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

:root {
    --primary: #00AED6;
    --primary-dark: #0088B8;
    --secondary: #33BFE3;
    --accent: #FFA62B;
    --accent-light: #FFC966;
    --bg-light: #F0F9FC;
    --white: #ffffff;
    --text-dark: #263238;
    --text-light: #546e7a;
    --border: #DDF0F7;
    --shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
    --shadow-hover: 0 8px 30px rgba(0, 0, 0, 0.12);
    --radius: 12px;
    --radius-sm: 8px;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
    background: linear-gradient(135deg, #f5f7fa 0%, #e4edf5 100%);
    color: var(--text-dark);
    line-height: 1.6;
    min-height: 100vh;
    font-size: 16px;
}

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

.navbar {
    background: linear-gradient(135deg, #00AED6, #0088B8);
    padding: 12px 0;
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: 0 2px 10px rgba(0, 136, 184, 0.25);
}

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

.logo {
    display: flex;
    align-items: center;
    gap: 12px;
    text-decoration: none;
}

.logo-icon {
    display: flex;
    align-items: center;
    justify-content: center;
}

.logo-icon svg {
    display: block;
    height: 50px;
    width: auto;
}

.logo-text {
    display: flex;
    flex-direction: column;
}

.logo-title {
    font-size: 1.1rem;
    font-weight: 700;
    color: #ffffff;
    letter-spacing: 1px;
}

.logo-subtitle {
    font-size: 0.7rem;
    color: rgba(255, 255, 255, 0.75);
    letter-spacing: 0.5px;
}

.nav-links {
    display: flex;
    list-style: none;
    gap: 32px;
}

.nav-links a {
    color: rgba(255, 255, 255, 0.92);
    text-decoration: none;
    font-weight: 500;
    transition: color 0.3s;
    font-size: 1rem;
}

.nav-links a:hover {
    color: #ffffff;
}

.hero {
    padding: 44px 0 30px;
    text-align: center;
    background: transparent;
    border-bottom: none;
}

.hero h1 {
    font-size: 1.7rem;
    color: var(--text-dark);
    margin-bottom: 10px;
    font-weight: 700;
}

.hero p {
    font-size: 1.15rem;
    color: var(--text-light);
}

.main-content {
    padding: 60px 0;
}

.section-title {
    text-align: center;
    margin-bottom: 48px;
}

.section-title h2 {
    font-size: 2rem;
    color: var(--text-dark);
    margin-bottom: 12px;
    font-weight: 600;
}

.section-title p {
    color: var(--text-light);
    font-size: 1rem;
}

.cards-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 28px;
}

.card {
    background: var(--white);
    border-radius: 14px;
    padding: 36px 28px;
    text-decoration: none;
    color: var(--text-dark);
    box-shadow: 0 4px 14px rgba(0, 60, 90, 0.06);
    transition: all 0.3s ease;
    border: 1px solid #E1EEF5;
}

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

.card-icon {
    width: 64px;
    height: 64px;
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    border-radius: 14px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--white);
    margin-bottom: 20px;
}

.card-icon svg {
    width: 32px;
    height: 32px;
}

.card h3 {
    font-size: 1.3rem;
    margin-bottom: 10px;
    font-weight: 600;
}

.card p {
    color: var(--text-light);
    font-size: 0.95rem;
    line-height: 1.7;
}

.page-header {
    background: var(--white);
    padding: 48px 0;
    border-bottom: 1px solid var(--border);
}

.page-header h1 {
    font-size: 2.2rem;
    color: var(--text-dark);
    font-weight: 600;
}

.page-content {
    padding: 48px 0;
}

.tabs {
    display: flex;
    gap: 8px;
    margin-bottom: 32px;
    flex-wrap: wrap;
}

.tab {
    padding: 14px 28px;
    background: var(--white);
    border: none;
    border-radius: var(--radius-sm);
    cursor: pointer;
    font-size: 1rem;
    font-weight: 500;
    color: var(--text-light);
    transition: all 0.3s;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.04);
    min-height: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.tab:hover {
    color: var(--primary);
}

.tab.active {
    background: var(--primary);
    color: var(--white);
    box-shadow: 0 4px 12px rgba(30, 136, 229, 0.3);
}

.subcategory-container {
    margin-bottom: 32px;
}

.subcategory-grid {
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
}

.subcategory-btn {
    padding: 12px 22px;
    background: var(--white);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    cursor: pointer;
    font-size: 1rem;
    color: var(--text-dark);
    transition: all 0.3s;
    min-height: 44px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.subcategory-btn:hover {
    border-color: var(--primary);
    color: var(--primary);
}

