/* Ki Browser — design system
 * Quiet, premium, on-brand. The page itself should feel like a deep breath.
 * Plain CSS. No build step. */

/* ─── Tokens ─────────────────────────────────────────────────────────── */

:root {
    --ki-ink: #0B1020;
    --ki-ink-soft: #1B2238;
    --ki-paper: #FCFCFD;
    --ki-paper-soft: #F4F5F8;
    --ki-surface: #FFFFFF;
    --ki-muted: #5B6175;
    --ki-muted-soft: #8B92A8;
    --ki-border: #E4E6EC;
    --ki-border-soft: #EFF1F5;
    --ki-accent: #4F46E5;
    --ki-accent-hover: #3730A3;
    --ki-accent-soft: #EEF0FE;
    --ki-watermark: rgba(11, 16, 32, 0.04);
    --ki-card-shadow: 0 1px 2px rgba(11, 16, 32, 0.04), 0 6px 24px rgba(11, 16, 32, 0.04);
    --ki-card-shadow-hover: 0 1px 2px rgba(11, 16, 32, 0.05), 0 12px 36px rgba(11, 16, 32, 0.08);
    --ki-icon-shadow: 0 1px 2px rgba(11, 16, 32, 0.06), 0 14px 48px rgba(11, 16, 32, 0.18);

    /* Type stack. Serif for display copy (Apple's New York on Apple devices,
     * graceful fallback to Georgia / Charter elsewhere); humanist sans for
     * running body. Both are system-installed everywhere, no web fetches.
     *
     * The CJK fallbacks (Hiragino Mincho ProN, Yu Mincho) make sure the
     * kanji 気 picks up Apple's serif Japanese (Mincho) — the cultural
     * equivalent of New York — instead of falling through to the gothic
     * Hiragino Sans default. Browsers walk the stack per-glyph: Latin uses
     * New York; CJK skips the Latin-only fonts and lands on Mincho. */
    --font-display: ui-serif, "New York", "Charter", "Iowan Old Style", Georgia, "Hiragino Mincho ProN", "Yu Mincho", "YuMincho", "Times New Roman", serif;
    --font-body: -apple-system, BlinkMacSystemFont, "SF Pro Text", "Inter", "Segoe UI", Roboto, sans-serif;

    --bs-primary: var(--ki-accent);
    --bs-body-bg: var(--ki-paper);
    --bs-body-color: var(--ki-ink);
    --bs-link-color: var(--ki-accent);
    --bs-link-hover-color: var(--ki-accent-hover);
    --bs-border-color: var(--ki-border);
    --bs-border-color-translucent: var(--ki-border-soft);
    --bs-body-font-family: var(--font-body);
    --bs-font-sans-serif: var(--font-body);
    --bs-font-serif: var(--font-display);
    /* Bootstrap 5.3+ uses these for .text-muted, .text-secondary,
     * .text-body-secondary, .text-body-tertiary, and .text-emphasis.
     * Without these overrides those utilities ignore data-theme. */
    --bs-secondary-color: var(--ki-muted);
    --bs-tertiary-color: var(--ki-muted-soft);
    --bs-secondary-bg: var(--ki-paper-soft);
    --bs-tertiary-bg: var(--ki-paper-soft);
    --bs-emphasis-color: var(--ki-ink);
    --bs-heading-color: var(--ki-ink);
}

[data-theme="dark"] {
    --ki-ink: #ECEFF7;
    --ki-ink-soft: #C5C9DA;
    --ki-paper: #07091A;
    --ki-paper-soft: #0E1228;
    --ki-surface: #11163A;
    --ki-muted: #97A0BC;
    --ki-muted-soft: #6F7795;
    --ki-border: #1F2542;
    --ki-border-soft: #181E37;
    --ki-accent: #8B85FF;
    --ki-accent-hover: #B7B2FF;
    --ki-accent-soft: rgba(139, 133, 255, 0.12);
    --ki-watermark: rgba(236, 239, 247, 0.04);
    --ki-card-shadow: 0 1px 2px rgba(0, 0, 0, 0.4), 0 8px 28px rgba(0, 0, 0, 0.35);
    --ki-card-shadow-hover: 0 1px 2px rgba(0, 0, 0, 0.5), 0 16px 44px rgba(0, 0, 0, 0.5);
    --ki-icon-shadow: 0 2px 4px rgba(0, 0, 0, 0.5), 0 18px 56px rgba(139, 133, 255, 0.25);

