:root {
    --canvas: #ffffff;
    --canvas-alt: #f5f5f7;
    --ink: #1d1d1f;
    --ink-soft: #6e6e73;
    --ink-faint: #86868b;
    --line: #d2d2d7;
    --accent: #0071e3;
    --accent-hover: #0077ed;
    --link: #0066cc;
    --on-accent: #ffffff;
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 18px;
    --radius-xl: 28px;
    --pill: 980px;
    --container: 980px;
    --shadow-sm: 0 4px 20px rgba(0, 0, 0, 0.07);
    --shadow-md: 0 12px 36px rgba(0, 0, 0, 0.10);
    --ease: cubic-bezier(0.25, 0.1, 0.25, 1);
}

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

html {
    scroll-behavior: smooth;
    scroll-padding-top: 64px;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "SF Pro Display", "SF Pro Text",
        "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Segoe UI", sans-serif;
    color: var(--ink);
    background: var(--canvas);
    line-height: 1.47;
    letter-spacing: -0.01em;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

a {
    color: inherit;
    text-decoration: none;
    transition: color 0.22s var(--ease);
}

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

/* ---------- Text wrapping ---------- */

h1,
h2,
h3 {
    text-wrap: balance;
}

p,
li,
dd {
    text-wrap: pretty;
}

/* 不让关键短语在词中间断行 */
.nw {
    white-space: nowrap;
}


.container {
    width: min(var(--container), calc(100vw - 44px));
    margin: 0 auto;
}

a:focus-visible,
button:focus-visible {
    outline: 2px solid var(--accent);
    outline-offset: 3px;
    border-radius: 4px;
}

/* ---------- Navigation ---------- */

.nav-wrap {
    position: sticky;
    top: 0;
    z-index: 50;
    background: rgba(255, 255, 255, 0.8);
    -webkit-backdrop-filter: saturate(180%) blur(20px);
    backdrop-filter: saturate(180%) blur(20px);
    border-bottom: 1px solid rgba(0, 0, 0, 0.06);
}

.nav-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 24px;
    height: 52px;
}

.brand {
    display: flex;
    align-items: center;
    gap: 10px;
}

.brand-icon {
    width: 26px;
    height: 26px;
}

.brand-text {
    font-size: 16px;
    font-weight: 600;
}

.nav {
    display: flex;
    flex-wrap: wrap;
    gap: 22px;
}

.nav a {
    font-size: 13px;
    color: var(--ink-soft);
    white-space: nowrap;
}

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

/* ---------- Hero ---------- */

.hero {
    position: relative;
    padding: 112px 0 88px;
    text-align: center;
    overflow: hidden;
}

.hero::after {
    content: "";
    position: absolute;
    top: -240px;
    left: 50%;
    transform: translateX(-50%);
    width: 760px;
    height: 540px;
    border-radius: 50%;
    background: radial-gradient(circle, rgba(0, 113, 227, 0.10) 0%, transparent 68%);
    pointer-events: none;
    z-index: -1;
}

.hero h1 {
    font-size: clamp(34px, 6vw, 56px);
    line-height: 1.08;
    font-weight: 600;
    letter-spacing: -0.015em;
    margin-bottom: 20px;
}

.hero-sub {
    font-size: clamp(17px, 2.2vw, 21px);
    line-height: 1.5;
    color: var(--ink-soft);
    max-width: 700px;
    margin: 0 auto 32px;
    text-wrap: balance;
}

.hero-actions {
    display: flex;
    flex-wrap: wrap;
    gap: 20px;
    justify-content: center;
    align-items: center;
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-height: 44px;
    font-size: 17px;
    transition: background-color 0.22s var(--ease), color 0.22s var(--ease),
        transform 0.22s var(--ease);
}

.btn-primary {
    padding: 0 22px;
    border-radius: var(--pill);
    background: var(--accent);
    color: var(--on-accent);
    font-weight: 500;
}

