/* ==========================================
   Connecting Dots Office - Main Stylesheet
   Academic & Professional Design
   ========================================== */

/* ==========================================
   CSS Variables & Design Tokens
   ========================================== */
:root {
    /* Color Palette - Academic & Professional */
    --color-primary: #1a4d8f;
    --color-primary-light: #2563a8;
    --color-primary-dark: #0f3566;
    --color-secondary: #5c6f82;
    --color-accent: #d4a574;
    --color-text: #1f2937;
    --color-text-light: #6b7280;
    --color-background: #ffffff;
    --color-background-alt: #f9fafb;
    --color-border: #e5e7eb;
    --color-success: #059669;
    --color-error: #dc2626;
    
    /* Typography */
    --font-primary: 'Noto Sans JP', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --font-serif: 'Noto Serif JP', Georgia, serif;
    --font-mono: 'Source Code Pro', monospace;
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    --spacing-2xl: 4rem;
    --spacing-3xl: 6rem;
    
    /* Layout */
    --container-max-width: 1200px;
    --container-padding: 2rem;
    --border-radius: 8px;
    --box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --box-shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    
    /* Transitions */
    --transition-fast: 150ms ease-in-out;
    --transition-normal: 300ms ease-in-out;
    --transition-slow: 500ms ease-in-out;
}

/* ==========================================
   Reset & Base Styles
   ========================================== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: var(--font-primary);
    font-size: 1rem;
    line-height: 1.7;
    color: var(--color-text);
    background-color: var(--color-background);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* ==========================================
   Typography
   ========================================== */
h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-serif);
    font-weight: 600;
    line-height: 1.3;
    color: var(--color-text);
    margin-bottom: var(--spacing-md);
}

h1 {
    font-size: clamp(2rem, 5vw, 3rem);
}

h2 {
    font-size: clamp(1.75rem, 4vw, 2.5rem);
}

h3 {
    font-size: clamp(1.5rem, 3vw, 2rem);
}

h4 {
    font-size: clamp(1.25rem, 2.5vw, 1.5rem);
}

p {
    margin-bottom: var(--spacing-md);
}

a {
    color: var(--color-primary);
    text-decoration: none;
    transition: color var(--transition-fast);
}

a:hover {
    color: var(--color-primary-light);
}

/* ==========================================
   Layout Components
   ========================================== */
.container {
    max-width: var(--container-max-width);
    margin: 0 auto;
    padding: 0 var(--container-padding);
}

/* ==========================================
   Header & Navigation
   ========================================== */
.site-header {
    background-color: var(--color-background);
    border-bottom: 1px solid var(--color-border);
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.05);
}

.main-nav {
    padding: 1rem 0;
}

.nav-wrapper {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo a {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--color-primary);
    transition: color var(--transition-fast);
}

.logo a:hover {
    color: var(--color-primary-light);
}

.logo i {
    font-size: 1.5rem;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 2rem;
    align-items: center;
}

.nav-menu a {
    font-weight: 500;
    color: var(--color-text);
    padding: 0.5rem 1rem;
    border-radius: var(--border-radius);
    transition: all var(--transition-fast);
}

.nav-menu a:hover,
.nav-menu a.active {
    color: var(--color-primary);
    background-color: rgba(26, 77, 143, 0.05);
}

/* Dropdown Menu */
.nav-dropdown {
    position: relative;
}

.dropdown-toggle {
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.dropdown-toggle i {
    font-size: 0.75rem;
    transition: transform var(--transition-fast);
}

.nav-dropdown:hover .dropdown-toggle i {
    transform: rotate(180deg);
}

.dropdown-menu {
    position: absolute;
    top: 100%;
    left: 0;
    background-color: var(--color-background);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow-lg);
    min-width: 250px;
    padding: 0.5rem 0;
    opacity: 0;
    visibility: hidden;
    transform: translateY(-10px);
    transition: all var(--transition-fast);
    list-style: none;
}

.nav-dropdown:hover .dropdown-menu {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.dropdown-menu li {
    margin: 0;
}

.dropdown-menu a {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.75rem 1.25rem;
    color: var(--color-text);
    border-radius: 0;
}

.dropdown-menu a:hover {
    background-color: var(--color-background-alt);
    color: var(--color-primary);
}

.dropdown-menu i {
    width: 20px;
    color: var(--color-primary);
}

/* Mobile Menu Toggle */
.mobile-menu-toggle {
    display: none;
    flex-direction: column;
    gap: 0.35rem;
    background: none;
    border: none;
    cursor: pointer;
    padding: 0.5rem;
}

.mobile-menu-toggle span {
    display: block;
    width: 25px;
    height: 3px;
    background-color: var(--color-text);
    transition: all var(--transition-fast);
    border-radius: 2px;
}