    /* Re-point Bootstrap tokens for dark mode. */
    --bs-body-bg: var(--ki-paper);
    --bs-body-color: var(--ki-ink);
    --bs-link-color: var(--ki-accent);
    --bs-link-hover-color: var(--ki-accent-hover);
    --bs-border-color: var(--ki-border);
    --bs-border-color-translucent: var(--ki-border-soft);
    --bs-secondary-color: var(--ki-muted);
    --bs-tertiary-color: var(--ki-muted-soft);
    --bs-secondary-bg: var(--ki-paper-soft);
    --bs-tertiary-bg: var(--ki-paper-soft);
    --bs-emphasis-color: var(--ki-ink);
    --bs-heading-color: var(--ki-ink);
}

/* Belt-and-suspenders: a few Bootstrap utility classes still hardcode
 * the secondary token at !important. Mirror them explicitly so the
 * theme is never overridden, even if Bootstrap's load order shifts. */
.text-muted,
.text-secondary,
.text-body-secondary {
    color: var(--ki-muted) !important;
}
.text-body-tertiary {
    color: var(--ki-muted-soft) !important;
}

/* Dark mode: Bootstrap's default <hr> renders too faintly. */
hr {
    border-color: var(--ki-border-soft);
    opacity: 1;
}

/* Bootstrap's navbar-toggler-icon is a fixed dark SVG image and
 * disappears against a dark navbar. Switch to a light one in dark mode. */
[data-theme="dark"] .navbar-toggler-icon {
    background-image: url("data:image/svg+xml;charset=utf8,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 30 30'%3E%3Cpath stroke='rgba%28236,239,247,0.85%29' stroke-linecap='round' stroke-miterlimit='10' stroke-width='2' d='M4 7h22M4 15h22M4 23h22'/%3E%3C/svg%3E");
}
[data-theme="dark"] .navbar-toggler {
    border-color: var(--ki-border);
}

/* ─── Base ──────────────────────────────────────────────────────────── */

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

html { scroll-behavior: smooth; }

body {
    font-family: var(--font-body);
    background-color: var(--ki-paper);
    color: var(--ki-ink);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    text-rendering: optimizeLegibility;
    line-height: 1.55;
}

h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-display);
    color: var(--ki-ink);
    letter-spacing: -0.015em;
    line-height: 1.12;
    margin: 0;
    font-weight: 600;
}

p { margin: 0; }

a {
    color: var(--ki-accent);
    text-decoration: none;
    transition: color 0.15s ease;
}
a:hover { color: var(--ki-accent-hover); }

.skip-link {
    position: absolute;
    top: 0;
    left: 0;
    background: var(--ki-accent);
    color: white;
    padding: 0.75rem 1rem;
    z-index: 9999;
}

.eyebrow {
    text-transform: uppercase;
    letter-spacing: 0.12em;
    font-size: 0.78rem;
    font-weight: 600;
    color: var(--ki-muted);
    margin-bottom: 0.6rem;
}

.section-title {
    font-family: var(--font-display);
    font-size: clamp(1.95rem, 3.6vw, 2.75rem);
    font-weight: 600;
    letter-spacing: -0.018em;
    line-height: 1.1;
}

.section-subtitle {
    color: var(--ki-muted);
    font-size: 1.1rem;
    margin-top: 0.6rem;
    max-width: 56ch;
}

.text-link {
    color: var(--ki-muted);
    font-weight: 500;
    transition: color 0.15s;
}
.text-link:hover { color: var(--ki-ink); }

/* ─── Navbar ────────────────────────────────────────────────────────── */

.navbar {
    background-color: rgba(252, 252, 253, 0.72);
    backdrop-filter: saturate(180%) blur(16px);
    -webkit-backdrop-filter: saturate(180%) blur(16px);
    border-bottom: 1px solid var(--ki-border-soft);
    padding: 0.85rem 0;
}
[data-theme="dark"] .navbar {
    background-color: rgba(7, 9, 26, 0.72);
}

