/* =========================================================
 * 湖南啸莱科技 - iOS 26 海洋蓝 + 珊瑚橙 · Bento Grid 风
 * ========================================================= */

:root {
    /* 主色 - 海洋蓝 + 珊瑚橙 */
    --primary: #0EA5E9;
    --primary-deep: #0369A1;
    --primary-soft: rgba(14, 165, 233, 0.12);
    --coral: #FF6B5B;
    --coral-light: #FF8C7A;
    --coral-soft: rgba(255, 107, 91, 0.12);
    --sand: #F4E4BC;
    --sand-deep: #D4B68C;
    --teal: #14B8A6;
    --sun: #FBBF24;

    /* 中性 - 沙白 */
    --bg-primary: #FCFAF5;
    --bg-secondary: #F2EDE0;
    --bg-cream: #FFF8E8;
    --bg-ocean: #E8F4F8;
    --surface: rgba(255, 255, 255, 0.78);
    --surface-strong: rgba(255, 255, 255, 0.92);

    --text-primary: #0F2942;
    --text-secondary: #4A6577;
    --text-tertiary: #8DA0AE;
    --text-muted: #B8C4CD;

    --border: rgba(15, 41, 66, 0.08);
    --border-strong: rgba(15, 41, 66, 0.16);

    --r-xs: 8px;
    --r-sm: 14px;
    --r-md: 20px;
    --r-lg: 28px;
    --r-xl: 36px;
    --r-2xl: 48px;
    --r-full: 9999px;

    --shadow-sm: 0 2px 8px rgba(15, 41, 66, 0.06);
    --shadow-md: 0 12px 30px rgba(15, 41, 66, 0.08);
    --shadow-lg: 0 24px 50px rgba(15, 41, 66, 0.12);

    --font: -apple-system, BlinkMacSystemFont, "SF Pro Display", "PingFang SC", "Helvetica Neue", Helvetica, Arial, sans-serif;

    --t-fast: 200ms cubic-bezier(0.4, 0, 0.2, 1);
    --t-base: 320ms cubic-bezier(0.4, 0, 0.2, 1);
    --t-slow: 600ms cubic-bezier(0.4, 0, 0.2, 1);
}

* { margin: 0; padding: 0; box-sizing: border-box; -webkit-tap-highlight-color: transparent; }

html, body {
    font-family: var(--font);
    color: var(--text-primary);
    background: var(--bg-primary);
    line-height: 1.7;
    -webkit-font-smoothing: antialiased;
    text-rendering: optimizeLegibility;
    overflow-x: hidden;
}

body {
    background:
        radial-gradient(ellipse at top right, rgba(14, 165, 233, 0.10), transparent 50%),
        radial-gradient(ellipse at bottom left, rgba(255, 107, 91, 0.08), transparent 50%),
        radial-gradient(circle at 20% 80%, rgba(244, 228, 188, 0.40), transparent 50%),
        var(--bg-primary);
    background-attachment: fixed;
    min-height: 100vh;
}

a { color: inherit; text-decoration: none; transition: color var(--t-fast); }
a:hover { color: var(--primary); }
img { max-width: 100%; height: auto; display: block; }
button { font: inherit; cursor: pointer; border: none; background: none; }
input, textarea, select { font: inherit; }

::selection { background: var(--primary); color: white; }

.container {
    max-width: 1280px;
    margin: 0 auto;
    padding: 0 28px;
}

/* =========================================================
 * 导航 - 半透明分段
 * ========================================================= */
.nav {
    position: fixed;
    top: 18px;
    left: 50%;
    transform: translateX(-50%);
    width: calc(100% - 36px);
    max-width: 1280px;
    background: var(--surface-strong);
    backdrop-filter: blur(28px) saturate(180%);
    -webkit-backdrop-filter: blur(28px) saturate(180%);
    border: 1px solid var(--border);
    border-radius: var(--r-2xl);
    padding: 12px 28px;
    z-index: 100;
    box-shadow: var(--shadow-md);
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.nav-logo {
    display: flex;
    align-items: center;
    gap: 12px;
    font-weight: 800;
    font-size: 18px;
    color: var(--text-primary);
}

