:root {
    --primary-color: #007aff;
    --primary-dark: #005ecb;
    --secondary-color: #f2f2f7;
    --text-dark: #1c1c1e;
    --text-light: #636366;
    --background-light: #ffffff;
    --gradient-start: #4f9cff;
    --gradient-end: #7b5cff;
    --nav-height: 70px;
}
html { scroll-behavior: smooth; }

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", "PingFang SC", "Microsoft YaHei", Arial, sans-serif;
    line-height: 1.7;
    margin: 0;
    padding-top: var(--nav-height);
    background-color: var(--secondary-color);
    color: var(--text-dark);
    overflow-x: hidden;
}

.container { max-width: 1100px; margin: auto; padding: 0 20px; }

/* 滚动动画 */
.fade-in-up {
    opacity: 0;
    transform: translateY(40px);
    transition: opacity 0.8s ease-out, transform 0.8s ease-out;
}
.fade-in-up.visible {
    opacity: 1;
    transform: translateY(0);
}
.fade-in-left {
    opacity: 0;
    transform: translateX(-40px);
    transition: opacity 0.8s ease-out, transform 0.8s ease-out;
}
.fade-in-left.visible {
    opacity: 1;
    transform: translateX(0);
}
.fade-in-right {
    opacity: 0;
    transform: translateX(40px);
    transition: opacity 0.8s ease-out, transform 0.8s ease-out;
}
.fade-in-right.visible {
    opacity: 1;
    transform: translateX(0);
}

/* Navigation Bar */
.navbar {
    display: flex;
    justify-content: center;
    align-items: center;
    height: var(--nav-height);
    padding: 0;
    position: fixed;
    top: 0; left: 0; right: 0;
    background: rgba(255, 255, 255, 0.85);
    backdrop-filter: saturate(180%) blur(20px);
    -webkit-backdrop-filter: saturate(180%) blur(20px);
    border-bottom: 1px solid rgba(0,0,0,0.07);
    z-index: 1000;
    transition: all 0.3s ease;
}
.navbar.scrolled {
    background: rgba(255, 255, 255, 0.98);
    box-shadow: 0 4px 20px rgba(0,0,0,0.1);
}
.navbar .container { display: flex; justify-content: space-between; align-items: center; width: 100%; }

.nav-logo { display: flex; align-items: center; gap: 12px; text-decoration: none; color: var(--text-dark); transition: transform 0.3s ease; }
.nav-logo:hover { transform: scale(1.05); }
.nav-logo svg { width: 40px; height: 40px; }
.nav-logo span { font-size: 1.5em; font-weight: 600; }

.nav-links { display: flex; align-items: center; gap: 24px; }
.nav-links a:not(.btn-invert) { text-decoration: none; color: var(--text-light); font-weight: 500; transition: color 0.3s, transform 0.2s; position: relative; }
.nav-links a:not(.btn-invert):hover { color: var(--primary-color); transform: translateY(-2px); }
.nav-links a:not(.btn-invert)::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--primary-color);
    transition: width 0.3s ease;
}
.nav-links a:not(.btn-invert):hover::after { width: 100%; }

/* 语言切换 */
.lang-switch { display: flex; align-items: center; gap: 4px; background: rgba(0,0,0,0.05); border-radius: 20px; padding: 4px; }
.lang-btn { 
    padding: 6px 12px; 
    font-size: 0.85em; 
    border-radius: 16px; 
    background: transparent; 
    color: var(--text-light); 
    text-decoration: none; 
    font-weight: 500; 
    border: none; 
    cursor: pointer; 
    transition: all 0.2s ease;
}
.lang-btn:hover { background: rgba(0,0,0,0.08); color: var(--text-dark); }
.lang-btn.active { background: var(--primary-color); color: #fff; }

