/* ==================== 全局重置 & 变量 ==================== */
:root {
    --primary: #6366f1;
    --primary-dark: #4f46e5;
    --primary-light: #a5b4fc;
    --secondary: #06b6d4;
    --accent: #f59e0b;
    --bg-light: #f8fafc;
    --bg-dark: #0f172a;
    --text-dark: #1e293b;
    --text-muted: #64748b;
    --text-light: #94a3b8;
    --white: #ffffff;
    --shadow-sm: 0 1px 3px rgba(0,0,0,0.08);
    --shadow-md: 0 4px 20px rgba(0,0,0,0.1);
    --shadow-lg: 0 20px 60px rgba(0,0,0,0.15);
    --radius: 16px;
    --radius-sm: 10px;
    --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    background: var(--bg-light);
    color: var(--text-dark);
    line-height: 1.7;
    overflow-x: hidden;
}

a {
    text-decoration: none;
    color: inherit;
}

ul {
    list-style: none;
}

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

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

.section-padding {
    padding: 100px 0;
}

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

.section-header h2 {
    font-size: 2.5rem;
    font-weight: 800;
    margin-bottom: 12px;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.section-header p {
    font-size: 1.1rem;
    color: var(--text-muted);
    max-width: 500px;
    margin: 0 auto;
}

/* ==================== 按钮 ==================== */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 14px 32px;
    border-radius: 50px;
    font-weight: 600;
    font-size: 1rem;
    border: none;
    cursor: pointer;
    transition: var(--transition);
    text-decoration: none;
}

.btn i {
    font-size: 1.1rem;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    color: var(--white);
    box-shadow: 0 4px 15px rgba(99, 102, 241, 0.4);
}

.btn-primary:hover {
    transform: translateY(-3px);
    box-shadow: 0 8px 30px rgba(99, 102, 241, 0.5);
}

.btn-secondary {
    background: var(--white);
    color: var(--primary);
    border: 2px solid var(--primary);
}

.btn-secondary:hover {
    background: var(--primary);
    color: var(--white);
    transform: translateY(-3px);
}

.btn-block {
    width: 100%;
    justify-content: center;
}

/* ==================== 导航栏 ==================== */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 1000;
    padding: 16px 0;
    transition: var(--transition);
}

.navbar.scrolled {
    background: rgba(255,255,255,0.95);
    backdrop-filter: blur(20px);
    box-shadow: 0 2px 20px rgba(0,0,0,0.08);
    padding: 10px 0;
}

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

.logo {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 1.4rem;
    font-weight: 800;
    color: var(--text-dark);
}

.logo-icon {
    font-size: 1.8rem;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.nav-menu {
    display: flex;
    align-items: center;
    gap: 32px;
}

.nav-menu a {
    font-weight: 500;
    color: var(--text-muted);
    transition: var(--transition);
    position: relative;
    font-size: 0.95rem;
}

.nav-menu a::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--primary);
    transition: var(--transition);
}

.nav-menu a:hover {
    color: var(--primary);
}

.nav-menu a:hover::after {
    width: 100%;
}

.nav-btn {
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    color: var(--white) !important;
    padding: 10px 24px;
    border-radius: 50px;
    font-weight: 600 !important;
}

.nav-btn::after {
    display: none !important;
}

.nav-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 15px rgba(99, 102, 241, 0.4);
}

.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    cursor: pointer;
    padding: 4px;
}

.nav-toggle span {
    display: block;
    width: 28px;
    height: 3px;
    background: var(--text-dark);
    border-radius: 3px;
    transition: var(--transition);
}

/* ==================== Hero ==================== */
.hero {
    padding: 160px 0 100px;
    background: linear-gradient(135deg, #f0f4ff 0%, #e0e7ff 50%, #fce7f3 100%);
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: -50%;
    right: -20%;
    width: 600px;
    height: 600px;
    background: radial-gradient(circle, rgba(99,102,241,0.1) 0%, transparent 70%);
    border-radius: 50%;
}

.hero-container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 60px;
    align-items: center;
}

.hero-badge {
    display: inline-block;
    background: rgba(99,102,241,0.1);
    color: var(--primary);
    padding: 8px 20px;
    border-radius: 50px;
    font-weight: 600;
    font-size: 0.9rem;
    margin-bottom: 20px;
}

.hero-title {
    font-size: 3.2rem;
    font-weight: 800;
    line-height: 1.2;
    margin-bottom: 20px;
    color: var(--text-dark);
}

.hero-title span {
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-description {
    font-size: 1.1rem;
    color: var(--text-muted);
    max-width: 500px;
    margin-bottom: 32px;
    line-height: 1.8;
}

