:root {
    --bg-primary: #ffffff;
    --bg-secondary: #f8f9fa;
    --bg-card: #ffffff;
    --text-primary: #1a1a1a;
    --text-secondary: #666666;
    --text-tertiary: #999999;
    --border-color: #e5e5e5;
    --accent-color: #007aff;
    --accent-hover: #0051d5;
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.08);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.12);
    --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.16);
}

[data-theme="dark"] {
    --bg-primary: #000000;
    --bg-secondary: #1a1a1a;
    --bg-card: #1a1a1a;
    --text-primary: #ffffff;
    --text-secondary: #b0b0b0;
    --text-tertiary: #666666;
    --border-color: #333333;
    --accent-color: #0a84ff;
    --accent-hover: #409cff;
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.5);
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    transition: background-color 0.3s ease, color 0.3s ease;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
}

/* Navigation */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background-color: var(--bg-primary);
    border-bottom: 1px solid var(--border-color);
    z-index: 1000;
    backdrop-filter: blur(10px);
    background-color: rgba(255, 255, 255, 0.8);
}

[data-theme="dark"] .navbar {
    background-color: rgba(0, 0, 0, 0.8);
}

.nav-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 64px;
}

.logo {
    display: flex;
    align-items: center;
    gap: 12px;
}

.logo-img {
    height: 36px;
    width: 36px;
    object-fit: contain;
}

.logo-text {
    font-size: 20px;
    font-weight: 600;
    color: var(--text-primary);
}

.nav-controls {
    display: flex;
    align-items: center;
    gap: 8px;
}

.nav-link {
    background: none;
    border: none;
    color: var(--text-secondary);
    font-size: 15px;
    padding: 8px 16px;
    cursor: pointer;
    transition: color 0.2s ease;
    border-radius: 8px;
}

.nav-link:hover {
    color: var(--text-primary);
    background-color: var(--bg-secondary);
}

.lang-toggle {
    background: none;
    border: 1px solid var(--border-color);
    color: var(--text-primary);
    font-size: 14px;
    font-weight: 500;
    padding: 8px 12px;
    cursor: pointer;
    border-radius: 8px;
    transition: all 0.2s ease;
    height: 36px;
    min-width: 60px;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 6px;
}

.lang-toggle:hover {
    background-color: var(--bg-secondary);
}

.lang-icon {
    display: none;
}

.theme-toggle {
    background: none;
    border: 1px solid var(--border-color);
    color: var(--text-primary);
    padding: 8px;
    cursor: pointer;
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.2s ease;
    height: 36px;
    width: 36px;
}

.theme-toggle:hover {
    background-color: var(--bg-secondary);
}

.sun-icon {
    display: none;
}

.moon-icon {
    display: block;
}

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

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

/* Hero Section */
.hero {
    padding: 120px 0 80px;
    background: linear-gradient(180deg, var(--bg-secondary) 0%, var(--bg-primary) 100%);
}

.hero-content {
    text-align: center;
    max-width: 800px;
    margin: 0 auto 60px;
}

.hero-title {
    font-size: 48px;
    font-weight: 700;
    margin-bottom: 20px;
    line-height: 1.2;
}

.hero-subtitle {
    font-size: 20px;
    color: var(--text-secondary);
    margin-bottom: 40px;
    line-height: 1.6;
}

.hero-buttons {
    display: flex;
    gap: 16px;
    justify-content: center;
    flex-wrap: wrap;
}

.btn {
    padding: 14px 32px;
    font-size: 16px;
    font-weight: 500;
    border-radius: 12px;
    text-decoration: none;
    transition: all 0.2s ease;
    display: inline-block;
}

.btn-primary {
    background-color: var(--accent-color);
    color: white;
    border: none;
}

.btn-primary:hover {
    background-color: var(--accent-hover);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.btn-secondary {
    background-color: transparent;
    color: var(--text-primary);
    border: 1px solid var(--border-color);
}

.btn-secondary:hover {
    background-color: var(--bg-secondary);
}

/* Carousel - Desktop (4 items) */
.hero-carousel-desktop {
    display: block;
}

.hero-carousel-mobile {
    display: none;
}

.hero-carousel {
    position: relative;
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 60px;
}

