/* ============================================================
   Yozora Finance — Corporate Design System
   Aesthetic: Quiet Authority — editorial precision, institutional trust
   ============================================================ */

:root {
    /* Color System */
    --bg-body: #f7f8fa;
    --bg-surface: #ffffff;
    --bg-surface-alt: #f0f2f6;

    --text-primary: #111827;
    --text-secondary: #4b5563;
    --text-tertiary: #9ca3af;

    --brand-primary: #0a0f1e;
    --brand-accent: #1d4ed8;
    --brand-accent-light: #3b82f6;

    --border-color: #e5e7eb;
    --border-hover: #d1d5db;

    --bg-dark: #080d1a;
    --text-on-dark: #f9fafb;
    --text-on-dark-secondary: #94a3b8;
    --border-on-dark: rgba(255, 255, 255, 0.08);

    --shadow-xs: 0 1px 2px rgba(0, 0, 0, 0.04);
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.06), 0 1px 2px rgba(0, 0, 0, 0.04);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.07), 0 2px 4px rgba(0, 0, 0, 0.04);
    --shadow-lg: 0 12px 32px rgba(0, 0, 0, 0.08), 0 4px 8px rgba(0, 0, 0, 0.04);

    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;

    --font-display-jp: 'Shippori Mincho', serif;
    --font-display-en: 'Cormorant Garamond', serif;
    --font-body: 'Noto Sans JP', sans-serif;

    --ease-out-expo: cubic-bezier(0.16, 1, 0.3, 1);
    --transition-fast: 0.15s ease;
    --transition-base: 0.25s ease;
}

/* ---- Reset & Base ---- */

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

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

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

body.no-scroll {
    overflow: hidden;
}

p {
    margin-bottom: 1.25rem;
}

p:last-child {
    margin-bottom: 0;
}

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

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

/* ---- Layout ---- */

.container {
    max-width: 1080px;
    margin: 0 auto;
    padding: 0 2rem;
    position: relative;
    z-index: 2;
}

/* ---- Header ---- */

header {
    position: sticky;
    top: 0;
    z-index: 1000;
    background: rgba(255, 255, 255, 0.88);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid transparent;
    transition: border-color var(--transition-base), box-shadow var(--transition-base);
}

header.scrolled {
    border-bottom-color: var(--border-color);
    box-shadow: var(--shadow-xs);
}

.header-inner {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 72px;
}

.logo img {
    height: 34px;
    width: auto;
    mix-blend-mode: multiply;
    transition: opacity var(--transition-fast);
}

.logo:hover img {
    opacity: 0.6;
}

nav ul {
    display: flex;
    gap: 2.5rem;
    list-style: none;
}

nav a {
    font-size: 0.85rem;
    font-weight: 500;
    color: var(--text-secondary);
    position: relative;
    padding-bottom: 4px;
    letter-spacing: 0.02em;
}

nav a::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 1px;
    background-color: var(--brand-accent);
    transition: width 0.3s var(--ease-out-expo);
}

nav a:hover {
    color: var(--brand-accent);
}

nav a:hover::after {
    width: 100%;
}

/* Mobile Menu */

.mobile-menu-btn {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
    width: 28px;
    height: 20px;
    position: relative;
    z-index: 1001;
    padding: 0;
}

.mobile-menu-btn span {
    display: block;
    width: 100%;
    height: 1.5px;
    background-color: var(--text-primary);
    position: absolute;
    left: 0;
    transition: all 0.3s ease;
}

.mobile-menu-btn span:nth-child(1) {
    top: 0;
}

.mobile-menu-btn span:nth-child(2) {
    top: 9px;
}

.mobile-menu-btn span:nth-child(3) {
    bottom: 0;
}

.mobile-menu-btn.active span:nth-child(1) {
    transform: rotate(45deg);
    top: 9px;
}

