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

:root {
    --primary: #2563eb;
    --primary-dark: #1e40af;
    --primary-light: #60a5fa;
    --gray-50: #f9fafb;
    --gray-100: #f3f4f6;
    --gray-200: #e5e7eb;
    --gray-800: #1f2937;
    --gray-900: #111827;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, .05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, .1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, .1);
    --radius-lg: 1rem;
    --radius-md: .75rem;
    --radius-sm: .5rem
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    background: linear-gradient(145deg, #fff 0%, var(--gray-50) 100%);
    color: var(--gray-800);
    line-height: 1.5;
    scroll-behavior: smooth
}

.container {
    width: 100%;
    max-width: 1280px;
    margin: 0 auto;
    padding: 0 1.5rem
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: .5rem;
    padding: .75rem 1.5rem;
    font-size: 1rem;
    font-weight: 600;
    line-height: 1.2;
    text-decoration: none;
    border-radius: var(--radius-md);
    transition: all .2s ease;
    cursor: pointer;
    border: none;
    background: transparent;
    min-height: 48px;
    white-space: nowrap
}

.btn-primary {
    background: var(--primary);
    color: #fff;
    box-shadow: var(--shadow-sm)
}

.btn-primary:hover,
.btn-primary:active {
    background: var(--primary-dark);
    transform: translateY(-1px);
    box-shadow: var(--shadow-md)
}

.btn-outline {
    border: 1.5px solid var(--gray-200);
    background: #fff;
    color: var(--gray-800)
}

.btn-outline:active {
    background: var(--gray-100)
}

@media (max-width:640px) {
    .btn {
        width: 100%;
        white-space: normal;
        padding: .75rem 1rem
    }

    .btn-group {
        flex-direction: column;
        gap: 1.5rem
    }

    .btn-group>div {
        width: 100%
    }
}

.card {
    background: #fff;
    border-radius: var(--radius-lg);
    padding: 1.5rem;
    box-shadow: var(--shadow-sm);
    transition: box-shadow .2s
}

.card:hover {
    box-shadow: var(--shadow-md)
}

.grid {
    display: grid;
    gap: 2rem;
    grid-template-columns: 1fr
}

@media (min-width:768px) {
    .grid-2 {
        grid-template-columns: repeat(2, 1fr)
    }

    .grid-3 {
        grid-template-columns: repeat(3, 1fr)
    }
}

.pain-point {
    background: rgba(239, 68, 68, .1);
    border-left: 4px solid #ef4444;
    padding: 1rem;
    border-radius: var(--radius-sm);
    margin-bottom: 0
}

.solution-point {
    background: rgba(16, 185, 129, .1);
    border-left: 4px solid #10b981
}

.navbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    padding: 1rem 0;
    position: relative
}

.nav-links {
    display: none;
    width: 100%;
    flex-direction: column;
    gap: 1rem;
    margin-top: 1rem;
    background: #fff;
    border-radius: var(--radius-md);
    padding: 1.5rem;
    box-shadow: var(--shadow-lg);
    transition: all .3s ease
}

.nav-links a {
    text-decoration: none;
    color: var(--gray-800);
    font-weight: 500;
    padding: .5rem 0;
    transition: color .2s
}

.menu-toggle {
    background: 0 0;
    border: none;
    font-size: 1.8rem;
    cursor: pointer;
    min-height: 48px;
    min-width: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 20
}

@media (min-width:768px) {
    .menu-toggle {
        display: none
    }

    .nav-links {
        display: flex !important;
        flex-direction: row;
        width: auto;
        background: transparent;
        box-shadow: none;
        padding: 0;
        margin: 0;
        gap: 2rem
    }

    .navbar {
        flex-wrap: nowrap
    }
}

section {
    padding: 1rem 0
}

h1 {
    font-size: 2.5rem;
    font-weight: 800;
    line-height: 1.2;
    letter-spacing: -.02em
}

h2 {
    font-size: 1.875rem;
    font-weight: 700;
    margin-bottom: 1.5rem
}

h3 {
    font-weight: 600;
    font-size: 1.25rem
}

@media (min-width:768px) {
    h1 {
        font-size: 3.5rem
    }

    h2 {
        font-size: 2.25rem
    }
}

.hero {
    text-align: center
}

.hero p {
    font-size: 1.125rem;
    color: #4b5563;
    margin: 1.5rem 0
}

.badge {
    display: inline-block;
    background: #e0e7ff;
    color: var(--primary-dark);
    border-radius: 9999px;
    padding: .25rem .75rem;
    font-size: .875rem;
    font-weight: 500
}

.download-card {
    text-align: center
}

#download {
    padding-top: 25px;
    padding-bottom: 25px;
}

footer {
    background: var(--gray-900);
    color: #9ca3af;
    text-align: center;
    padding: 2rem 0;
    font-size: .875rem
}

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

.carousel-container {
    position: relative;
    width: 100%;
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-lg);
    background-color: #f5f7fa
}

.carousel-container::before {
    content: "";
    display: block;
    padding-bottom: 56.25%
}