.carousel-container {
    overflow: hidden;
    border-radius: 0;
}

.hero-carousel-desktop .carousel-track {
    display: flex;
    gap: 16px;
    transition: transform 0.4s ease;
}

.hero-carousel-desktop .carousel-item {
    flex: 0 0 calc(25% - 12px);
    width: calc(25% - 12px);
    height: auto;
    border-radius: 12px;
    box-shadow: var(--shadow-md);
    transition: all 0.3s ease;
}

.hero-carousel-mobile .carousel-track {
    display: flex;
    gap: 0;
    transition: transform 0.4s ease;
}

.hero-carousel-mobile .carousel-item {
    flex: 0 0 100%;
    width: 100%;
    height: auto;
    border-radius: 12px;
    box-shadow: var(--shadow-md);
}

.carousel-item:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.carousel-btn {
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    background-color: rgba(255, 255, 255, 0.9);
    border: none;
    width: 48px;
    height: 48px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all 0.2s ease;
    z-index: 10;
    box-shadow: var(--shadow-md);
}

[data-theme="dark"] .carousel-btn {
    background-color: rgba(26, 26, 26, 0.9);
}

.carousel-btn:hover {
    background-color: rgba(255, 255, 255, 1);
    transform: translateY(-50%) scale(1.1);
}

[data-theme="dark"] .carousel-btn:hover {
    background-color: rgba(26, 26, 26, 1);
}

.carousel-btn svg {
    color: var(--text-primary);
}

.carousel-prev {
    left: -24px;
}

.carousel-next {
    right: -24px;
}

/* Features Section */
.features {
    padding: 80px 0;
}

.section-title {
    font-size: 36px;
    font-weight: 700;
    text-align: center;
    margin-bottom: 60px;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 32px;
}

.feature-card {
    background-color: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    padding: 32px;
    transition: all 0.3s ease;
}

.feature-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-md);
}

.feature-icon {
    font-size: 48px;
    margin-bottom: 16px;
}

.feature-title {
    font-size: 20px;
    font-weight: 600;
    margin-bottom: 12px;
}

.feature-desc {
    font-size: 15px;
    color: var(--text-secondary);
    line-height: 1.6;
}

/* Guide Section */
.guide {
    padding: 80px 0;
}

.guide-content {
    max-width: 800px;
    margin: 0 auto;
}

.guide-step {
    display: flex;
    gap: 24px;
    margin-bottom: 40px;
}

.step-number {
    flex-shrink: 0;
    width: 48px;
    height: 48px;
    background-color: var(--accent-color);
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 20px;
    font-weight: 600;
}

.step-content {
    flex: 1;
}

.step-title {
    font-size: 22px;
    font-weight: 600;
    margin-bottom: 8px;
}

.step-desc {
    font-size: 16px;
    color: var(--text-secondary);
    line-height: 1.6;
}

/* Privacy Section */
.privacy {
    padding: 80px 0;
    background-color: var(--bg-secondary);
}

.privacy-content {
    max-width: 900px;
    margin: 0 auto;
}

.privacy-block {
    background-color: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 32px;
    margin-bottom: 24px;
}

.privacy-block h3 {
    font-size: 20px;
    font-weight: 600;
    margin-bottom: 12px;
}

.privacy-block p {
    font-size: 16px;
    color: var(--text-secondary);
    line-height: 1.6;
}

/* Footer */
.footer {
    padding: 40px 0;
    border-top: 1px solid var(--border-color);
}

.footer-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 16px;
}

.footer-logo {
    display: flex;
    align-items: center;
    gap: 12px;
}

.footer-logo-img {
    height: 32px;
    width: 32px;
    object-fit: contain;
}

.footer-logo-text {
    font-size: 18px;
    font-weight: 600;
    color: var(--text-primary);
}

.footer-text {
    font-size: 14px;
    color: var(--text-tertiary);
}

/* Responsive */
@media (max-width: 768px) {
    .container {
        padding: 0 16px;
    }

    .nav-content {
        height: 56px;
    }

    .logo-img {
        height: 28px;
        width: 28px;
    }

    .logo-text {
        font-size: 16px;
    }

    .nav-controls {
        gap: 4px;
    }

    .nav-link {
        display: none;
    }

    .lang-toggle {
        padding: 8px;
        min-width: 36px;
        width: 36px;
    }

