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

:root {
    --blue-50: #E3F2FD;
    --blue-100: #BBDEFB;
    --blue-200: #90CAF9;
    --blue-300: #64B5F6;
    --blue-400: #42A5F5;
    --blue-500: #4A9EFF;
    --blue-600: #1E88E5;
    --blue-700: #1976D2;
    --blue-800: #1565C0;
    --accent: #4A9EFF;
    --accent-hover: #2196F3;
    --text-primary: #1a2332;
    --text-secondary: #4a5a6e;
    --text-muted: #8a9bb0;
    --card-bg: rgba(255, 255, 255, 0.78);
    --card-border: rgba(255, 255, 255, 0.95);
    --radius: 6px;
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.04);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.08);
    --max-width: 1080px;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Noto Sans SC', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    background: #0b1422;
    background-image: url('https://gwebcdn260523.pages.dev/v1/static/KivotosBg2.jpg');
    background-size: cover;
    background-position: center;
    background-attachment: fixed;
    background-repeat: no-repeat;
    color: var(--text-primary);
    min-height: 100vh;
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
}

/* ========== Scrollbar ========== */
::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: rgba(74, 158, 255, 0.3); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: rgba(74, 158, 255, 0.5); }

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

/* ========== Navbar ========== */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 100;
    background: rgba(255, 255, 255, 0.55);
    backdrop-filter: none;
    border-bottom: 1px solid rgba(255, 255, 255, 0.7);
    transition: background 0.3s ease;
}

.navbar .container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 60px;
}

.navbar-brand {
    display: flex;
    align-items: center;
    gap: 10px;
    text-decoration: none;
    color: var(--text-primary);
    font-weight: 600;
    font-size: 1.05rem;
    letter-spacing: -0.2px;
}

.navbar-links {
    display: flex;
    align-items: center;
    gap: 8px;
    list-style: none;
}

.navbar-links a {
    text-decoration: none;
    color: var(--text-secondary);
    font-size: 0.9rem;
    font-weight: 500;
    padding: 6px 14px;
    border-radius: var(--radius);
    transition: all 0.2s ease;
}

.navbar-links a:hover {
    background: rgba(74, 158, 255, 0.1);
    color: var(--accent);
}

/* nav-cta removed — unified with navbar-links a */

.mobile-toggle {
    display: none;
    flex-direction: column;
    gap: 4px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 4px;
}

.mobile-toggle span {
    display: block;
    width: 22px;
    height: 2px;
    background: var(--text-primary);
    border-radius: 2px;
    transition: 0.3s;
}

/* ========== Hero ========== */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 100px 0 80px;
    position: relative;
}

.hero-content {
    text-align: center;
    max-width: 780px;
}

/* Light blue badge */
.hero-badge {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 4px 16px;
    background: rgba(144, 202, 249, 0.18);
    color: white;
    border: 1px solid rgba(255, 255, 255, 0.4);
    border-radius: 20px;
    font-size: 0.8rem;
    font-weight: 500;
    margin-bottom: 24px;
    letter-spacing: 0.3px;
    text-shadow: 0 1px 6px rgba(0,0,0,0.25);
}

.hero-title {
    font-size: clamp(2.5rem, 6vw, 4rem);
    font-weight: 700;
    line-height: 1.15;
    color: var(--text-primary);
    margin-bottom: 16px;
    letter-spacing: -0.5px;
}

/* White Sensei highlight */
.hero-title .highlight {
    color: white;
    text-shadow: 0 1px 6px rgba(0,0,0,0.25);
    background: none;
    -webkit-text-fill-color: initial;
    background-clip: initial;
}

.hero-subtitle {
    font-size: clamp(1.05rem, 2vw, 1.25rem);
    color: var(--text-secondary);
    font-weight: 400;
    margin-bottom: 36px;
    line-height: 1.7;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.hero-actions {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    justify-content: center;
    gap: 12px;
}

/* ========== Buttons ========== */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 12px 28px;
    border-radius: var(--radius);
    font-size: 0.95rem;
    font-weight: 600;
    text-decoration: none;
    border: none;
    cursor: pointer;
    transition: all 0.25s ease;
    font-family: inherit;
}