.carousel-slides {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    display: flex;
    transition: transform .5s ease-in-out
}

.carousel-slide {
    flex: 0 0 100%;
    width: 100%;
    height: 100%
}

.carousel-slide img {
    width: 100%;
    height: 100%;
    object-fit: contain;
    display: block
}

.carousel-dots {
    display: flex;
    justify-content: center;
    gap: .5rem;
    margin-top: 1rem
}

.dot {
    width: 8px;
    height: 8px;
    background-color: var(--gray-300);
    border-radius: 50%;
    cursor: pointer;
    transition: all .3s
}

.dot.active {
    background-color: var(--primary);
    width: 20px;
    border-radius: 4px
}

.carousel-btn {
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    background: rgba(0, 0, 0, .5);
    color: #fff;
    border: none;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    font-size: 1.2rem;
    transition: background .2s;
    z-index: 2
}

.btn-android {
    background: #3DDC84;
    color: #fff;
    border: none
}

.btn-mac {
    background: #f5f5f7;
    color: #1d1d1f;
    border: 1px solid #d2d2d6;
    box-shadow: 0 1px 1px rgba(0, 0, 0, .02)
}

.btn-android:hover {
    background: #34a853;
    transform: translateY(-1px)
}

.carousel-btn:hover {
    background: rgba(0, 0, 0, .7)
}

.btn-prev {
    left: 16px
}

.btn-next {
    right: 16px
}

@media (max-width:640px) {
    .carousel-btn {
        width: 32px;
        height: 32px;
        font-size: .9rem
    }
}

.btn-group {
    display: flex;
    gap: 1rem;
    justify-content: center;
    margin-top: 2rem;
    flex-wrap: wrap
}

.btn-group>div {
    flex: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: .5rem;
    min-width: 180px
}

.btn-group>div .btn {
    width: 70%
}

.btn-group>div small {
    font-size: .75rem;
    color: #6b7280;
    text-align: center;
    display: block;
    line-height: 1.4
}

.logo {
    display: flex;
    align-items: center;
    gap: .5rem;
    font-size: 1.3rem;
    font-weight: 500;
    background: linear-gradient(135deg, var(--primary), #1e3a8a);
    -webkit-background-clip: text;
    background-clip: text;
    color: #4684ff;
    letter-spacing: -.02em
}

.logo img {
    height: 2rem;
    width: auto;
    display: block
}

.wechat-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, .85);
    z-index: 9999;
    display: flex;
    align-items: center;
    justify-content: center;
    backdrop-filter: blur(4px);
    animation: fadeIn .3s ease
}

.wechat-guide {
    background: #fff;
    border-radius: 24px;
    max-width: 280px;
    width: 80%;
    padding: 2rem 1.5rem;
    text-align: center;
    box-shadow: 0 20px 35px rgba(0, 0, 0, .3);
    animation: scaleIn .3s ease
}

.wechat-guide i {
    font-size: 3rem;
    color: #07c160;
    margin-bottom: 1rem
}

.wechat-guide h3 {
    font-size: 1.3rem;
    margin-bottom: .75rem;
    color: #1f2937
}

.wechat-guide p {
    color: #6b7280;
    font-size: .9rem;
    line-height: 1.4;
    margin-bottom: 1.5rem
}

.wechat-guide button {
    background: #07c160;
    color: #fff;
    border: none;
    padding: .6rem 1.5rem;
    border-radius: 40px;
    font-weight: 600;
    cursor: pointer;
    font-size: .9rem
}

@keyframes fadeIn {
    0% {
        opacity: 0
    }

    to {
        opacity: 1
    }
}

@keyframes scaleIn {
    0% {
        transform: scale(.9);
        opacity: 0
    }

    to {
        transform: scale(1);
        opacity: 1
    }
}

#langSelect {
    padding: .3rem .8rem;
    border-radius: 20px;
    border: 1px solid var(--gray-200);
    background: #fff;
    font-size: .9rem;
    cursor: pointer;
    outline: 0
}

.lang-item {
    display: flex;
    align-items: center
}

@media (max-width:767px) {
    .nav-links .lang-item {
        margin-top: .5rem
    }
}

/* ----- 新增：header 固定悬浮（高度 72px） ----- */
header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 1000;
    background: #fff;
    box-shadow: 0 2px 8px rgba(0, 0, 0, .08);
    transition: box-shadow .3s;
    height: 72px
}

body {
    padding-top: 72px
}

section {
    scroll-margin-top: 72px
}

/* ----- 回到顶部按钮 ----- */
.back-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 48px;
    height: 48px;
    border-radius: 50%;
    background: var(--primary);
    color: #fff;
    border: none;
    font-size: 1.2rem;
    cursor: pointer;
    box-shadow: var(--shadow-md);
    transition: opacity 0.3s, transform 0.3s;
    opacity: 0;
    transform: translateY(20px);
    pointer-events: none;
    z-index: 999;
}

.back-to-top.visible {
    opacity: 1;
    transform: translateY(0);
    pointer-events: auto;
}

.back-to-top:hover {
    background: var(--primary-dark);
    transform: scale(1.05);
}