/* --- Reset & Basic Styles --- */
:root {
    --primary-color: #3b82f6;
    --secondary-color: #10b981;
    --text-color: #334155;
    --bg-color: #f8fafc;
    --card-bg: #ffffff;
    --font-primary: 'Noto Sans JP', sans-serif;
    --font-secondary: 'Poppins', sans-serif;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-primary);
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.7;
}

.container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 20px;
}

/* --- Header --- */
.header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 1000;
    padding: 15px 0;
    transition: all 0.3s ease;
    background: rgba(255, 255, 255, 0.7);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid #e5e7eb;
}

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

.logo {
    font-family: var(--font-secondary);
    font-size: 24px;
    font-weight: 600;
    text-decoration: none;
    color: var(--primary-color);
}

.nav {
    display: flex;
    align-items: center;
    gap: 25px;
}

.nav a {
    text-decoration: none;
    color: #4b5563;
    font-weight: 500;
    transition: color 0.3s;
}

.nav a:hover {
    color: var(--primary-color);
}

.nav-button {
    background-color: var(--primary-color);
    color: white !important;
    padding: 8px 18px;
    border-radius: 50px;
    transition: background-color 0.3s, transform 0.3s;
}

.nav-button:hover {
    background-color: #2563eb;
    transform: translateY(-2px);
}

/* --- Hero Section --- */
#hero {
    padding: 180px 0 100px;
    text-align: center;
    overflow: hidden;
    position: relative;
    background: linear-gradient(135deg, #e0f2fe, #f0e6ff);
}

.hero-content {
    position: relative;
    z-index: 2;
}

.hero-title {
    font-size: 3.5rem;
    font-weight: 700;
    color: #1e293b;
    line-height: 1.2;
    margin-bottom: 20px;
}

.hero-subtitle {
    font-size: 1.25rem;
    color: #475569;
}

/* Phone Mockup & Animation */
.hero-mockup {
    margin-top: 60px;
    display: flex;
    justify-content: center;
    align-items: center;
    perspective: 1000px;
}

.phone-mockup {
    width: 280px;
    height: 560px;
    background: #1f2937;
    border-radius: 40px;
    padding: 15px;
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.25), inset 0 0 10px rgba(0,0,0,0.5);
    position: relative;
    transform: rotateX(15deg) rotateY(-10deg);
}

.phone-screen {
    width: 100%;
    height: 100%;
    background: #f0f0f0;
    border-radius: 25px;
    position: relative;
    overflow: hidden;
}

.phone-screen .card {
    position: absolute;
    width: 80%;
    height: 80%;
    top: 10%;
    left: 10%;
    background-size: cover;
    background-position: center;
    border-radius: 15px;
    box-shadow: 0 10px 20px rgba(0,0,0,0.1);
    background-color: #fff;
    border: 1px solid #e5e7eb;
}

.card.center {
    background-image: url('https://source.unsplash.com/random/400x600?nature,3');
    animation: swipe-center 10s infinite ease-in-out;
    z-index: 3;
}
.card.right {
    background-image: url('https://source.unsplash.com/random/400x600?people,3');
    animation: swipe-right 10s infinite ease-in-out;
    z-index: 2;
}
.card.left {
    background-image: url('https://source.unsplash.com/random/400x600?city,3');
    animation: swipe-left 10s infinite ease-in-out;
    z-index: 1;
}

@keyframes swipe-center {
    0%, 25% { transform: translateX(0) rotate(0); opacity: 1; }
    30% { transform: translateX(-150%) rotate(-20deg); opacity: 0; }
    31% { transform: translateX(150%) rotate(20deg); }
    35%, 100% { transform: translateX(0) rotate(0); opacity: 1; }
}
@keyframes swipe-right {
    0%, 25% { transform: scale(0.9) translateY(20px); opacity: 1; }
    35%, 60% { transform: translateX(0) rotate(0); opacity: 1; }
    65% { transform: translateX(150%) rotate(20deg); opacity: 0; }
    66% { transform: translateX(-150%) rotate(-20deg); }
    70%, 100% { transform: scale(0.9) translateY(20px); opacity: 1; }
}
@keyframes swipe-left {
    0%, 60% { transform: scale(0.8) translateY(40px); opacity: 1; }
    70%, 100% { transform: translateX(0) rotate(0); opacity: 1; }
}


/* --- General Section Styles --- */
.content-section {
    padding: 100px 0;
}

.section-title {
    text-align: center;
    font-size: 2.25rem;
    color: #1e293b;
    margin-bottom: 60px;
    font-weight: 700;
}

/* --- Features Section --- */
.features-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 40px;
}

.feature-card {
    background: var(--card-bg);
    padding: 40px;
    border-radius: 16px;
    box-shadow: 0 8px 16px rgba(0,0,0,0.05);
    transition: transform 0.3s, box-shadow 0.3s;
    text-align: center;
}

.feature-card:hover {
    transform: translateY(-10px);
    box-shadow: 0 12px 24px rgba(0,0,0,0.1);
}