.btn-primary:hover {
    background: var(--accent-hover);
    color: var(--on-accent);
}

.btn-text {
    color: var(--link);
}

.btn-text:hover {
    text-decoration: underline;
}

/* ---------- Sections ---------- */

.section {
    padding: 96px 0;
}

.section-alt {
    background: var(--canvas-alt);
}

.section-head {
    text-align: center;
    margin-bottom: 56px;
}

.section-head h2 {
    font-size: clamp(28px, 4vw, 40px);
    font-weight: 600;
    letter-spacing: -0.01em;
    line-height: 1.15;
    margin-bottom: 16px;
}

.lede {
    font-size: clamp(17px, 2vw, 19px);
    line-height: 1.55;
    color: var(--ink-soft);
    max-width: 680px;
    margin: 0 auto;
    text-wrap: balance;
}

/* ---------- About ---------- */

.value-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
    gap: 20px;
}

.value-grid-2 {
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    margin-bottom: 44px;
}

.values-title {
    font-size: 20px;
    font-weight: 600;
    margin-bottom: 18px;
}

.value-card {
    background: var(--canvas-alt);
    border-radius: var(--radius-lg);
    padding: 32px 28px;
}

.value-card h3 {
    font-size: 20px;
    font-weight: 600;
    margin-bottom: 12px;
}

.value-card p,
.value-card li {
    color: var(--ink-soft);
    font-size: 16px;
}

.value-card ul {
    padding-left: 18px;
    list-style-type: disc;
}

/* ---------- AI-native ---------- */

.ai-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 20px;
}

.ai-card {
    background: var(--canvas);
    border-radius: var(--radius-lg);
    padding: 32px 28px;
    box-shadow: var(--shadow-sm);
}

.ai-card h3 {
    font-size: 20px;
    font-weight: 600;
    margin-bottom: 12px;
}

.ai-card p {
    color: var(--ink-soft);
    font-size: 16px;
}

/* ---------- Courses ---------- */

.course-series {
    margin-bottom: 56px;
}

.course-series:last-child {
    margin-bottom: 0;
}

.series-title {
    font-size: 24px;
    font-weight: 600;
    letter-spacing: -0.01em;
    margin-bottom: 20px;
}

.course-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 20px;
}

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

.course-card {
    display: flex;
    flex-direction: column;
    background: var(--canvas);
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-sm);
    transition: transform 0.3s var(--ease), box-shadow 0.3s var(--ease);
}

@media (min-width: 601px) {
    .course-card {
        aspect-ratio: 10 / 9;
    }

    /* Descriptive cards in the 2-up grids grow with their text instead of clipping the status line. */
    .course-grid-2 .course-card {
        aspect-ratio: auto;
    }
}

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

.course-card > a {
    display: flex;
    flex-direction: column;
    flex: 1;
}

.course-cover {
    width: 100%;
    height: auto;
    aspect-ratio: 16 / 9;
    object-fit: cover;
    flex: none;
}

.course-info {
    display: flex;
    flex-direction: column;
    flex: 1;
    padding: 20px 22px 22px;
}

.course-info h3 {
    font-size: 19px;
    font-weight: 600;
    margin-bottom: 6px;
}

.course-desc {
    color: var(--ink-soft);
    font-size: 15px;
    line-height: 1.6;
    margin-bottom: 12px;
}

.course-status {
    margin-top: auto;
    font-size: 14px;
    color: var(--ink-soft);
}

.course-status.course-coming {
    color: var(--ink-faint);
}

.course-card-placeholder {
    opacity: 0.62;
    pointer-events: none;
}

.course-placeholder-bg {
    background: linear-gradient(135deg, var(--canvas-alt) 0%, #ececf0 100%);
}

/* ---------- Game teaching courses ---------- */

.game-courses .course-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    justify-content: start;
}

