/* ================================
   语知星 - 门户网站样式
   主题色：蓝色 + 绿色
   ================================ */

:root {
    --blue-50: #eff6ff;
    --blue-100: #dbeafe;
    --blue-200: #bfdbfe;
    --blue-400: #60a5fa;
    --blue-500: #3b82f6;
    --blue-600: #2563eb;
    --blue-700: #1d4ed8;
    --blue-800: #1e40af;
    --blue-900: #1e3a5f;

    --green-50: #ecfdf5;
    --green-100: #d1fae5;
    --green-200: #a7f3d0;
    --green-400: #34d399;
    --green-500: #10b981;
    --green-600: #059669;
    --green-700: #047857;

    --teal: #0d9488;
    --teal-light: #14b8a6;

    --gray-50: #f8fafc;
    --gray-100: #f1f5f9;
    --gray-200: #e2e8f0;
    --gray-300: #cbd5e1;
    --gray-400: #94a3b8;
    --gray-500: #64748b;
    --gray-600: #475569;
    --gray-700: #334155;
    --gray-800: #1e293b;
    --gray-900: #0f172a;

    --gradient-blue: linear-gradient(135deg, var(--blue-600), var(--blue-400));
    --gradient-green: linear-gradient(135deg, var(--green-600), var(--green-400));
    --gradient-hero: linear-gradient(135deg, #0a1628 0%, #0d2847 40%, #0a3d2e 100%);
    --gradient-teal: linear-gradient(135deg, var(--blue-600), var(--teal));
    --gradient-card-blue: linear-gradient(135deg, rgba(59,130,246,0.08), rgba(59,130,246,0.02));
    --gradient-card-green: linear-gradient(135deg, rgba(16,185,129,0.08), rgba(16,185,129,0.02));

    --shadow-sm: 0 1px 3px rgba(0,0,0,0.08);
    --shadow-md: 0 4px 20px rgba(0,0,0,0.08);
    --shadow-lg: 0 10px 40px rgba(0,0,0,0.12);
    --shadow-blue: 0 8px 30px rgba(59,130,246,0.25);
    --shadow-green: 0 8px 30px rgba(16,185,129,0.25);

    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 20px;
    --radius-xl: 28px;

    --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-slow: 0.6s cubic-bezier(0.4, 0, 0.2, 1);
}

/* Reset & Base */
*, *::before, *::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
    scroll-padding-top: 80px;
}

body {
    font-family: 'Noto Sans SC', -apple-system, BlinkMacSystemFont, sans-serif;
    color: var(--gray-700);
    background: #fff;
    line-height: 1.7;
    overflow-x: hidden;
}

a {
    text-decoration: none;
    color: inherit;
    transition: color var(--transition);
}

ul { list-style: none; }

img { max-width: 100%; }

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

/* ================================
   导航栏
   ================================ */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    padding: 16px 0;
    transition: all var(--transition);
    background: transparent;
}

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

.navbar.scrolled .nav-logo .logo-text { color: var(--gray-800); }
.navbar.scrolled .nav-links a { color: var(--gray-600); }
.navbar.scrolled .nav-links a:hover { color: var(--blue-600); }
.navbar.scrolled .nav-toggle span { background: var(--gray-700); }

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.nav-logo {
    display: flex;
    align-items: center;
    gap: 8px;
    font-weight: 700;
    font-size: 1.3rem;
}

.logo-icon {
    font-size: 1.6rem;
    background: var(--gradient-teal);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.logo-text {
    color: #fff;
    transition: color var(--transition);
}

.nav-links {
    display: flex;
    gap: 32px;
}

.nav-links a {
    color: rgba(255,255,255,0.85);
    font-size: 0.95rem;
    font-weight: 500;
    position: relative;
    padding: 4px 0;
}

.nav-links a::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--gradient-teal);
    border-radius: 2px;
    transition: width var(--transition);
}

