/* ============================================================
   YuanLab AI 前台预览版 · 增量样式
   基线：现有站点 style.css / custom.css / theme.css（toutiao-news 主题）
   色板沿用现有主题：米白底 #f5f4ed / 深蓝主色 #1B365D / 墨色 #222226
   新增：暖铜色点缀、首屏、服务区块、FAQ、表单、预览标识
   ============================================================ */

:root {
    --yl-bg: #f5f4ed;
    --yl-card: #faf9f5;
    --yl-ink: #141413;
    --yl-text: #222226;
    --yl-muted: #5e5d59;
    --yl-line: #e8e5da;
    --yl-primary: #1B365D;
    --yl-primary-dark: #142946;
    --yl-soft: #EEF2F7;
    --yl-copper: #9a6a3f;      /* 暖铜色：链接与重点，少量使用 */
    --yl-copper-soft: #f2e9df;
    --yl-warn-bg: #fdf6e7;
    --yl-warn-line: #e5cf9f;
    --yl-warn-ink: #6b5518;
}

/* ---------- 预览版标识横幅 ---------- */
.yl-preview-banner {
    background: var(--yl-warn-bg);
    border-bottom: 1px solid var(--yl-warn-line);
    color: var(--yl-warn-ink);
    font-size: 13px;
    line-height: 1.6;
}
.yl-preview-banner .tt-shell {
    display: flex;
    flex-wrap: wrap;
    gap: 4px 16px;
    padding-top: 8px;
    padding-bottom: 8px;
    align-items: baseline;
}
.yl-preview-banner strong { font-weight: 700; }

/* ---------- 通用 section ---------- */
.yl-section { padding: 56px 0; border-top: 1px solid var(--yl-line); }
.yl-section:first-of-type { border-top: 0; }
.yl-kicker {
    font-size: 13px;
    letter-spacing: .12em;
    color: var(--yl-copper);
    font-weight: 600;
    margin-bottom: 10px;
}
.yl-h2 {
    font-size: clamp(22px, 3vw, 30px);
    line-height: 1.35;
    color: var(--yl-ink);
    font-weight: 700;
    margin: 0 0 12px;
}
.yl-lead { color: var(--yl-muted); font-size: 16px; line-height: 1.8; max-width: 46em; }
.yl-section-head { margin-bottom: 28px; }

/* ---------- 按钮 ---------- */
.yl-btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    min-height: 46px;
    padding: 10px 22px;
    border-radius: 8px;
    font-size: 15px;
    font-weight: 600;
    text-decoration: none;
    border: 1px solid transparent;
    transition: background-color .15s ease, color .15s ease, border-color .15s ease;
}
.yl-btn-primary { background: var(--yl-primary); color: #fff; }
.yl-btn-primary:hover { background: var(--yl-primary-dark); color: #fff; }
.yl-btn-ghost { background: transparent; color: var(--yl-primary); border-color: var(--yl-primary); }
.yl-btn-ghost:hover { background: var(--yl-soft); color: var(--yl-primary-dark); }
.yl-btn:focus-visible, a:focus-visible, button:focus-visible {
    outline: 2px solid var(--yl-primary);
    outline-offset: 2px;
    border-radius: 4px;
}
.yl-btn:disabled, .yl-btn[aria-disabled="true"] {
    background: #b9b4a8;
    color: #fff;
    cursor: not-allowed;
}

/* ---------- 首屏 ---------- */
.yl-hero { padding: 72px 0 64px; background: linear-gradient(180deg, #f8f7f1 0%, var(--yl-bg) 100%); border-bottom: 1px solid var(--yl-line); }
.yl-hero-inner { max-width: 760px; }
.yl-hero h1 {
    font-size: clamp(28px, 5vw, 44px);
    line-height: 1.3;
    color: var(--yl-ink);
    font-weight: 800;
    margin: 0 0 18px;
    letter-spacing: .01em;
}
.yl-hero .yl-lead { font-size: 17px; }
.yl-hero-actions { display: flex; flex-wrap: wrap; gap: 14px; margin-top: 28px; }
.yl-hero-note { margin-top: 18px; font-size: 13px; color: var(--yl-muted); }

/* ---------- 三问题入口 ---------- */
.yl-entry-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; }
.yl-entry-card {
    background: var(--yl-card);
    border: 1px solid var(--yl-line);
    border-radius: 12px;
    padding: 24px;
    display: flex;
    flex-direction: column;
    gap: 10px;
}
.yl-entry-card h3 { font-size: 18px; color: var(--yl-ink); margin: 0; font-weight: 700; }
.yl-entry-q { color: var(--yl-primary); font-weight: 600; font-size: 15px; line-height: 1.6; margin: 0; }
.yl-entry-card p.yl-entry-desc { color: var(--yl-muted); font-size: 14px; line-height: 1.7; margin: 0; flex: 1; }
.yl-entry-link { color: var(--yl-copper); font-weight: 600; font-size: 14px; text-decoration: none; }
.yl-entry-link:hover { text-decoration: underline; }