.game-cover-link {
    display: block;
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-sm);
    transition: transform 0.3s var(--ease), box-shadow 0.3s var(--ease);
}

.game-cover-link:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-md);
}

.game-cover {
    display: block;
    width: 100%;
    height: auto;
    aspect-ratio: 1 / 1;
    object-fit: cover;
}

@media (max-width: 900px) {
    .game-courses .course-grid {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }
}

@media (max-width: 600px) {
    .game-courses .course-grid {
        grid-template-columns: 1fr;
    }
}

/* ---------- Business ---------- */

.biz-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 20px;
}

.biz-card {
    display: flex;
    flex-direction: column;
    background: var(--canvas);
    border-radius: var(--radius-lg);
    padding: 32px 28px;
    box-shadow: var(--shadow-sm);
    transition: transform 0.3s var(--ease), box-shadow 0.3s var(--ease);
}

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

.biz-num {
    display: block;
    font-size: 13px;
    font-weight: 600;
    letter-spacing: 0.08em;
    color: var(--accent);
    margin-bottom: 14px;
}

.biz-card h3 {
    font-size: 20px;
    font-weight: 600;
    margin-bottom: 10px;
}

.biz-card p {
    color: var(--ink-soft);
    font-size: 16px;
    margin-bottom: 14px;
}

.biz-more {
    margin-top: auto;
    color: var(--link);
    font-size: 15px;
}

/* ---------- Careers ---------- */

.recruit-card {
    max-width: 640px;
    margin: 0 auto;
    padding: 56px 40px;
    text-align: center;
    background: var(--canvas-alt);
    border-radius: var(--radius-xl);
}

.recruit-card-icon {
    width: 60px;
    height: 60px;
    margin: 0 auto 24px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: var(--radius-md);
    background: var(--canvas);
    color: var(--accent);
}

.recruit-card h3 {
    font-size: 24px;
    font-weight: 600;
    margin-bottom: 12px;
}

.recruit-card p {
    color: var(--ink-soft);
    margin-bottom: 28px;
}

.recruit-mail {
    margin-top: 18px;
    margin-bottom: 0;
    font-size: 14px;
    color: var(--ink-faint);
}

/* ---------- Contact ---------- */

.contact-card {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
    gap: 40px;
    background: var(--canvas-alt);
    border-radius: var(--radius-xl);
    padding: 48px;
}

.contact-card h2 {
    font-size: 20px;
    font-weight: 600;
    margin-bottom: 12px;
}

.contact-card p {
    color: var(--ink-soft);
    font-size: 15px;
}

/* ---------- Footer ---------- */

.footer {
    background: var(--canvas);
    border-top: 1px solid var(--line);
    padding: 40px 0;
}

.footer-inner {
    display: flex;
    flex-direction: column;
    gap: 8px;
    align-items: center;
    text-align: center;
    color: var(--ink-soft);
    font-size: 13px;
}

.footer-brand {
    font-weight: 600;
    color: var(--ink);
    font-size: 14px;
}

/* ---------- Responsive ---------- */

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

@media (max-width: 720px) {
    .nav-inner {
        height: auto;
        padding: 12px 0;
        flex-direction: column;
        align-items: flex-start;
        gap: 12px;
    }

    .nav {
        gap: 12px 18px;
    }

    .hero {
        padding: 72px 0 64px;
    }

    .section {
        padding: 72px 0;
    }

    .section-head {
        margin-bottom: 40px;
    }

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

@media (max-width: 600px) {
    .course-grid {
        grid-template-columns: 1fr;
    }

    .container {
        width: min(100vw - 32px, var(--container));
    }

    .hero h1 {
        letter-spacing: -0.01em;
    }

    .contact-card {
        padding: 32px 24px;
        gap: 28px;
    }

    .recruit-card {
        padding: 40px 24px;
    }
}

@media (prefers-reduced-motion: reduce) {
    html {
        scroll-behavior: auto;
    }

    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}