/* =========================================
   CSS Custom Properties (Variables)
   ========================================= */
   :root {
    --color-primary: #1A365D; /* Deep Blue for trust and professionalism */
    --color-primary-light: #2B6CB0;
    --color-secondary: #E2E8F0;
    --color-text-main: #2D3748;
    --color-text-muted: #718096;
    --color-bg-main: #FFFFFF;
    --color-bg-alt: #F8FAFC;
    
    --font-sans: 'Inter', 'Noto Sans JP', sans-serif;
    
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 2rem;
    --spacing-xl: 4rem;
    --spacing-xxl: 6rem;
    
    --radius-md: 8px;
    --radius-lg: 12px;
    
    --shadow-sm: 0 1px 3px rgba(0,0,0,0.1);
    --shadow-md: 0 4px 6px -1px rgba(0,0,0,0.1), 0 2px 4px -1px rgba(0,0,0,0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0,0,0,0.1), 0 4px 6px -2px rgba(0,0,0,0.05);

    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s ease;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-sans);
    color: var(--color-text-main);
    background-color: var(--color-bg-main);
    line-height: 1.6;
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
}

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

ul {
    list-style: none;
}

/* =========================================
   Typography
   ========================================= */
h1, h2, h3, h4 {
    color: var(--color-primary);
    line-height: 1.3;
    font-weight: 700;
}

/* =========================================
   Layout Utilities
   ========================================= */
.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

.section {
    padding: var(--spacing-xxl) 0;
}

.section-alt {
    background-color: var(--color-bg-alt);
}

.section-header {
    text-align: center;
    margin-bottom: var(--spacing-xl);
}

.section-subtitle {
    color: var(--color-primary-light);
    font-weight: 600;
    font-size: 0.875rem;
    letter-spacing: 0.05em;
    text-transform: uppercase;
    margin-bottom: var(--spacing-sm);
}

.section-title {
    font-size: 2.25rem;
    margin-bottom: var(--spacing-md);
}

.section-desc {
    color: var(--color-text-muted);
    font-size: 1.125rem;
    max-width: 600px;
    margin: 0 auto;
}

.mt-4 { margin-top: var(--spacing-xl); }

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.75rem 1.5rem;
    border-radius: var(--radius-md);
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-fast);
    border: none;
}

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

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

/* =========================================
   Components
   ========================================= */

/* Header */
.header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    background-color: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(8px);
    border-bottom: 1px solid var(--color-secondary);
    z-index: 1000;
    height: 70px;
    display: flex;
    align-items: center;
}

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

.logo {
    font-size: 1.25rem;
    font-weight: 800;
    letter-spacing: -0.5px;
}

.logo-kinetic {
    color: var(--color-text-main);
}

.logo-lablink {
    color: var(--color-primary);
}

.nav {
    display: none; /* Mobile first */
}

@media (min-width: 768px) {
    .nav {
        display: flex;
        gap: var(--spacing-lg);
    }
    
    .nav a {
        font-weight: 500;
        font-size: 0.95rem;
    }
    
    .nav a:hover {
        color: var(--color-primary);
    }
}

.lang-switch {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-size: 0.875rem;
    font-weight: 500;
}

.lang-switch button {
    background: none;
    border: none;
    cursor: pointer;
    font-family: inherit;
    font-weight: inherit;
    color: var(--color-text-muted);
    transition: color var(--transition-fast);
}

.lang-switch button.active {
    color: var(--color-primary);
    font-weight: 700;
}

.lang-switch button:hover {
    color: var(--color-text-main);
}

/* Hero */
.hero {
    padding-top: calc(70px + var(--spacing-lg));
    padding-bottom: var(--spacing-lg);
    background: url('../images/sunset_bg.jpg') center/cover no-repeat;
    min-height: 33vh;
    display: flex;
    align-items: center;
    position: relative;
    overflow: hidden;

/* 追加：画像自体を20%明るくし、彩度を少し上げます */
    filter: brightness(1.2) saturate(1.1);
}

/* style.css 内の該当箇所を修正 */
.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    /* 白のグラデーションから、黒（rgba(0,0,0,...)）のグラデーションに変更 */
    background: linear-gradient(135deg, rgba(0, 0, 0, 0.1) 0%, rgba(0, 0, 0, 0.1) 100%);
    pointer-events: none;
}

/* style.css の修正 */
.hero-title {
    font-weight: 700; /* より太く（Noto Sans JPのボールド） */
    color: #FFFFFF;
}

