottom: 3rem;
    border-bottom: 1px solid var(--border-color);
    text-align: center;
}
.hero-section h1 {
    font-size: 3.5rem;
}
.hero-section p {
    font-size: 1.1rem;
    max-width: 800px;
    margin-left: auto;
    margin-right: auto;
}

.articles-section h2 {
    text-align: center;
    margin-bottom: 3rem;
}

.articles-grid {
    display: grid;
    gap: 30px;
    grid-template-columns: 1fr;
}

@media (min-width: 768px) {
    .articles-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

.article-card {
    background-color: var(--bg-main);
    border: 1px solid var(--border-color);
    padding: 30px;
    display: flex;
    flex-direction: column;
    transition: transform 0.2s ease, box-shadow 0.2s ease;
}
.article-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 16px rgba(0, 0, 0, 0.07);
}
.article-card h3 {
    margin-bottom: 15px;
    font-size: 1.4rem;
}
.article-card p {
    flex-grow: 1;
    font-size: 0.95rem;
}
.btn {
    display: inline-block;
    background-color: var(--accent-color);
    color: #fff;
    padding: 12px 28px;
    text-align: center;
    align-self: flex-start;
    margin-top: 20px;
    font-size: 0.9rem;
    font-family: var(--font-heading);
    font-weight: 600;
    transition: all 0.2s ease;
    text-decoration: none;
    text-transform: uppercase;
    letter-spacing: 1px;
}
.btn:hover {
    background-color: var(--accent-hover);
    color: #fff;
    text-decoration: none;
}

/* --- Sidebar --- */
.sidebar-widget {
    margin-bottom: 40px;
}
.sidebar-widget h3 {
    font-size: 1.3rem;
    margin-bottom: 20px;
    padding-bottom: 15px;
    border-bottom: 2px solid var(--accent-color);
}
.sidebar-widget ul {
    list-style-type: none;
}
.sidebar-widget ul li {
    margin-bottom: 15px;
}
.promo-widget {
    background-color: var(--bg-surface);
    border: 1px solid var(--border-color);
    padding: 25px;
    font-size: 1rem;
    text-align: center;
}

/* --- Article Page --- */
.article-header {
    margin-bottom: 2rem;
    padding-bottom: 2rem;
    border-bottom: 1px solid var(--border-color);
}
.article-header h1 {
    font-size: 3.25rem;
}
.article-meta {
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin-top: -1rem;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}
.article-content h2 {
    margin-top: 3rem;
}
.article-content ul {
    list-style-position: inside;
    margin-bottom: 1.5rem;
}
.article-content li {
    margin-bottom: 0.75rem;
}
.cta-box {
    margin-top: 3.5rem;
    padding: 2.5rem;
    background-color: var(--bg-surface);
    border-top: 3px solid var(--accent-color);
    text-align: center;
}
.cta-box p {
    font-size: 1.2rem;
    margin: 0;
    font-weight: 600;
}

/* --- Footer --- */
.site-footer {
    background-color: var(--bg-surface);
    color: var(--text-secondary);
    padding: 2.5rem 0;
    text-align: center;
    font-size: 0.9rem;
    margin-top: 60px;
    border-top: 1px solid var(--border-color);
}
.site-footer p {
    margin: 0;
}

/* --- Responsive Design --- */
@media (max-width: 768px) {
    body { font-size: 15px; }
    h1 { font-size: 2.25rem; }
    h2 { font-size: 1.75rem; }
    .hero-section h1 { font-size: 2.5rem; }
    .article-header h1 { font-size: 2.5rem; }

    .site-header {
        padding: 1rem 0;
    }
    .site-header .container {
        flex-direction: column;
        align-items: center;
    }
    .site-title {
        margin-bottom: 1rem;
    }
    .main-nav ul {
        justify-content: center;
        flex-wrap: wrap;
    }
    .main-nav li {
        margin: 5px 10px;
    }
}