:root {
    /* Color Palette - Minimalist Japanese aesthetic */
    --color-bg: #F8F7F4; /* Soft warm paper tone */
    --color-text-main: #2A2A28; /* Soft black/charcoal */
    --color-text-muted: #72726F;
    --color-accent: #87948B; /* Sage green */
    --color-accent-hover: #707E74;
    --color-surface: rgba(255, 255, 255, 0.6);
    --color-border: rgba(42, 42, 40, 0.1);

    /* Typography */
    --font-serif: 'Shippori Mincho', serif;
    --font-sans: 'Zen Kaku Gothic New', sans-serif;

    /* Spacing */
    --space-sm: 1rem;
    --space-md: 2rem;
    --space-lg: 4rem;
    --space-xl: 6rem;
}

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

body {
    background-color: var(--color-bg);
    color: var(--color-text-main);
    font-family: var(--font-sans);
    line-height: 1.8;
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
    font-size: 16px;
}

/* Zen Background Effects */
.background-gradient {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    background: radial-gradient(circle at 50% 50%, rgba(135, 148, 139, 0.12) 0%, rgba(248, 247, 244, 0) 70%);
    z-index: -2;
    animation: pulseBg 18s infinite alternate ease-in-out;
}

@keyframes pulseBg {
    0% { transform: scale(1); opacity: 0.7; }
    100% { transform: scale(1.15); opacity: 1; }
}

/* Subtle grain noise to mimic paper */
.noise-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 200 200' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='noiseFilter'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.8' numOctaves='3' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23noiseFilter)' opacity='0.03'/%3E%3C/svg%3E");
    pointer-events: none;
    z-index: -1;
}

/* Layout */
.container {
    max-width: 800px;
    margin: 0 auto;
    padding: 0 20px;
}

h1, h2, h3 {
    font-family: var(--font-serif);
    font-weight: 500;
    line-height: 1.4;
    color: var(--color-text-main);
}

/* Hero Section */
.hero {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    text-align: center;
    padding: var(--space-xl) 0;
}

.hero-title {
    font-size: clamp(1.8rem, 8vw, 3.2rem);
    margin-bottom: var(--space-md);
    letter-spacing: 0.1em;
    display: flex;
    flex-direction: column;
    gap: 0.6rem;
    line-height: 1.3;
}

.hero-subtitle {
    font-family: var(--font-serif);
    font-size: clamp(1.1rem, 2vw, 1.4rem);
    color: var(--color-text-muted);
    margin-bottom: var(--space-lg);
    letter-spacing: 0.1em;
}

.hero-copy {
    font-size: 1rem;
    line-height: 1.8;
    margin-bottom: var(--space-lg);
    color: var(--color-text-main);
    letter-spacing: 0.02em;
    max-width: 90%;
}

/* Buttons */
.btn-primary {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 12px;
    background-color: var(--color-text-main);
    color: var(--color-bg);
    text-decoration: none;
    padding: 20px 48px;
    border-radius: 50px;
    font-family: var(--font-sans);
    font-weight: 500;
    font-size: 1.1rem;
    letter-spacing: 0.05em;
    transition: all 0.4s cubic-bezier(0.16, 1, 0.3, 1);
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
}

.btn-primary svg {
    width: 20px;
    height: 20px;
    transition: transform 0.3s ease;
}

.btn-primary:hover {
    background-color: var(--color-accent);
    transform: translateY(-4px);
    box-shadow: 0 15px 40px rgba(135, 148, 139, 0.35);
}

.btn-primary:hover svg {
    transform: translateX(5px);
}

/* General Sections */
.section {
    padding: var(--space-xl) 0;
}

/* Alternating subtle dividers */
.section:not(.letter-section):not(.hero) {
    position: relative;
}
.section:not(.letter-section):not(.hero)::before {
    content: '';
    position: absolute;
    top: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 60px;
    height: 1px;
    background-color: var(--color-border);
}

.section-title {
    font-size: clamp(1.8rem, 4vw, 2.2rem);
    margin-bottom: var(--space-lg);
    text-align: center;
    letter-spacing: 0.1em;
}

/* Target List (こんな方へ) */
.target-list {
    list-style: none;
    max-width: 600px;
    margin: 0 auto;
}

.target-list li {
    font-size: 1.1rem;
    padding: 20px 0;
    border-bottom: 1px solid var(--color-border);
    position: relative;
    padding-left: 36px;
    letter-spacing: 0.02em;
}

.target-list li::before {
    content: '';
    position: absolute;
    left: 8px;
    top: 50%;
    transform: translateY(-50%);
    width: 6px;
    height: 6px;
    background-color: var(--color-accent);
    border-radius: 50%;
}

