:root {
    --blue: #2563eb;
    --deep: #0f2b5f;
    --text: #17233c;
    --muted: #64748b;
    --bg: #f5f9ff;
    --card: #fff;
}

* {
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    margin: 0;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Microsoft YaHei", Arial, sans-serif;
    color: var(--text);
    background: linear-gradient(180deg, #f8fbff, #eef6ff);
}

a {
    text-decoration: none;
}

.topbar {
    position: sticky;
    top: 0;
    background: rgba(255,255,255,.92);
    backdrop-filter: blur(10px);
    z-index: 10;
    box-shadow: 0 1px 12px rgba(30,64,175,.08);
}

.nav-wrap {
    max-width: 1180px;
    margin: auto;
    height: 72px;
    padding: 0 24px;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.brand {
    display: flex;
    align-items: center;
    gap: 10px;
    color: #15315f;
    font-weight: 800;
    font-size: 24px;
}

.brand-icon {
    color: var(--blue);
    font-size: 24px;
}

.brand em {
    font-size: 14px;
    color: #7a8aa5;
    font-style: normal;
    font-weight: 500;
}

.nav {
    display: flex;
    gap: 34px;
}

.nav a {
    color: #17233c;
    font-weight: 700;
}

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

.login-btn {
    background: var(--blue);
    color: white;
    padding: 11px 18px;
    border-radius: 8px;
    font-weight: 700;
}

.hero {
    max-width: 1180px;
    margin: 0 auto;
    min-height: 480px;
    padding: 70px 24px 45px;
    display: grid;
    grid-template-columns: 1fr 1fr;
    align-items: center;
    gap: 40px;
}

.hero-text h1 {
    font-size: 46px;
    line-height: 1.2;
    margin: 0 0 22px;
    color: #0f2448;
}

.hero-text p {
    font-size: 18px;
    line-height: 1.9;
    color: #40506b;
    max-width: 580px;
}

.hero-actions {
    display: flex;
    gap: 18px;
    margin-top: 30px;
}

.primary-btn,
.ghost-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-width: 130px;
    height: 48px;
    border-radius: 8px;
    font-weight: 800;
}

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

.ghost-btn {
    color: var(--blue);
    border: 1px solid var(--blue);
    background: white;
}

.hero-img img {
    width: 100%;
    filter: drop-shadow(0 20px 35px rgba(37,99,235,.12));
}

.about,
.courses {
    max-width: 1180px;
    margin: 0 auto;
    padding: 48px 24px;
    text-align: center;
}

.about h2,
.courses h2 {
    font-size: 32px;
    margin: 0 0 12px;
    color: #10264f;
}

.section-desc {
    max-width: 820px;
    margin: 0 auto 36px;
    color: #52627a;
    line-height: 1.9;
}

.features {
    display: grid;
    grid-template-columns: repeat(4,1fr);
    gap: 20px;
}

.feature {
    background: rgba(255,255,255,.78);
    border-radius: 18px;
    padding: 26px;
    box-shadow: 0 10px 35px rgba(30,64,175,.07);
}

.feature span {
    font-size: 34px;
}

.feature h3 {
    margin: 12px 0 8px;
}

.feature p {
    margin: 0;
    color: #64748b;
}

.course-grid {
    display: grid;
    grid-template-columns: repeat(3,1fr);
    gap: 30px;
    text-align: left;
}

.course-card {
    background: white;
    border-radius: 14px;
    overflow: hidden;
    box-shadow: 0 14px 34px rgba(30,64,175,.13);
    transition: .25s;
}

.course-card:hover {
    transform: translateY(-7px);
}

.course-card > img {
    width: 100%;
    height: 190px;
    object-fit: cover;
    display: block;
}

.course-body {
    padding: 22px;
}

.course-body h3 {
    font-size: 22px;
    margin: 0 0 10px;
}

.course-body p {
    color: #58677f;
    line-height: 1.7;
    min-height: 58px;
}

.course-body strong {
    display: block;
    color: #ef4444;
    font-size: 20px;
    margin-bottom: 18px;
}

.card-actions {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 14px;
}

.card-actions button,
.card-actions a {
    height: 44px;
    border-radius: 8px;
    font-weight: 800;
    cursor: pointer;
    text-align: center;
    line-height: 44px;
}

.card-actions button {
    border: 1px solid var(--blue);
    color: var(--blue);
    background: #fff;
}

