:root {
    /* Colors */
    --primary-color: #F97316; /* Warm Orange */
    --secondary-color: #0EA5E9; /* Fresh Sky Blue */
    --text-color: #334155; /* Slate 700 */
    --bg-color: #F8FAFC; /* Slate 50 */
    --white: #FFFFFF;
    --accent-color: #FCD34D; /* Amber 300 */

    /* Typography */
    --font-base: 'Noto Sans JP', sans-serif;
    
    /* Spacing */
    --spacing-sm: 8px;
    --spacing-md: 16px;
    --spacing-lg: 32px;
    --spacing-xl: 64px;

    /* Border Radius */
    --radius-md: 8px;
    --radius-lg: 16px;
    --radius-full: 9999px;
}

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

body {
    font-family: var(--font-base);
    color: var(--text-color);
    background-color: var(--bg-color);
    line-height: 1.6;
}

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

a:hover {
    opacity: 0.8;
}

ul {
    list-style: none;
}

.container {
    max-width: 1024px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

/* Header */
.header {
    background-color: rgba(255, 255, 255, 0.9);
    backdrop-filter: blur(10px);
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 1000;
    box-shadow: 0 2px 10px rgba(0,0,0,0.05);
}

.header-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 70px;
}

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
}

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

.nav a {
    font-size: 0.95rem;
    font-weight: 500;
}

/* Hero Section */
.hero {
    position: relative;
    padding: 120px 0 60px;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    background: linear-gradient(135deg, #E0F2FE 0%, #FFF7ED 100%);
}

.hero-content {
    z-index: 10;
    width: 100%;
}

.hero-image {
    max-width: 100%;
    height: auto;
    border-radius: var(--radius-lg);
    box-shadow: 0 10px 30px rgba(0,0,0,0.1);
    margin-bottom: var(--spacing-lg);
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 12px 32px;
    border-radius: var(--radius-full);
    font-weight: 700;
    cursor: pointer;
    transition: transform 0.2s, box-shadow 0.2s;
}

.btn-primary {
    background-color: var(--primary-color);
    color: var(--white);
    box-shadow: 0 4px 14px rgba(249, 115, 22, 0.4);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(249, 115, 22, 0.5);
    opacity: 1;
}

.btn-sm {
    padding: 8px 20px;
    font-size: 0.9rem;
    background-color: var(--secondary-color);
    color: var(--white);
}

.btn-large {
    font-size: 1.5rem;
    padding: 16px 48px;
    background-color: var(--secondary-color);
    color: var(--white);
    box-shadow: 0 4px 14px rgba(14, 165, 233, 0.4);
}

/* Sections */
.section {
    padding: 80px 0;
}

.section-title {
    text-align: center;
    font-size: 2rem;
    margin-bottom: var(--spacing-sm);
    color: var(--primary-color);
}

.section-desc {
    text-align: center;
    margin-bottom: var(--spacing-xl);
    color: #64748B;
}

/* Features (About) */
.features {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--spacing-lg);
}

.feature-card {
    background: var(--white);
    padding: var(--spacing-lg);
    border-radius: var(--radius-lg);
    text-align: center;
    box-shadow: 0 4px 6px rgba(0,0,0,0.02);
    transition: transform 0.3s;
}

.feature-card:hover {
    transform: translateY(-5px);
}

.feature-icon {
    font-size: 3rem;
    margin-bottom: var(--spacing-md);
}

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

/* Activity */
.activity {
    background-color: #FFF7ED; /* Very light orange */
}

.activity-text {
    text-align: center;
    max-width: 700px;
    margin: 0 auto;
}

.activity-text h3 {
    margin-bottom: var(--spacing-md);
    font-size: 1.5rem;
}

/* Info */
.info-card {
    background: var(--white);
    max-width: 600px;
    margin: 0 auto;
    padding: var(--spacing-lg);
    border-radius: var(--radius-lg);
    box-shadow: 0 10px 25px rgba(0,0,0,0.05);
}