.navbar-brand {
    display: flex;
    align-items: center;
    gap: 0.55rem;
    font-weight: 600;
    color: var(--ki-ink);
}
.navbar-brand:hover { color: var(--ki-ink); }

.brand-icon {
    border-radius: 7px;
    box-shadow: 0 1px 2px rgba(0, 0, 0, 0.08);
}

.brand-name {
    font-family: var(--font-display);
    font-size: 1.25rem;
    letter-spacing: -0.005em;
    font-weight: 600;
}

.nav-link {
    color: var(--ki-muted);
    font-weight: 500;
    font-size: 0.95rem;
    padding: 0.4rem 0.9rem !important;
    transition: color 0.15s;
}
.nav-link:hover { color: var(--ki-ink); }

.theme-toggle {
    background: transparent;
    border: 1px solid var(--ki-border);
    border-radius: 999px;
    width: 38px;
    height: 38px;
    color: var(--ki-muted);
    cursor: pointer;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    transition: color 0.15s, border-color 0.15s, background-color 0.15s;
    padding: 0;
}
.theme-toggle:hover {
    color: var(--ki-ink);
    border-color: var(--ki-ink);
    background-color: var(--ki-paper-soft);
}

.theme-icon { display: none; }
[data-theme="light"] .theme-icon--moon { display: inline-block; }
[data-theme="dark"] .theme-icon--sun { display: inline-block; }

/* ─── Hero ──────────────────────────────────────────────────────────── */

.hero {
    position: relative;
    overflow: hidden;
    padding: 6rem 0 5rem;
    background: linear-gradient(180deg, var(--ki-paper) 0%, var(--ki-paper-soft) 100%);
    border-bottom: 1px solid var(--ki-border-soft);
}

.hero-watermark {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    font-family: var(--font-display);
    font-size: clamp(28rem, 60vw, 48rem);
    line-height: 1;
    color: var(--ki-watermark);
    font-weight: 300;
    pointer-events: none;
    user-select: none;
    z-index: 0;
}

.hero-container {
    position: relative;
    z-index: 1;
}

.hero-grid {
    display: grid;
    grid-template-columns: minmax(0, 1.2fr) minmax(0, 1fr);
    gap: 4rem;
    align-items: center;
}

.hero-copy {
    max-width: 36rem;
}

.badge-beta {
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
    background: var(--ki-accent-soft);
    color: var(--ki-accent);
    border: 1px solid transparent;
    border-radius: 999px;
    padding: 0.32rem 0.85rem;
    font-size: 0.82rem;
    font-weight: 600;
    letter-spacing: 0.02em;
    margin-bottom: 1.4rem;
}
.badge-beta::before {
    content: "";
    width: 6px;
    height: 6px;
    border-radius: 50%;
    background: var(--ki-accent);
    box-shadow: 0 0 0 4px var(--ki-accent-soft);
}

.hero-wordmark {
    font-family: var(--font-display);
    font-size: clamp(6rem, 15vw, 10.5rem);
    font-weight: 600;
    letter-spacing: -0.035em;
    line-height: 0.95;
    margin-bottom: 1.4rem;
    background: linear-gradient(135deg, var(--ki-ink) 0%, var(--ki-ink-soft) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-lead {
    font-family: var(--font-display);
    font-size: clamp(1.55rem, 2.6vw, 1.95rem);
    font-weight: 500;
    color: var(--ki-ink);
    letter-spacing: -0.012em;
    margin-bottom: 0.85rem;
    line-height: 1.25;
}

.hero-sub {
    font-size: 1.1rem;
    color: var(--ki-muted);
    margin-bottom: 1.6rem;
    max-width: 36rem;
}

.hero-pills {
    display: flex;
    flex-wrap: wrap;
    gap: 0.55rem;
    margin-bottom: 2rem;
}

.hero-pill {
    background: var(--ki-surface);
    border: 1px solid var(--ki-border);
    border-radius: 999px;
    padding: 0.4rem 0.85rem;
    font-size: 0.85rem;
    color: var(--ki-muted);
    font-weight: 500;
}

.hero-actions {
    display: flex;
    align-items: center;
    flex-wrap: wrap;
    gap: 1.25rem;
}