/* ---------- 实践卡 / 文章卡（新布局内复用） ---------- */
.yl-card-list { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; }
.yl-item-card {
    background: var(--yl-card);
    border: 1px solid var(--yl-line);
    border-radius: 12px;
    padding: 22px;
    display: flex;
    flex-direction: column;
    gap: 10px;
}
.yl-tag {
    display: inline-block;
    font-size: 12px;
    font-weight: 600;
    padding: 3px 10px;
    border-radius: 999px;
    background: var(--yl-soft);
    color: var(--yl-primary);
    align-self: flex-start;
}
.yl-tag-draft { background: var(--yl-warn-bg); color: var(--yl-warn-ink); }
.yl-item-card h3 { font-size: 16px; line-height: 1.55; margin: 0; color: var(--yl-ink); font-weight: 700; }
.yl-item-card h3 a { color: inherit; text-decoration: none; }
.yl-item-card h3 a:hover { color: var(--yl-copper); }
.yl-item-card p { color: var(--yl-muted); font-size: 14px; line-height: 1.7; margin: 0; flex: 1; }
.yl-item-meta { font-size: 13px; color: var(--yl-muted); }
.yl-empty {
    border: 1px dashed var(--yl-line);
    background: var(--yl-card);
    border-radius: 12px;
    padding: 32px 28px;
    color: var(--yl-muted);
    font-size: 15px;
    line-height: 1.8;
    text-align: center;
}

/* ---------- 工作方式四步 ---------- */
.yl-steps { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; counter-reset: step; }
.yl-step { position: relative; padding-top: 14px; border-top: 3px solid var(--yl-primary); }
.yl-step::before {
    counter-increment: step;
    content: "0" counter(step);
    font-size: 13px;
    font-weight: 700;
    color: var(--yl-copper);
    letter-spacing: .08em;
}
.yl-step h3 { font-size: 16px; color: var(--yl-ink); margin: 6px 0 6px; font-weight: 700; }
.yl-step p { color: var(--yl-muted); font-size: 14px; line-height: 1.7; margin: 0; }

/* ---------- 服务对比表 / 详情模块 ---------- */
.yl-table-wrap { overflow-x: auto; }
.yl-table { width: 100%; border-collapse: collapse; font-size: 14px; line-height: 1.7; background: var(--yl-card); border: 1px solid var(--yl-line); border-radius: 12px; }
.yl-table th, .yl-table td { text-align: left; padding: 14px 16px; border-bottom: 1px solid var(--yl-line); vertical-align: top; }
.yl-table th { color: var(--yl-ink); font-weight: 700; background: var(--yl-soft); white-space: nowrap; }
.yl-table tr:last-child td { border-bottom: 0; }
.yl-table a { color: var(--yl-primary); font-weight: 600; }

.yl-deliver-list { margin: 0; padding-left: 20px; color: var(--yl-text); font-size: 15px; line-height: 1.9; }
.yl-deliver-list li { margin-bottom: 6px; }
.yl-boundary {
    background: var(--yl-warn-bg);
    border: 1px solid var(--yl-warn-line);
    border-radius: 12px;
    padding: 20px 24px;
    font-size: 14px;
    line-height: 1.8;
    color: var(--yl-warn-ink);
}
.yl-boundary strong { display: block; margin-bottom: 6px; color: #4d3d0f; }

.yl-faq { border-top: 1px solid var(--yl-line); }
.yl-faq-item { border-bottom: 1px solid var(--yl-line); padding: 18px 0; }
.yl-faq-item h3 { font-size: 16px; font-weight: 700; color: var(--yl-ink); margin: 0 0 8px; }
.yl-faq-item p { margin: 0; color: var(--yl-muted); font-size: 15px; line-height: 1.8; }

.yl-service-head { padding: 56px 0 40px; border-bottom: 1px solid var(--yl-line); background: linear-gradient(180deg, #f8f7f1 0%, var(--yl-bg) 100%); }
.yl-service-head .yl-h2 { margin-bottom: 10px; }
.yl-service-head-actions { margin-top: 22px; display: flex; flex-wrap: wrap; gap: 12px; }

/* ---------- 关于 / 联系 ---------- */
.yl-about-grid { display: grid; grid-template-columns: 1.2fr .8fr; gap: 40px; align-items: start; }
.yl-prose { color: var(--yl-text); font-size: 15.5px; line-height: 1.9; }
.yl-prose p { margin: 0 0 14px; }
.yl-prose h3 { color: var(--yl-ink); font-size: 17px; font-weight: 700; margin: 22px 0 8px; }
.yl-prose ul { padding-left: 20px; margin: 0 0 14px; }
.yl-prose li { margin-bottom: 6px; }

