:root {
    --bg-color: #ffffff;
    --text-color: #111111;
    --text-light: #666666;
    --accent-color: rgb(18, 62, 97);
    --accent-hover: rgb(28, 76, 115);
    --gray-light: #f5f5f5;
    --border-color: #e5e5e5;
    --font-heading: 'Outfit', 'Inter', system-ui, -apple-system, sans-serif;
    --font-main: 'Inter', system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol", sans-serif;
    --container-width: 1000px;
}

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

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

a {
    text-decoration: none;
    color: inherit;
    transition: opacity 0.2s;
}

ul {
    list-style: none;
}

.container {
    max-width: var(--container-width);
    margin: 0 auto;
    padding: 0 24px;
}

/* Header */
.site-header {
    padding: 40px 0;
    position: sticky;
    top: 0;
    background: rgba(255, 255, 255, 0.9);
    backdrop-filter: blur(10px);
    z-index: 100;
}

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

.logo {
    font-family: var(--font-heading);
    color: var(--accent-color);
    font-weight: 600;
    font-size: 1.5rem;
    letter-spacing: -0.02em;
}

.site-header nav a {
    margin-left: 32px;
    font-size: 0.95rem;
    color: var(--text-light);
}

.site-header nav a:hover,
.site-header nav a.active {
    color: var(--accent-color);
}

/* Hero */
.hero {
    padding: 80px 0 120px;
    display: flex;
    flex-direction: column;
    justify-content: center;
}

.hero .container {
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
    max-width: 800px;
    /* Optional: Constrain width for better readability on large screens */
}

.hero h1 {
    font-family: var(--font-heading);
    font-size: 4rem;
    line-height: 1.1;
    font-weight: 600;
    letter-spacing: -0.03em;
    margin-bottom: 24px;
}

.subtitle {
    font-size: 1.25rem;
    color: var(--text-light);
    margin-bottom: 40px;
    max-width: 600px;
    /* Increased max-width slightly for centered layout */
    font-weight: 300;
}

.cta-group {
    display: flex;
    gap: 16px;
    justify-content: center;
}

.btn {
    padding: 14px 28px;
    border-radius: 8px;
    font-weight: 500;
    font-size: 1rem;
    transition: all 0.2s ease;
}

.btn.primary {
    background-color: var(--accent-color);
    color: #fff;
}

.btn.primary:hover {
    background-color: var(--accent-hover);
    transform: translateY(-1px);
}

.btn.secondary {
    background-color: var(--gray-light);
    color: var(--text-color);
}

.btn.secondary:hover {
    background-color: #e0e0e0;
}

/* Abstract Visual */
.hero-visual {
    display: flex;
    justify-content: center;
    align-items: center;
}

.abstract-shape {
    width: 300px;
    height: 300px;
    background: radial-gradient(circle at 30% 30%, #f0f0f0, #ffffff);
    border-radius: 50%;
    box-shadow: 20px 20px 60px #d9d9d9, -20px -20px 60px #ffffff;
    animation: float 6s ease-in-out infinite;
}

@keyframes float {
    0% {
        transform: translateY(0px) rotate(0deg);
    }

    50% {
        transform: translateY(-20px) rotate(5deg);
    }

    100% {
        transform: translateY(0px) rotate(0deg);
    }
}

/* Features */
.features {
    padding: 100px 0;
    background-color: #fafafa;
}

.section-title {
    text-align: center;
    font-family: var(--font-heading);
    font-size: 2.5rem;
    margin-bottom: 48px;
    color: var(--text-color);
    font-weight: 600;
    letter-spacing: -0.02em;
}

.feature-grid {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 24px;
}

.feature-card {
    flex: 1 1 280px;
    /* Allows 3 items per row on desktop (1000px container) */
    max-width: 320px;
    text-align: center;
    padding: 32px 24px;
    background-color: #ffffff;
    border: 1px solid var(--border-color);
    border-radius: 12px;
    transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.feature-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 10px 30px rgba(18, 62, 97, 0.1);
    border-color: var(--accent-color);
}

.feature-card h3 {
    font-family: var(--font-heading);
    font-size: 1.1rem;
    margin-bottom: 12px;
    font-weight: 600;
}

.feature-card p {
    color: var(--text-light);
    font-size: 0.95rem;
    line-height: 1.5;
}

/* Footer */
footer {
    padding: 60px 0;
    text-align: center;
    color: var(--text-light);
    font-size: 0.9rem;
    border-top: 1px solid var(--border-color);
}


/* Changelog Styles */
.changelog-section {
    padding: 80px 0;
}

.version-item {
    margin-bottom: 60px;
    border-left: 2px solid var(--accent-color);
    padding-left: 24px;
}

.version-header {
    display: flex;
    align-items: baseline;
    gap: 16px;
    margin-bottom: 16px;
}

.version-tag {
    background: var(--accent-color);
    color: #fff;
    padding: 4px 12px;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 600;
}

