/* ============================================================
   学生发展指导平台 · 重新设计的静态页面样式
   设计说明：现代简洁风格，蓝紫主色 + 橙色点缀，卡片化布局
   ============================================================ */

:root {
    --c-primary: #4361ee;
    --c-primary-dark: #3148c7;
    --c-primary-light: #eef1fe;
    --c-accent: #ff7849;
    --c-accent-soft: #fff1ea;
    --c-ink: #1f2540;
    --c-text: #4a5068;
    --c-muted: #8b91a7;
    --c-line: #e7eaf3;
    --c-bg: #f7f9fc;
    --c-white: #ffffff;
    --radius: 14px;
    --shadow-sm: 0 2px 10px rgba(31, 37, 64, 0.06);
    --shadow-md: 0 10px 30px rgba(31, 37, 64, 0.10);
    --shadow-lg: 0 18px 45px rgba(67, 97, 238, 0.18);
    --header-h: 72px;
}

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

html { scroll-behavior: smooth; }

body {
    font-family: "PingFang SC", "Microsoft YaHei", "Hiragino Sans GB", "Helvetica Neue", Arial, sans-serif;
    color: var(--c-text);
    background: var(--c-white);
    line-height: 1.75;
    -webkit-font-smoothing: antialiased;
}

img { display: block; max-width: 100%; }
a { color: inherit; text-decoration: none; transition: color .2s; }
button { font-family: inherit; cursor: pointer; border: none; background: none; }

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

/* ===================== 顶部导航 ===================== */
.site-header {
    position: sticky;
    top: 0;
    z-index: 100;
    background: rgba(255, 255, 255, 0.92);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--c-line);
}

.header-inner {
    max-width: 1320px;
    margin: 0 auto;
    padding: 0 24px;
    height: var(--header-h);
    display: flex;
    align-items: center;
    gap: 32px;
}

.brand img { height: 44px; width: auto; }

.main-nav { flex: 1; }

.nav-list {
    list-style: none;
    display: flex;
    align-items: center;
    gap: 6px;
}

.nav-item { position: relative; }

.nav-item > a {
    display: inline-flex;
    align-items: center;
    height: var(--header-h);
    padding: 0 14px;
    font-size: 15px;
    font-weight: 600;
    color: var(--c-ink);
    position: relative;
    white-space: nowrap;
}

.nav-item > a::after {
    content: "";
    position: absolute;
    left: 14px;
    right: 14px;
    bottom: 14px;
    height: 3px;
    border-radius: 3px;
    background: linear-gradient(90deg, var(--c-primary), var(--c-accent));
    transform: scaleX(0);
    transform-origin: left;
    transition: transform .25s;
}

.nav-item:hover > a,
.nav-item.active > a { color: var(--c-primary); }

.nav-item:hover > a::after,
.nav-item.active > a::after { transform: scaleX(1); }

/* ---- 下拉面板 ---- */
.drop-panel {
    position: absolute;
    top: calc(var(--header-h) - 4px);
    left: 50%;
    transform: translateX(-50%) translateY(8px);
    background: var(--c-white);
    border: 1px solid var(--c-line);
    border-radius: var(--radius);
    box-shadow: var(--shadow-md);
    padding: 20px 24px;
    opacity: 0;
    visibility: hidden;
    transition: opacity .22s, transform .22s, visibility .22s;
    min-width: 320px;
    max-width: 640px;
}

.drop-panel::before {
    content: "";
    position: absolute;
    top: -7px;
    left: 50%;
    width: 12px;
    height: 12px;
    background: var(--c-white);
    border-left: 1px solid var(--c-line);
    border-top: 1px solid var(--c-line);
    transform: translateX(-50%) rotate(45deg);
}

.nav-item:hover .drop-panel,
.nav-item.open .drop-panel {
    opacity: 1;
    visibility: visible;
    transform: translateX(-50%) translateY(0);
}

.drop-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 6px 24px;
    max-width: 560px;
}

.drop-grid.narrow { grid-template-columns: 1fr; max-width: 420px; }

.drop-grid a,
.drop-group a {
    display: block;
    padding: 7px 10px;
    font-size: 14px;
    color: var(--c-text);
    border-radius: 8px;
    white-space: nowrap;
}

.drop-grid a:hover,
.drop-group a:hover {
    background: var(--c-primary-light);
    color: var(--c-primary);
}

.drop-cols { display: flex; gap: 36px; }

.drop-group { min-width: 190px; }

.drop-title {
    font-size: 14px;
    font-weight: 700;
    color: var(--c-ink);
    padding: 4px 10px 10px;
    border-bottom: 2px solid var(--c-primary-light);
    margin-bottom: 8px;
}