.feature-icon {
    width: 60px;
    height: 60px;
    margin: 0 auto 20px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
}

.feature-icon svg {
    width: 30px;
    height: 30px;
    color: white;
}

.feature-card h3 {
    font-size: 1.5rem;
    margin-bottom: 15px;
    color: #1e293b;
}

.feature-card p {
    color: #475569;
    font-size: 1rem;
    line-height: 1.8;
}

/* --- How to Use Section --- */
#how-to-use {
    background-color: #f1f5f9;
}

.how-to-use-steps {
    display: flex;
    justify-content: center;
    gap: 80px;
    text-align: center;
}

.step h4 {
    font-size: 1.25rem;
    margin-top: 20px;
    margin-bottom: 10px;
    color: #1e293b;
}

.step p {
    color: #475569;
}

.step-image {
    width: 250px;
    height: 180px;
    border-radius: 12px;
    background-color: var(--card-bg);
    box-shadow: 0 8px 16px rgba(0,0,0,0.05);
    background-image: url('https://source.unsplash.com/random/500x360?nature,5');
    background-size: cover;
    background-position: center;
    position: relative;
    overflow: hidden;
}

.step-image::after {
    content: '';
    position: absolute;
    width: 100px;
    height: 100px;
    background: rgba(255,255,255,0.5);
    border-radius: 50%;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    opacity: 0;
    transition: all 0.5s ease-out;
}
.step:hover .step-image::after {
    opacity: 1;
    animation-duration: 1.5s;
    animation-iteration-count: infinite;
}

.left-swipe:hover::after { animation-name: swipe-effect-left; }
.right-swipe:hover::after { animation-name: swipe-effect-right; }

@keyframes swipe-effect-left {
    0% { transform: translate(-50%, -50%) scale(0.5); opacity: 1; }
    100% { transform: translate(-200%, -50%) scale(1.5); opacity: 0; }
}

@keyframes swipe-effect-right {
    0% { transform: translate(-50%, -50%) scale(0.5); opacity: 1; }
    100% { transform: translate(100%, -50%) scale(1.5); opacity: 0; }
}

/* --- Footer --- */
.footer {
    background-color: #1e293b;
    color: #cbd5e1;
    padding: 50px 0;
    text-align: center;
}

.footer-links {
    margin-bottom: 20px;
}

.footer-links a {
    color: #cbd5e1;
    text-decoration: none;
    margin: 0 15px;
    transition: color 0.3s;
}

.footer-links a:hover {
    color: white;
    text-decoration: underline;
}

.copyright {
    font-size: 0.9rem;
    color: #94a3b8;
}


/* --- Modal --- */
.modal {
    display: none;
    position: fixed;
    z-index: 2000;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    overflow: auto;
    background-color: rgba(0,0,0,0.6);
    animation: fadeIn 0.3s;
}

.modal-content {
    background-color: #fefefe;
    margin: 5% auto;
    padding: 30px 40px;
    border-radius: 8px;
    max-width: 800px;
    width: 90%;
    position: relative;
    box-shadow: 0 10px 30px rgba(0,0,0,0.2);
    animation: slideIn 0.4s ease-out;
}

#modal-body {
    max-height: 75vh;
    overflow-y: auto;
}

#modal-body h2 { color: #1e293b; font-size: 1.8rem; margin-bottom: 10px; }
#modal-body h3 { color: #334155; font-size: 1.3rem; margin-top: 25px; margin-bottom: 10px; border-bottom: 2px solid #e2e8f0; padding-bottom: 5px; }
#modal-body p { margin-bottom: 15px; line-height: 1.8; color: #475569; }
#modal-body ul { list-style-position: inside; padding-left: 10px; margin-bottom: 15px; color: #475569; }
#modal-body li { margin-bottom: 8px; }
#modal-body .date { font-style: italic; color: #64748b; margin-bottom: 20px; }


.close-button {
    color: #aaa;
    position: absolute;
    top: 15px;
    right: 25px;
    font-size: 28px;
    font-weight: bold;
    cursor: pointer;
}

.close-button:hover,
.close-button:focus {
    color: black;
}

@keyframes fadeIn { from { opacity: 0; } to { opacity: 1; } }
@keyframes slideIn { from { transform: translateY(-50px); opacity: 0; } to { transform: translateY(0); opacity: 1; } }

/* --- Scroll Animation --- */
.animate-on-scroll {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.6s ease-out, transform 0.6s ease-out;
}

.animate-on-scroll.is-visible {
    opacity: 1;
    transform: translateY(0);
}

/* --- Responsive Design --- */
@media (max-width: 768px) {
    .hero-title { font-size: 2.5rem; }
    .nav { display: none; } /* Simplified for example; a hamburger menu would be ideal */
    .features-grid { grid-template-columns: 1fr; }
    .how-to-use-steps { flex-direction: column; gap: 50px; }
    .phone-mockup { width: 240px; height: 480px; }
    .modal-content { margin: 10% auto; }
}