.mobile-menu-btn.active span:nth-child(2) {
    opacity: 0;
}

.mobile-menu-btn.active span:nth-child(3) {
    transform: rotate(-45deg);
    bottom: 9px;
}

/* ---- Hero ---- */

.hero {
    background-color: var(--bg-dark);
    color: var(--text-on-dark);
    padding: clamp(120px, 16vh, 200px) 0 clamp(100px, 12vh, 160px);
    position: relative;
    overflow: hidden;
}

/* Dot grid — precision, data, structure */
.hero::before {
    content: '';
    position: absolute;
    inset: 0;
    background-image: radial-gradient(circle, rgba(255, 255, 255, 0.035) 1px, transparent 1px);
    background-size: 32px 32px;
    z-index: 1;
    pointer-events: none;
}

/* Gradient glow accent */
.hero::after {
    content: '';
    position: absolute;
    top: -40%;
    right: -15%;
    width: 65%;
    height: 180%;
    background: radial-gradient(ellipse, rgba(29, 78, 216, 0.08) 0%, transparent 55%);
    z-index: 1;
    pointer-events: none;
}

.hero-content {
    max-width: 680px;
    position: relative;
    z-index: 2;
}

.hero h1 {
    font-family: var(--font-display-jp);
    font-size: clamp(2rem, 4.5vw, 3.25rem);
    font-weight: 700;
    color: var(--text-on-dark);
    margin-bottom: 2.5rem;
    letter-spacing: 0.03em;
    line-height: 1.4;
    opacity: 0;
    animation: heroReveal 0.9s var(--ease-out-expo) 0.15s forwards;
}

.hero h1::after {
    content: '';
    display: block;
    width: 40px;
    height: 1px;
    background: var(--brand-accent-light);
    margin-top: 2rem;
    opacity: 0.4;
}

.hero-lead {
    font-size: 1rem;
    color: var(--text-on-dark-secondary);
    max-width: 560px;
    line-height: 2;
    opacity: 0;
    animation: heroReveal 0.9s var(--ease-out-expo) 0.4s forwards;
}

@keyframes heroReveal {
    from {
        opacity: 0;
        transform: translateY(16px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* ---- Sections (Global) ---- */

section {
    padding: 120px 0;
}

.section-header {
    margin-bottom: 3.5rem;
    text-align: center;
}

.section-label {
    font-family: var(--font-display-en);
    font-size: 0.9rem;
    font-weight: 400;
    letter-spacing: 0.15em;
    text-transform: uppercase;
    color: var(--brand-accent);
    margin-bottom: 1rem;
    display: block;
    border: none;
    background: none;
    padding: 0;
    border-radius: 0;
}

.section-title {
    font-family: var(--font-display-jp);
    font-size: clamp(1.625rem, 3vw, 2.125rem);
    font-weight: 600;
    color: var(--text-primary);
    letter-spacing: 0.04em;
    line-height: 1.35;
}

.section-header::after {
    content: '';
    display: block;
    width: 28px;
    height: 1px;
    background: var(--brand-accent);
    margin: 1.5rem auto 0;
    opacity: 0.35;
}

/* ---- About ---- */

.about {
    background-color: var(--bg-surface);
}

.about-content {
    max-width: 680px;
    margin: 0 auto;
    font-size: 1.025rem;
    color: var(--text-secondary);
    line-height: 2;
}

.about-content a {
    color: var(--brand-accent);
    border-bottom: 1px solid var(--border-color);
    transition: border-color var(--transition-fast);
}

.about-content a:hover {
    border-bottom-color: var(--brand-accent);
}

/* ---- Activity ---- */

.activity {
    background-color: var(--bg-body);
}

.activity-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1.5rem;
}

.activity-item {
    background: var(--bg-surface);
    padding: 2.5rem;
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow-xs);
    transition: box-shadow var(--transition-base), transform var(--transition-base);
}