.app-store-link { display: inline-flex; }

.app-store-badge {
    height: 50px;
    transition: transform 0.15s, opacity 0.15s;
}
.app-store-badge:hover { opacity: 0.88; transform: translateY(-1px); }

[data-theme="dark"] .app-store-badge {
    filter: invert(1);
}

.hero-visual {
    display: flex;
    justify-content: center;
    align-items: center;
}

.hero-icon-frame {
    position: relative;
    width: 280px;
    height: 280px;
    display: flex;
    align-items: center;
    justify-content: center;
}
.hero-icon-frame::before {
    content: "";
    position: absolute;
    inset: -20px;
    background: radial-gradient(circle at center, var(--ki-accent-soft) 0%, transparent 70%);
    border-radius: 50%;
    z-index: 0;
}

.hero-icon {
    position: relative;
    z-index: 1;
    border-radius: 28%;
    box-shadow: var(--ki-icon-shadow);
    animation: float 6s ease-in-out infinite;
}

@keyframes float {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-8px); }
}

@media (max-width: 880px) {
    .hero { padding: 4rem 0 3rem; }
    .hero-grid {
        grid-template-columns: 1fr;
        gap: 3rem;
        text-align: center;
    }
    .hero-copy { max-width: none; margin: 0 auto; }
    .hero-pills { justify-content: center; }
    .hero-actions { justify-content: center; }
    .hero-icon-frame { width: 200px; height: 200px; }
    .hero-icon { width: 180px !important; height: 180px !important; }
}

/* ─── Principle section ─────────────────────────────────────────────── */

.principle {
    padding: 6rem 0;
}

.principle-intro {
    text-align: center;
    max-width: 56ch;
    margin: 0 auto 3.5rem;
}
.principle-intro .section-subtitle { margin-left: auto; margin-right: auto; }

.principle-row { row-gap: 2rem; }

.principle-card {
    height: 100%;
    background: transparent;
    padding: 1.5rem 1rem 0;
    text-align: center;
}

.principle-icon {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 56px;
    height: 56px;
    border-radius: 16px;
    background: var(--ki-accent-soft);
    color: var(--ki-accent);
    margin-bottom: 1.2rem;
}

.principle-card h3 {
    font-family: var(--font-display);
    font-size: 1.4rem;
    font-weight: 600;
    margin-bottom: 0.6rem;
    letter-spacing: -0.012em;
}

.principle-card p {
    color: var(--ki-muted);
    font-size: 0.98rem;
    line-height: 1.6;
}

@media (max-width: 880px) {
    .principle { padding: 4rem 0; }
}

/* ─── Features ──────────────────────────────────────────────────────── */

.features {
    padding: 6rem 0;
    background: var(--ki-paper-soft);
    border-top: 1px solid var(--ki-border-soft);
    border-bottom: 1px solid var(--ki-border-soft);
}

.features-intro {
    text-align: center;
    margin-bottom: 3.5rem;
}

.feature-card {
    height: 100%;
    background: var(--ki-surface);
    border: 1px solid var(--ki-border-soft);
    border-radius: 20px;
    padding: 1.75rem;
    transition: transform 0.18s ease, box-shadow 0.18s ease, border-color 0.18s ease;
    box-shadow: var(--ki-card-shadow);
}
.feature-card:hover {
    transform: translateY(-3px);
    box-shadow: var(--ki-card-shadow-hover);
    border-color: var(--ki-border);
}

.feature-icon {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 44px;
    height: 44px;
    border-radius: 12px;
    background: var(--ki-accent-soft);
    color: var(--ki-accent);
    margin-bottom: 1.2rem;
}

.feature-card h5 {
    font-family: var(--font-display);
    font-size: 1.18rem;
    font-weight: 600;
    margin: 0 0 0.5rem;
    letter-spacing: -0.01em;
    color: var(--ki-ink);
}

.feature-card p {
    color: var(--ki-muted);
    font-size: 0.96rem;
    line-height: 1.6;
    margin: 0;
}

