/* ============================================
   KUROKO LLC. Corporate Website
   黒基調のシンプルで洗練されたデザイン
   ============================================ */

/* カラー変数定義 */
:root {
    --primary-black: #000000;
    --secondary-black: #1a1a1a;
    --dark-gray: #333333;
    --medium-gray: #555555;
    --light-gray: #999999;
    --pure-white: #ffffff;
    --off-white: #f5f5f5;
    --gold: #d4af37;
    --silver: #c0c0c0;
    --accent: #d4af37;
}

/* リセット・基本設定 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Noto Sans JP', 'Yu Gothic', 'YuGothic', 'Hiragino Kaku Gothic ProN', 'Meiryo', sans-serif;
    background-color: var(--primary-black);
    color: var(--pure-white);
    line-height: 1.8;
    overflow-x: hidden;
    padding-top: 100px;
}

/* タイポグラフィ */
h1, h2, h3, h4, h5, h6 {
    font-weight: 700;
    letter-spacing: 0.05em;
}

h1 {
    font-size: 3rem;
    line-height: 1.2;
}

h2 {
    font-size: 2.5rem;
    line-height: 1.3;
}

h3 {
    font-size: 2rem;
    line-height: 1.4;
}

h4 {
    font-size: 1.5rem;
    line-height: 1.5;
}

p {
    font-size: 1rem;
    line-height: 1.8;
}

a {
    color: inherit;
    text-decoration: none;
    transition: all 0.3s ease;
}

/* コンテナ */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

.container-wide {
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 20px;
}

/* ヘッダー */
header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background-color: rgba(0, 0, 0, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
    transition: all 0.3s ease;
}

header.scrolled {
    background-color: rgba(0, 0, 0, 0.98);
    box-shadow: 0 2px 20px rgba(0, 0, 0, 0.5);
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 20px 0;
}

.logo {
    display: flex;
    align-items: center;
}

.logo a {
    display: block;
    line-height: 0;
}

.logo img {
    height: 120px;
    width: auto;
    transition: opacity 0.3s ease;
}

.logo img:hover {
    opacity: 0.8;
}

nav ul {
    display: flex;
    list-style: none;
    gap: 40px;
}

nav ul li a {
    font-size: 0.95rem;
    font-weight: 500;
    letter-spacing: 0.05em;
    position: relative;
    padding: 5px 0;
}

nav ul li a::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background-color: var(--gold);
    transition: width 0.3s ease;
}

nav ul li a:hover::after,
nav ul li a.active::after {
    width: 100%;
}

/* モバイルメニュー */
.mobile-menu-toggle {
    display: none;
    flex-direction: column;
    gap: 6px;
    cursor: pointer;
    padding: 10px;
}

.mobile-menu-toggle span {
    width: 25px;
    height: 2px;
    background-color: var(--pure-white);
    transition: all 0.3s ease;
}

/* ヒーローセクション */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
    overflow: hidden;
    background: linear-gradient(135deg, var(--primary-black) 0%, var(--secondary-black) 100%);
    padding-top: 60px;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-image: 
        linear-gradient(rgba(255, 255, 255, 0.03) 1px, transparent 1px),
        linear-gradient(90deg, rgba(255, 255, 255, 0.03) 1px, transparent 1px);
    background-size: 50px 50px;
    opacity: 0.3;
}

.hero-content {
    text-align: center;
    z-index: 1;
    max-width: 900px;
    padding: 0 20px;
}

.hero-subtitle {
    font-size: 1.2rem;
    color: var(--gold);
    letter-spacing: 0.2em;
    margin-bottom: 20px;
    text-transform: uppercase;
    font-weight: 500;
}

.hero h1 {
    font-size: 3.5rem;
    margin-bottom: 30px;
    line-height: 1.3;
}

.hero-description {
    font-size: 1.2rem;
    color: var(--light-gray);
    margin-bottom: 50px;
    line-height: 1.8;
}

/* ボタン */
.btn {
    display: inline-block;
    padding: 16px 48px;
    font-size: 1rem;
    font-weight: 600;
    letter-spacing: 0.05em;
    border: 2px solid var(--gold);
    background-color: transparent;
    color: var(--pure-white);
    cursor: pointer;
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
}

.btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background-color: var(--gold);
    transition: left 0.3s ease;
    z-index: -1;
}

.btn:hover::before {
    left: 0;
}

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

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

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

/* セクション共通 */
section {
    padding: 100px 0;
    position: relative;
}

.section-header {
    text-align: center;
    margin-bottom: 80px;
}

.section-subtitle {
    font-size: 0.9rem;
    color: var(--gold);
    letter-spacing: 0.2em;
    text-transform: uppercase;
    margin-bottom: 15px;
    font-weight: 500;
}