.nav-logo-icon {
    width: 36px;
    height: 36px;
    background: linear-gradient(135deg, var(--primary), var(--teal));
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 18px;
    font-weight: 800;
    position: relative;
    box-shadow: 0 6px 18px rgba(14, 165, 233, 0.35), inset 0 0 0 1px rgba(255, 255, 255, 0.2);
}

.nav-logo-icon::after {
    content: '';
    position: absolute;
    bottom: 4px;
    left: 6px;
    right: 6px;
    height: 2px;
    background: rgba(255, 255, 255, 0.5);
    border-radius: 2px;
    box-shadow: 0 -4px 0 rgba(255, 255, 255, 0.3);
}

.nav-menu {
    display: flex;
    gap: 6px;
    list-style: none;
}

.nav-menu a {
    padding: 8px 18px;
    border-radius: var(--r-full);
    font-size: 14px;
    font-weight: 500;
    color: var(--text-secondary);
    transition: all var(--t-fast);
}

.nav-menu a:hover, .nav-menu a.active {
    color: var(--primary);
    background: var(--primary-soft);
}

.nav-cta {
    background: linear-gradient(135deg, var(--coral), var(--coral-light));
    color: white !important;
    padding: 9px 22px !important;
    border-radius: var(--r-full);
    font-size: 13.5px;
    font-weight: 700 !important;
    box-shadow: 0 6px 16px rgba(255, 107, 91, 0.35);
    transition: all var(--t-fast);
}

.nav-cta:hover {
    transform: translateY(-2px);
    color: white !important;
    box-shadow: 0 10px 24px rgba(255, 107, 91, 0.45);
}

.nav-toggle {
    display: none;
    width: 38px;
    height: 38px;
    border-radius: var(--r-full);
    background: var(--primary-soft);
    color: var(--primary);
    align-items: center;
    justify-content: center;
    font-size: 18px;
}

@media (max-width: 900px) {
    .nav-menu { display: none; }
    .nav-cta { display: none; }
    .nav-toggle { display: flex; }
    .nav-menu.open {
        display: flex;
        position: absolute;
        top: 60px;
        left: 0;
        right: 0;
        background: var(--surface-strong);
        backdrop-filter: blur(30px);
        flex-direction: column;
        padding: 14px;
        border-radius: var(--r-md);
        gap: 6px;
        box-shadow: var(--shadow-lg);
    }
}

/* =========================================================
 * Hero
 * ========================================================= */
.hero {
    padding: 130px 0 60px;
    text-align: center;
    position: relative;
}

.hero-tag {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    background: var(--surface-strong);
    backdrop-filter: blur(20px);
    border: 1px solid var(--border);
    padding: 8px 18px;
    border-radius: var(--r-full);
    font-size: 13px;
    font-weight: 600;
    color: var(--primary-deep);
    margin-bottom: 24px;
    box-shadow: var(--shadow-sm);
}

.hero h1 {
    font-size: clamp(36px, 6.5vw, 76px);
    font-weight: 800;
    line-height: 1.05;
    letter-spacing: -0.03em;
    margin-bottom: 24px;
    color: var(--text-primary);
}

.hero h1 .accent {
    background: linear-gradient(135deg, var(--primary), var(--teal));
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    display: inline-block;
}

.hero h1 .coral {
    background: linear-gradient(135deg, var(--coral), var(--coral-light));
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    display: inline-block;
    position: relative;
}

.hero p.lead {
    font-size: clamp(15px, 1.8vw, 19px);
    color: var(--text-secondary);
    line-height: 1.75;
    margin: 0 auto 36px;
    max-width: 720px;
}

.hero-actions {
    display: flex;
    gap: 14px;
    justify-content: center;
    flex-wrap: wrap;
    margin-bottom: 50px;
}