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

.activity-item h3 {
    font-family: var(--font-display-jp);
    font-size: 1.2rem;
    font-weight: 600;
    margin-bottom: 1.25rem;
    padding-bottom: 1rem;
    border-bottom: 1px solid var(--border-color);
    letter-spacing: 0.04em;
    line-height: 1.3;
}

.activity-item p {
    font-size: 0.95rem;
    color: var(--text-secondary);
    line-height: 1.85;
}

.product-link {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--brand-accent);
    font-weight: 500;
    font-size: 0.9rem;
    padding: 0;
    background: none;
    border: none;
    border-radius: 0;
    border-bottom: 1px solid var(--brand-accent);
    padding-bottom: 2px;
    letter-spacing: 0;
    margin-top: 0.25rem;
    transition: gap var(--transition-base);
}

.product-link::after {
    content: '\2192';
    font-size: 1rem;
    transition: transform var(--transition-base);
}

.product-link:hover {
    background: none;
    transform: none;
}

.product-link:hover::after {
    transform: translateX(4px);
}

/* Zenn Cards */

.zenn-cards {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.zenn-card {
    background: var(--bg-body);
    padding: 1.25rem 1.5rem;
    border-radius: var(--radius-md);
    border: 1px solid var(--border-color);
}

.zenn-card h4 {
    font-family: var(--font-body);
    font-size: 0.95rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
    line-height: 1.4;
}

.zenn-card p {
    font-size: 0.875rem;
    color: var(--text-secondary);
    margin-bottom: 0.75rem;
    line-height: 1.7;
}

.zenn-card-links {
    display: flex;
    flex-wrap: wrap;
    gap: 0.375rem;
}

.zenn-link {
    display: inline-block;
    color: var(--brand-accent);
    font-weight: 500;
    font-size: 0.8rem;
    padding: 0.3rem 0.7rem;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    transition: all var(--transition-fast);
}

.zenn-link:hover {
    background-color: var(--brand-accent);
    color: #fff;
    border-color: var(--brand-accent);
}

/* ---- Products ---- */

.products {
    background-color: var(--bg-surface);
}

.product-block {
    display: flex;
    flex-direction: column;
    gap: 3rem;
    background: none;
    border: none;
    border-radius: 0;
    padding: 0;
    box-shadow: none;
}

.product-header {
    display: flex;
    align-items: baseline;
    gap: 1.25rem;
    margin-bottom: 0.5rem;
}

.product-name {
    font-family: var(--font-display-en);
    font-size: 2.25rem;
    font-weight: 500;
    color: var(--brand-primary);
    letter-spacing: -0.01em;
    line-height: 1.2;
}

.product-status {
    font-size: 0.65rem;
    padding: 0.2rem 0.65rem;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    text-transform: uppercase;
    letter-spacing: 0.1em;
    font-weight: 600;
    color: var(--text-tertiary);
    font-family: var(--font-body);
    white-space: nowrap;
}

.product-status.active {
    background: #ecfdf5;
    color: #059669;
    border-color: #a7f3d0;
}

.product-tagline {
    font-size: 1.05rem;
    color: var(--brand-accent);
    margin-bottom: 1rem;
    font-weight: 500;
}

.product-desc {
    color: var(--text-secondary);
    font-size: 0.975rem;
    line-height: 1.9;
    max-width: 680px;
}

.product-features {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 1.25rem;
    counter-reset: feature;
    background: none;
    padding: 0;
    border: none;
}

.feature-item {
    counter-increment: feature;
    background: var(--bg-body);
    padding: 1.75rem;
    border-radius: var(--radius-md);
    border: 1px solid var(--border-color);
    position: relative;
    transition: border-color var(--transition-base), box-shadow var(--transition-base);
}

.feature-item:hover {
    border-color: var(--border-hover);
    box-shadow: var(--shadow-sm);
}