.hero-buttons {
    display: flex;
    gap: 16px;
    margin-bottom: 48px;
}

.hero-stats {
    display: flex;
    gap: 48px;
}

.stat-item {
    text-align: center;
}

.stat-number {
    display: block;
    font-size: 2.2rem;
    font-weight: 800;
    color: var(--primary);
    line-height: 1;
}

.stat-label {
    font-size: 0.9rem;
    color: var(--text-muted);
    margin-top: 4px;
}

.hero-img-wrapper {
    position: relative;
    border-radius: var(--radius);
    overflow: hidden;
    box-shadow: var(--shadow-lg);
}

.hero-img-wrapper img {
    width: 100%;
    height: 450px;
    object-fit: cover;
    transition: var(--transition);
}

.hero-img-wrapper:hover img {
    transform: scale(1.03);
}

.hero-floating-card {
    position: absolute;
    background: var(--white);
    padding: 12px 20px;
    border-radius: 50px;
    box-shadow: var(--shadow-md);
    font-weight: 600;
    font-size: 0.9rem;
    display: flex;
    align-items: center;
    gap: 8px;
    color: var(--primary);
    animation: float 3s ease-in-out infinite;
}

.hero-floating-card i {
    font-size: 1.1rem;
}

.card-1 {
    top: 20px;
    left: -20px;
    animation-delay: 0s;
}

.card-2 {
    bottom: 30px;
    right: -20px;
    animation-delay: 1.5s;
}

@keyframes float {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-10px); }
}

/* ==================== 课程 ==================== */
.courses {
    background: var(--white);
}

.course-filters {
    display: flex;
    justify-content: center;
    gap: 12px;
    margin-bottom: 40px;
    flex-wrap: wrap;
}

.filter-btn {
    padding: 10px 28px;
    border: 2px solid #e2e8f0;
    border-radius: 50px;
    background: transparent;
    font-weight: 500;
    color: var(--text-muted);
    cursor: pointer;
    transition: var(--transition);
    font-size: 0.95rem;
}

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

.filter-btn.active {
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    border-color: transparent;
    color: var(--white);
    box-shadow: 0 4px 15px rgba(99, 102, 241, 0.3);
}

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

.course-card {
    background: var(--white);
    border-radius: var(--radius);
    overflow: hidden;
    box-shadow: var(--shadow-sm);
    border: 1px solid #f1f5f9;
    transition: var(--transition);
    cursor: pointer;
}

.course-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-lg);
    border-color: transparent;
}

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

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

.course-card:hover .course-card-image img {
    transform: scale(1.08);
}

.course-card-badge {
    position: absolute;
    top: 12px;
    left: 12px;
    background: var(--accent);
    color: var(--white);
    padding: 4px 14px;
    border-radius: 50px;
    font-size: 0.8rem;
    font-weight: 600;
}

.course-card-body {
    padding: 24px;
}

.course-card-body h3 {
    font-size: 1.2rem;
    font-weight: 700;
    margin-bottom: 8px;
}

.course-card-body p {
    color: var(--text-muted);
    font-size: 0.9rem;
    margin-bottom: 16px;
    line-height: 1.6;
}

.course-card-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-top: 16px;
    border-top: 1px solid #f1f5f9;
}

.course-duration {
    display: flex;
    align-items: center;
    gap: 6px;
    color: var(--text-muted);
    font-size: 0.85rem;
}

.course-price {
    font-weight: 700;
    font-size: 1.2rem;
    color: var(--primary);
}

/* ==================== 核心优势 ==================== */
.features {
    background: var(--bg-light);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 28px;
}

.feature-card {
    background: var(--white);
    padding: 36px 28px;
    border-radius: var(--radius);
    box-shadow: var(--shadow-sm);
    border: 1px solid #f1f5f9;
    transition: var(--transition);
    text-align: center;
}

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

.feature-icon {
    width: 64px;
    height: 64px;
    background: linear-gradient(135deg, rgba(99,102,241,0.1), rgba(6,182,212,0.1));
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 20px;
    font-size: 1.6rem;
    color: var(--primary);
    transition: var(--transition);
}

.feature-card:hover .feature-icon {
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    color: var(--white);
}

.feature-card h3 {
    font-size: 1.2rem;
    font-weight: 700;
    margin-bottom: 12px;
}

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

/* ==================== 师资 ==================== */
.teachers {
    background: var(--white);
}

.teacher-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
    gap: 28px;
}

.teacher-card {
    background: var(--bg-light);
    border-radius: var(--radius);
    padding: 32px 24px;
    text-align: center;
    transition: var(--transition);
    border: 1px solid transparent;
}

