/* ========================================
   Industrial Intelligence Lab - Business Media Style
   東洋経済・ダイヤモンドオンライン風デザイン
   ======================================== */

/* ========================================
   CSS Variables
   ======================================== */
:root {
    --color-primary: #d32f2f;
    --color-primary-dark: #b71c1c;
    --color-primary-light: #ef5350;
    --color-secondary: #1976d2;
    --color-text: #212121;
    --color-text-light: #757575;
    --color-text-lighter: #9e9e9e;
    --color-border: #e0e0e0;
    --color-bg: #ffffff;
    --color-bg-alt: #fafafa;
    --color-bg-gray: #f5f5f5;

    --font-primary: 'Noto Sans JP', 'Hiragino Kaku Gothic ProN', sans-serif;
    --font-serif: 'Noto Serif JP', serif;

    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;

    --border-radius: 4px;
    --transition: all 0.2s ease;

    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.08);
    --shadow-md: 0 2px 8px rgba(0, 0, 0, 0.1);

    --max-width: 1200px;
}

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

html {
    font-size: 16px;
}

body {
    font-family: var(--font-primary);
    color: var(--color-text);
    background-color: var(--color-bg-gray);
    line-height: 1.8;
    -webkit-font-smoothing: antialiased;
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

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

ul {
    list-style: none;
}

button {
    font-family: inherit;
    cursor: pointer;
    border: none;
    background: none;
}

/* ========================================
   Utility Classes
   ======================================== */
.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

/* ========================================
   Header
   ======================================== */
.header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    background-color: white;
    border-bottom: 3px solid var(--color-primary);
    z-index: 1000;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.05);
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-sm) 0;
}

.logo a {
    font-size: 1.4rem;
    font-weight: 900;
    color: var(--color-text);
    letter-spacing: -0.02em;
}

.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 4px;
    padding: var(--spacing-xs);
}

.nav-toggle span {
    width: 24px;
    height: 2px;
    background-color: var(--color-text);
    transition: var(--transition);
}

.nav-list {
    display: flex;
    gap: var(--spacing-md);
    align-items: center;
}

.nav-list a {
    color: var(--color-text);
    font-weight: 500;
    font-size: 0.9rem;
    padding: var(--spacing-xs) var(--spacing-sm);
    transition: var(--transition);
}

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

.nav-feature {
    background-color: var(--color-primary);
    color: white !important;
    border-radius: var(--border-radius);
    font-weight: 700;
}

.nav-feature:hover {
    background-color: var(--color-primary-dark);
}

/* ========================================
   Breaking News Bar
   ======================================== */
.breaking-news {
    position: fixed;
    top: 60px;
    left: 0;
    width: 100%;
    background: linear-gradient(135deg, #1a1a1a 0%, #2d2d2d 100%);
    z-index: 999;
    border-bottom: 2px solid var(--color-primary);
}

.breaking-news-content {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: 0.75rem 0;
}

.breaking-label {
    background-color: var(--color-primary);
    color: white;
    padding: 0.25rem 0.75rem;
    font-size: 0.75rem;
    font-weight: 700;
    letter-spacing: 0.05em;
    border-radius: var(--border-radius);
}

.breaking-text {
    color: white;
    font-size: 0.9rem;
    font-weight: 500;
    flex: 1;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.breaking-text:hover {
    color: var(--color-primary-light);
}

/* ========================================
   Main Content
   ======================================== */
.main-content {
    margin-top: 120px;
    padding: var(--spacing-lg) 0;
    background-color: var(--color-bg-gray);
}

.content-grid {
    display: grid;
    grid-template-columns: 1fr 320px;
    gap: var(--spacing-lg);
}

/* ========================================
   Article Column
   ======================================== */
.article-column {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
}

/* Top Story */
.top-story {
    background-color: white;
    border-radius: var(--border-radius);
    overflow: hidden;
    box-shadow: var(--shadow-sm);
}

.top-story-image {
    width: 100%;
    height: 400px;
    overflow: hidden;
    position: relative;
}

.top-story-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.top-story-content {
    padding: var(--spacing-lg);
}

.top-story-category {
    display: inline-block;
    color: var(--color-primary);
    font-size: 0.75rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    margin-bottom: var(--spacing-xs);
}

.top-story-title {
    font-size: 1.75rem;
    font-weight: 900;
    color: var(--color-text);
    line-height: 1.4;
    margin-bottom: var(--spacing-sm);
    font-family: var(--font-serif);
}

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

.top-story-excerpt {
    font-size: 1rem;
    color: var(--color-text-light);
    line-height: 1.7;
    margin-bottom: var(--spacing-md);
}

.top-story-meta {
    display: flex;
    gap: var(--spacing-sm);
    font-size: 0.85rem;
    color: var(--color-text-lighter);
}

/* Category Tabs */
.category-tabs {
    display: flex;
    gap: 0.5rem;
    overflow-x: auto;
    padding-bottom: 0.5rem;
    border-bottom: 2px solid var(--color-border);
}

.tab-btn {
    padding: 0.5rem 1rem;
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--color-text-light);
    background-color: transparent;
    border-bottom: 2px solid transparent;
    white-space: nowrap;
    transition: var(--transition);
}