.subcategory-btn.active {
    background: var(--primary);
    color: var(--white);
    border-color: var(--primary);
}

.age-selector {
    display: flex;
    gap: 12px;
    margin-bottom: 32px;
    flex-wrap: wrap;
}

.age-btn {
    padding: 16px 32px;
    background: var(--white);
    border: 2px solid var(--border);
    border-radius: var(--radius-sm);
    cursor: pointer;
    font-size: 1rem;
    font-weight: 500;
    color: var(--text-dark);
    transition: all 0.3s;
    min-height: 52px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.age-btn:hover {
    border-color: var(--primary);
    color: var(--primary);
}

.age-btn.active {
    background: var(--primary);
    color: var(--white);
    border-color: var(--primary);
}

.training-types-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(160px, 1fr));
    gap: 16px;
    margin-bottom: 32px;
}

.training-type-btn {
    padding: 24px 20px;
    background: var(--white);
    border: 2px solid var(--border);
    border-radius: var(--radius);
    cursor: pointer;
    text-align: center;
    transition: all 0.3s;
    font-size: 1rem;
    font-weight: 500;
    color: var(--text-dark);
    min-height: 100px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 10px;
}

.training-type-btn:hover {
    border-color: var(--primary);
    color: var(--primary);
    transform: translateY(-2px);
}

.training-type-btn.active {
    background: var(--primary);
    color: var(--white);
    border-color: var(--primary);
}

.training-type-icon {
    font-size: 2.2rem;
}

.videos-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: 24px;
}

.video-card {
    background: var(--white);
    border-radius: var(--radius);
    overflow: hidden;
    box-shadow: var(--shadow);
}

.video-player {
    background: #1a1a1a;
    aspect-ratio: 16/9;
    position: relative;
    overflow: hidden;
}

.video-player video {
    width: 100%;
    height: 100%;
    display: block;
}

.video-player iframe {
    width: 100%;
    height: 100%;
    display: block;
}

.video-info {
    padding: 20px;
}

.video-info h4 {
    font-size: 1.05rem;
    margin-bottom: 8px;
    font-weight: 600;
}

.video-info p {
    color: var(--text-light);
    font-size: 0.9rem;
}

.no-videos {
    text-align: center;
    padding: 60px 20px;
    color: var(--text-light);
}

.no-videos svg {
    width: 64px;
    height: 64px;
    margin-bottom: 16px;
    opacity: 0.4;
}

.login-container {
    min-height: 80vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 40px 24px;
}

.login-box {
    background: var(--white);
    border-radius: var(--radius);
    padding: 40px;
    box-shadow: var(--shadow);
    width: 100%;
    max-width: 420px;
}

.login-box h2 {
    text-align: center;
    margin-bottom: 32px;
    font-size: 1.6rem;
    font-weight: 600;
}

.form-group {
    margin-bottom: 24px;
}

.form-group label {
    display: block;
    margin-bottom: 8px;
    font-weight: 500;
    color: var(--text-dark);
    font-size: 1rem;
}

.form-group input,
.form-group select {
    width: 100%;
    padding: 14px 18px;
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    font-size: 1.05rem;
    font-family: inherit;
    transition: border-color 0.3s;
    min-height: 50px;
}

.form-group input:focus,
.form-group select:focus {
    outline: none;
    border-color: var(--primary);
}

.form-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 16px;
}

.btn {
    width: 100%;
    padding: 16px 28px;
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    color: var(--white);
    border: none;
    border-radius: var(--radius-sm);
    font-size: 1.05rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s;
    font-family: inherit;
    min-height: 52px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(30, 136, 229, 0.4);
}

.btn-block {
    display: block;
    width: 100%;
}

.error-message {
    background: #ffebee;
    color: #c62828;
    padding: 14px 18px;
    border-radius: var(--radius-sm);
    margin-bottom: 20px;
    font-size: 1rem;
}

.admin-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 32px;
}

.admin-header h2 {
    font-size: 1.6rem;
    font-weight: 600;
}

.admin-header p {
    color: var(--text-light);
}

.upload-form {
    background: var(--white);
    border-radius: var(--radius);
    padding: 32px;
    box-shadow: var(--shadow);
    margin-bottom: 32px;
}

.upload-form h3 {
    font-size: 1.25rem;
    margin-bottom: 24px;
    font-weight: 600;
}