/* ---- 头部右侧 ---- */
.header-right { display: flex; align-items: center; gap: 14px; }

.btn-contact {
    display: inline-flex;
    align-items: center;
    padding: 9px 26px;
    border-radius: 999px;
    background: linear-gradient(135deg, var(--c-primary), #6a5af9);
    color: #fff;
    font-size: 15px;
    font-weight: 600;
    letter-spacing: 2px;
    box-shadow: var(--shadow-lg);
    transition: transform .2s, box-shadow .2s;
}

.btn-contact:hover { transform: translateY(-2px); box-shadow: 0 22px 50px rgba(67, 97, 238, 0.3); }

.nav-toggle { display: none; flex-direction: column; gap: 5px; padding: 8px; }
.nav-toggle span { width: 24px; height: 3px; border-radius: 2px; background: var(--c-ink); transition: .3s; }

/* ===================== 首页横幅 ===================== */
.hero { position: relative; overflow: hidden; }

.hero-img { width: 100%; height: 420px; object-fit: cover; }

.hero-overlay {
    position: absolute;
    inset: 0;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    text-align: center;
    padding: 0 24px;
    background: linear-gradient(180deg, rgba(20, 30, 80, 0.25), rgba(20, 30, 80, 0.55));
    color: #fff;
}

.hero-overlay h1 {
    font-size: 46px;
    letter-spacing: 8px;
    text-shadow: 0 4px 18px rgba(0, 0, 0, 0.35);
    margin-bottom: 14px;
}

.hero-overlay p {
    font-size: 18px;
    letter-spacing: 2px;
    opacity: .95;
    text-shadow: 0 2px 10px rgba(0, 0, 0, 0.35);
}

.btn-hero {
    margin-top: 28px;
    padding: 12px 42px;
    border-radius: 999px;
    background: var(--c-accent);
    color: #fff;
    font-size: 16px;
    font-weight: 600;
    letter-spacing: 4px;
    box-shadow: 0 12px 30px rgba(255, 120, 73, 0.45);
    transition: transform .2s, box-shadow .2s;
}

.btn-hero:hover { transform: translateY(-3px); box-shadow: 0 18px 38px rgba(255, 120, 73, 0.55); }

/* ===================== 通用区块 ===================== */
.section { padding: 84px 0; }

.alt-bg { background: var(--c-bg); }

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

.section-title {
    font-size: 30px;
    font-weight: 700;
    color: var(--c-ink);
    letter-spacing: 2px;
}

.section-title img { max-height: 72px; margin: 0 auto; }

.section-divider {
    display: block;
    width: 64px;
    height: 5px;
    margin: 16px auto 0;
    border-radius: 5px;
    background: linear-gradient(90deg, var(--c-primary), var(--c-accent));
}

.section-desc { margin-top: 14px; color: var(--c-muted); font-size: 15px; }

/* ===================== 致老师和同学 ===================== */
.letter-card {
    max-width: 860px;
    margin: 0 auto;
    background: var(--c-white);
    border: 1px solid var(--c-line);
    border-radius: var(--radius);
    box-shadow: var(--shadow-sm);
    padding: 48px 56px;
    font-size: 16px;
    position: relative;
}

.letter-card::before {
    content: "\201C";
    position: absolute;
    top: 6px;
    left: 18px;
    font-size: 84px;
    line-height: 1;
    color: var(--c-primary-light);
    font-family: Georgia, serif;
}

.letter-card p { margin-bottom: 14px; text-indent: 2em; position: relative; }

.letter-salutation { text-indent: 0 !important; font-weight: 600; color: var(--c-ink); }

.letter-sign {
    text-align: right;
    text-indent: 0 !important;
    font-weight: 700;
    color: var(--c-primary);
    margin-top: 24px;
}

/* ===================== 平台服务总览 ===================== */
.service-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
}

.service-card {
    background: var(--c-white);
    border: 1px solid var(--c-line);
    border-radius: var(--radius);
    padding: 32px 28px;
    transition: transform .25s, box-shadow .25s, border-color .25s;
    position: relative;
    overflow: hidden;
}

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

.service-card::after {
    content: "";
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 4px;
    background: linear-gradient(90deg, var(--c-primary), var(--c-accent));
    transform: scaleX(0);
    transform-origin: left;
    transition: transform .3s;
}

.service-card:hover::after { transform: scaleX(1); }

.service-card.wide { grid-column: span 3; display: flex; align-items: center; gap: 24px; }
.service-card.wide p { margin: 0; }

.service-num {
    font-size: 34px;
    font-weight: 800;
    font-style: italic;
    background: linear-gradient(135deg, var(--c-primary), var(--c-accent));
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
    margin-bottom: 10px;
}