.feature-item::before {
    content: counter(feature, decimal-leading-zero);
    font-family: var(--font-display-en);
    font-size: 2rem;
    font-weight: 400;
    color: var(--brand-accent);
    opacity: 0.12;
    line-height: 1;
    display: block;
    margin-bottom: 1rem;
}

.feature-item h4 {
    font-family: var(--font-body);
    font-size: 0.925rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
    border-left: none;
    padding-left: 0;
    line-height: 1.4;
}

.feature-item p {
    font-size: 0.85rem;
    color: var(--text-secondary);
    margin: 0;
    line-height: 1.75;
    padding-left: 0;
}

/* ---- Contact ---- */

.contact {
    background-color: var(--bg-dark);
    color: var(--text-on-dark);
    text-align: center;
    padding: 100px 0;
}

.contact .section-label {
    color: var(--brand-accent-light);
}

.contact .section-title {
    color: var(--text-on-dark);
}

.contact .section-header::after {
    background: var(--brand-accent-light);
}

.contact-email {
    display: inline-block;
    font-size: clamp(1.25rem, 2.5vw, 1.625rem);
    font-family: var(--font-display-en);
    font-weight: 400;
    color: var(--text-on-dark);
    letter-spacing: 0.04em;
    padding-bottom: 0.5rem;
    border-bottom: 1px solid var(--border-on-dark);
    transition: all var(--transition-base);
}

.contact-email:hover {
    color: var(--brand-accent-light);
    border-bottom-color: var(--brand-accent-light);
}

/* ---- Footer ---- */

footer {
    background-color: #050810;
    color: #6b7280;
    padding: 2.5rem 0;
    border-top: 1px solid rgba(255, 255, 255, 0.04);
    font-size: 0.8rem;
    letter-spacing: 0.01em;
}

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

.footer-links {
    display: flex;
    gap: 2rem;
}

/* ---- Animations ---- */

.fade-in-section {
    opacity: 0;
    transform: translateY(20px);
    transition: opacity 0.7s var(--ease-out-expo), transform 0.7s var(--ease-out-expo);
    will-change: opacity, transform;
}

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

/* ---- Responsive: Tablet ---- */

@media (max-width: 1024px) {
    .product-features {
        grid-template-columns: repeat(2, 1fr);
    }
}

/* ---- Responsive: Mobile ---- */

@media (max-width: 768px) {
    .container {
        padding: 0 1.25rem;
    }

    .mobile-menu-btn {
        display: block;
    }

    nav {
        position: fixed;
        top: 0;
        right: -100%;
        width: 100%;
        height: 100vh;
        height: 100dvh;
        background: rgba(255, 255, 255, 0.98);
        backdrop-filter: blur(20px);
        -webkit-backdrop-filter: blur(20px);
        padding: 100px 2rem 2rem;
        transition: right 0.35s var(--ease-out-expo);
        display: block;
    }

    nav.active {
        right: 0;
    }

    nav ul {
        flex-direction: column;
        align-items: center;
        gap: 2rem;
    }

    nav a {
        font-size: 1.15rem;
    }

    section {
        padding: 80px 0;
    }

    .section-header {
        margin-bottom: 2.5rem;
    }

    .hero {
        padding: 110px 0 80px;
    }

    .hero h1 {
        font-size: 1.75rem;
        line-height: 1.5;
    }

    .hero-lead {
        font-size: 0.925rem;
    }

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

    .activity-item {
        padding: 2rem;
    }

    .product-features {
        grid-template-columns: 1fr;
    }

    .product-name {
        font-size: 1.75rem;
    }

    .contact {
        padding: 80px 0;
    }

    .footer-content {
        flex-direction: column;
        gap: 1rem;
        text-align: center;
    }
}

/* ---- Reduced Motion ---- */

@media (prefers-reduced-motion: reduce) {

    .hero h1,
    .hero-lead {
        opacity: 1;
        animation: none;
    }

    .fade-in-section {
        opacity: 1;
        transform: none;
        transition: none;
    }
}