.btn {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    padding: 14px 30px;
    border-radius: var(--r-full);
    font-weight: 600;
    font-size: 15px;
    transition: all var(--t-fast);
    cursor: pointer;
    text-decoration: none;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary), var(--primary-deep));
    color: white;
    box-shadow: 0 10px 26px rgba(14, 165, 233, 0.35);
}

.btn-primary:hover {
    transform: translateY(-2px);
    color: white;
    box-shadow: 0 14px 34px rgba(14, 165, 233, 0.5);
}

.btn-coral {
    background: linear-gradient(135deg, var(--coral), var(--coral-light));
    color: white;
    box-shadow: 0 10px 26px rgba(255, 107, 91, 0.35);
}

.btn-coral:hover {
    transform: translateY(-2px);
    color: white;
}

.btn-glass {
    background: var(--surface-strong);
    color: var(--text-primary);
    border: 1px solid var(--border-strong);
    box-shadow: var(--shadow-sm);
}

.btn-glass:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

/* =========================================================
 * Bento 数据网格
 * ========================================================= */
.bento-stats {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 16px;
    max-width: 940px;
    margin: 0 auto;
}

.bento-stat {
    background: var(--surface-strong);
    backdrop-filter: blur(20px);
    border: 1px solid var(--border);
    border-radius: var(--r-md);
    padding: 22px 18px;
    text-align: center;
    transition: all var(--t-base);
}

.bento-stat:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-md);
}

.bento-stat-icon { font-size: 22px; margin-bottom: 8px; }
.bento-stat-num {
    font-size: 28px;
    font-weight: 800;
    color: var(--primary);
    letter-spacing: -0.02em;
    line-height: 1;
}
.bento-stat-label {
    font-size: 12.5px;
    color: var(--text-tertiary);
    margin-top: 6px;
}

@media (max-width: 640px) {
    .bento-stats { grid-template-columns: repeat(2, 1fr); }
}

/* =========================================================
 * Section
 * ========================================================= */
.section {
    padding: 90px 0;
    position: relative;
}

.section-header {
    text-align: center;
    margin-bottom: 60px;
}

.section-eyebrow {
    display: inline-block;
    font-size: 12.5px;
    font-weight: 700;
    color: var(--coral);
    letter-spacing: 0.18em;
    text-transform: uppercase;
    margin-bottom: 14px;
    padding: 5px 16px;
    background: var(--coral-soft);
    border-radius: var(--r-full);
}

.section-header h2 {
    font-size: clamp(30px, 4.5vw, 46px);
    font-weight: 800;
    letter-spacing: -0.025em;
    line-height: 1.1;
    color: var(--text-primary);
    margin-bottom: 14px;
}

.section-header p {
    color: var(--text-secondary);
    font-size: 16px;
    max-width: 620px;
    margin: 0 auto;
    line-height: 1.7;
}

/* =========================================================
 * Bento Grid 课程区
 * ========================================================= */
.bento-grid {
    display: grid;
    grid-template-columns: repeat(6, 1fr);
    grid-auto-rows: 240px;
    gap: 18px;
}

@media (max-width: 900px) {
    .bento-grid { grid-template-columns: repeat(2, 1fr); grid-auto-rows: 220px; }
}

@media (max-width: 540px) {
    .bento-grid { grid-template-columns: 1fr; }
}

.bento-card {
    background: white;
    border-radius: var(--r-lg);
    overflow: hidden;
    transition: all var(--t-base);
    cursor: pointer;
    display: flex;
    flex-direction: column;
    text-decoration: none;
    color: inherit;
    border: 1px solid var(--border);
    position: relative;
    box-shadow: var(--shadow-sm);
}

.bento-card:hover {
    transform: translateY(-6px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary);
}

/* Bento 跨格 */
.bento-3 { grid-column: span 3; }
.bento-2 { grid-column: span 2; }
.bento-4 { grid-column: span 4; }
.bento-row-2 { grid-row: span 2; }