    .lang-text {
        display: none;
    }

    .lang-icon {
        display: block;
    }

    .theme-toggle {
        padding: 8px;
        width: 36px;
    }

    .theme-toggle svg {
        width: 20px;
        height: 20px;
    }

    .hero {
        padding: 80px 0 60px;
    }

    /* Hide desktop carousel, show mobile carousel */
    .hero-carousel-desktop {
        display: none;
    }

    .hero-carousel-mobile {
        display: block;
    }

    .hero-carousel {
        padding: 0 48px;
    }

    .carousel-container {
        border-radius: 16px;
    }

    .hero-content {
        margin-bottom: 40px;
    }

    .hero-title {
        font-size: 32px;
    }

    .hero-subtitle {
        font-size: 16px;
    }

    .btn {
        padding: 12px 24px;
        font-size: 15px;
    }

    /* Mobile: 1 item per view */
    .carousel-btn {
        width: 40px;
        height: 40px;
    }

    .carousel-btn svg {
        width: 20px;
        height: 20px;
    }

    .carousel-prev {
        left: 8px;
    }

    .carousel-next {
        right: 8px;
    }

    .section-title {
        font-size: 28px;
        margin-bottom: 40px;
    }

    .features {
        padding: 60px 0;
    }

    .features-grid {
        grid-template-columns: 1fr;
        gap: 20px;
    }

    .feature-card {
        padding: 24px;
    }

    .feature-icon {
        font-size: 40px;
    }

    .feature-title {
        font-size: 18px;
    }

    .feature-desc {
        font-size: 14px;
    }

    .screenshots {
        padding: 60px 0;
    }

    /* Mobile: 1 item per view */
    .screenshots-carousel .carousel-container {
        overflow: hidden;
        border-radius: 16px;
    }

    .screenshots-carousel .carousel-track {
        gap: 0;
    }

    .screenshots-carousel .carousel-item {
        min-width: 100%;
        border-radius: 0;
    }

    .screenshots {
        padding: 60px 0;
    }

    /* Mobile: 1 item per view */
    .screenshots-carousel .carousel-container {
        overflow: hidden;
        border-radius: 16px;
    }

    .screenshots-carousel .carousel-track {
        gap: 0;
    }

    .screenshots-carousel .carousel-item {
        min-width: 100%;
        border-radius: 0;
    }

    .guide {
        padding: 60px 0;
    }

    .guide-step {
        flex-direction: column;
        gap: 16px;
        margin-bottom: 32px;
    }

    .step-number {
        width: 40px;
        height: 40px;
        font-size: 18px;
    }

    .step-title {
        font-size: 20px;
    }

    .step-desc {
        font-size: 15px;
    }

    .privacy {
        padding: 60px 0;
    }

    .privacy-block {
        padding: 24px;
        margin-bottom: 16px;
    }

    .privacy-block h3 {
        font-size: 18px;
    }

    .privacy-block p {
        font-size: 15px;
    }

    .footer {
        padding: 32px 0;
    }

    .footer-logo-img {
        height: 28px;
        width: 28px;
    }

    .footer-logo-text {
        font-size: 16px;
    }

    .footer-text {
        font-size: 13px;
    }
}

@media (max-width: 480px) {
    .hero-title {
        font-size: 28px;
    }

    .hero-subtitle {
        font-size: 15px;
    }

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

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

    .hero-carousel {
        padding: 0 40px;
    }

    .nav-link span {
        display: none;
    }

    .nav-link::after {
        content: attr(data-section);
        font-size: 11px;
        text-transform: capitalize;
    }

    .nav-link[data-section="features"]::after {
        content: "•••";
    }

    .nav-link[data-section="guide"]::after {
        content: "?";
    }

    .nav-link[data-section="privacy"]::after {
        content: "🔒";
    }

    .carousel-prev {
        left: 4px;
    }

    .carousel-next {
        right: 4px;
    }

    .carousel-btn {
        width: 36px;
        height: 36px;
        background-color: rgba(255, 255, 255, 0.8);
    }

    [data-theme="dark"] .carousel-btn {
        background-color: rgba(26, 26, 26, 0.8);
    }
}

/* Smooth Scroll */
html {
    scroll-behavior: smooth;
}

/* Selection */
::selection {
    background-color: var(--accent-color);
    color: white;
}