.admin-videos-list {
    display: grid;
    gap: 16px;
}

.admin-video-item {
    background: var(--white);
    border-radius: var(--radius);
    padding: 20px;
    box-shadow: var(--shadow);
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 16px;
}

.admin-video-info h4 {
    margin-bottom: 4px;
    font-weight: 600;
}

.admin-video-info p {
    color: var(--text-light);
    font-size: 0.9rem;
}

.btn-delete {
    padding: 12px 24px;
    background: #ef5350;
    color: var(--white);
    border: none;
    border-radius: var(--radius-sm);
    cursor: pointer;
    font-size: 1rem;
    font-weight: 500;
    transition: all 0.3s;
    font-family: inherit;
    min-height: 44px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.btn-delete:hover {
    background: #e53935;
}

.logout-link {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 12px 24px;
    color: var(--text-light);
    text-decoration: none;
    font-weight: 500;
    transition: color 0.3s;
    min-height: 44px;
}

.logout-link:hover {
    color: var(--accent);
}

.footer {
    background: transparent;
    padding: 24px 0;
    margin-top: 60px;
    border-top: none;
}

.footer p {
    text-align: center;
    color: var(--text-light);
    font-size: 0.95rem;
}

/* 平板端响应式 */
@media (max-width: 1024px) {
    .container {
        padding: 0 20px;
    }
    
    .navbar {
        padding: 10px 0;
    }
    
    .logo-icon svg {
        height: 45px;
    }
    
    .logo-title {
        font-size: 1rem;
    }
    
    .nav-links {
        gap: 24px;
    }
    
    .nav-links a {
        font-size: 0.95rem;
    }
    
    .hero h1 {
        font-size: 2.2rem;
    }
    
    .cards-grid {
        grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
        gap: 24px;
    }
    
    .video-card {
        min-height: 280px;
    }
}

/* 手机端响应式 */
@media (max-width: 768px) {
    html {
        font-size: 15px;
    }
    
    body {
        font-size: 15px;
    }
    
    .container {
        padding: 0 16px;
    }
    
    .navbar {
        padding: 8px 0;
    }
    
    .logo {
        gap: 8px;
    }
    
    .logo-icon svg {
        height: 38px;
    }
    
    .logo-title {
        font-size: 0.9rem;
    }
    
    .logo-subtitle {
        display: none;
    }
    
    .nav-links {
        gap: 16px;
    }
    
    .nav-links a {
        font-size: 0.9rem;
        padding: 8px 0;
    }
    
    .hero {
        padding: 50px 0 40px;
    }
    
    .hero h1 {
        font-size: 1.8rem;
        line-height: 1.3;
    }
    
    .hero p {
        font-size: 1rem;
        padding: 0 10px;
    }
    
    .main-content {
        padding: 40px 0;
    }
    
    .section-title {
        margin-bottom: 32px;
    }
    
    .section-title h2 {
        font-size: 1.6rem;
    }
    
    .cards-grid {
        grid-template-columns: 1fr;
        gap: 20px;
    }
    
    .card {
        padding: 32px 24px;
        min-height: 180px;
    }
    
    .card-icon {
        width: 70px;
        height: 70px;
        margin-bottom: 16px;
    }
    
    .card-icon svg {
        width: 36px;
        height: 36px;
    }
    
    .card h3 {
        font-size: 1.3rem;
        margin-bottom: 8px;
    }
    
    .card p {
        font-size: 1rem;
        line-height: 1.6;
    }
    
    .page-header {
        padding: 32px 0;
    }
    
    .page-header h1 {
        font-size: 1.6rem;
    }
    
    .page-content {
        padding: 32px 0;
    }
    
    .tabs {
        gap: 6px;
        margin-bottom: 24px;
    }
    
    .tab {
        padding: 16px 20px;
        font-size: 0.95rem;
        min-height: 52px;
        flex: 1;
        min-width: 120px;
    }
    
    .subcategory-grid {
        gap: 10px;
    }
    
    .subcategory-btn {
        padding: 14px 18px;
        font-size: 0.95rem;
        min-height: 48px;
        flex: 1;
        min-width: 100px;
    }
    
    .age-selector {
        gap: 10px;
        margin-bottom: 24px;
    }
    
    .age-btn {
        padding: 16px 20px;
        font-size: 0.95rem;
        min-height: 52px;
        flex: 1;
        min-width: 100px;
    }
    
    .training-types-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 14px;
        margin-bottom: 24px;
    }
    
    .training-type-btn {
        padding: 24px 16px;
        font-size: 0.95rem;
        min-height: 110px;
    }
    