.btn-primary {
    background: var(--accent);
    color: white;
    box-shadow: 0 4px 14px rgba(74, 158, 255, 0.35);
}

.btn-primary:hover {
    background: var(--accent-hover);
    box-shadow: 0 6px 20px rgba(74, 158, 255, 0.45);
    transform: translateY(-1px);
}

.btn-secondary {
    background: rgba(255, 255, 255, 0.7);
    color: var(--text-primary);
    border: 1px solid rgba(255, 255, 255, 0.9);
}

.btn-secondary:hover {
    background: rgba(255, 255, 255, 0.9);
    transform: translateY(-1px);
}

.btn-outline {
    background: transparent;
    color: var(--text-secondary);
    border: 1px solid rgba(255, 255, 255, 0.5);
    backdrop-filter: none;
}

.btn-outline:hover {
    background: rgba(255, 255, 255, 0.5);
    color: var(--text-primary);
}

/* "下载历史版本" — more transparent */
#dlHistoryBtn {
    background: rgba(255, 255, 255, 0.15);
    border-color: rgba(255, 255, 255, 0.25);
    color: var(--text-muted);
}

#dlHistoryBtn:hover {
    background: rgba(255, 255, 255, 0.3);
    color: var(--text-secondary);
}

/* ========== Hero Stats ========== */
.hero-stats {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 32px;
    margin-top: 48px;
    padding: 20px 32px;
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: var(--radius);
    backdrop-filter: none;
}

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

.stat-number {
    font-size: 1.4rem;
    font-weight: 700;
    color: var(--accent);
}

.stat-label {
    font-size: 0.78rem;
    color: var(--text-muted);
    font-weight: 400;
}

/* ========== Section ========== */
.section {
    padding: 80px 0;
}

.section-header {
    text-align: center;
    margin-bottom: 56px;
}

/* White section tags */
.section-tag {
    display: inline-block;
    padding: 3px 14px;
    background: rgba(255, 255, 255, 0.15);
    color: white;
    text-shadow: 0 1px 6px rgba(0,0,0,0.25);
    border-radius: 20px;
    font-size: 0.78rem;
    font-weight: 600;
    letter-spacing: 0.5px;
    margin-bottom: 12px;
    text-transform: uppercase;
}

.section-title {
    font-size: clamp(1.8rem, 3.5vw, 2.4rem);
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 12px;
    letter-spacing: -0.3px;
}

.section-desc {
    font-size: 1rem;
    color: var(--text-secondary);
    max-width: 540px;
    margin: 0 auto;
    line-height: 1.7;
}

/* ========== Features ========== */
.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 20px;
}

.feature-card {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: var(--radius);
    padding: 32px 28px;
    backdrop-filter: none;
    transition: all 0.3s ease;
}

.feature-card:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-lg);
    border-color: rgba(74, 158, 255, 0.2);
}

/* feature-icon removed — emojis no longer used */

.feature-card h3 {
    font-size: 1.05rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 8px;
}

.feature-card p {
    font-size: 0.88rem;
    color: var(--text-secondary);
    line-height: 1.65;
}

/* ========== Quick Start ========== */
.start-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 20px;
}

.start-card {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: var(--radius);
    padding: 28px;
    backdrop-filter: none;
    transition: all 0.3s ease;
}

.start-card:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-lg);
    border-color: rgba(74, 158, 255, 0.2);
}

.start-card .step-number {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 28px;
    height: 28px;
    background: var(--accent);
    color: white;
    border-radius: var(--radius);
    font-size: 0.8rem;
    font-weight: 700;
    margin-bottom: 14px;
}

.start-card h3 {
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 8px;
}

.start-card p {
    font-size: 0.88rem;
    color: var(--text-secondary);
    line-height: 1.6;
    margin-bottom: 12px;
}

.code-block {
    background: rgba(10, 20, 40, 0.06);
    border-radius: var(--radius);
    padding: 10px 14px;
    font-family: 'SF Mono', 'Fira Code', 'Consolas', monospace;
    font-size: 0.82rem;
    color: var(--text-primary);
    overflow-x: auto;
    white-space: nowrap;
    border: 1px solid rgba(0, 0, 0, 0.04);
}

.code-block .comment {
    color: var(--text-muted);
}

.code-block .cmd {
    color: var(--blue-600);
}

.start-links {
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
    margin-top: 28px;
}