.version-date {
    color: var(--text-light);
    font-size: 0.9rem;
}

.change-list {
    padding-left: 20px;
}

.change-list li {
    margin-bottom: 8px;
    position: relative;
    list-style-type: none;
}

.change-list li::before {
    content: "•";
    color: var(--accent-color);
    position: absolute;
    left: -15px;
    font-weight: bold;
}

/* About Page Styles */
.about-content {
    max-width: 700px;
    margin: 0 auto;
}

.about-content h2 {
    font-family: var(--font-heading);
    font-size: 2.5rem;
    margin-bottom: 24px;
    font-weight: 600;
    letter-spacing: -0.02em;
}

.about-content p {
    margin-bottom: 24px;
    font-size: 1.1rem;
    color: var(--text-light);
}

.about-image-img {
    width: 100%;
    max-width: 352px;
    height: auto;
    border-radius: 12px;
    margin: 40px auto;
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.08);
    display: block;
}

/* Modal Styles */
.modal-overlay {
    background: rgba(0, 0, 0, 0.4);
    backdrop-filter: blur(4px);
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    z-index: 1000;
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.3s ease;
}

.modal-overlay.active {
    opacity: 1;
    pointer-events: auto;
}

.modal-content {
    background: #fff;
    width: 90%;
    max-width: 900px;
    border-radius: 16px;
    padding: 32px;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.2);
    transform: translateY(20px);
    transition: transform 0.3s ease;
    position: relative;
    max-height: 90vh;
    overflow-y: auto;
}

.modal-overlay.active .modal-content {
    transform: translateY(0);
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 24px;
    padding-bottom: 16px;
    border-bottom: 1px solid var(--border-color);
}

.modal-header h2 {
    font-family: var(--font-heading);
    color: var(--text-color);
    font-size: 1.5rem;
    margin: 0;
}

.modal-close {
    background: transparent;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--text-light);
    padding: 4px;
    line-height: 1;
}

.modal-close:hover {
    color: var(--text-color);
}

.guide-section {
    margin-bottom: 32px;
}

.guide-section h3 {
    font-size: 1.1rem;
    color: var(--accent-color);
    margin-bottom: 16px;
    display: flex;
    align-items: center;
    gap: 8px;
}

.guide-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 20px;
}

.guide-item {
    text-align: center;
}

.guide-item img {
    width: 100%;
    border-radius: 8px;
    border: 1px solid var(--border-color);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.05);
    margin-bottom: 12px;
    transition: transform 0.2s;
}

.guide-item img:hover {
    transform: scale(1.02);
}

.guide-item p {
    font-size: 0.9rem;
    color: var(--text-light);
    line-height: 1.4;
}

.step-badge {
    display: inline-block;
    background: var(--gray-light);
    color: var(--text-color);
    padding: 2px 8px;
    border-radius: 4px;
    font-size: 0.8rem;
    font-weight: 600;
    margin-bottom: 4px;
}

/* Mobile Responsive */
@media (max-width: 768px) {

    /* Header */
    .site-header {
        padding: 20px 0;
    }

    .site-header .container {
        flex-direction: column;
        gap: 16px;
    }

    .site-header nav {
        display: flex;
        flex-wrap: wrap;
        justify-content: center;
        gap: 16px;
    }

    .site-header nav a {
        margin-left: 0;
        font-size: 0.9rem;
        padding: 4px 8px;
    }

    /* Hero */
    .hero {
        padding: 60px 0 80px;
    }

    .hero .container {
        text-align: center;
    }

    .hero h1 {
        font-size: 2.5rem;
    }

    .subtitle {
        font-size: 1.1rem;
        margin: 0 auto 32px;
        line-height: 1.5;
    }

    .cta-group {
        flex-direction: column;
        /* Stack buttons vertically */
        width: 100%;
        max-width: 300px;
        /* Limit width */
        margin: 0 auto;
        gap: 12px;
    }

    .btn {
        width: 100%;
        text-align: center;
        display: block;
    }

    /* About Page */
    .about-content {
        padding: 0 4px;
    }

    .about-content h2 {
        font-size: 2rem;
        margin-top: 30px;
    }

    .about-image-img {
        max-width: 100%;
        height: auto;
        margin: 30px auto;
    }

    /* Changelog Page */
    .changelog-section {
        padding: 40px 0;
    }

    .version-item {
        margin-bottom: 40px;
        padding-left: 16px;
    }

    .version-header {
        flex-direction: column;
        align-items: flex-start;
        gap: 8px;
    }

    .change-list {
        padding-left: 10px;
    }

    /* General Layout */
    .container {
        padding: 0 20px;
    }

    .feature-grid {
        gap: 16px;
    }

    .feature-card {
        padding: 24px 20px;
    }

    /* Hide float animation on mobile */
    .abstract-shape {
        display: none;
    }
}