/* 通用按钮样式（白底蓝字） */
.btn { display:inline-flex; align-items:center; gap:12px; padding:14px 32px; font-size:1.05em; border-radius:999px; background:#fff; color:var(--primary-color); text-decoration:none; font-weight:600; box-shadow:0 4px 12px rgba(0,0,0,0.08); transition:background .25s, transform .2s, box-shadow .3s; position: relative; overflow: hidden; }
.btn:hover { background:#f0f0f0; transform:translateY(-2px); box-shadow:0 8px 20px rgba(0,0,0,0.1); }
.btn::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 0;
    height: 0;
    border-radius: 50%;
    background: rgba(0, 122, 255, 0.1);
    transform: translate(-50%, -50%);
    transition: width 0.6s ease, height 0.6s ease;
}
.btn:active::before { width: 300px; height: 300px; }
.btn svg { width:20px; height:20px; }

/* 按钮组 */
.btn-group { display: flex; gap: 16px; justify-content: center; flex-wrap: wrap; }
.btn-group .btn { min-width: 160px; }

/* 描边按钮（用于深色背景） */
.btn-outline {
    background: transparent !important;
    color: #fff !important;
    border: 2px solid rgba(255, 255, 255, 0.9);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
}
.btn-outline:hover {
    background: rgba(255, 255, 255, 0.15) !important;
    border-color: #fff;
    transform: translateY(-2px);
    box-shadow: 0 8px 20px rgba(0, 0, 0, 0.2);
}
.btn-outline::before {
    background: rgba(255, 255, 255, 0.2);
}

/* 反色按钮：蓝底白字（导航用） */
.btn-invert { display:inline-flex; align-items:center; gap:8px; padding:8px 20px; font-size:.9em; border-radius:999px; background:var(--primary-color); color:#fff !important; text-decoration:none; font-weight:600; box-shadow:0 4px 12px rgba(0,122,255,0.3); transition:background .25s, transform .2s, box-shadow .3s; position: relative; overflow: hidden; }
.btn-invert:hover { background:var(--primary-dark); transform:translateY(-2px); box-shadow:0 8px 22px rgba(0,94,203,0.45); }
.btn-invert:active { transform:translateY(0); box-shadow:0 4px 10px rgba(0,94,203,0.35); }
.btn-invert svg { width:18px; height:18px; fill:currentColor; }
.btn-invert::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 0;
    height: 0;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.2);
    transform: translate(-50%, -50%);
    transition: width 0.6s ease, height 0.6s ease;
}
.btn-invert:active::before { width: 300px; height: 300px; }

/* Header */
.header { text-align: center; padding: 80px 20px 100px; background: linear-gradient(135deg,#007aff,#0056b3); color: #fff; position: relative; overflow: hidden; }
.header-background { position: absolute; inset: 0; opacity: .1; pointer-events: none; }
.header-content { position: relative; z-index: 2; }
.header h1 { font-size: 3.5em; font-weight: 700; margin: 0 0 15px; background: linear-gradient(135deg, #fff 0%, #e0e7ff 100%); -webkit-background-clip: text; -webkit-text-fill-color: transparent; background-clip: text; animation: gradientShift 3s ease infinite; }
@keyframes gradientShift {
    0%, 100% { filter: brightness(1); }
    50% { filter: brightness(1.2); }
}
.header p { font-size: 1.4em; color: rgba(255,255,255,.85); max-width: 600px; margin: 0 auto 40px; animation: fadeInUp 1s ease-out 0.3s both; }
@keyframes fadeInUp {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}
.header .btn { padding: 18px 40px; font-size: 1.2em; border-radius: 999px; background: #fff; color: #007aff; text-decoration: none; display: inline-flex; align-items: center; gap: 12px; animation: fadeInUp 1s ease-out 0.6s both; }
.header .btn:hover { background: #f0f0f0; }