.tab-btn:hover {
    color: var(--color-text);
}

.tab-btn.active {
    color: var(--color-primary);
    border-bottom-color: var(--color-primary);
    font-weight: 700;
}

/* Article List */
.article-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.article-item {
    background-color: white;
    border-radius: var(--border-radius);
    overflow: hidden;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
}

.article-item:hover {
    box-shadow: var(--shadow-md);
    transform: translateY(-2px);
}

.article-item-link {
    display: flex;
    gap: var(--spacing-md);
}

.article-image {
    width: 200px;
    height: 150px;
    flex-shrink: 0;
    overflow: hidden;
    background-color: var(--color-bg-alt);
}

.article-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: var(--transition);
}

.article-item:hover .article-image img {
    transform: scale(1.05);
}

.article-content {
    flex: 1;
    padding: var(--spacing-md);
}

.article-category {
    display: inline-block;
    color: var(--color-primary);
    font-size: 0.7rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    margin-bottom: 0.5rem;
}

.article-title {
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--color-text);
    line-height: 1.5;
    margin-bottom: 0.5rem;
}

.article-excerpt {
    font-size: 0.9rem;
    color: var(--color-text-light);
    line-height: 1.6;
    margin-bottom: 0.75rem;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.article-meta {
    display: flex;
    gap: var(--spacing-sm);
    font-size: 0.8rem;
    color: var(--color-text-lighter);
}

/* Load More */
.load-more {
    text-align: center;
    padding: var(--spacing-md) 0;
}

/* ========================================
   Sidebar
   ======================================== */
.sidebar {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
}

.sidebar-section {
    background-color: white;
    border-radius: var(--border-radius);
    padding: var(--spacing-md);
    box-shadow: var(--shadow-sm);
}

.sidebar-title {
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--color-text);
    margin-bottom: var(--spacing-md);
    padding-bottom: var(--spacing-xs);
    border-bottom: 3px solid var(--color-primary);
}

/* Ranking List */
.ranking-list {
    display: flex;
    flex-direction: column;
}

.ranking-item {
    display: flex;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm) 0;
    border-bottom: 1px solid var(--color-border);
    transition: var(--transition);
}

.ranking-item:last-child {
    border-bottom: none;
}

.ranking-item:hover {
    background-color: var(--color-bg-alt);
    margin: 0 calc(-1 * var(--spacing-sm));
    padding-left: var(--spacing-sm);
    padding-right: var(--spacing-sm);
}

.ranking-number {
    font-size: 1.5rem;
    font-weight: 900;
    color: var(--color-primary);
    line-height: 1;
    min-width: 30px;
}

.ranking-content {
    flex: 1;
}

.ranking-category {
    font-size: 0.7rem;
    color: var(--color-text-lighter);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: 0.25rem;
}

.ranking-title {
    font-size: 0.9rem;
    font-weight: 700;
    color: var(--color-text);
    line-height: 1.4;
}

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

/* Newsletter */
.newsletter {
    background: linear-gradient(135deg, #1976d2 0%, #1565c0 100%);
    color: white;
}

.newsletter .sidebar-title {
    color: white;
    border-bottom-color: rgba(255, 255, 255, 0.3);
}

.newsletter-title {
    font-size: 1.1rem;
    font-weight: 700;
    margin-bottom: var(--spacing-xs);
}

.newsletter-text {
    font-size: 0.85rem;
    margin-bottom: var(--spacing-md);
    opacity: 0.9;
}

.newsletter-form {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.newsletter-input {
    padding: 0.75rem;
    border: 1px solid rgba(255, 255, 255, 0.3);
    border-radius: var(--border-radius);
    font-size: 0.9rem;
    background-color: rgba(255, 255, 255, 0.1);
    color: white;
}

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

.newsletter-input:focus {
    outline: none;
    background-color: rgba(255, 255, 255, 0.2);
    border-color: white;
}

/* Category List */
.category-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xs);
}

.category-list li a {
    display: flex;
    justify-content: space-between;
    padding: 0.75rem;
    color: var(--color-text);
    font-weight: 500;
    border-radius: var(--border-radius);
    transition: var(--transition);
}

.category-list li a:hover {
    background-color: var(--color-bg-alt);
    color: var(--color-primary);
}

.category-list li a::after {
    content: '›';
    font-size: 1.2rem;
    color: var(--color-text-lighter);
}

/* Ad Space */
.ad-space {
    min-height: 250px;
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: var(--color-bg-alt);
}

.ad-placeholder {
    text-align: center;
    color: var(--color-text-lighter);
    font-size: 0.9rem;
}

/* ========================================
   Featured Section
   ======================================== */
.featured-section {
    padding: var(--spacing-xl) 0;
    background-color: white;
}

.section-title {
    font-size: 1.75rem;
    font-weight: 900;
    color: var(--color-text);
    margin-bottom: var(--spacing-lg);
    padding-bottom: var(--spacing-sm);
    border-bottom: 3px solid var(--color-primary);
    text-align: center;
}