.info-card dl {
    display: grid;
    grid-template-columns: 100px 1fr;
    gap: var(--spacing-md);
    align-items: baseline;
}

.info-card dt {
    font-weight: 700;
    color: var(--secondary-color);
}

.info-card dd {
    border-bottom: 1px solid #E2E8F0;
    padding-bottom: var(--spacing-sm);
}
.info-card dd:last-child {
    border-bottom: none;
}

/* Organizers */
.organizers {
    background-color: var(--white);
}

.text-link {
    color: var(--secondary-color);
    text-decoration: underline;
    font-weight: bold;
}

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

.organizer-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: var(--spacing-lg);
    margin-top: var(--spacing-lg);
}

.organizer-card {
    text-align: center;
}

.organizer-img {
    width: 180px;
    height: 180px;
    border-radius: 50%;
    object-fit: cover;
    margin-bottom: var(--spacing-md);
    box-shadow: 0 8px 20px rgba(0,0,0,0.08);
    transition: transform 0.3s;
}

.organizer-card:hover .organizer-img {
    transform: translateY(-5px);
}

.organizer-name {
    font-size: 1.25rem;
    margin-bottom: 4px;
    color: var(--text-color);
}

.organizer-company {
    font-size: 0.95rem;
    color: #64748B;
}

.organizer-company a {
    color: var(--secondary-color);
}

.organizer-company a:hover {
    text-decoration: underline;
}

/* Join */
.join {
    text-align: center;
    background: linear-gradient(135deg, #0EA5E9 0%, #38BDF8 100%);
    color: var(--white);
}

.join .section-title {
    color: var(--white);
}

.join .section-desc, .join p {
    color: #E0F2FE;
    margin-bottom: var(--spacing-lg);
}

.join .btn {
    background-color: var(--white);
    color: var(--secondary-color);
    box-shadow: 0 4px 14px rgba(0,0,0,0.2);
}

.join-zoom {
    margin-bottom: var(--spacing-xl);
}

.join-fb {
    border-top: 1px solid rgba(255, 255, 255, 0.3);
    padding-top: var(--spacing-xl);
    margin-top: var(--spacing-xl);
}

.fb-title {
    font-size: 1.5rem;
    margin-bottom: var(--spacing-md);
    color: var(--white);
}

.btn-fb {
    font-size: 1.2rem;
    padding: 14px 40px;
    background-color: var(--primary-color);
    color: var(--white);
    border-radius: var(--radius-full);
    display: inline-block;
    font-weight: 700;
    cursor: pointer;
    transition: transform 0.2s, box-shadow 0.2s;
    box-shadow: 0 4px 14px rgba(249, 115, 22, 0.4);
    text-decoration: none;
}

.btn-fb:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(249, 115, 22, 0.5);
    opacity: 1;
}

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

.note {
    margin-top: var(--spacing-md);
    font-size: 0.9rem;
    opacity: 0.8;
}

/* Footer */
.footer {
    background-color: #334155;
    color: #94A3B8;
    text-align: center;
    padding: var(--spacing-lg) 0;
    font-size: 0.9rem;
}

/* Animations */
.fade-in {
    opacity: 0;
    animation: fadeIn 0.8s ease-out forwards;
}

.delay-1 { animation-delay: 0.2s; }
.delay-2 { animation-delay: 0.4s; }
.delay-3 { animation-delay: 0.6s; }

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

/* Responsive */
@media (max-width: 768px) {
    .header-container {
        flex-direction: column;
        height: auto;
        padding: var(--spacing-md) 0;
    }

    .nav ul {
        gap: var(--spacing-sm);
        margin-top: var(--spacing-sm);
    }

    .hero-title {
        font-size: 2.5rem;
    }
    
    .info-card dl {
        grid-template-columns: 1fr;
    }
    
    .info-card dt {
        margin-top: var(--spacing-sm);
    }
}