.yl-form { background: var(--yl-card); border: 1px solid var(--yl-line); border-radius: 12px; padding: 28px; }
.yl-form-field { margin-bottom: 18px; }
.yl-form-field label { display: block; font-size: 14px; font-weight: 600; color: var(--yl-ink); margin-bottom: 6px; }
.yl-form-field .yl-req { color: var(--yl-copper); }
.yl-form-field .yl-opt { color: var(--yl-muted); font-weight: 400; font-size: 12px; }
.yl-form-field input[type="text"], .yl-form-field input[type="email"], .yl-form-field input[type="tel"],
.yl-form-field select, .yl-form-field textarea {
    width: 100%;
    box-sizing: border-box;
    min-height: 44px;
    padding: 10px 12px;
    border: 1px solid var(--yl-line);
    border-radius: 8px;
    background: #fff;
    font-size: 15px;
    color: var(--yl-text);
    font-family: inherit;
}
.yl-form-field textarea { min-height: 110px; resize: vertical; }
.yl-form-field input:focus, .yl-form-field select:focus, .yl-form-field textarea:focus {
    outline: 2px solid var(--yl-primary);
    outline-offset: 1px;
}
.yl-form-hint { font-size: 12.5px; color: var(--yl-muted); margin-top: 5px; line-height: 1.6; }
.yl-radio-row { display: flex; flex-wrap: wrap; gap: 10px 18px; }
.yl-radio-row label { display: inline-flex; align-items: center; gap: 6px; font-weight: 400; font-size: 14.5px; color: var(--yl-text); margin: 0; }
.yl-form-status {
    margin-top: 16px;
    padding: 12px 14px;
    border-radius: 8px;
    font-size: 14px;
    line-height: 1.7;
    background: var(--yl-warn-bg);
    border: 1px solid var(--yl-warn-line);
    color: var(--yl-warn-ink);
}
.yl-form-consent { display: flex; gap: 8px; align-items: flex-start; font-size: 13.5px; color: var(--yl-muted); line-height: 1.7; }
.yl-form-consent input { margin-top: 3px; }

/* ---------- CTA 区 ---------- */
.yl-cta {
    background: var(--yl-primary-dark);
    color: #fff;
    padding: 56px 0;
}
.yl-cta .yl-h2 { color: #fff; }
.yl-cta p { color: rgba(255,255,255,.82); font-size: 16px; line-height: 1.8; max-width: 40em; margin: 0 0 24px; }
.yl-cta .yl-btn-primary { background: #fff; color: var(--yl-primary-dark); }
.yl-cta .yl-btn-primary:hover { background: var(--yl-soft); color: var(--yl-primary-dark); }

/* ---------- 页脚补充 ---------- */
.yl-footer-cols { display: grid; grid-template-columns: 2fr 1fr 1fr 1fr; gap: 28px; padding-bottom: 28px; border-bottom: 1px solid rgba(255,255,255,.14); }
.yl-footer-cols h3 { font-size: 14px; color: #fff; margin: 0 0 10px; font-weight: 700; }
.yl-footer-cols p, .yl-footer-cols a { color: rgba(255,255,255,.72); font-size: 13.5px; line-height: 1.9; }
.yl-footer-cols a { display: block; text-decoration: none; }
.yl-footer-cols a:hover { color: #fff; text-decoration: underline; }
.yl-footer-base { padding-top: 20px; font-size: 13px; color: rgba(255,255,255,.6); line-height: 2; }
.yl-footer-base a { color: rgba(255,255,255,.6); }