.section-title {
    font-size: 2.5rem;
    margin-bottom: 20px;
}

.section-description {
    font-size: 1.1rem;
    color: var(--light-gray);
    max-width: 700px;
    margin: 0 auto;
}

/* 背景バリエーション */
.bg-dark {
    background-color: var(--secondary-black);
}

.bg-darker {
    background-color: var(--primary-black);
}

.bg-subtle {
    background: linear-gradient(180deg, var(--primary-black) 0%, var(--secondary-black) 100%);
}

/* カード */
.card {
    background-color: var(--secondary-black);
    border: 1px solid rgba(255, 255, 255, 0.1);
    padding: 40px;
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
}

.card::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 2px;
    background-color: var(--gold);
    transition: left 0.3s ease;
}

.card:hover::before {
    left: 0;
}

.card:hover {
    transform: translateY(-5px);
    border-color: rgba(212, 175, 55, 0.3);
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.5);
}

.card-icon {
    width: 60px;
    height: 60px;
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: rgba(212, 175, 55, 0.1);
    border: 2px solid var(--gold);
    margin-bottom: 25px;
    font-size: 1.8rem;
    color: var(--gold);
}

.card h3 {
    font-size: 1.5rem;
    margin-bottom: 15px;
}

.card p {
    color: var(--light-gray);
    line-height: 1.8;
}

/* グリッドレイアウト */
.grid {
    display: grid;
    gap: 30px;
}

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

.grid-3 {
    grid-template-columns: repeat(3, 1fr);
}

.grid-4 {
    grid-template-columns: repeat(4, 1fr);
}

/* フッター */
footer {
    background-color: var(--primary-black);
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    padding: 60px 0 30px;
}

.footer-content {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr;
    gap: 50px;
    margin-bottom: 50px;
}

.footer-about .footer-logo {
    margin-bottom: 20px;
}

.footer-about .footer-logo img {
    height: 120px;
    width: auto;
}

.footer-about p {
    color: var(--light-gray);
    line-height: 1.8;
}

.footer-links h4 {
    font-size: 1.1rem;
    margin-bottom: 20px;
    color: var(--gold);
}

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

.footer-links ul li {
    margin-bottom: 12px;
}

.footer-links ul li a:hover {
    color: var(--gold);
}

.footer-bottom {
    text-align: center;
    padding-top: 30px;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    color: var(--light-gray);
    font-size: 0.9rem;
}

/* アニメーション */
.fade-in {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-in.visible {
    opacity: 1;
    transform: translateY(0);
}

.slide-in-left {
    opacity: 0;
    transform: translateX(-50px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}

.slide-in-left.visible {
    opacity: 1;
    transform: translateX(0);
}

.slide-in-right {
    opacity: 0;
    transform: translateX(50px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}

.slide-in-right.visible {
    opacity: 1;
    transform: translateX(0);
}

/* レスポンシブ対応 */
@media (max-width: 1024px) {
    h1 {
        font-size: 2.5rem;
    }
    
    h2 {
        font-size: 2rem;
    }
    
    .grid-3, .grid-4 {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .footer-content {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 768px) {
    nav ul {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background-color: rgba(0, 0, 0, 0.98);
        flex-direction: column;
        gap: 0;
        padding: 20px;
        border-top: 1px solid rgba(255, 255, 255, 0.1);
    }
    
    nav ul.active {
        display: flex;
    }
    
    nav ul li {
        width: 100%;
        text-align: center;
        padding: 15px 0;
        border-bottom: 1px solid rgba(255, 255, 255, 0.05);
    }
    
    .mobile-menu-toggle {
        display: flex;
    }
    
    .mobile-menu-toggle.active span:nth-child(1) {
        transform: rotate(45deg) translate(8px, 8px);
    }
    
    .mobile-menu-toggle.active span:nth-child(2) {
        opacity: 0;
    }
    
    .mobile-menu-toggle.active span:nth-child(3) {
        transform: rotate(-45deg) translate(7px, -7px);
    }
    
    .hero h1 {
        font-size: 2rem;
    }
    
    .hero-description {
        font-size: 1rem;
    }
    
    .grid-2, .grid-3, .grid-4 {
        grid-template-columns: 1fr;
    }
    
    .footer-content {
        grid-template-columns: 1fr;
    }
    
    section {
        padding: 60px 0;
    }
    
    .section-header {
        margin-bottom: 50px;
    }
}

@media (max-width: 480px) {
    h1 {
        font-size: 1.8rem;
    }
    
    .hero h1 {
        font-size: 1.6rem;
    }
    
    .btn {
        padding: 12px 32px;
        font-size: 0.9rem;
    }
    
    .card {
        padding: 25px;
    }
}