.service-card h3 { font-size: 20px; color: var(--c-ink); margin-bottom: 10px; }

.service-card p { font-size: 14px; color: var(--c-muted); }

/* ===================== 产品与服务 ===================== */
.product-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 28px;
}

.product-card {
    position: relative;
    border-radius: var(--radius);
    overflow: hidden;
    box-shadow: var(--shadow-sm);
    transition: transform .25s, box-shadow .25s;
    background: var(--c-white);
}

.product-card img { width: 100%; height: auto; }

.product-hover {
    position: absolute;
    inset: auto 0 0 0;
    padding: 12px 0;
    text-align: center;
    background: rgba(67, 97, 238, 0.92);
    color: #fff;
    font-size: 15px;
    letter-spacing: 4px;
    transform: translateY(100%);
    transition: transform .28s;
}

.product-card:hover { transform: translateY(-6px); box-shadow: var(--shadow-md); }
.product-card:hover .product-hover { transform: translateY(0); }

/* ===================== 平台展示 ===================== */
.showcase-frame {
    border-radius: var(--radius);
    overflow: hidden;
    box-shadow: var(--shadow-md);
    border: 8px solid var(--c-white);
    background: var(--c-white);
}

/* ===================== 教师培训轮播 ===================== */
.training {
    background: url("../images/section-bg.png") center / cover no-repeat;
}

.training .section-title { color: var(--c-ink); }

.training-box {
    display: flex;
    align-items: center;
    gap: 48px;
    background: rgba(255, 255, 255, 0.94);
    border-radius: var(--radius);
    box-shadow: var(--shadow-md);
    padding: 44px;
}

.training-left { flex: 0 0 34%; }
.training-left img { border-radius: 10px; }

.training-right { flex: 1; min-width: 0; }

.carousel { position: relative; overflow: hidden; }

.carousel-track {
    display: flex;
    transition: transform .5s ease;
}

.carousel-slide {
    flex: 0 0 33.3333%;
    padding: 0 12px;
}

.carousel-slide img {
    margin: 0 auto;
    border-radius: 10px;
    box-shadow: var(--shadow-sm);
}

.carousel-btn {
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    width: 40px;
    height: 40px;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.95);
    color: var(--c-primary);
    font-size: 16px;
    box-shadow: var(--shadow-sm);
    transition: background .2s, color .2s;
    z-index: 2;
}

.carousel-btn:hover { background: var(--c-primary); color: #fff; }
.carousel-btn.prev { left: 6px; }
.carousel-btn.next { right: 6px; }

.carousel-dots {
    display: flex;
    justify-content: center;
    gap: 8px;
    margin-top: 22px;
}

.carousel-dots button {
    width: 9px;
    height: 9px;
    border-radius: 999px;
    background: #cdd4e8;
    transition: width .25s, background .25s;
}

.carousel-dots button.active { width: 26px; background: var(--c-primary); }

/* ===================== 页脚 ===================== */
.site-footer {
    background: #171c33;
    color: #aab0c7;
    padding: 56px 0 40px;
}

.footer-inner {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
    display: flex;
    gap: 60px;
    align-items: flex-start;
}

.footer-main { flex: 1; }

.footer-links { display: flex; flex-wrap: wrap; align-items: center; gap: 10px; margin-bottom: 26px; }

.footer-links a { font-size: 15px; color: #dfe3f0; }
.footer-links a:hover { color: var(--c-accent); }
.footer-links .dot { color: #4a5170; }

.footer-contact { display: flex; flex-direction: column; gap: 10px; margin-bottom: 26px; }

.contact-item { display: flex; align-items: center; gap: 12px; font-size: 14px; }
.contact-item img { width: 17px; height: auto; opacity: .85; }

.footer-copy { font-size: 13px; color: #767d99; }

.footer-qrcode { text-align: center; flex: 0 0 130px; }
.footer-qrcode img {
    width: 120px;
    height: 120px;
    border-radius: 10px;
    background: #fff;
    padding: 6px;
    margin: 0 auto;
}
.footer-qrcode p { margin-top: 10px; font-size: 13px; }

/* ===================== 联系我们弹窗 ===================== */
.modal-mask {
    position: fixed;
    inset: 0;
    z-index: 200;
    background: rgba(15, 20, 45, 0.55);
    backdrop-filter: blur(4px);
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 24px;
}

.modal-mask[hidden] { display: none; }

.modal-box {
    width: 100%;
    max-width: 400px;
    background: var(--c-white);
    border-radius: 18px;
    padding: 40px 36px 32px;
    position: relative;
    box-shadow: 0 30px 80px rgba(0, 0, 0, 0.3);
    animation: modalIn .28s ease;
}