/* ---------- 页头（预览版自有结构，无 JS 依赖） ---------- */
.yl-header {
    position: sticky;
    top: 0;
    z-index: 50;
    background: rgba(250, 249, 245, .96);
    backdrop-filter: blur(6px);
    border-bottom: 1px solid var(--yl-line);
}
.yl-header-row {
    display: flex;
    align-items: center;
    gap: 20px;
    min-height: 62px;
}
.yl-brand {
    display: inline-flex;
    flex-direction: column;
    text-decoration: none;
    margin-right: auto;
}
.yl-brand .yl-brand-name { font-size: 19px; font-weight: 800; color: var(--yl-ink); letter-spacing: .01em; }
.yl-brand .yl-brand-sub { font-size: 11.5px; color: var(--yl-muted); letter-spacing: .06em; }
.yl-nav { display: flex; align-items: center; gap: 4px; }
.yl-nav > a, .yl-nav summary {
    display: inline-flex;
    align-items: center;
    gap: 4px;
    padding: 8px 12px;
    border-radius: 8px;
    color: var(--yl-text);
    font-size: 15px;
    text-decoration: none;
    cursor: pointer;
    list-style: none;
    white-space: nowrap;
}
.yl-nav > a:hover, .yl-nav summary:hover { background: var(--yl-soft); color: var(--yl-primary); }
.yl-nav > a.is-active { color: var(--yl-primary); font-weight: 700; }
.yl-nav summary::-webkit-details-marker { display: none; }
.yl-nav summary::after { content: "▾"; font-size: 11px; color: var(--yl-muted); }
details[open].yl-dd > summary { background: var(--yl-soft); color: var(--yl-primary); }
.yl-dd { position: relative; }
.yl-dd-menu {
    position: absolute;
    top: calc(100% + 6px);
    left: 0;
    min-width: 220px;
    background: #fff;
    border: 1px solid var(--yl-line);
    border-radius: 10px;
    box-shadow: 0 10px 28px rgba(20, 41, 70, .10);
    padding: 8px;
    z-index: 60;
}
.yl-dd-menu a {
    display: block;
    padding: 10px 12px;
    border-radius: 8px;
    text-decoration: none;
    color: var(--yl-text);
    font-size: 14.5px;
    line-height: 1.5;
}
.yl-dd-menu a:hover { background: var(--yl-soft); color: var(--yl-primary); }
.yl-dd-menu .yl-dd-desc { display: block; font-size: 12px; color: var(--yl-muted); }
.yl-header-cta { flex-shrink: 0; }
.yl-mobile-nav { display: none; }

@media (max-width: 860px) {
    .yl-nav, .yl-header-cta { display: none; }
    .yl-mobile-nav { display: block; }
    .yl-mobile-nav > summary {
        display: inline-flex;
        align-items: center;
        justify-content: center;
        width: 42px;
        height: 42px;
        border-radius: 8px;
        border: 1px solid var(--yl-line);
        background: #fff;
        cursor: pointer;
        list-style: none;
        font-size: 20px;
        line-height: 1;
        color: var(--yl-ink);
    }
    .yl-mobile-nav > summary::-webkit-details-marker { display: none; }
    .yl-mobile-panel {
        border-top: 1px solid var(--yl-line);
        padding: 10px 0 16px;
        background: var(--yl-card);
    }
    .yl-mobile-panel a, .yl-mobile-panel summary {
        display: block;
        padding: 12px 14px;
        color: var(--yl-text);
        text-decoration: none;
        font-size: 15.5px;
        border-radius: 8px;
        cursor: pointer;
        list-style: none;
    }
    .yl-mobile-panel summary::-webkit-details-marker { display: none; }
    .yl-mobile-panel summary::after { content: " ▾"; color: var(--yl-muted); font-size: 12px; }
    .yl-mobile-panel .yl-dd-menu { position: static; box-shadow: none; border: 0; background: transparent; padding: 0 0 0 16px; }
}

/* ---------- 页脚 ---------- */
.yl-footer { background: var(--yl-primary-dark); color: rgba(255,255,255,.72); margin-top: 0; }
.yl-footer .tt-shell { padding: 48px 16px 24px; box-sizing: border-box; }

/* ---------- 响应式 ---------- */
@media (max-width: 900px) {
    .yl-entry-grid, .yl-card-list { grid-template-columns: 1fr 1fr; }
    .yl-steps { grid-template-columns: 1fr 1fr; }
    .yl-about-grid { grid-template-columns: 1fr; }
    .yl-footer-cols { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 600px) {
    .yl-hero { padding: 48px 0 44px; }
    .yl-section { padding: 40px 0; }
    .yl-entry-grid, .yl-card-list, .yl-steps { grid-template-columns: 1fr; }
    .yl-form { padding: 20px 16px; }
    .yl-footer-cols { grid-template-columns: 1fr; }
}

/* ---------- 生产站主题色对齐（2026-10-27：以预览版视觉为基线） ---------- */
:root {
    --tt-red: #1B365D;
    --tt-red-dark: #142946;
    --tt-bg: #f5f4ed;
    --tt-ink: #141413;
    --tt-line: #e8e5da;
    --tt-soft: #EEF2F7;
}
.tt-body { background: var(--yl-bg); color: var(--yl-text); }

/* 首页段落与现有列表衔接 */
.yl-section + .tt-shell.tt-layout { margin-top: 8px; }
.yl-hero-inner { padding-bottom: 40px; }
@media (max-width: 860px) {
    .yl-header-row { gap: 10px; }
}

/* ---------- 移动端菜单面板修正（2026-10-27） ---------- */
@media (max-width: 860px) {
    .yl-mobile-nav { position: absolute; top: 100%; left: 0; right: 0; width: auto; }
    .yl-mobile-nav > summary { position: absolute; top: -52px; right: 12px; margin: 0; }
    .yl-mobile-panel { width: 100%; box-sizing: border-box; border-bottom: 1px solid var(--yl-line); box-shadow: 0 14px 28px rgba(20, 41, 70, .10); }
}