.card-actions a {
    background: var(--blue);
    color: #fff;
}

.more-btn {
    display: inline-block;
    margin-top: 32px;
    border: 1px solid var(--blue);
    color: var(--blue);
    background: white;
    border-radius: 8px;
    padding: 13px 28px;
    font-weight: 800;
}

.cta {
    margin-top: 20px;
    background: linear-gradient(90deg,#0b5cff,#2563eb);
    color: white;
    padding: 36px calc((100% - 1180px)/2 + 24px);
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.cta div {
    display: flex;
    align-items: center;
    gap: 18px;
}

.cta span {
    font-size: 48px;
}

.cta h2 {
    margin: 0 0 6px;
}

.cta p {
    margin: 0;
    opacity: .9;
}

.cta a {
    background: white;
    color: var(--blue);
    font-weight: 900;
    border-radius: 8px;
    padding: 14px 38px;
}

.footer {
    background: #102033;
    color: #dbeafe;
    padding: 44px calc((100% - 1180px)/2 + 24px) 28px;
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr;
    gap: 30px;
}

.footer strong {
    font-size: 24px;
}

.footer a {
    display: block;
    color: #dbeafe;
    margin: 8px 0;
}

.footer h4 {
    margin: 0 0 12px;
    color: #fff;
}

.copyright {
    grid-column: 1/-1;
    text-align: center;
    border-top: 1px solid rgba(255,255,255,.12);
    padding-top: 22px;
    color: #9fb1cf;
}

/* 弹窗：支持长图上下滚动 */
.modal {
    position: fixed;
    inset: 0;
    background: rgba(5,15,35,.72);
    display: none;
    align-items: flex-start;
    justify-content: center;
    z-index: 99;
    padding: 40px 22px;
    overflow-y: auto;
}

.modal.show {
    display: flex;
}

.modal-card {
    position: relative;
    background: white;
    border-radius: 18px;
    max-width: 900px;
    width: 100%;
    padding: 22px;
    text-align: center;
    box-shadow: 0 24px 70px rgba(0,0,0,.28);
    margin: 0 auto;
}

.modal-card img {
    width: 100%;
    height: auto;
    max-height: none;
    object-fit: contain;
    border-radius: 14px;
    display: block;
}

.modal-card h3 {
    font-size: 26px;
    margin: 18px 0 8px;
}

.modal-card p {
    color: #53627c;
    line-height: 1.8;
}

.modal-close {
    position: absolute;
    right: 16px;
    top: 12px;
    width: 38px;
    height: 38px;
    border: 0;
    border-radius: 50%;
    background: #eff6ff;
    color: #1e40af;
    font-size: 26px;
    cursor: pointer;
    z-index: 100;
}

@media(max-width:900px) {
    .nav {
        display: none;
    }

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

    .hero-text h1 {
        font-size: 36px;
    }

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

    .cta,
    .cta div {
        display: block;
        text-align: center;
    }

    .cta a {
        display: inline-block;
        margin-top: 20px;
    }

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

    .brand em {
        display: none;
    }
}

.feature {
    text-align: left;
    padding: 28px;
}

.feature span {
    display: inline-flex;
    width: 58px;
    height: 58px;
    align-items: center;
    justify-content: center;
    background: #eff6ff;
    border-radius: 50%;
    font-size: 28px;
    margin-bottom: 18px;
}

.feature h3 {
    font-size: 22px;
    color: #10264f;
    margin: 0 0 10px;
}

.feature p {
    font-size: 15px;
    line-height: 1.7;
    color: #64748b;
    margin-bottom: 18px;
}

.feature ul {
    list-style: none;
    padding: 16px 0 0;
    margin: 0;
    border-top: 1px dashed #dbeafe;
}

.feature li {
    font-size: 14px;
    color: #475569;
    line-height: 2;
}

.feature li::before {
    content: "✓";
    color: #2563eb;
    font-weight: 900;
    margin-right: 8px;
}

.coach-team {
    max-width: 1180px;
    margin: 0 auto;
    padding: 70px 24px;
    text-align: center;
}

.coach-team-card {
    margin-top: 40px;
    background: white;
    border-radius: 26px;
    overflow: hidden;
    padding: 18px;
    box-shadow: 0 18px 50px rgba(15,43,95,.08);
}

.coach-team-card img {
    width: 100%;
    display: block;
    border-radius: 18px;
}