    .training-type-icon {
        font-size: 2.5rem;
    }
    
    .videos-grid {
        grid-template-columns: 1fr;
        gap: 20px;
    }
    
    .video-card {
        min-height: 260px;
    }
    
    .video-player {
        aspect-ratio: 9/16;
    }
    
    .video-info {
        padding: 16px;
    }
    
    .video-info h4 {
        font-size: 1.1rem;
        margin-bottom: 6px;
    }
    
    .video-info p {
        font-size: 0.95rem;
    }
    
    .login-container {
        padding: 30px 16px;
        min-height: 70vh;
    }
    
    .login-box {
        padding: 32px 24px;
    }
    
    .login-box h2 {
        font-size: 1.5rem;
        margin-bottom: 28px;
    }
    
    .form-group {
        margin-bottom: 20px;
    }
    
    .form-group label {
        font-size: 1rem;
    }
    
    .form-group input,
    .form-group select {
        padding: 16px 18px;
        font-size: 1.1rem;
        min-height: 54px;
    }
    
    .form-row {
        grid-template-columns: 1fr;
        gap: 20px;
    }
    
    .btn {
        padding: 18px 32px;
        font-size: 1.1rem;
        min-height: 56px;
    }
    
    .btn-delete {
        padding: 14px 28px;
        font-size: 1rem;
        min-height: 48px;
    }
    
    .upload-form {
        padding: 24px;
    }
    
    .admin-video-item {
        flex-direction: column;
        align-items: flex-start;
        gap: 16px;
    }
    
    .admin-video-item .btn-delete {
        width: 100%;
    }
    
    .footer {
        padding: 24px 0;
        margin-top: 40px;
    }
    
    .footer p {
        font-size: 0.9rem;
        padding: 0 16px;
    }
}

/* 小屏手机响应式 */
@media (max-width: 480px) {
    html {
        font-size: 14px;
    }
    
    body {
        font-size: 14px;
    }
    
    .container {
        padding: 0 12px;
    }
    
    .logo-icon svg {
        height: 32px;
    }
    
    .logo-title {
        font-size: 0.85rem;
    }
    
    .nav-links {
        gap: 12px;
    }
    
    .nav-links a {
        font-size: 0.85rem;
    }
    
    .hero h1 {
        font-size: 1.5rem;
    }
    
    .hero p {
        font-size: 0.95rem;
    }
    
    .card {
        padding: 28px 20px;
        min-height: 160px;
    }
    
    .card-icon {
        width: 60px;
        height: 60px;
    }
    
    .card-icon svg {
        width: 32px;
        height: 32px;
    }
    
    .tab {
        padding: 14px 16px;
        font-size: 0.9rem;
        min-width: 100px;
    }
    
    .subcategory-btn {
        padding: 12px 14px;
        font-size: 0.9rem;
        min-width: 80px;
    }
    
    .age-btn {
        padding: 14px 16px;
        font-size: 0.9rem;
        min-width: 80px;
    }
    
    .training-types-grid {
        grid-template-columns: 1fr;
    }
    
    .training-type-btn {
        min-height: 90px;
    }
    
    .video-player {
        aspect-ratio: 9/16;
    }
    
    .login-box {
        padding: 24px 20px;
    }
    
    .form-group input,
    .form-group select {
        padding: 14px 16px;
        min-height: 50px;
    }
    
    .btn {
        padding: 16px 28px;
        min-height: 52px;
    }
}
/* 家长视图：隐藏教练入口与顶部导航（卡片已可达，导航冗余；蔚蓝品牌化改造） */
.parent-view .nav-coach { display: none !important; }
.parent-view .coach-card { display: none !important; }
.parent-view .nav-links { display: none !important; }
.parent-view .mobile-menu-btn { display: none !important; }
.mobile-menu-btn { display: none; background: none; border: none; color: #fff; cursor: pointer; padding: 6px; }
@media (max-width: 768px) {
    .mobile-menu-btn { display: inline-block; }
}

/* ============================================================
   渐进式学习页（st- 前缀，仅泳姿技术/综合训练两页使用）
   设计语言：浅蓝主色渐变 + 暖橙点缀 + 大圆角卡片 + 柔和投影
   ============================================================ */