@media (max-width: 900px) {
    .bento-3, .bento-2, .bento-4 { grid-column: span 1; }
    .bento-row-2 { grid-row: span 1; }
}

@media (min-width: 901px) {
    /* 第一个大卡占 4×2 */
    .bento-card.feature { grid-column: span 4; grid-row: span 2; }
    .bento-card.tall { grid-column: span 2; grid-row: span 2; }
    .bento-card.wide { grid-column: span 4; }
    .bento-card.normal { grid-column: span 2; }
}

.bento-card-img {
    height: 100%;
    overflow: hidden;
    position: relative;
}

.bento-card-img img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform var(--t-slow);
}

.bento-card:hover .bento-card-img img { transform: scale(1.06); }

.bento-card-overlay {
    position: absolute;
    inset: 0;
    background: linear-gradient(180deg, transparent 30%, rgba(15, 41, 66, 0.85) 100%);
    padding: 24px;
    display: flex;
    flex-direction: column;
    justify-content: flex-end;
    color: white;
}

.bento-card-tag {
    align-self: flex-start;
    background: rgba(255, 255, 255, 0.95);
    color: var(--coral);
    padding: 5px 14px;
    border-radius: var(--r-full);
    font-size: 11px;
    font-weight: 700;
    letter-spacing: 0.05em;
    margin-bottom: 12px;
    backdrop-filter: blur(10px);
    box-shadow: var(--shadow-sm);
}

.bento-card-cat {
    font-size: 11px;
    font-weight: 700;
    color: rgba(255, 255, 255, 0.8);
    letter-spacing: 0.12em;
    text-transform: uppercase;
    margin-bottom: 6px;
}

.bento-card-title {
    font-size: 18px;
    font-weight: 700;
    line-height: 1.3;
    margin-bottom: 10px;
    color: white;
}

.bento-card.feature .bento-card-title { font-size: 26px; }
.bento-card.tall .bento-card-title { font-size: 18px; }

.bento-card-desc {
    font-size: 13px;
    color: rgba(255, 255, 255, 0.85);
    line-height: 1.5;
    margin-bottom: 12px;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.bento-card.feature .bento-card-desc { -webkit-line-clamp: 3; font-size: 14px; }

.bento-card-meta {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 12px;
    padding-top: 12px;
    border-top: 1px solid rgba(255, 255, 255, 0.2);
}

.bento-card-price {
    font-size: 22px;
    font-weight: 800;
    color: var(--coral-light);
}

.bento-card-price small {
    font-size: 12px;
    font-weight: 500;
    color: rgba(255, 255, 255, 0.6);
    text-decoration: line-through;
    margin-left: 6px;
}

.bento-card-info {
    display: flex;
    gap: 12px;
    font-size: 12px;
    color: rgba(255, 255, 255, 0.85);
}

/* =========================================================
 * 普通课程网格
 * ========================================================= */
.course-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(290px, 1fr));
    gap: 24px;
}

.course-card {
    background: white;
    border: 1px solid var(--border);
    border-radius: var(--r-lg);
    overflow: hidden;
    transition: all var(--t-base);
    box-shadow: var(--shadow-sm);
    cursor: pointer;
    display: flex;
    flex-direction: column;
    text-decoration: none;
    color: inherit;
}

.course-card:hover {
    transform: translateY(-6px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary);
}

.course-card-img {
    height: 180px;
    overflow: hidden;
    position: relative;
}

.course-card-img img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform var(--t-slow);
}

.course-card:hover .course-card-img img { transform: scale(1.06); }

.course-card-tag {
    position: absolute;
    top: 14px;
    left: 14px;
    background: white;
    color: var(--coral);
    padding: 5px 12px;
    border-radius: var(--r-full);
    font-size: 11px;
    font-weight: 700;
    letter-spacing: 0.05em;
    box-shadow: var(--shadow-sm);
}