.teacher-card:hover {
    background: var(--white);
    box-shadow: var(--shadow-md);
    border-color: #f1f5f9;
    transform: translateY(-4px);
}

.teacher-avatar {
    width: 100px;
    height: 100px;
    border-radius: 50%;
    object-fit: cover;
    margin: 0 auto 16px;
    border: 4px solid var(--primary-light);
    transition: var(--transition);
}

.teacher-card:hover .teacher-avatar {
    border-color: var(--primary);
    transform: scale(1.05);
}

.teacher-card h4 {
    font-size: 1.1rem;
    font-weight: 700;
    margin-bottom: 4px;
}

.teacher-title {
    color: var(--primary);
    font-weight: 500;
    font-size: 0.9rem;
    margin-bottom: 12px;
}

.teacher-desc {
    color: var(--text-muted);
    font-size: 0.88rem;
    line-height: 1.6;
}

/* ==================== 学员口碑 ==================== */
.testimonials {
    background: linear-gradient(135deg, #eef2ff, #f0fdf4);
}

.testimonial-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: 28px;
}

.testimonial-card {
    background: var(--white);
    border-radius: var(--radius);
    padding: 32px;
    box-shadow: var(--shadow-sm);
    border: 1px solid #f1f5f9;
    transition: var(--transition);
}

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

.testimonial-stars {
    color: var(--accent);
    font-size: 1rem;
    margin-bottom: 16px;
}

.testimonial-text {
    color: var(--text-muted);
    font-size: 0.95rem;
    line-height: 1.8;
    margin-bottom: 20px;
    font-style: italic;
}

.testimonial-author {
    display: flex;
    align-items: center;
    gap: 14px;
}

.testimonial-author img {
    width: 48px;
    height: 48px;
    border-radius: 50%;
    object-fit: cover;
}

.testimonial-author h4 {
    font-size: 1rem;
    font-weight: 600;
}

.testimonial-author span {
    font-size: 0.85rem;
    color: var(--text-light);
}

/* ==================== 联系我们 ==================== */
.contact {
    background: var(--white);
}

.contact-wrapper {
    display: grid;
    grid-template-columns: 1fr 1.5fr;
    gap: 60px;
    align-items: start;
}

.contact-info {
    display: flex;
    flex-direction: column;
    gap: 28px;
}

.contact-item {
    display: flex;
    gap: 16px;
    align-items: flex-start;
}

.contact-item i {
    font-size: 1.6rem;
    color: var(--primary);
    margin-top: 4px;
    width: 40px;
    text-align: center;
}

.contact-item h4 {
    font-weight: 600;
    font-size: 1rem;
    margin-bottom: 4px;
}

.contact-item p {
    color: var(--text-muted);
    font-size: 0.95rem;
    line-height: 1.6;
}

.contact-form {
    background: var(--bg-light);
    padding: 40px;
    border-radius: var(--radius);
    box-shadow: var(--shadow-sm);
}

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

.contact-form input,
.contact-form select,
.contact-form textarea {
    width: 100%;
    padding: 14px 18px;
    border: 2px solid #e2e8f0;
    border-radius: var(--radius-sm);
    font-size: 0.95rem;
    font-family: inherit;
    transition: var(--transition);
    background: var(--white);
    outline: none;
}

.contact-form input:focus,
.contact-form select:focus,
.contact-form textarea:focus {
    border-color: var(--primary);
    box-shadow: 0 0 0 4px rgba(99, 102, 241, 0.1);
}

.contact-form textarea {
    resize: vertical;
    margin-bottom: 16px;
}

/* ==================== 页脚 ==================== */
.footer {
    background: var(--bg-dark);
    color: var(--white);
    padding: 80px 0 0;
}

.footer-container {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1.5fr;
    gap: 48px;
    padding-bottom: 48px;
    border-bottom: 1px solid rgba(255,255,255,0.1);
}

.footer-about h3 {
    font-size: 1.3rem;
    font-weight: 700;
    margin-bottom: 16px;
}

.footer-about p {
    color: var(--text-light);
    font-size: 0.95rem;
    line-height: 1.8;
    margin-bottom: 20px;
}

.footer-social {
    display: flex;
    gap: 12px;
}

.footer-social a {
    width: 42px;
    height: 42px;
    background: rgba(255,255,255,0.08);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--white);
    transition: var(--transition);
    font-size: 1.2rem;
}

.footer-social a:hover {
    background: var(--primary);
    transform: translateY(-3px);
}

.footer-links h4 {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 20px;
    color: var(--white);
}