/* ==========================================
   Hero Section
   ========================================== */
.hero {
    background: linear-gradient(135deg, #1a4d8f 0%, #2563a8 100%);
    color: white;
    padding: var(--spacing-3xl) 0;
    text-align: center;
}

.hero-content {
    max-width: 800px;
    margin: 0 auto;
}

.hero-title {
    color: white;
    font-size: clamp(2.5rem, 6vw, 4rem);
    font-weight: 700;
    margin-bottom: var(--spacing-md);
    line-height: 1.2;
}

.hero-subtitle {
    font-size: clamp(1rem, 2vw, 1.25rem);
    margin-bottom: var(--spacing-xl);
    opacity: 0.95;
    line-height: 1.8;
}

.hero-cta {
    display: flex;
    gap: 1rem;
    justify-content: center;
    flex-wrap: wrap;
}

/* ==========================================
   Mission Section
   ========================================== */
.mission {
    padding: var(--spacing-3xl) 0;
    background-color: var(--color-background-alt);
}

.mission-content {
    max-width: 800px;
    margin: 0 auto;
    text-align: center;
}

.mission-text {
    font-size: 1.125rem;
    line-height: 1.9;
    color: var(--color-text-light);
}

/* ==========================================
   Section Titles
   ========================================== */
.section-title {
    text-align: center;
    margin-bottom: var(--spacing-xl);
    position: relative;
    padding-bottom: var(--spacing-md);
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 60px;
    height: 4px;
    background: linear-gradient(90deg, var(--color-primary), var(--color-accent));
    border-radius: 2px;
}

/* ==========================================
   Categories Section
   ========================================== */
.categories {
    padding: var(--spacing-3xl) 0;
}

.category-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: var(--spacing-lg);
}

.category-card {
    background-color: var(--color-background);
    border: 2px solid var(--color-border);
    border-radius: var(--border-radius);
    padding: var(--spacing-xl);
    text-align: center;
    transition: all var(--transition-normal);
    display: block;
    color: var(--color-text);
}

.category-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--box-shadow-lg);
    border-color: var(--color-primary);
}

.category-icon {
    width: 80px;
    height: 80px;
    margin: 0 auto var(--spacing-md);
    background: linear-gradient(135deg, var(--color-primary), var(--color-primary-light));
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2rem;
    color: white;
}

.category-card h3 {
    font-size: 1.5rem;
    margin-bottom: var(--spacing-sm);
    color: var(--color-text);
}

.category-card p {
    color: var(--color-text-light);
    margin-bottom: var(--spacing-md);
    line-height: 1.7;
}

.category-link {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--color-primary);
    font-weight: 600;
    transition: gap var(--transition-fast);
}

.category-card:hover .category-link {
    gap: 0.75rem;
}

/* ==========================================
   Featured Articles Section
   ========================================== */
.featured-articles {
    padding: var(--spacing-3xl) 0;
    background-color: var(--color-background-alt);
}

.articles-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(350px, 1fr));
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-xl);
}

.article-card {
    background-color: var(--color-background);
    border-radius: var(--border-radius);
    padding: var(--spacing-lg);
    box-shadow: var(--box-shadow);
    transition: all var(--transition-normal);
    display: flex;
    flex-direction: column;
}

.article-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--box-shadow-lg);
}

.article-category {
    display: inline-block;
    background-color: rgba(26, 77, 143, 0.1);
    color: var(--color-primary);
    padding: 0.375rem 0.875rem;
    border-radius: 20px;
    font-size: 0.875rem;
    font-weight: 600;
    margin-bottom: var(--spacing-md);
    width: fit-content;
}

.article-title {
    font-size: 1.25rem;
    margin-bottom: var(--spacing-sm);
    line-height: 1.4;
}

.article-title a {
    color: var(--color-text);
    transition: color var(--transition-fast);
}

.article-title a:hover {
    color: var(--color-primary);
}

.article-excerpt {
    color: var(--color-text-light);
    line-height: 1.7;
    margin-bottom: var(--spacing-md);
    flex-grow: 1;
}

.article-meta {
    display: flex;
    gap: var(--spacing-md);
    font-size: 0.875rem;
    color: var(--color-text-light);
    padding-top: var(--spacing-md);
    border-top: 1px solid var(--color-border);
}

.article-meta i {
    margin-right: 0.375rem;
}

.load-more-wrapper {
    text-align: center;
    margin-top: var(--spacing-xl);
}

/* ==========================================
   Newsletter Section
   ========================================== */
.newsletter {
    padding: var(--spacing-3xl) 0;
    background: linear-gradient(135deg, #1a4d8f 0%, #2563a8 100%);
    color: white;
}