.nav-links a:hover::after,
.nav-links a.active::after {
    width: 100%;
}

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

.nav-toggle span {
    display: block;
    width: 24px;
    height: 2px;
    background: #fff;
    border-radius: 2px;
    transition: var(--transition);
}

/* ================================
   Hero 首屏
   ================================ */
.hero {
    position: relative;
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--gradient-hero);
    overflow: hidden;
}

.hero-particles {
    position: absolute;
    inset: 0;
    pointer-events: none;
}

.particle {
    position: absolute;
    width: 3px;
    height: 3px;
    background: rgba(255,255,255,0.4);
    border-radius: 50%;
    animation: particleFloat linear infinite;
}

@keyframes particleFloat {
    0% { transform: translateY(100vh) scale(0); opacity: 0; }
    10% { opacity: 1; }
    90% { opacity: 1; }
    100% { transform: translateY(-10vh) scale(1); opacity: 0; }
}

.hero-content {
    position: relative;
    z-index: 2;
    text-align: center;
    padding: 0 24px;
}

.hero-title {
    margin-bottom: 20px;
}

.title-line {
    display: block;
    font-size: clamp(2.2rem, 6vw, 4rem);
    font-weight: 900;
    color: #fff;
    line-height: 1.2;
    letter-spacing: -0.02em;
}

.title-line.highlight {
    background: linear-gradient(135deg, var(--blue-400), var(--green-400));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: clamp(1rem, 2.5vw, 1.3rem);
    color: rgba(255,255,255,0.7);
    letter-spacing: 0.2em;
    margin-bottom: 36px;
}

.hero-buttons {
    display: flex;
    gap: 16px;
    justify-content: center;
    margin-bottom: 60px;
    flex-wrap: wrap;
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 14px 36px;
    font-size: 1rem;
    font-weight: 600;
    border-radius: 50px;
    border: none;
    cursor: pointer;
    transition: all var(--transition);
    font-family: inherit;
}

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

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 12px 35px rgba(59,130,246,0.35);
}

.btn-outline {
    background: transparent;
    color: #fff;
    border: 2px solid rgba(255,255,255,0.3);
}

.btn-outline:hover {
    border-color: var(--green-400);
    color: var(--green-400);
    transform: translateY(-2px);
}

.btn-full { width: 100%; }

.hero-stats {
    display: flex;
    gap: 48px;
    justify-content: center;
    flex-wrap: wrap;
}

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

.stat-number {
    font-size: 2.5rem;
    font-weight: 900;
    color: #fff;
    font-variant-numeric: tabular-nums;
}

.stat-suffix {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--blue-400);
}

.stat-label {
    display: block;
    font-size: 0.9rem;
    color: rgba(255,255,255,0.5);
    margin-top: 4px;
}

.hero-scroll-hint {
    position: absolute;
    bottom: 32px;
    left: 50%;
    transform: translateX(-50%);
    text-align: center;
    color: rgba(255,255,255,0.4);
    font-size: 0.8rem;
    animation: fadeInUp 1s ease 2s both;
}

.scroll-arrow {
    width: 20px;
    height: 20px;
    border-right: 2px solid rgba(255,255,255,0.3);
    border-bottom: 2px solid rgba(255,255,255,0.3);
    transform: rotate(45deg);
    margin: 8px auto 0;
    animation: scrollBounce 2s ease infinite;
}

@keyframes scrollBounce {
    0%, 100% { transform: rotate(45deg) translateY(0); }
    50% { transform: rotate(45deg) translateY(8px); }
}

/* ================================
   通用 Section
   ================================ */
.section {
    padding: 100px 0;
}

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

.section-tag {
    display: inline-block;
    font-size: 0.8rem;
    font-weight: 700;
    letter-spacing: 0.2em;
    color: var(--blue-600);
    background: var(--blue-50);
    padding: 6px 16px;
    border-radius: 50px;
    margin-bottom: 16px;
}