.course-card-region {
    position: absolute;
    bottom: 14px;
    right: 14px;
    background: rgba(15, 41, 66, 0.85);
    backdrop-filter: blur(10px);
    color: white;
    padding: 4px 10px;
    border-radius: var(--r-full);
    font-size: 11px;
    font-weight: 600;
}

.course-card-body {
    padding: 22px;
    flex: 1;
    display: flex;
    flex-direction: column;
}

.course-card-cat {
    font-size: 11px;
    font-weight: 700;
    color: var(--primary);
    letter-spacing: 0.12em;
    text-transform: uppercase;
    margin-bottom: 8px;
}

.course-card-title {
    font-size: 17px;
    font-weight: 700;
    margin-bottom: 10px;
    line-height: 1.4;
    color: var(--text-primary);
}

.course-card-desc {
    font-size: 13.5px;
    color: var(--text-secondary);
    line-height: 1.6;
    margin-bottom: 18px;
    flex: 1;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.course-card-meta {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding-top: 16px;
    border-top: 1px solid var(--border);
}

.course-card-price {
    font-size: 22px;
    font-weight: 800;
    color: var(--coral);
}

.course-card-price small {
    font-size: 12px;
    font-weight: 500;
    color: var(--text-tertiary);
    text-decoration: line-through;
    margin-left: 6px;
}

.course-card-info {
    display: flex;
    gap: 12px;
    font-size: 12px;
    color: var(--text-tertiary);
}

/* =========================================================
 * 全球地区数据
 * ========================================================= */
.region-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 16px;
}

.region-card {
    background: white;
    border-radius: var(--r-md);
    padding: 22px;
    border: 1px solid var(--border);
    transition: all var(--t-base);
    text-align: center;
    box-shadow: var(--shadow-sm);
}

.region-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-md);
    border-color: var(--primary);
}

.region-flag {
    font-size: 36px;
    margin-bottom: 12px;
}

.region-name {
    font-size: 16px;
    font-weight: 700;
    margin-bottom: 4px;
    color: var(--text-primary);
}

.region-num {
    font-size: 22px;
    font-weight: 800;
    color: var(--primary);
    margin: 6px 0;
    letter-spacing: -0.01em;
}

.region-desc {
    font-size: 12px;
    color: var(--text-tertiary);
}

/* =========================================================
 * 评价
 * ========================================================= */
.review-item {
    background: white;
    border-radius: var(--r-md);
    padding: 22px;
    margin-bottom: 14px;
    border: 1px solid var(--border);
    box-shadow: var(--shadow-sm);
    transition: all var(--t-fast);
}

.review-item:hover {
    border-color: var(--primary);
    transform: translateY(-2px);
}

.review-meta {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 14px;
}

.review-avatar {
    width: 44px;
    height: 44px;
    border-radius: var(--r-full);
    background: linear-gradient(135deg, var(--primary), var(--teal));
    color: white;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    flex-shrink: 0;
    font-size: 16px;
}

.review-name { font-weight: 700; font-size: 14px; color: var(--text-primary); }
.review-job { font-size: 12px; color: var(--coral); margin-top: 2px; }
.review-stars { color: var(--sun); font-size: 13px; letter-spacing: 1px; margin-left: auto; }
.review-time { font-size: 11.5px; color: var(--text-tertiary); margin-left: 8px; }

.review-text {
    font-size: 14px;
    color: var(--text-secondary);
    line-height: 1.7;
}

/* =========================================================
 * 表单
 * ========================================================= */
.form-group { margin-bottom: 18px; }

.form-label {
    display: block;
    font-size: 13px;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 8px;
}

.form-input, .form-select, .form-textarea {
    width: 100%;
    padding: 13px 16px;
    background: white;
    border: 1.5px solid var(--border-strong);
    border-radius: var(--r-md);
    font-size: 14px;
    color: var(--text-primary);
    transition: all var(--t-fast);
}

.form-input:focus, .form-select:focus, .form-textarea:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 4px var(--primary-soft);
}