.hero-desc {
    font-weight: 500; /* 標準より少しだけ太く */
    color: #FFFFFF;
}

.hero-subtitle {
    color: #90CDF4; /* 背景が暗くなるので、少し明るめの水色などに調整すると綺麗です */
}

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

.hero-subtitle {
    font-weight: 600;
    color: var(--color-primary-light);
    margin-bottom: var(--spacing-md);
    letter-spacing: 0.05em;
}

.hero-title {
    font-size: clamp(2rem, 4vw, 3rem);
    line-height: 1.2;
    margin-bottom: var(--spacing-md);
    color: var(--color-text-main);
}

.hero-desc {
    font-size: 1.125rem;
    color: var(--color-text-muted);
    margin-bottom: var(--spacing-lg);
}

/* Concept */
.concept {
    background-color: var(--color-bg-main);
}

.concept-text {
    max-width: 800px;
    margin: 0 auto;
}

.member-name {
    font-size: 1.5rem;
    margin-bottom: 0.25rem;
}

.member-title {
    color: var(--color-primary-light);
    font-weight: 500;
    margin-bottom: var(--spacing-md);
}

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

.mission-box {
    margin-top: var(--spacing-xl);
    background-color: var(--color-bg-alt);
    padding: var(--spacing-lg);
    border-left: 4px solid var(--color-primary);
    border-radius: 0 var(--radius-md) var(--radius-md) 0;
}

.mission-box h4 {
    margin-bottom: var(--spacing-sm);
    font-size: 1.25rem;
}

/* Method */
.method {
    background-color: var(--color-bg-alt);
}

.method-steps {
    display: grid;
    grid-template-columns: 1fr;
    gap: var(--spacing-lg);
    margin-top: var(--spacing-xl);
}

@media (min-width: 768px) {
    .method-steps {
        grid-template-columns: repeat(3, 1fr);
    }
}

.step-card {
    background-color: var(--color-bg-main);
    padding: var(--spacing-xl) var(--spacing-lg);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
    transition: transform var(--transition-normal), box-shadow var(--transition-normal);
}

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

.step-num {
    font-size: 3rem;
    font-weight: 800;
    color: var(--color-secondary);
    margin-bottom: var(--spacing-md);
    line-height: 1;
}

.step-card h3 {
    margin-bottom: var(--spacing-sm);
    font-size: 1.25rem;
}

.step-card p {
    color: var(--color-text-muted);
}

/* Features */
.features {
    background-color: var(--color-bg-main);
}

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

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

.feature-item {
    padding: var(--spacing-lg);
    border: 1px solid var(--color-secondary);
    border-radius: var(--radius-lg);
}

.feature-item h3 {
    margin-bottom: var(--spacing-sm);
}

.feature-item p {
    color: var(--color-text-muted);
}

/* Specs */
.specs {
    background-color: var(--color-bg-alt);
}

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

.spec-text h3 {
    margin-bottom: var(--spacing-md);
}

.spec-text p {
    margin-bottom: var(--spacing-md);
    color: var(--color-text-muted);
}

/* Contact */
.contact {
    background-color: var(--color-bg-main);
}

.contact-box {
    text-align: center;
    max-width: 600px;
    margin: 0 auto;
    padding: var(--spacing-xl);
    background-color: var(--color-bg-alt);
    border-radius: var(--radius-lg);
}

.contact-box p {
    margin-bottom: var(--spacing-lg);
    color: var(--color-text-muted);
}

.contact-links {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
    align-items: center;
}

@media (min-width: 600px) {
    .contact-links {
        flex-direction: row;
        justify-content: center;
    }
}

.contact-link {
    color: var(--color-primary);
    font-weight: 600;
    text-decoration: underline;
    text-decoration-color: transparent;
    transition: text-decoration-color var(--transition-fast);
}

.contact-link:hover {
    text-decoration-color: var(--color-primary);
}

/* Footer */
.footer {
    background-color: #0f172a;
    color: white;
    padding: var(--spacing-xl) 0;
}

.footer-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-md);
}

@media (min-width: 768px) {
    .footer-content {
        flex-direction: row;
        justify-content: space-between;
    }
}

.footer-logo {
    font-size: 1.5rem;
    font-weight: 800;
}

.footer-logo .logo-kinetic {
    color: white;
}

.footer-logo .logo-lablink {
    color: #60a5fa; /* Lighter blue for dark background */
}

.copyright {
    color: #94a3b8;
    font-size: 0.875rem;
}