.section-title {
    font-size: clamp(1.8rem, 4vw, 2.5rem);
    font-weight: 800;
    color: var(--gray-900);
    margin-bottom: 12px;
}

.section-desc {
    font-size: 1.05rem;
    color: var(--gray-500);
    max-width: 560px;
    margin: 0 auto;
}

/* ================================
   关于我们
   ================================ */
.about { background: var(--gray-50); }

.about-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 32px;
}

.about-card {
    background: #fff;
    padding: 40px 32px;
    border-radius: var(--radius-lg);
    text-align: center;
    transition: all var(--transition);
    border: 1px solid var(--gray-100);
}

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

.about-icon {
    width: 64px;
    height: 64px;
    margin: 0 auto 20px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: var(--radius-md);
    color: var(--blue-600);
    background: var(--gradient-card-blue);
    transition: all var(--transition);
}

.about-card:hover .about-icon {
    background: var(--gradient-teal);
    color: #fff;
}

.about-card h3 {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--gray-800);
    margin-bottom: 12px;
}

.about-card p {
    font-size: 0.95rem;
    color: var(--gray-500);
    line-height: 1.7;
}

/* ================================
   知识资源
   ================================ */
.resources { background: #fff; }

/* 学段切换 */
.phase-tabs {
    display: flex;
    justify-content: center;
    gap: 8px;
    margin-bottom: 40px;
}

.phase-tab {
    padding: 12px 36px;
    font-size: 1rem;
    font-weight: 600;
    font-family: inherit;
    border: 2px solid var(--gray-200);
    border-radius: 50px;
    background: #fff;
    color: var(--gray-500);
    cursor: pointer;
    transition: all var(--transition);
}

.phase-tab:hover {
    border-color: var(--blue-300);
    color: var(--blue-600);
}

.phase-tab.active {
    background: var(--gradient-teal);
    border-color: transparent;
    color: #fff;
    box-shadow: var(--shadow-blue);
}

.phase-content {
    display: none;
}

.phase-content.active {
    display: block;
    animation: fadeInUp 0.5s ease;
}

.resource-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 24px;
}

.resource-card {
    padding: 28px 24px;
    border-radius: var(--radius-lg);
    background: var(--gray-50);
    border: 1px solid var(--gray-100);
    transition: all var(--transition);
}

.resource-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-md);
    background: #fff;
}

.resource-icon {
    width: 48px;
    height: 48px;
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 16px;
}

.resource-icon.icon-blue {
    color: var(--blue-600);
    background: var(--gradient-card-blue);
}

.resource-icon.icon-green {
    color: var(--green-600);
    background: var(--gradient-card-green);
}

.resource-icon.icon-teal {
    color: var(--teal);
    background: linear-gradient(135deg, rgba(13,148,136,0.08), rgba(13,148,136,0.02));
}

.resource-card h4 {
    font-size: 1.05rem;
    font-weight: 700;
    color: var(--gray-800);
    margin-bottom: 8px;
}

.resource-card p {
    font-size: 0.88rem;
    color: var(--gray-500);
    line-height: 1.7;
    margin-bottom: 14px;
}

.resource-count {
    display: inline-block;
    font-size: 0.8rem;
    font-weight: 700;
    color: var(--blue-600);
    background: var(--blue-50);
    padding: 4px 12px;
    border-radius: 50px;
}

.resource-icon.icon-green + h4 ~ .resource-count {
    color: var(--green-600);
    background: var(--green-50);
}

/* ================================
   共建生态
   ================================ */
.co-creation { background: var(--gray-50); }

.cocreation-flow {
    max-width: 800px;
    margin: 0 auto 60px;
    display: flex;
    flex-direction: column;
    gap: 0;
}

.cocreation-step {
    display: flex;
    align-items: flex-start;
    gap: 24px;
    position: relative;
    padding-bottom: 40px;
}

