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

html {
    scroll-behavior: smooth;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: 'Google Sans', -apple-system, BlinkMacSystemFont, sans-serif;
    background: var(--bg);
    color: var(--text);
    font-size: 14px;
    line-height: 1.7;
}

:root {
    --bg: #fff;
    --text: #000;
    --text-dim: #666;
    --text-muted: #777;
    --border: #e5e5e5;
    --action-color: #16a34a;
}

[data-theme="dark"] {
    --bg: #000;
    --text: #fff;
    --text-dim: #999;
    --text-muted: #555;
    --border: #222;
    --action-color: #22c55e;
}

[data-theme="dark"] nav {
    background: rgba(0, 0, 0, 0.5);
}

[data-theme="dark"] .hero {
    background-image: linear-gradient(to bottom, transparent 0%, var(--bg) 100%), url('../images/hero-dark.png');
}

.theme-img-light + .theme-img-dark {
    display: none;
}

.theme-img-dark {
    display: none;
}

[data-theme="dark"] .theme-img-light {
    display: none;
}

[data-theme="dark"] .theme-img-dark {
    display: block;
}

.wrap {
    max-width: 720px;
    margin: 0 auto;
    padding: 0 24px;
}

.wrap-wide {
    max-width: 960px;
    margin: 0 auto;
    padding: 0 24px;
}

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

a:hover {
    text-decoration: underline;
}

hr {
    border: none;
    border-top: 1px solid var(--border);
}

::selection {
    background: var(--text);
    color: var(--bg);
}

/* nav */
nav {
    max-width: 560px;
    margin: 16px auto 0;
    padding: 8px 20px;
    position: sticky;
    top: 16px;
    z-index: 100;
    display: flex;
    justify-content: space-between;
    align-items: center;
    border: 1px solid var(--border);
    border-radius: 999px;
    background: rgba(255, 255, 255, 0.6);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
}

.logo {
    font-weight: 700;
    font-size: 15px;
    letter-spacing: -0.02em;
}

.nav-right {
    display: flex;
    gap: 24px;
    font-size: 13px;
}

.nav-right a {
    color: var(--text-muted);
}

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

.theme-btn {
    background: none;
    border: none;
    cursor: pointer;
    font-size: 14px;
    color: var(--text-muted);
    padding: 0;
    line-height: 1;
    transition: color 0.2s;
}

.theme-btn:hover {
    color: var(--text);
}

/* hero */
.hero {
    margin-top: -68px;
    padding: 100px 0 80px;
    background-image: linear-gradient(to bottom, transparent 0%, var(--bg) 100%), url('../images/hero.png');
    background-size: cover;
    background-position: center;
    background-repeat: no-repeat;
}

.hero-img {
    width: 100%;
    max-width: 720px;
    border-radius: 12px;
    overflow: hidden;
}

.hero-img img {
    width: 100%;
    height: auto;
    display: block;
}

.wrap-wide {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 40px;
}

.hero-demo {
    width: 100%;
    max-width: 560px;
}

.hero-text {
    text-align: center;
    max-width: 680px;
}

.hero-text .sub {
    margin-left: auto;
    margin-right: auto;
}

h1 {
    font-size: clamp(28px, 4vw, 40px);
    font-weight: 700;
    line-height: 1.15;
    letter-spacing: -0.03em;
    margin-bottom: 24px;
}

.sub {
    color: var(--text-dim);
    max-width: 520px;
    margin-bottom: 32px;
    font-size: 14px;
}

.btn {
    display: inline-block;
    font-family: inherit;
    font-size: 14px;
    font-weight: 600;
    border: none;
    padding: 10px 24px;
    color: var(--bg);
    background: var(--text);
    text-decoration: none;
    transition: background 0.2s, color 0.2s;
    margin-right: 8px;
}

.btn:hover {
    text-decoration: none;
    background: var(--text-dim);
}



.meta, .btn-note {
    margin-top: 16px;
    font-size: 12px;
    color: var(--text-muted);
    clear: both;
}

.btn-note {
    margin-top: 8px;
    font-size: 12px;
    color: var(--text-dim);
}