/* Header 动态背景 */
.header::before {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle, rgba(255,255,255,0.1) 0%, transparent 50%);
    animation: rotate 20s linear infinite;
}
@keyframes rotate {
    from { transform: rotate(0deg); }
    to { transform: rotate(360deg); }
}
.header::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: url("data:image/svg+xml,%3Csvg width='60' height='60' viewBox='0 0 60 60' xmlns='http://www.w3.org/2000/svg'%3E%3Cg fill='none' fill-rule='evenodd'%3E%3Cg fill='%23ffffff' fill-opacity='0.05'%3E%3Cpath d='M36 34v-4h-2v4h-4v2h4v4h2v-4h4v-2h-4zm0-30V0h-2v4h-4v2h4v4h2V6h4V4h-4zM6 34v-4H4v4H0v2h4v4h2v-4h4v-2H6zM6 4V0H4v4H0v2h4v4h2V6h4V4H6z'/%3E%3C/g%3E%3C/g%3E%3C/svg%3E");
    opacity: 0.3;
    animation: patternMove 20s linear infinite;
}
@keyframes patternMove {
    0% { transform: translate(0, 0); }
    100% { transform: translate(-60px, -60px); }
}

/* Section */
.section { padding: 80px 0; }
.section h2 { text-align: center; margin-bottom: 60px; font-size: 2.6em; color: var(--text-dark); font-weight: 600; position: relative; }
.section h2::after {
    content: '';
    display: block;
    width: 60px;
    height: 4px;
    background: linear-gradient(90deg, var(--primary-color), var(--gradient-end));
    margin: 20px auto 0;
    border-radius: 2px;
}

/* Features */
#features { background-color: var(--background-light); }
.features-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: 30px; }
.feature-item { background: #fff; padding: 35px; border: 1px solid #e5e5e5; border-radius: 12px; text-align: center; transition: transform .3s, box-shadow .3s; position: relative; overflow: hidden; }
.feature-item::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(90deg, var(--primary-color), var(--gradient-end));
    transform: scaleX(0);
    transition: transform 0.3s ease;
}
.feature-item:hover { transform: translateY(-6px); box-shadow: 0 12px 35px rgba(0,0,0,.08); }
.feature-item:hover::before { transform: scaleX(1); }
.feature-icon { width: 50px; height: 50px; margin-bottom: 20px; color: var(--primary-color); transition: transform 0.3s ease; }
.feature-item:hover .feature-icon { transform: scale(1.1) rotate(5deg); }
.feature-item h3 { font-size: 1.6em; margin-top: 0; margin-bottom: 10px; color: var(--text-dark); }
.feature-item p { color: var(--text-light); font-size: 1em; }

/* Screenshots */
.screenshots-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 40px; justify-items: center; }
.phone-mockup { background: #1c1c1e; border-radius: 40px; padding: 12px; box-shadow: 0 20px 50px -10px rgba(0,0,0,.3); width: 100%; max-width: 300px; box-sizing: border-box; transition: transform 0.4s ease, box-shadow 0.4s ease; }
.phone-mockup:hover { transform: translateY(-10px) rotateY(5deg); box-shadow: 0 30px 60px -10px rgba(0,0,0,.4); }
.phone-screen { background: #fff; border-radius: 28px; overflow: hidden; aspect-ratio: 9 / 19.5; }
.phone-screen img { width: 100%; height: 100%; object-fit: cover; display: block; }