.target-list li:first-child {
    border-top: 1px solid var(--color-border);
}

/* Concept Section */
.concept-content {
    text-align: center;
    max-width: 620px;
    margin: 0 auto;
    font-size: 1.05rem;
}

.highlight-box {
    background: var(--color-surface);
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255,255,255,0.4);
    border-radius: 16px;
    padding: 32px 24px;
    margin: var(--space-md) 0;
    font-size: clamp(1.1rem, 3vw, 1.3rem);
    font-family: var(--font-serif);
    color: var(--color-text-main);
    box-shadow: 0 8px 32px rgba(0,0,0,0.02);
    letter-spacing: 0.05em;
    line-height: 1.6;
}

.mt-4 {
    margin-top: 1.5rem;
}

.link-wrapper {
    margin-top: var(--space-lg);
}

.link-secondary {
    display: inline-block;
    color: var(--color-accent);
    text-decoration: none;
    border-bottom: 1px solid var(--color-accent);
    padding-bottom: 4px;
    transition: opacity 0.3s ease;
    font-family: var(--font-sans);
    letter-spacing: 0.05em;
}

.link-secondary:hover {
    opacity: 0.7;
}

/* Content Grid (メルマガでお届けする内容) */
.content-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 16px;
    margin-bottom: var(--space-lg);
}

.content-card {
    background: var(--color-surface);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border: 1px solid rgba(255,255,255,0.3);
    padding: 28px 20px;
    border-radius: 12px;
    text-align: center;
    transition: transform 0.4s ease, box-shadow 0.4s ease;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: 0 4px 15px rgba(0,0,0,0.01);
}

.content-card:hover {
    transform: translateY(-5px);
    background: rgba(255,255,255,0.8);
    box-shadow: 0 10px 30px rgba(0,0,0,0.04);
}

.content-card h3 {
    font-size: 1.1rem;
    letter-spacing: 0.05em;
}

.content-point {
    text-align: center;
    font-family: var(--font-serif);
    font-size: 1.3rem;
    line-height: 2;
    color: var(--color-accent);
    margin-top: var(--space-md);
}

/* Letter Section (なぜメールなのか) */
.letter-section {
    padding: var(--space-xl) 0;
    margin-top: var(--space-lg);
}

.letter-container {
    max-width: 100vw;
    margin: 0 calc(50% - 50vw);
    padding: var(--space-xl) 24px;
    background-color: var(--color-text-main);
    color: var(--color-bg);
}

.letter-title {
    color: var(--color-bg);
}

.letter-content {
    font-family: var(--font-serif);
    font-size: clamp(1.1rem, 3vw, 1.3rem);
    line-height: 2.4;
    text-align: center;
    max-width: 500px;
    margin: 0 auto;
    letter-spacing: 0.08em;
}

/* Final CTA */
.cta-section {
    min-height: 40vh;
    display: flex;
    align-items: center;
    justify-content: center;
}

/* Footer */
.footer {
    text-align: center;
    padding: var(--space-md) 0 var(--space-lg);
    font-size: 0.9rem;
    color: var(--color-text-muted);
    font-family: var(--font-sans);
    letter-spacing: 0.05em;
}

/* Initial Load Animations */
.fade-in-line {
    opacity: 0;
    transform: translateY(15px);
    animation: fadeInUp 1.2s cubic-bezier(0.16, 1, 0.3, 1) forwards;
}

.fade-in-up {
    opacity: 0;
    transform: translateY(20px);
    animation: fadeInUp 1.2s cubic-bezier(0.16, 1, 0.3, 1) forwards;
}

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

/* Scroll Reveal Animations */
.scroll-reveal {
    opacity: 0;
    transform: translateY(40px);
    transition: opacity 1.2s cubic-bezier(0.16, 1, 0.3, 1), transform 1.2s cubic-bezier(0.16, 1, 0.3, 1);
}

.scroll-reveal.visible {
    opacity: 1;
    transform: translateY(0);
}

/* Responsive Adjustments */
@media (max-width: 768px) {
    :root {
        --space-lg: 2.5rem;
        --space-xl: 3.5rem;
    }
    
    body {
        font-size: 15px;
    }

    .hero-title {
        gap: 0.4rem;
    }

    .btn-primary {
        padding: 18px 28px;
        width: 100%;
        max-width: 100%;
        font-size: 1rem;
    }
    
    .target-list li {
        font-size: 1rem;
        padding: 16px 0;
        padding-left: 28px;
    }

    .highlight-box {
        padding: 24px 16px;
        font-size: 1.1rem;
    }

    .content-point {
        font-size: 1.1rem;
        line-height: 1.8;
    }

    .letter-container {
        padding: var(--space-xl) 20px;
    }

    .letter-content {
        line-height: 2.2;
    }
}

/* Very Small Screens */
@media (max-width: 375px) {
    .hero-title {
        font-size: 1.6rem;
    }
}