:root {
    --st-primary: #00AED6;
    --st-primary-dark: #0088B8;
    --st-warm: #FFA62B;
    --st-ink: #1B3A4B;
    --st-sub: #6B8A99;
    --st-bg: #F4FAFD;
    --st-card: #ffffff;
    --st-border: #E2F0F7;
    --st-grad: linear-gradient(135deg, #00AED6 0%, #33BFE3 55%, #5CD0F0 100%);
    --st-grad-warm: linear-gradient(135deg, #FFA62B 0%, #FFC966 100%);
    --st-shadow: 0 6px 24px rgba(0, 90, 130, 0.08);
    --st-shadow-lg: 0 14px 40px rgba(0, 90, 130, 0.14);
    --st-radius: 20px;
}

/* —— 顶部 Hero —— */
.st-hero {
    background:
        radial-gradient(ellipse 80% 60% at 15% 0%, rgba(0, 174, 214, 0.10), transparent),
        radial-gradient(ellipse 60% 50% at 90% 10%, rgba(255, 166, 43, 0.08), transparent),
        var(--st-bg);
    padding: 44px 0 30px;
    text-align: center;
}
.st-hero h1 {
    font-size: 1.9rem;
    font-weight: 800;
    color: var(--st-ink);
    letter-spacing: 1px;
    margin-bottom: 8px;
}
.st-hero p {
    color: var(--st-sub);
    font-size: 1rem;
}
.st-hero-tag {
    display: inline-block;
    font-size: 0.68rem;
    letter-spacing: 3px;
    font-weight: 700;
    color: var(--st-primary-dark);
    background: rgba(0, 174, 214, 0.10);
    padding: 5px 14px;
    border-radius: 100px;
    margin-bottom: 14px;
}

/* —— 步骤指示器 —— */
.st-steps-bar {
    position: sticky;
    top: 66px;
    z-index: 90;
    background: rgba(255, 255, 255, 0.86);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--st-border);
    padding: 12px 0;
}
.st-steps-track {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
}
.st-step {
    display: flex;
    align-items: center;
    gap: 8px;
    opacity: 0.45;
    transition: opacity 0.3s;
}
.st-step.active, .st-step.done { opacity: 1; }
.st-step-num {
    width: 28px;
    height: 28px;
    border-radius: 50%;
    background: #DCEEF6;
    color: var(--st-sub);
    font-size: 0.85rem;
    font-weight: 700;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.3s;
    flex-shrink: 0;
}
.st-step.active .st-step-num {
    background: var(--st-grad);
    color: #fff;
    box-shadow: 0 4px 12px rgba(0, 174, 214, 0.35);
}
.st-step.done .st-step-num {
    background: var(--st-primary-dark);
    color: #fff;
}
.st-step.done .st-step-num::before { content: "✓"; }
.st-step.done .st-step-num { font-size: 0; }
.st-step-label {
    font-size: 0.88rem;
    font-weight: 600;
    color: var(--st-ink);
}
.st-step-line {
    width: 44px;
    height: 2px;
    background: #DCEEF6;
    border-radius: 2px;
    transition: background 0.3s;
}
.st-step-line.on { background: var(--st-primary); }

/* —— 主体舞台 —— */
.st-main { padding: 36px 0 60px; }
.st-stage { margin-bottom: 8px; }
.st-q {
    font-size: 1.35rem;
    font-weight: 800;
    color: var(--st-ink);
    text-align: center;
    margin-bottom: 24px;
    letter-spacing: 0.5px;
}

/* 入场动画 */
.st-anim-in { animation: stFadeUp 0.45s cubic-bezier(0.22, 0.61, 0.36, 1) both; }
@keyframes stFadeUp {
    from { opacity: 0; transform: translateY(18px); }
    to   { opacity: 1; transform: translateY(0); }
}

/* —— 泳姿大卡片 —— */
.st-stroke-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 16px;
    max-width: 860px;
    margin: 0 auto;
}
.st-stroke-card {
    background: var(--st-card);
    border: 1.5px solid var(--st-border);
    border-radius: var(--st-radius);
    padding: 26px 20px 22px;
    cursor: pointer;
    text-align: center;
    transition: all 0.28s cubic-bezier(0.22, 0.61, 0.36, 1);
    box-shadow: var(--st-shadow);
    font-family: inherit;
    position: relative;
    overflow: hidden;
}
.st-stroke-card::after {
    content: "";
    position: absolute;
    inset: 0;
    background: linear-gradient(160deg, rgba(0,174,214,0.04), transparent 45%);
    pointer-events: none;
}
.st-stroke-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--st-shadow-lg);
    border-color: rgba(0, 174, 214, 0.5);
}
.st-stroke-card.picked {
    border-color: var(--st-primary);
    box-shadow: 0 0 0 3px rgba(0, 174, 214, 0.18), var(--st-shadow-lg);
}
.st-stroke-ico {
    width: 68px;
    height: 68px;
    border-radius: 20px;
    margin: 0 auto 14px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2rem;
    color: #fff;
}
.st-ico-freestyle   { background: linear-gradient(135deg, #00AED6, #33BFE3); }
.st-ico-backstroke  { background: linear-gradient(135deg, #2E9BD6, #5FB9E8); }
.st-ico-breaststroke{ background: linear-gradient(135deg, #FFA62B, #FFC966); }
.st-ico-butterfly   { background: linear-gradient(135deg, #6C7AE0, #98A4F0); }
.st-stroke-name {
    font-size: 1.18rem;
    font-weight: 800;
    color: var(--st-ink);
    margin-bottom: 2px;
}
.st-stroke-en {
    font-size: 0.62rem;
    letter-spacing: 2.5px;
    color: var(--st-sub);
    font-weight: 600;
    margin-bottom: 10px;
}
.st-stroke-desc {
    font-size: 0.82rem;
    color: var(--st-sub);
    line-height: 1.55;
}