.cocreation-step:last-child { padding-bottom: 0; }

.cocreation-step .step-number {
    flex-shrink: 0;
    width: 56px;
    height: 56px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.1rem;
    font-weight: 800;
    color: #fff;
    background: var(--gradient-teal);
    position: relative;
    z-index: 2;
}

.cocreation-step .step-connector {
    position: absolute;
    left: 28px;
    top: 56px;
    width: 2px;
    bottom: 0;
    background: linear-gradient(to bottom, var(--blue-300), var(--green-300));
}

.cocreation-step:last-child .step-connector { display: none; }

.cocreation-step .step-content h4 {
    font-size: 1.15rem;
    font-weight: 700;
    color: var(--gray-800);
    margin-bottom: 6px;
}

.cocreation-step .step-content p {
    color: var(--gray-500);
    font-size: 0.95rem;
}

/* 共建数据面板 */
.cocreation-stats {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 28px;
}

.cocreation-stat {
    text-align: center;
    padding: 36px 20px;
    border-radius: var(--radius-lg);
    background: #fff;
    border: 1px solid var(--gray-100);
    transition: all var(--transition);
}

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

.cocreation-ring {
    position: relative;
    width: 120px;
    height: 120px;
    margin: 0 auto 16px;
}

.cocreation-ring svg {
    width: 100%;
    height: 100%;
    transform: rotate(-90deg);
}

.ring-bg {
    fill: none;
    stroke: var(--gray-200);
    stroke-width: 8;
}

.ring-fill {
    fill: none;
    stroke-width: 8;
    stroke-linecap: round;
    stroke-dasharray: 314;
    stroke-dashoffset: 314;
    transition: stroke-dashoffset 1.5s cubic-bezier(0.4, 0, 0.2, 1);
}

.ring-fill.animated { stroke-dashoffset: var(--offset); }

.ring-blue { stroke: var(--blue-500); }
.ring-green { stroke: var(--green-500); }
.ring-teal { stroke: var(--teal-light); }

.ring-text {
    position: absolute;
    inset: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    font-weight: 800;
    color: var(--gray-800);
}

.cocreation-stat h4 {
    font-size: 1.05rem;
    font-weight: 700;
    color: var(--gray-800);
    margin-bottom: 6px;
}

.cocreation-stat p {
    font-size: 0.85rem;
    color: var(--gray-500);
}

/* ================================
   平台特色
   ================================ */
.platform { background: #fff; }

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

.feature-card {
    padding: 36px 28px;
    border-radius: var(--radius-lg);
    background: var(--gray-50);
    border: 1px solid var(--gray-100);
    transition: all var(--transition);
}

.feature-card:hover {
    transform: translateY(-6px);
    box-shadow: var(--shadow-lg);
    background: #fff;
}

.feature-icon {
    width: 56px;
    height: 56px;
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 20px;
}

.feature-icon.icon-blue {
    color: var(--blue-600);
    background: var(--gradient-card-blue);
}

.feature-icon.icon-green {
    color: var(--green-600);
    background: var(--gradient-card-green);
}

.feature-icon.icon-teal {
    color: var(--teal);
    background: linear-gradient(135deg, rgba(13,148,136,0.08), rgba(13,148,136,0.02));
}

.feature-card h3 {
    font-size: 1.15rem;
    font-weight: 700;
    color: var(--gray-800);
    margin-bottom: 10px;
}

.feature-card p {
    font-size: 0.92rem;
    color: var(--gray-500);
    line-height: 1.7;
}

/* ================================
   教师风采（轮播）
   ================================ */
.teachers { background: var(--gray-50); }

.testimonial-slider {
    overflow: hidden;
    position: relative;
}

.testimonial-track {
    display: flex;
    transition: transform 0.5s cubic-bezier(0.4, 0, 0.2, 1);
}

.testimonial-card {
    flex: 0 0 100%;
    padding: 0 20px;
}

@media (min-width: 768px) {
    .testimonial-card { flex: 0 0 50%; }
}

@media (min-width: 1024px) {
    .testimonial-card { flex: 0 0 33.333%; }
}

.testimonial-card > * {
    background: #fff;
    border-radius: var(--radius-lg);
    padding: 32px;
    border: 1px solid var(--gray-100);
    height: 100%;
}