.form-textarea { min-height: 110px; resize: vertical; }

/* =========================================================
 * 联系卡片
 * ========================================================= */
.feature-card {
    background: white;
    border-radius: var(--r-md);
    padding: 28px;
    border: 1px solid var(--border);
    transition: all var(--t-base);
    box-shadow: var(--shadow-sm);
}

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

.feature-icon {
    width: 52px;
    height: 52px;
    background: linear-gradient(135deg, var(--primary-soft), var(--coral-soft));
    border-radius: var(--r-md);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 24px;
    margin-bottom: 16px;
    border: 1px solid var(--border);
}

.feature-card h3 {
    font-size: 17px;
    font-weight: 700;
    margin-bottom: 10px;
    color: var(--text-primary);
}

.feature-card p {
    font-size: 14px;
    color: var(--text-secondary);
    line-height: 1.7;
}

/* =========================================================
 * 时间线
 * ========================================================= */
.timeline-card {
    background: white;
    border-radius: var(--r-md);
    padding: 22px 26px;
    border: 1px solid var(--border);
    margin-bottom: 14px;
    border-left: 3px solid var(--primary);
    box-shadow: var(--shadow-sm);
}

.timeline-card-year {
    display: inline-block;
    font-size: 12px;
    font-weight: 700;
    color: var(--coral);
    background: var(--coral-soft);
    padding: 3px 10px;
    border-radius: var(--r-full);
    letter-spacing: 0.05em;
    margin-bottom: 10px;
}

.timeline-card h4 {
    font-size: 17px;
    font-weight: 700;
    margin-bottom: 6px;
}

.timeline-card p {
    font-size: 14px;
    color: var(--text-secondary);
    line-height: 1.7;
}

/* =========================================================
 * 页脚
 * ========================================================= */
.footer {
    background: linear-gradient(180deg, transparent, var(--bg-ocean));
    border-top: 1px solid var(--border);
    padding: 70px 0 30px;
    margin-top: 100px;
}

.footer-grid {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr;
    gap: 40px;
    margin-bottom: 50px;
}

.footer-brand {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 18px;
    font-weight: 800;
    font-size: 18px;
}

.footer-desc {
    font-size: 14px;
    color: var(--text-secondary);
    line-height: 1.7;
    max-width: 340px;
    margin-bottom: 18px;
}

.footer-tag {
    font-size: 12px;
    color: var(--coral);
    font-style: italic;
    letter-spacing: 0.05em;
}

.footer h4 {
    font-size: 13px;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 18px;
    text-transform: uppercase;
    letter-spacing: 0.1em;
}

.footer ul { list-style: none; }
.footer ul li { margin-bottom: 10px; }
.footer ul a { font-size: 13.5px; color: var(--text-secondary); }
.footer ul a:hover { color: var(--primary); }

.footer-bottom {
    padding-top: 30px;
    border-top: 1px solid var(--border);
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 16px;
    font-size: 13px;
    color: var(--text-tertiary);
}

.footer-bottom a { color: var(--text-secondary); }
.footer-bottom a:hover { color: var(--primary); }

@media (max-width: 768px) {
    .footer-grid { grid-template-columns: 1fr 1fr; gap: 30px; }
    .footer-brand { grid-column: 1 / -1; }
}

/* =========================================================
 * 返回顶部 - 海浪圆形
 * ========================================================= */
.back-to-top {
    position: fixed;
    right: 28px;
    bottom: 110px;
    width: 48px;
    height: 48px;
    background: white;
    border: 2px solid var(--primary);
    border-radius: var(--r-full);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--primary);
    font-size: 20px;
    cursor: pointer;
    opacity: 0;
    visibility: hidden;
    transform: translateY(10px);
    transition: all var(--t-base);
    box-shadow: var(--shadow-md);
    z-index: 99;
    font-weight: 700;
}

.back-to-top.show {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.back-to-top:hover {
    background: var(--primary);
    color: white;
    transform: translateY(-3px);
}