/* —— 已选回显条 —— */
.st-picked {
    display: flex;
    align-items: center;
    justify-content: space-between;
    max-width: 860px;
    margin: 0 auto 22px;
    background: linear-gradient(135deg, rgba(0,174,214,0.08), rgba(51,191,227,0.06));
    border: 1px solid rgba(0, 174, 214, 0.22);
    border-radius: 14px;
    padding: 12px 18px;
    cursor: pointer;
    transition: all 0.25s;
}
.st-picked:hover { border-color: var(--st-primary); }
.st-picked-label {
    font-weight: 800;
    color: var(--st-primary-dark);
    font-size: 1rem;
}
.st-picked-change {
    font-size: 0.82rem;
    color: var(--st-sub);
}
.st-picked-change::before { content: "↺ "; }

/* —— 部位/类型卡片 —— */
.st-part-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 14px;
    max-width: 860px;
    margin: 0 auto;
}
.st-part-card {
    background: var(--st-card);
    border: 1.5px solid var(--st-border);
    border-radius: 16px;
    padding: 20px 12px 16px;
    cursor: pointer;
    text-align: center;
    transition: all 0.25s cubic-bezier(0.22, 0.61, 0.36, 1);
    box-shadow: var(--st-shadow);
    font-family: inherit;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 6px;
}
.st-part-card:hover {
    transform: translateY(-3px);
    border-color: rgba(0, 174, 214, 0.5);
    box-shadow: var(--st-shadow-lg);
}
.st-part-card.picked {
    border-color: var(--st-primary);
    background: linear-gradient(160deg, rgba(0,174,214,0.07), #fff 70%);
    box-shadow: 0 0 0 3px rgba(0, 174, 214, 0.15), var(--st-shadow);
}
.st-part-all { border-style: dashed; }
.st-part-all.picked { border-style: solid; }
.st-part-icon { font-size: 1.7rem; line-height: 1; }
.st-part-name {
    font-size: 0.95rem;
    font-weight: 700;
    color: var(--st-ink);
}
.st-part-en {
    font-size: 0.55rem;
    letter-spacing: 1.5px;
    color: #AEC8D4;
    font-weight: 600;
}

/* —— 年龄大卡片 —— */
.st-age-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 16px;
    max-width: 860px;
    margin: 0 auto;
}
.st-age-card {
    background: var(--st-card);
    border: 1.5px solid var(--st-border);
    border-radius: var(--st-radius);
    padding: 28px 20px 22px;
    cursor: pointer;
    text-align: center;
    transition: all 0.28s cubic-bezier(0.22, 0.61, 0.36, 1);
    box-shadow: var(--st-shadow);
    font-family: inherit;
    position: relative;
    overflow: hidden;
}
.st-age-card::before {
    content: "";
    position: absolute;
    top: 0; left: 0; right: 0;
    height: 4px;
    background: var(--st-grad);
    opacity: 0;
    transition: opacity 0.3s;
}
.st-age-card:hover { transform: translateY(-5px); box-shadow: var(--st-shadow-lg); border-color: rgba(0,174,214,0.5); }
.st-age-card:hover::before { opacity: 1; }
.st-age-card.picked { border-color: var(--st-primary); box-shadow: 0 0 0 3px rgba(0,174,214,0.18), var(--st-shadow-lg); }
.st-age-card.picked::before { opacity: 1; }
.st-age-num {
    font-size: 2rem;
    font-weight: 800;
    background: var(--st-grad);
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
    line-height: 1.1;
}
.st-age-num small { font-size: 0.95rem; font-weight: 700; margin-left: 2px; }
.st-age-name {
    font-size: 1.05rem;
    font-weight: 800;
    color: var(--st-ink);
    margin: 8px 0 6px;
}
.st-age-desc {
    font-size: 0.8rem;
    color: var(--st-sub);
    line-height: 1.55;
}