.btn-note a {
    color: var(--text);
    text-decoration: underline;
    font-weight: 600;
}





/* sections */
.feature-section {
    padding: 80px 0;
}

.feature-section .wrap-wide {
    flex-direction: row;
    align-items: center;
    gap: 64px;
}

.feature-section.feature-reverse .wrap-wide {
    flex-direction: row-reverse;
}

.feature-img {
    flex: 1;
    max-width: 480px;
}

.feature-img img {
    width: 100%;
    height: auto;
    border-radius: 12px;
}

.feature-text {
    flex: 1;
    max-width: 400px;
}

.feature-desc {
    color: var(--text-dim);
    font-size: 14px;
    line-height: 1.7;
    margin-bottom: 24px;
}

.feature-list {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.feature-list li {
    font-size: 14px;
    color: var(--text-dim);
    padding-left: 16px;
    position: relative;
}

.feature-list li::before {
    content: ">";
    position: absolute;
    left: 0;
    color: var(--text-muted);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 32px;
}

.feature-box h3 {
    font-size: 14px;
    font-weight: 700;
    margin-bottom: 8px;
}

.feature-box p {
    font-size: 13px;
    color: var(--text-dim);
    line-height: 1.6;
}

.divider {
    padding: 0;
}

section:not(.animation-section):not(.divider):not(.hero) {
    padding: 64px 0;
}

.label {
    font-size: 12px;
    color: var(--text-muted);
    text-transform: lowercase;
    margin-bottom: 32px;
    letter-spacing: 0;
}

h2 {
    font-size: clamp(24px, 3.5vw, 32px);
    font-weight: 700;
    line-height: 1.2;
    letter-spacing: -0.02em;
    margin-bottom: 16px;
}

/* how it works */
.cols {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 32px;
}

.col h2 {
    font-size: 48px;
    margin-bottom: 12px;
    color: var(--text-muted);
}

.col p {
    font-size: 13px;
    color: var(--text-dim);
    line-height: 1.6;
}

/* rules */
.rules-list {
    display: flex;
    flex-direction: column;
}

.rule-row {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    padding: 14px 0;
    border-bottom: 1px solid var(--border);
    font-size: 13px;
}

.rule-row:last-child {
    border-bottom: none;
}

.rule-name {
    font-weight: 600;
    white-space: nowrap;
}

.rule-desc {
    color: var(--text-muted);
}

/* who is it for */
.for-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 40px 32px;
}

.for-item h3 {
    font-size: 14px;
    font-weight: 700;
    margin-bottom: 8px;
}

.for-item p {
    font-size: 13px;
    color: var(--text-dim);
    line-height: 1.6;
}

/* footer */
footer {
    padding: 48px 0;
    border-top: 1px solid var(--border);
}

.footer-flex {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 12px;
}

footer p {
    font-size: 12px;
    color: var(--text-muted);
}

footer a {
    color: var(--text-muted);
}

footer a:hover {
    color: var(--text);
}

/* responsive */
@media (max-width: 600px) {
    .wrap-wide {
        gap: 40px;
    }

    .hero-text {
        text-align: left;
    }

    .hero-demo {
        max-width: 100%;
    }

    .feature-section .wrap-wide {
        flex-direction: column;
        gap: 40px;
    }

    .feature-section.feature-reverse .wrap-wide {
        flex-direction: column;
    }

    .feature-img {
        max-width: 100%;
        width: 100%;
    }

    .feature-text {
        max-width: 100%;
    }

    .features-grid {
        grid-template-columns: 1fr;
        gap: 24px;
    }
    }

    .cols {
        grid-template-columns: 1fr;
        gap: 24px;
    }

    .col h2 {
        font-size: 32px;
    }

    .nav-right {
        gap: 16px;
        font-size: 12px;
    }

    .rule-row {
        flex-direction: column;
        gap: 2px;
    }

    .for-grid {
        grid-template-columns: 1fr;
        gap: 32px;
    }

    .demo {
        height: 180px;
    }

    .footer-flex {
        flex-direction: column;
        text-align: center;
        gap: 8px;
    }
}