.testimonial-quote {
    font-size: 3rem;
    line-height: 1;
    background: var(--gradient-teal) !important;
    -webkit-background-clip: text !important;
    -webkit-text-fill-color: transparent !important;
    background-clip: text !important;
    margin-bottom: -10px;
    padding: 0 !important;
    border: none !important;
}

.testimonial-card p {
    font-size: 0.95rem;
    color: var(--gray-600);
    line-height: 1.8;
    margin-bottom: 20px;
    background: none !important;
    padding: 0 !important;
    border: none !important;
}

.testimonial-author {
    display: flex;
    align-items: center;
    gap: 12px;
    background: none !important;
    padding: 0 !important;
    border: none !important;
}

.author-avatar {
    width: 44px;
    height: 44px;
    border-radius: 50%;
    background: var(--gradient-teal);
    color: #fff;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 1.1rem;
    flex-shrink: 0;
}

.testimonial-author strong {
    display: block;
    font-size: 0.95rem;
    color: var(--gray-800);
}

.testimonial-author span {
    font-size: 0.8rem;
    color: var(--gray-400);
}

.testimonial-controls {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 16px;
    margin-top: 32px;
}

.slider-btn {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    border: 1px solid var(--gray-200);
    background: #fff;
    cursor: pointer;
    font-size: 1.2rem;
    color: var(--gray-600);
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all var(--transition);
}

.slider-btn:hover {
    background: var(--blue-600);
    color: #fff;
    border-color: var(--blue-600);
}

.slider-dots {
    display: flex;
    gap: 8px;
}

.slider-dot {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background: var(--gray-300);
    border: none;
    cursor: pointer;
    transition: all var(--transition);
}

.slider-dot.active {
    background: var(--blue-600);
    width: 24px;
    border-radius: 4px;
}

/* ================================
   联系我们
   ================================ */
.contact { background: #fff; }

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

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

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

.contact-icon {
    width: 48px;
    height: 48px;
    flex-shrink: 0;
    border-radius: var(--radius-md);
    background: var(--gradient-card-blue);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--blue-600);
}

.contact-item h4 {
    font-size: 1rem;
    font-weight: 700;
    color: var(--gray-800);
    margin-bottom: 2px;
}

.contact-item p {
    font-size: 0.9rem;
    color: var(--gray-500);
}

.contact-form-wrapper {
    background: var(--gray-50);
    border-radius: var(--radius-lg);
    padding: 36px;
    border: 1px solid var(--gray-100);
}

.contact-form {
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.form-group input,
.form-group select,
.form-group textarea {
    width: 100%;
    padding: 14px 18px;
    font-size: 0.95rem;
    font-family: inherit;
    border: 1px solid var(--gray-200);
    border-radius: var(--radius-sm);
    background: #fff;
    color: var(--gray-700);
    transition: border-color var(--transition), box-shadow var(--transition);
    outline: none;
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
    border-color: var(--blue-400);
    box-shadow: 0 0 0 3px rgba(59,130,246,0.1);
}

.form-group textarea { resize: vertical; }

.form-group select {
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath d='M6 8L1 3h10z' fill='%2394a3b8'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 16px center;
    padding-right: 40px;
}

/* ================================
   页脚
   ================================ */
.footer {
    background: var(--gray-900);
    color: var(--gray-400);
    padding: 60px 0 0;
}

.footer-grid {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr;
    gap: 48px;
    margin-bottom: 40px;
}

.footer-logo {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 1.3rem;
    font-weight: 700;
    color: #fff;
    margin-bottom: 12px;
}

.footer-brand p {
    font-size: 0.9rem;
    line-height: 1.8;
}

.footer-links h4 {
    font-size: 1rem;
    font-weight: 700;
    color: #fff;
    margin-bottom: 16px;
}