.start-links .btn {
    font-size: 0.85rem;
    padding: 10px 20px;
}

/* ========== About Grid ========== */
.about-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 20px;
}

.about-grid .feature-card {
    transition: all 0.3s ease;
}

.about-grid .feature-card:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-lg);
    border-color: rgba(74, 158, 255, 0.2);
}

/* ========== Footer ========== */
.footer {
    background: rgba(255, 255, 255, 0.5);
    border-top: 1px solid rgba(255, 255, 255, 0.7);
    padding: 48px 0 32px;
}

.footer-grid {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr;
    gap: 40px;
    margin-bottom: 40px;
}

.footer-brand h3 {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 8px;
}

.footer-brand p {
    font-size: 0.85rem;
    color: var(--text-secondary);
    line-height: 1.6;
    max-width: 320px;
}

.footer-col h4 {
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 12px;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.footer-col a {
    display: block;
    font-size: 0.85rem;
    color: var(--text-secondary);
    text-decoration: none;
    padding: 4px 0;
    transition: color 0.2s;
}

.footer-col a:hover {
    color: var(--accent);
}

.footer-bottom {
    border-top: 1px solid rgba(0, 0, 0, 0.06);
    padding-top: 20px;
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    align-items: center;
    gap: 12px;
}

.footer-bottom p {
    font-size: 0.78rem;
    color: var(--text-muted);
}

.footer-bottom-links {
    display: flex;
    gap: 16px;
}

.footer-bottom-links a {
    font-size: 0.78rem;
    color: var(--text-muted);
    text-decoration: none;
}

.footer-bottom-links a:hover {
    color: var(--accent);
}

/* ========== Animations ========== */
@keyframes fadeUp {
    from { opacity: 0; transform: translateY(20px); }
    to   { opacity: 1; transform: translateY(0); }
}

.animate-in {
    animation: fadeUp 0.6s ease-out forwards;
    opacity: 0;
}

.animate-in:nth-child(2) { animation-delay: 0.1s; }
.animate-in:nth-child(3) { animation-delay: 0.2s; }
.animate-in:nth-child(4) { animation-delay: 0.3s; }

/* Intersection Observer fade-in */
.fade-in {
    opacity: 0;
    transform: translateY(24px);
    transition: opacity 0.6s ease-out, transform 0.6s ease-out;
}

.fade-in.visible {
    opacity: 1;
    transform: translateY(0);
}

/* ========== Responsive ========== */
@media (max-width: 768px) {
    .mobile-toggle {
        display: flex;
    }

    .navbar-links {
        display: none;
        position: absolute;
        top: 60px;
        left: 0;
        right: 0;
        background: rgba(255, 255, 255, 0.92);
        border-bottom: 1px solid rgba(0, 0, 0, 0.06);
        flex-direction: column;
        padding: 12px 24px;
        gap: 4px;
        backdrop-filter: none;
    }

    .navbar-links.open {
        display: flex;
    }

    .navbar-links a {
        padding: 10px 14px;
        width: 100%;
    }

    .hero-stats {
        gap: 20px;
        padding: 16px 20px;
    }

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

    .footer-bottom {
        flex-direction: column;
        text-align: center;
    }
}

@media (max-width: 480px) {
    .hero {
        padding: 80px 0 60px;
    }

    .hero-actions {
        flex-direction: column;
        width: 100%;
    }

    .hero-actions .btn {
        width: 100%;
    }

    .section {
        padding: 56px 0;
    }

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

    .start-grid {
        grid-template-columns: 1fr;
    }

    .about-grid {
        grid-template-columns: 1fr;
    }
}

.start-card {
    transition: transform 0.25s ease, box-shadow 0.25s ease, border-color 0.25s ease;
}

.start-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
    border-color: rgba(74, 158, 255, 0.3);
}

.hero-stats {
    transition: transform 0.25s ease, box-shadow 0.25s ease, background 0.25s ease;
}

.hero-stats:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
    background: rgba(255, 255, 255, 0.9);
    border-color: rgba(74, 158, 255, 0.3);
}

.feature-card {
    transition: all 0.3s ease;
}

.feature-card:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-lg);
    border-color: rgba(74, 158, 255, 0.2);
}