@media (max-width: 880px) {
    .features { padding: 4rem 0; }
}

/* ─── CTA ───────────────────────────────────────────────────────────── */

.cta {
    padding: 6rem 0;
    text-align: center;
}

.cta-card {
    max-width: 720px;
    margin: 0 auto;
    background: var(--ki-surface);
    border: 1px solid var(--ki-border);
    border-radius: 28px;
    padding: 3.5rem 2.5rem;
    box-shadow: var(--ki-card-shadow);
    position: relative;
    overflow: hidden;
}
.cta-card::before {
    content: "気";
    position: absolute;
    top: -3rem;
    right: -3rem;
    font-family: var(--font-display);
    font-size: 22rem;
    line-height: 1;
    color: var(--ki-watermark);
    font-weight: 300;
    pointer-events: none;
    user-select: none;
}

.cta-card .section-title {
    margin-bottom: 1rem;
}

.cta-lead {
    color: var(--ki-muted);
    font-size: 1.08rem;
    margin-bottom: 2rem;
    max-width: 48ch;
    margin-left: auto;
    margin-right: auto;
}

@media (max-width: 880px) {
    .cta { padding: 4rem 0; }
    .cta-card { padding: 2.5rem 1.5rem; }
    .cta-card::before { font-size: 14rem; top: -1.5rem; right: -1.5rem; }
}

/* ─── Long-form pages (privacy, support) ────────────────────────────── */

.legal-content,
.support-content {
    max-width: 760px;
    margin: 0 auto;
    padding: 4rem 0 5rem;
    line-height: 1.7;
}

.legal-content h1,
.support-content h1 {
    font-family: var(--font-display);
    font-size: clamp(2.4rem, 4.4vw, 3.2rem);
    margin-bottom: 0.6rem;
    letter-spacing: -0.02em;
}

.legal-content h2,
.support-content h2 {
    font-family: var(--font-display);
    margin-top: 3rem;
    margin-bottom: 1rem;
    font-size: 1.55rem;
    font-weight: 600;
    letter-spacing: -0.012em;
}

.legal-content p,
.legal-content ul,
.legal-content ol,
.support-content p {
    color: var(--ki-ink);
    font-size: 1.02rem;
}

.legal-content ul,
.legal-content ol { padding-left: 1.5rem; }
.legal-content li { margin-bottom: 0.5rem; }
.legal-content p { margin-bottom: 1rem; }

.last-updated {
    color: var(--ki-muted);
    font-size: 0.9rem;
    margin-bottom: 2.5rem !important;
}

.highlight-box {
    background-color: var(--ki-accent-soft);
    border-left: 3px solid var(--ki-accent);
    padding: 1.1rem 1.4rem;
    border-radius: 12px;
    margin: 2rem 0;
    color: var(--ki-ink);
    line-height: 1.6;
}

/* Support */
.contact-box {
    background: var(--ki-paper-soft);
    border: 1px solid var(--ki-border-soft);
    border-radius: 20px;
    padding: 2.5rem;
    margin-bottom: 3.5rem;
    text-align: center;
}
.contact-box h2 {
    font-size: 1.3rem;
    margin-top: 0;
    margin-bottom: 1rem;
}

.faq-item {
    border-bottom: 1px solid var(--ki-border-soft);
    padding: 1.5rem 0;
}
.faq-item:last-child { border-bottom: none; }
.faq-question {
    font-family: var(--font-display);
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--ki-ink);
    font-size: 1.15rem;
    letter-spacing: -0.008em;
}
.faq-answer {
    color: var(--ki-muted);
    margin-bottom: 0;
}

/* ─── Footer ────────────────────────────────────────────────────────── */

.footer {
    background-color: var(--ki-paper-soft);
    border-top: 1px solid var(--ki-border-soft);
    padding: 3.5rem 0 2.5rem;
    margin-top: 0;
    color: var(--ki-muted);
}
.footer h6 {
    color: var(--ki-ink);
    font-size: 0.92rem;
    font-weight: 600;
    margin-bottom: 1rem;
    letter-spacing: 0.01em;
}
.footer a {
    color: var(--ki-muted);
    transition: color 0.15s;
    font-size: 0.95rem;
}
.footer a:hover {
    color: var(--ki-ink);
    text-decoration: none;
}
.footer hr {
    border-color: var(--ki-border-soft);
    opacity: 1;
    margin: 2rem 0 1.5rem;
}

/* ─── Reduced motion ────────────────────────────────────────────────── */

@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after {
        animation-duration: 0s !important;
        transition-duration: 0s !important;
    }
}