.featured-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--spacing-lg);
}

.featured-item {
    background-color: white;
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius);
    overflow: hidden;
    transition: var(--transition);
}

.featured-item:hover {
    box-shadow: var(--shadow-md);
    transform: translateY(-4px);
}

.featured-image {
    width: 100%;
    height: 200px;
    overflow: hidden;
    background-color: var(--color-bg-alt);
}

.featured-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: var(--transition);
}

.featured-item:hover .featured-image img {
    transform: scale(1.05);
}

.featured-content {
    padding: var(--spacing-md);
}

.featured-tag {
    display: inline-block;
    background-color: var(--color-primary);
    color: white;
    font-size: 0.7rem;
    font-weight: 700;
    padding: 0.25rem 0.75rem;
    border-radius: var(--border-radius);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: var(--spacing-xs);
}

.featured-title {
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--color-text);
    line-height: 1.5;
    margin-bottom: var(--spacing-sm);
}

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

.featured-excerpt {
    font-size: 0.85rem;
    color: var(--color-text-light);
    line-height: 1.6;
}

/* ========================================
   Buttons
   ======================================== */
.btn {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    border-radius: var(--border-radius);
    font-weight: 700;
    font-size: 0.9rem;
    text-align: center;
    transition: var(--transition);
}

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

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

.btn-outline {
    border: 2px solid var(--color-text);
    color: var(--color-text);
    background-color: transparent;
}

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

.btn-block {
    width: 100%;
}

/* ========================================
   Footer
   ======================================== */
.footer {
    background-color: #1a1a1a;
    color: rgba(255, 255, 255, 0.8);
    padding: var(--spacing-xl) 0 var(--spacing-md);
}

.footer-content {
    display: grid;
    grid-template-columns: 1.5fr 1fr 1fr 1fr;
    gap: var(--spacing-lg);
    padding-bottom: var(--spacing-lg);
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.footer-brand {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.footer-logo {
    font-size: 1.4rem;
    font-weight: 900;
    color: white;
}

.footer-tagline {
    font-size: 0.95rem;
    font-weight: 500;
    color: var(--color-primary-light);
}

.footer-description {
    font-size: 0.85rem;
    line-height: 1.7;
}

.footer-nav {
    display: contents;
}

.footer-nav-column h4 {
    font-size: 0.9rem;
    font-weight: 700;
    margin-bottom: var(--spacing-sm);
    color: white;
}

.footer-nav-column ul {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.footer-nav-column a {
    font-size: 0.85rem;
    color: rgba(255, 255, 255, 0.7);
    transition: var(--transition);
}

.footer-nav-column a:hover {
    color: white;
    padding-left: 4px;
}

.social-links {
    display: flex;
    gap: var(--spacing-xs);
    margin-top: var(--spacing-sm);
}

.social-link {
    width: 36px;
    height: 36px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 50%;
    background-color: rgba(255, 255, 255, 0.1);
    color: white;
    transition: var(--transition);
}

.social-link:hover {
    background-color: var(--color-primary);
    transform: translateY(-2px);
}

.footer-bottom {
    text-align: center;
    padding-top: var(--spacing-md);
    font-size: 0.8rem;
    color: rgba(255, 255, 255, 0.5);
}

/* ========================================
   Responsive Design
   ======================================== */

/* Tablet */
@media (max-width: 968px) {
    .content-grid {
        grid-template-columns: 1fr;
    }

    .sidebar {
        display: grid;
        grid-template-columns: repeat(2, 1fr);
        gap: var(--spacing-md);
    }

    .featured-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .footer-content {
        grid-template-columns: repeat(2, 1fr);
    }
}

/* Mobile */
@media (max-width: 640px) {
    .header-content {
        padding: 0.75rem 0;
    }

    .logo a {
        font-size: 1.1rem;
    }

    .nav-toggle {
        display: flex;
    }

    .nav-list {
        position: absolute;
        top: 100%;
        left: 0;
        width: 100%;
        background-color: white;
        flex-direction: column;
        padding: var(--spacing-md);
        box-shadow: var(--shadow-md);
        transform: translateY(-100%);
        opacity: 0;
        pointer-events: none;
        transition: var(--transition);
    }

    .nav-list.active {
        transform: translateY(0);
        opacity: 1;
        pointer-events: all;
    }

    .breaking-news-content {
        padding: 0.5rem 0;
    }

    .breaking-text {
        font-size: 0.8rem;
    }

    .main-content {
        margin-top: 110px;
    }

    .top-story-image {
        height: 200px;
    }

    .top-story-content {
        padding: var(--spacing-md);
    }

    .top-story-title {
        font-size: 1.3rem;
    }

    .article-item-link {
        flex-direction: column;
    }

    .article-image {
        width: 100%;
        height: 180px;
    }

    .category-tabs {
        gap: 0.25rem;
    }

    .tab-btn {
        padding: 0.5rem 0.75rem;
        font-size: 0.8rem;
    }

    .sidebar {
        grid-template-columns: 1fr;
    }

    .featured-grid {
        grid-template-columns: 1fr;
    }

    .footer-content {
        grid-template-columns: 1fr;
    }

    .section-title {
        font-size: 1.4rem;
    }
}