/* —— 视频区 —— */
.st-video-head {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 20px;
}
.st-video-head .st-q { margin-bottom: 0; text-align: left; }
.st-back-btn {
    background: #fff;
    border: 1.5px solid var(--st-border);
    border-radius: 100px;
    padding: 9px 18px;
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--st-sub);
    cursor: pointer;
    transition: all 0.25s;
    font-family: inherit;
    flex-shrink: 0;
}
.st-back-btn:hover { border-color: var(--st-primary); color: var(--st-primary-dark); }
.st-videos {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 20px;
    max-width: 1100px;
    margin: 0 auto;
}
.st-video-card {
    background: var(--st-card);
    border-radius: var(--st-radius);
    overflow: hidden;
    box-shadow: var(--st-shadow);
    border: 1px solid var(--st-border);
    transition: all 0.3s;
    animation: stFadeUp 0.5s cubic-bezier(0.22, 0.61, 0.36, 1) both;
}
.st-video-card:hover { transform: translateY(-4px); box-shadow: var(--st-shadow-lg); }
.st-video-player {
    background: #0F2733;
    aspect-ratio: 16/9;
    position: relative;
}
.st-video-player video, .st-video-player iframe {
    width: 100%;
    height: 100%;
    display: block;
}
.st-video-none {
    position: absolute;
    inset: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    color: rgba(255,255,255,0.5);
    font-size: 0.9rem;
}
.st-video-info { padding: 16px 18px 18px; }
.st-video-badge {
    display: inline-block;
    font-size: 0.68rem;
    font-weight: 700;
    letter-spacing: 1px;
    color: var(--st-primary-dark);
    background: rgba(0, 174, 214, 0.10);
    padding: 3px 10px;
    border-radius: 100px;
    margin-bottom: 8px;
}
.st-badge-warm { color: #C77A00; background: rgba(255, 166, 43, 0.14); }
.st-video-info h4 {
    font-size: 1.02rem;
    font-weight: 700;
    color: var(--st-ink);
    line-height: 1.45;
}
.st-video-info p {
    font-size: 0.83rem;
    color: var(--st-sub);
    margin-top: 4px;
}

/* —— 加载/空状态 —— */
.st-loading, .st-empty {
    grid-column: 1 / -1;
    text-align: center;
    padding: 52px 20px;
    color: var(--st-sub);
    background: var(--st-card);
    border-radius: var(--st-radius);
    border: 1.5px dashed var(--st-border);
}
.st-empty-ico { font-size: 2.2rem; margin-bottom: 10px; }
.st-spinner {
    width: 34px;
    height: 34px;
    border: 3px solid #DCEEF6;
    border-top-color: var(--st-primary);
    border-radius: 50%;
    margin: 0 auto 14px;
    animation: stSpin 0.8s linear infinite;
}
@keyframes stSpin { to { transform: rotate(360deg); } }

/* —— 移动端适配 —— */
@media (max-width: 768px) {
    .st-hero { padding: 34px 0 24px; }
    .st-hero h1 { font-size: 1.55rem; }
    .st-hero p { font-size: 0.92rem; }
    .st-steps-bar { top: 56px; padding: 10px 0; }
    .st-step-label { font-size: 0.78rem; }
    .st-step-num { width: 24px; height: 24px; font-size: 0.78rem; }
    .st-step-line { width: 26px; }
    .st-q { font-size: 1.18rem; margin-bottom: 18px; }
    .st-main { padding: 26px 0 48px; }
    .st-stroke-grid { gap: 12px; }
    .st-stroke-card { padding: 20px 14px 18px; }
    .st-stroke-ico { width: 56px; height: 56px; font-size: 1.6rem; border-radius: 16px; }
    .st-stroke-name { font-size: 1.05rem; }
    .st-stroke-desc { font-size: 0.76rem; }
    .st-part-grid { grid-template-columns: repeat(3, 1fr); gap: 10px; }
    .st-part-card { padding: 16px 8px 12px; border-radius: 14px; }
    .st-part-icon { font-size: 1.5rem; }
    .st-part-name { font-size: 0.85rem; }
    .st-part-en { display: none; }
    .st-age-grid { grid-template-columns: 1fr; gap: 12px; }
    .st-age-card { padding: 20px; display: flex; flex-direction: column; align-items: center; }
    .st-videos { grid-template-columns: 1fr; gap: 16px; }
    .st-video-head { flex-wrap: wrap; gap: 10px; }
    .st-picked { padding: 11px 15px; }
}
@media (max-width: 380px) {
    .st-part-grid { grid-template-columns: repeat(2, 1fr); }
    .st-stroke-grid { grid-template-columns: 1fr; }
}