.newsletter-content {
    max-width: 600px;
    margin: 0 auto;
    text-align: center;
}

.newsletter-title {
    color: white;
    margin-bottom: var(--spacing-sm);
}

.newsletter-text {
    margin-bottom: var(--spacing-lg);
    opacity: 0.95;
}

.newsletter-form {
    display: flex;
    gap: var(--spacing-sm);
    flex-wrap: wrap;
    justify-content: center;
}

.newsletter-form input {
    flex: 1;
    min-width: 250px;
    padding: 0.875rem 1.25rem;
    border: 2px solid rgba(255, 255, 255, 0.3);
    border-radius: var(--border-radius);
    font-size: 1rem;
    background-color: rgba(255, 255, 255, 0.1);
    color: white;
    transition: all var(--transition-fast);
}

.newsletter-form input::placeholder {
    color: rgba(255, 255, 255, 0.7);
}

.newsletter-form input:focus {
    outline: none;
    background-color: rgba(255, 255, 255, 0.15);
    border-color: rgba(255, 255, 255, 0.5);
}

/* ==========================================
   Buttons
   ========================================== */
.btn {
    display: inline-block;
    padding: 0.875rem 1.75rem;
    font-size: 1rem;
    font-weight: 600;
    text-align: center;
    border: 2px solid transparent;
    border-radius: var(--border-radius);
    cursor: pointer;
    transition: all var(--transition-fast);
    text-decoration: none;
}

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

.btn-primary:hover {
    background-color: var(--color-primary-dark);
    transform: translateY(-2px);
    box-shadow: var(--box-shadow);
    color: white;
}

.btn-secondary {
    background-color: transparent;
    color: white;
    border-color: white;
}

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

.btn-outline {
    background-color: transparent;
    color: var(--color-primary);
    border-color: var(--color-primary);
}

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

/* ==========================================
   Footer
   ========================================== */
.site-footer {
    background-color: var(--color-text);
    color: rgba(255, 255, 255, 0.8);
    padding: var(--spacing-3xl) 0 var(--spacing-lg);
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-xl);
    margin-bottom: var(--spacing-xl);
}

.footer-section h3 {
    color: white;
    font-size: 1.25rem;
    margin-bottom: var(--spacing-md);
}

.footer-section p {
    line-height: 1.7;
}

.footer-links {
    list-style: none;
}

.footer-links li {
    margin-bottom: var(--spacing-sm);
}

.footer-links a {
    color: rgba(255, 255, 255, 0.8);
    transition: color var(--transition-fast);
}

.footer-links a:hover {
    color: white;
}

.footer-bottom {
    text-align: center;
    padding-top: var(--spacing-lg);
    border-top: 1px solid rgba(255, 255, 255, 0.1);
}

/* ==========================================
   Responsive Design
   ========================================== */
@media (max-width: 768px) {
    :root {
        --container-padding: 1rem;
        --spacing-xl: 2rem;
        --spacing-2xl: 3rem;
        --spacing-3xl: 4rem;
    }
    
    .mobile-menu-toggle {
        display: flex;
    }
    
    .nav-menu {
        position: fixed;
        top: 70px;
        left: 0;
        right: 0;
        background-color: var(--color-background);
        flex-direction: column;
        align-items: stretch;
        padding: var(--spacing-md);
        box-shadow: var(--box-shadow-lg);
        transform: translateY(-100%);
        opacity: 0;
        visibility: hidden;
        transition: all var(--transition-normal);
        gap: 0;
    }
    
    .nav-menu.active {
        transform: translateY(0);
        opacity: 1;
        visibility: visible;
    }
    
    .nav-menu li {
        margin: 0;
    }
    
    .nav-menu a {
        display: block;
        padding: var(--spacing-sm);
    }
    
    .dropdown-menu {
        position: static;
        opacity: 1;
        visibility: visible;
        transform: none;
        box-shadow: none;
        border: none;
        border-left: 2px solid var(--color-primary);
        margin-left: var(--spacing-sm);
        padding-left: var(--spacing-sm);
        max-height: 0;
        overflow: hidden;
        transition: max-height var(--transition-normal);
    }
    
    .nav-dropdown.active .dropdown-menu {
        max-height: 500px;
    }
    
    .hero {
        padding: var(--spacing-2xl) 0;
    }
    
    .hero-cta {
        flex-direction: column;
    }
    
    .hero-cta .btn {
        width: 100%;
    }
    
    .category-grid {
        grid-template-columns: 1fr;
    }
    
    .articles-grid {
        grid-template-columns: 1fr;
    }
    
    .newsletter-form {
        flex-direction: column;
    }
    
    .newsletter-form input {
        width: 100%;
    }
    
    .footer-content {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    html {
        font-size: 14px;
    }
}