/* =========================================================
 * AI 客服 - 海浪波纹
 * ========================================================= */
.ai-chat-btn {
    position: fixed;
    right: 28px;
    bottom: 32px;
    width: 60px;
    height: 60px;
    background: linear-gradient(135deg, var(--primary), var(--teal));
    border-radius: var(--r-full);
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 28px;
    cursor: pointer;
    box-shadow: 0 12px 30px rgba(14, 165, 233, 0.4);
    transition: all var(--t-base);
    z-index: 99;
}

.ai-chat-btn::before, .ai-chat-btn::after {
    content: '';
    position: absolute;
    inset: 0;
    border-radius: inherit;
    border: 2px solid var(--primary);
    opacity: 0;
    animation: wave 2.5s infinite;
}

.ai-chat-btn::after { animation-delay: 1.25s; }

@keyframes wave {
    0% { transform: scale(0.95); opacity: 0.8; }
    100% { transform: scale(1.6); opacity: 0; }
}

.ai-chat-btn:hover {
    transform: scale(1.06);
    box-shadow: 0 16px 36px rgba(14, 165, 233, 0.55);
}

.ai-chat-panel {
    position: fixed;
    right: 28px;
    bottom: 100px;
    width: 360px;
    max-width: calc(100vw - 56px);
    height: 480px;
    background: var(--surface-strong);
    backdrop-filter: blur(40px) saturate(180%);
    border: 1px solid var(--border);
    border-radius: var(--r-lg);
    box-shadow: var(--shadow-lg);
    z-index: 98;
    opacity: 0;
    visibility: hidden;
    transform: translateY(20px) scale(0.95);
    transform-origin: bottom right;
    transition: all var(--t-base);
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

.ai-chat-panel.open {
    opacity: 1;
    visibility: visible;
    transform: translateY(0) scale(1);
}

.ai-chat-header {
    padding: 18px 20px;
    background: linear-gradient(135deg, var(--primary), var(--teal));
    color: white;
    display: flex;
    align-items: center;
    gap: 12px;
}

.ai-chat-header-avatar {
    width: 38px;
    height: 38px;
    background: rgba(255, 255, 255, 0.25);
    border-radius: var(--r-full);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 20px;
}

.ai-chat-header-info { flex: 1; }
.ai-chat-header-info h4 { font-size: 15px; font-weight: 700; margin-bottom: 2px; }
.ai-chat-header-info p { font-size: 12px; opacity: 0.85; }

.ai-chat-body {
    flex: 1;
    padding: 18px;
    overflow-y: auto;
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.ai-chat-msg {
    max-width: 80%;
    padding: 10px 14px;
    border-radius: var(--r-md);
    font-size: 14px;
    line-height: 1.5;
}

.ai-chat-msg.bot {
    background: var(--bg-ocean);
    color: var(--text-primary);
    align-self: flex-start;
    border-bottom-left-radius: 4px;
}

.ai-chat-msg.user {
    background: linear-gradient(135deg, var(--primary), var(--teal));
    color: white;
    align-self: flex-end;
    border-bottom-right-radius: 4px;
}

.ai-chat-input {
    padding: 14px;
    border-top: 1px solid var(--border);
    display: flex;
    gap: 8px;
}

.ai-chat-input input {
    flex: 1;
    padding: 10px 14px;
    background: var(--bg-ocean);
    border: 1px solid var(--border);
    border-radius: var(--r-full);
    font-size: 14px;
    outline: none;
}

.ai-chat-input input:focus { border-color: var(--primary); }

.ai-chat-input button {
    background: var(--coral);
    color: white;
    width: 38px;
    height: 38px;
    border-radius: var(--r-full);
    font-size: 16px;
}

@media (max-width: 640px) {
    .container { padding: 0 16px; }
    .hero { padding: 100px 0 50px; }
    .section { padding: 56px 0; }
    .ai-chat-panel { right: 12px; bottom: 88px; width: calc(100% - 24px); height: 60vh; }
    .ai-chat-btn { right: 16px; bottom: 16px; }
    .back-to-top { right: 16px; bottom: 90px; }
}