/* ===== 首页（板块入口）新设计 ===== */
.st-home-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 18px; }
.st-home-card {
    display: flex; align-items: center; gap: 16px;
    background: #fff; border: 1px solid rgba(0, 168, 214, 0.10);
    border-radius: 22px; padding: 26px 22px;
    text-decoration: none; box-shadow: 0 10px 30px rgba(0, 106, 160, 0.08);
    transition: transform 0.25s ease, box-shadow 0.25s ease, border-color 0.25s ease;
    position: relative; overflow: hidden;
}
.st-home-card::after {
    content: ""; position: absolute; left: 0; top: 0; bottom: 0; width: 4px;
    background: linear-gradient(180deg, #00AED6, #0077B6);
    opacity: 0; transition: opacity 0.25s ease;
}
.st-home-card:hover { transform: translateY(-4px); box-shadow: 0 16px 40px rgba(0, 106, 160, 0.16); border-color: rgba(0, 174, 214, 0.35); }
.st-home-card:hover::after { opacity: 1; }
.st-home-ico {
    flex: 0 0 auto; width: 64px; height: 64px; border-radius: 20px;
    display: flex; align-items: center; justify-content: center; font-size: 1.9rem;
    box-shadow: inset 0 0 0 1px rgba(255,255,255,0.25);
}
.st-home-ico-tech { background: linear-gradient(135deg, #E0F6FF, #B3E5F2); }
.st-home-ico-train { background: linear-gradient(135deg, #FFF1DC, #FFE0B2); }
.st-home-body { min-width: 0; }
.st-home-name { font-size: 1.15rem; font-weight: 700; color: #10394A; margin-bottom: 2px; }
.st-home-en { font-size: 0.68rem; letter-spacing: 0.16em; color: #7FA8BC; font-weight: 700; margin-bottom: 8px; }
.st-home-desc { font-size: 0.82rem; color: #5E7B8A; line-height: 1.6; }
.st-home-arrow { margin-left: auto; font-size: 1.2rem; color: #00AED6; font-weight: 700; transition: transform 0.25s ease; }
.st-home-card:hover .st-home-arrow { transform: translateX(4px); }
.st-home-tip {
    margin-top: 22px; display: flex; align-items: center; gap: 10px;
    background: linear-gradient(90deg, rgba(0, 174, 214, 0.08), rgba(255, 193, 7, 0.10));
    border: 1px dashed rgba(0, 168, 214, 0.30); border-radius: 14px;
    padding: 13px 16px; font-size: 0.85rem; color: #46626F;
}
.st-home-tip-ico { font-size: 1.1rem; }
.st-home-coach {
    margin-top: 18px; display: block; text-align: center;
    background: #F4FAFD; border: 1px solid rgba(0, 168, 214, 0.15);
    border-radius: 14px; padding: 13px 16px; font-size: 0.85rem;
    color: #4A7A90; text-decoration: none; transition: background 0.2s ease;
}
.st-home-coach:hover { background: #E8F5FB; }
@media (max-width: 768px) {
    .st-home-grid { grid-template-columns: 1fr; gap: 14px; }
    .st-home-card { padding: 22px 18px; }
    .st-home-ico { width: 56px; height: 56px; font-size: 1.6rem; border-radius: 16px; }
    .st-home-name { font-size: 1.08rem; }
    .st-home-desc { font-size: 0.78rem; }
}

/* —— 手机端导航：汉堡下拉（修复横向溢出） —— */
@media (max-width: 768px) {
    .navbar .nav-links {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        flex-direction: column;
        gap: 0;
        background: linear-gradient(135deg, #0088B8, #00AED6);
        padding: 8px 0;
        box-shadow: 0 10px 24px rgba(0, 60, 90, 0.25);
    }
    .navbar .nav-links.active { display: flex; }
    .navbar .nav-links li { text-align: center; }
    .navbar .nav-links a {
        display: block;
        padding: 13px 0;
        font-size: 1rem;
    }
}
.navbar { position: sticky; }
.navbar .container { position: relative; }