@keyframes modalIn {
    from { opacity: 0; transform: translateY(18px) scale(.97); }
    to   { opacity: 1; transform: translateY(0) scale(1); }
}

.modal-close { position: absolute; top: 14px; right: 14px; padding: 6px; }
.modal-close img { width: 18px; opacity: .45; transition: opacity .2s; }
.modal-close:hover img { opacity: .9; }

.modal-box h3 {
    font-size: 22px;
    color: var(--c-ink);
    text-align: center;
    margin-bottom: 26px;
}

.form-field { margin-bottom: 18px; }

.form-field label {
    display: block;
    font-size: 14px;
    font-weight: 600;
    color: var(--c-ink);
    margin-bottom: 6px;
}

.form-field label::before {
    content: "*";
    color: var(--c-accent);
    margin-right: 4px;
}

.form-field input {
    width: 100%;
    height: 46px;
    border: 1px solid var(--c-line);
    border-radius: 10px;
    background: var(--c-bg);
    padding: 0 14px;
    font-size: 14px;
    color: var(--c-ink);
    outline: none;
    transition: border-color .2s, background .2s;
}

.form-field input:focus { border-color: var(--c-primary); background: #fff; }

.form-field input.error { border-color: #e5484d; background: #fff5f5; }

.btn-submit {
    width: 100%;
    height: 46px;
    border-radius: 10px;
    background: linear-gradient(135deg, var(--c-primary), #6a5af9);
    color: #fff;
    font-size: 16px;
    font-weight: 600;
    letter-spacing: 8px;
    text-indent: 8px;
    box-shadow: var(--shadow-lg);
    transition: transform .2s, box-shadow .2s;
}

.btn-submit:hover { transform: translateY(-2px); box-shadow: 0 18px 40px rgba(67, 97, 238, 0.32); }

.form-tip { text-align: center; font-size: 13px; margin-top: 18px; color: var(--c-muted); }
.form-tip.success { color: #1a9e5c; font-weight: 600; }
.form-tip.error { color: #e5484d; }

.form-note { text-align: center; font-size: 12px; color: var(--c-muted); margin-top: 10px; opacity: .8; }

/* ===================== 响应式 ===================== */
@media (max-width: 1100px) {
    .nav-item > a { padding: 0 10px; font-size: 14px; }
}

@media (max-width: 960px) {
    :root { --header-h: 60px; }

    .brand img { height: 34px; }

    .nav-toggle { display: flex; }

    .main-nav {
        position: fixed;
        top: var(--header-h);
        left: 0;
        right: 0;
        bottom: 0;
        background: var(--c-white);
        transform: translateX(100%);
        transition: transform .3s;
        overflow-y: auto;
        padding: 16px 20px 40px;
    }

    .main-nav.open { transform: translateX(0); }

    .nav-list { flex-direction: column; align-items: stretch; gap: 0; }

    .nav-item > a {
        height: auto;
        padding: 14px 8px;
        border-bottom: 1px solid var(--c-line);
        display: flex;
        justify-content: space-between;
    }

    .nav-item > a::after { display: none; }

    .drop-panel {
        position: static;
        transform: none;
        opacity: 1;
        visibility: visible;
        box-shadow: none;
        border: none;
        border-radius: 0;
        padding: 4px 8px 12px;
        display: none;
        min-width: 0;
        max-width: none;
        background: var(--c-bg);
        border-radius: 10px;
        margin-bottom: 8px;
    }

    .drop-panel::before { display: none; }

    .nav-item.open .drop-panel { display: block; transform: none; }

    .drop-grid { grid-template-columns: 1fr; }
    .drop-cols { flex-direction: column; gap: 8px; }

    .hero-img { height: 300px; }
    .hero-overlay h1 { font-size: 30px; letter-spacing: 4px; }
    .hero-overlay p { font-size: 14px; }

    .section { padding: 56px 0; }
    .section-title { font-size: 24px; }

    .letter-card { padding: 32px 26px; }

    .service-grid { grid-template-columns: 1fr; }
    .service-card.wide { grid-column: span 1; flex-direction: column; align-items: flex-start; }

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

    .training-box { flex-direction: column; padding: 28px; gap: 28px; }
    .training-left { flex: none; width: 100%; max-width: 420px; }
    .carousel-slide { flex-basis: 50%; }

    .footer-inner { flex-direction: column; gap: 36px; }
    .footer-qrcode { align-self: center; }
}

@media (max-width: 560px) {
    .carousel-slide { flex-basis: 100%; }
    .modal-box { padding: 32px 22px 26px; }
}