/* 底部下载区域：平台卡片按钮 */
#download { background: var(--secondary-color); }
.download-section { text-align: center; }
.download-cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 18px; margin-top: 30px; }
.download-card { position: relative; display: flex; align-items: center; gap: 14px; padding: 16px 18px; border-radius: 16px; background: #fff; border: 1px solid #e8e8ef; text-decoration: none; color: var(--text-dark); box-shadow: 0 8px 24px rgba(0,0,0,0.06); transition: transform .2s, box-shadow .3s, border-color .3s; overflow: hidden; }
.download-card::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 0;
    height: 0;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--gradient-start), var(--gradient-end));
    transform: translate(-50%, -50%);
    transition: width 0.6s ease, height 0.6s ease, opacity 0.6s ease;
    opacity: 0;
}
.download-card:active::before { width: 300px; height: 300px; opacity: 0.1; }
.download-card:hover { transform: translateY(-3px); box-shadow: 0 12px 32px rgba(0,0,0,0.08); border-color: var(--primary-color); }
.download-card .icon-wrap { width: 40px; height: 40px; border-radius: 10px; background: linear-gradient(135deg, var(--gradient-start), var(--gradient-end)); display: flex; align-items: center; justify-content: center; color: #fff; box-shadow: 0 6px 16px rgba(123,92,255,0.25); transition: transform 0.3s ease; position: relative; z-index: 1; }
.download-card:hover .icon-wrap { transform: scale(1.1) rotate(-5deg); }
.download-card .text-wrap { text-align: left; position: relative; z-index: 1; }
.download-card .title { font-weight: 700; font-size: 1.05em; }
.download-card .subtitle { font-size: .9em; color: var(--text-light); }
.download-card .arrow { margin-left: auto; color: #9aa0a6; transition: transform 0.3s ease, color 0.3s ease; position: relative; z-index: 1; }
.download-card:hover .arrow { transform: translateX(5px); color: var(--primary-color); }
.download-card svg { width: 20px; height: 20px; }

/* 回到顶部按钮 */
.back-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 50px;
    height: 50px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--primary-color), var(--gradient-end));
    color: #fff;
    border: none;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: 0 4px 15px rgba(0, 122, 255, 0.4);
    opacity: 0;
    visibility: hidden;
    transform: translateY(20px);
    transition: all 0.3s ease;
    z-index: 999;
}
.back-to-top.visible {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}
.back-to-top:hover {
    transform: translateY(-3px);
    box-shadow: 0 8px 25px rgba(0, 122, 255, 0.5);
}
.back-to-top svg {
    width: 24px;
    height: 24px;
    transition: transform 0.3s ease;
}
.back-to-top:hover svg {
    transform: translateY(-3px);
}

/* Footer */
.footer { text-align: center; padding: 40px 20px; background: #343a40; color: #f8f9fa; font-size: .9em; }
.footer a { color: #cfe2ff; text-decoration: none; margin-left: 8px; font-weight: 500; transition: color 0.3s ease; }
.footer a:hover { color: #fff; text-decoration: underline; }
.footer .icp { display: inline-block; padding: 2px 6px; border-radius: 4px; background: rgba(255,255,255,.08); transition: background 0.3s ease; }
.footer .icp:hover { background: rgba(255,255,255,.15); }

a:focus, button:focus { outline: 2px solid var(--primary-color); outline-offset: 2px; }

/* 移动端菜单按钮 */
.menu-toggle { display: none; background: none; border: none; cursor: pointer; padding: 8px; color: var(--text-dark); }
.menu-toggle svg { width: 24px; height: 24px; }

@media (max-width: 768px) {
    .menu-toggle { display: block; }
    .nav-links { 
        display: none; 
        position: absolute; 
        top: var(--nav-height); 
        left: 0; 
        right: 0; 
        background: rgba(255, 255, 255, 0.98); 
        flex-direction: column; 
        padding: 20px; 
        gap: 16px;
        box-shadow: 0 4px 20px rgba(0,0,0,0.1);
        border-top: 1px solid rgba(0,0,0,0.07);
    }
    .nav-links.active { display: flex; }
    .nav-links a:not(.btn-invert) { padding: 12px 0; font-size: 1.1em; }
    .nav-links a:not(.btn-invert)::after { display: none; }
    .lang-switch { margin: 8px 0; }
}

@media (max-width: 600px) {
    .header h1 { font-size: 2.4em; }
    .header p { font-size: 1.1em; }
    .section h2 { font-size: 2.1em; }
    .back-to-top { bottom: 20px; right: 20px; width: 45px; height: 45px; }
}