.footer-links li { margin-bottom: 10px; }

.footer-links a {
    font-size: 0.9rem;
    color: var(--gray-400);
    transition: color var(--transition);
}

.footer-links a:hover { color: var(--blue-400); }

.footer-bottom {
    border-top: 1px solid rgba(255,255,255,0.08);
    padding: 20px 0;
    text-align: center;
    font-size: 0.85rem;
}

.footer-bottom a {
    color: var(--gray-400);
    transition: color var(--transition);
}

.footer-bottom a:hover { color: var(--blue-400); }

/* ================================
   回到顶部
   ================================ */
.back-to-top {
    position: fixed;
    bottom: 32px;
    right: 32px;
    width: 48px;
    height: 48px;
    border-radius: 50%;
    background: var(--gradient-teal);
    color: #fff;
    border: none;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    transform: translateY(20px);
    transition: all var(--transition);
    z-index: 999;
    box-shadow: var(--shadow-blue);
}

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

.back-to-top:hover {
    transform: translateY(-3px);
    box-shadow: 0 12px 35px rgba(59,130,246,0.4);
}

.back-to-top svg { width: 20px; height: 20px; }

/* ================================
   动画
   ================================ */
@keyframes fadeInUp {
    from { opacity: 0; transform: translateY(30px); }
    to { opacity: 1; transform: translateY(0); }
}

.animate-fade-up {
    opacity: 0;
    animation: fadeInUp 0.8s ease forwards;
}

.delay-1 { animation-delay: 0.2s; }
.delay-2 { animation-delay: 0.4s; }
.delay-3 { animation-delay: 0.6s; }

.animate-on-scroll {
    opacity: 0;
    transform: translateY(40px);
    transition: all 0.8s cubic-bezier(0.4, 0, 0.2, 1);
}

.animate-on-scroll.visible {
    opacity: 1;
    transform: translateY(0);
}

/* ================================
   响应式
   ================================ */
@media (max-width: 1024px) {
    .resource-grid { grid-template-columns: repeat(2, 1fr); }
    .feature-grid { grid-template-columns: repeat(2, 1fr); }
    .cocreation-stats { grid-template-columns: repeat(2, 1fr); }
    .footer-grid { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 768px) {
    .nav-links { display: none; }
    .nav-links.open {
        display: flex;
        flex-direction: column;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background: rgba(255,255,255,0.98);
        backdrop-filter: blur(20px);
        padding: 20px 24px;
        gap: 12px;
        box-shadow: var(--shadow-md);
    }
    .nav-links.open a { color: var(--gray-700); }
    .nav-links.open a:hover { color: var(--blue-600); }
    .nav-toggle { display: flex; }

    .section { padding: 72px 0; }

    .about-grid { grid-template-columns: 1fr; }
    .resource-grid { grid-template-columns: 1fr 1fr; }
    .feature-grid { grid-template-columns: 1fr; }
    .cocreation-stats { grid-template-columns: 1fr 1fr; }
    .contact-grid { grid-template-columns: 1fr; gap: 40px; }
    .footer-grid { grid-template-columns: 1fr; gap: 32px; }

    .hero-stats { gap: 28px; }
    .stat-number { font-size: 2rem; }

    .cocreation-step { gap: 16px; }
    .cocreation-step .step-number { width: 44px; height: 44px; font-size: 0.95rem; }
    .cocreation-step .step-connector { left: 22px; }

    .phase-tabs { flex-wrap: wrap; }
}

@media (max-width: 480px) {
    .resource-grid { grid-template-columns: 1fr; }
    .cocreation-stats { grid-template-columns: 1fr; }
    .hero-buttons { flex-direction: column; align-items: center; }
    .hero-stats { flex-direction: column; gap: 20px; }
    .testimonial-card { padding: 0 8px; }
    .phase-tab { padding: 10px 24px; font-size: 0.9rem; }
}