.footer-links ul li {
    margin-bottom: 12px;
}

.footer-links ul li a {
    color: var(--text-light);
    transition: var(--transition);
    font-size: 0.9rem;
}

.footer-links ul li a:hover {
    color: var(--primary-light);
    padding-left: 4px;
}

.footer-newsletter h4 {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 12px;
}

.footer-newsletter p {
    color: var(--text-light);
    font-size: 0.9rem;
    margin-bottom: 16px;
}

.qrcode-placeholder {
    width: 120px;
    height: 120px;
    background: rgba(255,255,255,0.06);
    border-radius: var(--radius-sm);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 8px;
    color: var(--text-light);
    font-size: 0.85rem;
    border: 2px dashed rgba(255,255,255,0.15);
}

.qrcode-placeholder i {
    font-size: 2rem;
}

.footer-bottom {
    text-align: center;
    padding: 24px 0;
    color: var(--text-light);
    font-size: 0.9rem;
}

/* ==================== 回到顶部 ==================== */
.back-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 48px;
    height: 48px;
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    color: var(--white);
    border: none;
    border-radius: 50%;
    font-size: 1.2rem;
    cursor: pointer;
    box-shadow: 0 4px 15px rgba(99, 102, 241, 0.4);
    opacity: 0;
    visibility: hidden;
    transform: translateY(20px);
    transition: var(--transition);
    z-index: 999;
}

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

.back-to-top:hover {
    transform: translateY(-4px);
    box-shadow: 0 8px 30px rgba(99, 102, 241, 0.5);
}

/* ==================== Toast 通知 ==================== */
.toast {
    position: fixed;
    top: 100px;
    right: 30px;
    background: var(--white);
    padding: 16px 28px;
    border-radius: var(--radius-sm);
    box-shadow: var(--shadow-lg);
    display: flex;
    align-items: center;
    gap: 12px;
    font-weight: 500;
    z-index: 9999;
    transform: translateX(120%);
    transition: var(--transition);
    border-left: 4px solid #10b981;
}

.toast.show {
    transform: translateX(0);
}

.toast-icon {
    font-size: 1.4rem;
    color: #10b981;
}

/* ==================== 响应式 ==================== */
@media (max-width: 1024px) {
    .hero-container {
        grid-template-columns: 1fr;
        text-align: center;
    }

    .hero-description {
        margin: 0 auto 32px;
    }

    .hero-buttons {
        justify-content: center;
    }

    .hero-stats {
        justify-content: center;
    }

    .hero-image {
        order: -1;
    }

    .hero-img-wrapper img {
        height: 300px;
    }

    .features-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .contact-wrapper {
        grid-template-columns: 1fr;
    }

    .footer-container {
        grid-template-columns: 1fr 1fr;
    }
}

@media (max-width: 768px) {
    .section-padding {
        padding: 60px 0;
    }

    .section-header h2 {
        font-size: 2rem;
    }

    .nav-menu {
        position: fixed;
        top: 0;
        right: -100%;
        width: 280px;
        height: 100vh;
        background: var(--white);
        flex-direction: column;
        padding: 80px 32px 32px;
        box-shadow: -10px 0 40px rgba(0,0,0,0.1);
        transition: var(--transition);
        gap: 20px;
        align-items: flex-start;
    }

    .nav-menu.active {
        right: 0;
    }

    .nav-toggle {
        display: flex;
    }

    .nav-toggle.active span:nth-child(1) {
        transform: rotate(45deg) translate(5px, 6px);
    }

    .nav-toggle.active span:nth-child(2) {
        opacity: 0;
    }

    .nav-toggle.active span:nth-child(3) {
        transform: rotate(-45deg) translate(5px, -6px);
    }

    .hero-title {
        font-size: 2.2rem;
    }

    .hero-stats {
        gap: 24px;
        flex-wrap: wrap;
    }

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

    .course-grid {
        grid-template-columns: 1fr;
    }

    .teacher-grid {
        grid-template-columns: 1fr;
    }

    .testimonial-grid {
        grid-template-columns: 1fr;
    }

    .contact-form .form-row {
        grid-template-columns: 1fr;
    }

    .footer-container {
        grid-template-columns: 1fr;
        gap: 32px;
    }

    .back-to-top {
        bottom: 20px;
        right: 20px;
        width: 42px;
        height: 42px;
    }
}

@media (max-width: 480px) {
    .hero-title {
        font-size: 1.8rem;
    }

    .hero-buttons {
        flex-direction: column;
        align-items: center;
    }

    .btn {
        width: 100%;
        justify-content: center;
    }

    .container {
        padding: 0 16px;
    }
}