/* ===== 基础 ===== */
        :root {
            --primary: #2563eb;
            --primary-dark: #1d4ed8;
            --bg: #f5f6f7;
            --card: #ffffff;
            --text: #333333;
            --text-light: #666666;
            --border: #dddddd;
        }
        * { margin: 0; padding: 0; box-sizing: border-box; }
        body {
            font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
            background: var(--bg);
            color: var(--text);
            line-height: 1.6;
        }
        a { color: var(--primary); text-decoration: none; }
        a:hover { color: var(--primary-dark); }
        img { max-width: 100%; }

        /* ===== 导航（构建时由 header.html 注入） ===== */
        .site-header {
            background: var(--card);
            border-bottom: 1px solid var(--border);
            position: sticky;
            top: 0;
            z-index: 100;
        }
        .site-header .nav-container {
            max-width: 1200px;
            margin: 0 auto;
            padding: 0 1rem;
            display: flex;
            align-items: center;
            justify-content: space-between;
            height: 60px;
        }
        .site-header .logo { font-size: 1.25rem; font-weight: 700; color: var(--primary); }
        .site-header .logo:hover { color: var(--primary-dark); text-decoration: none; }
        .site-header nav ul { display: flex; list-style: none; gap: 2rem; margin: 0; }
        .site-header nav li { margin: 0; }
        .site-header nav a { color: var(--text); font-weight: 500; font-size: 0.95rem; }
        .site-header nav a:hover, .site-header nav a.active { color: var(--primary); }
        .site-header .mobile-menu-btn {
            display: none;
            background: none;
            border: none;
            font-size: 1.5rem;
            cursor: pointer;
            color: var(--text);
        }
        .site-header .mobile-nav {
            display: none;
            position: absolute;
            top: 60px;
            left: 0;
            right: 0;
            background: var(--card);
            border-bottom: 1px solid var(--border);
            padding: 1rem;
        }
        .site-header .mobile-nav.active { display: block; }
        .site-header .mobile-nav a { display: block; padding: 0.75rem; color: var(--text); border-bottom: 1px solid var(--bg); }
        @media (max-width: 768px) {
            .site-header nav ul { display: none; }
            .site-header .mobile-menu-btn { display: block; }
        }

        /* ===== 主体布局 ===== */
        main {
            max-width: 1200px;
            margin: 0 auto;
            padding: 1.5rem 1rem 3rem;
        }
        h1 {
            font-size: 1.6rem;
            text-align: center;
            margin-bottom: 0.5rem;
            font-weight: 700;
        }
        h2 { font-size: 1.25rem; margin: 1.5rem 0 0.75rem; font-weight: 600; }
        h3 { font-size: 1.05rem; margin: 1rem 0 0.5rem; font-weight: 600; }
        p { margin-bottom: 0.75rem; }
        ul, ol { margin: 0 0 1rem 1.4rem; }
        li { margin-bottom: 0.3rem; }
        .subtitle {
            text-align: center;
            color: var(--text-light);
            font-size: 0.95rem;
            max-width: 720px;
            margin: 0 auto 0.75rem;
        }
        .update-time {
            text-align: center;
            color: var(--text-light);
            font-size: 0.85rem;
            margin-bottom: 1.5rem;
        }

        /* ===== 计算器：模式切换 ===== */
        .mode-tabs {
            display: flex;
            gap: 0.4rem;
            margin: 0 auto 1.25rem;
            max-width: 480px;
        }
        .mode-tab {
            flex: 1;
            text-align: center;
            padding: 0.65rem 0.5rem;
            border: 1px solid var(--border);
            background: var(--card);
            cursor: pointer;
            font-size: 0.95rem;
            color: var(--text);
        }
        .mode-tab:hover { background: #eef2ff; }
        .mode-tab.active {
            background: var(--primary);
            border-color: var(--primary);
            color: #fff;
            font-weight: 600;
        }

        /* ===== 计算器：左右布局 ===== */
        .calc-wrapper {
            display: grid;
            grid-template-columns: 380px 1fr;
            gap: 1rem;
            margin-bottom: 1.5rem;
            align-items: start;
        }
        @media (max-width: 900px) {
            .calc-wrapper { grid-template-columns: 1fr; }
        }

        .card {
            background: var(--card);
            border: 1px solid var(--border);
            border-radius: 4px;
            padding: 1.25rem;
        }
        .card h2 {
            font-size: 1.05rem;
            margin: 0 0 1rem;
            padding-bottom: 0.6rem;
            border-bottom: 1px solid var(--border);
        }

        .form-group { margin-bottom: 1rem; }
        label { display: block; font-weight: 600; margin-bottom: 0.3rem; font-size: 0.9rem; }
        input[type="number"], select {
            width: 100%;
            padding: 0.55rem 0.6rem;
            border: 1px solid #ccc;
            border-radius: 3px;
            font-size: 1rem;
            background: #fff;
            color: var(--text);
        }
        input[type="number"]:focus, select:focus {
            outline: none;
            border-color: var(--primary);
        }
        .input-suffix { position: relative; }
        .input-suffix input { padding-right: 3.4rem; }
        .input-suffix .suffix {
            position: absolute;
            right: 0.7rem;
            top: 50%;
            transform: translateY(-50%);
            color: var(--text-light);
            font-size: 0.85rem;
            pointer-events: none;
        }
        .rate-mode-tabs { display: flex; gap: 0.4rem; margin-bottom: 0.75rem; }
        .rate-mode-tab {
            flex: 1;
            text-align: center;
            padding: 0.4rem;
            border: 1px solid var(--border);
            background: var(--bg);
            cursor: pointer;
            font-size: 0.85rem;
            color: var(--text);
        }
        .rate-mode-tab.active {
            background: var(--primary);
            border-color: var(--primary);
            color: #fff;
        }
        .rate-input-group { display: grid; grid-template-columns: 1fr 1fr; gap: 0.5rem; }
        @media (max-width: 640px) { .rate-input-group { grid-template-columns: 1fr; } }
        .hidden { display: none !important; }

        .btn {
            display: block;
            width: 100%;
            padding: 0.7rem;
            margin-top: 0.75rem;
            background: var(--primary);
            border: 1px solid var(--primary);
            color: #fff;
            font-size: 1rem;
            font-weight: 600;
            cursor: pointer;
            border-radius: 3px;
        }
        .btn:hover { background: var(--primary-dark); border-color: var(--primary-dark); }

        /* ===== 结果区 ===== */
        .result-placeholder {
            text-align: center;
            padding: 2.5rem 1rem;
            color: var(--text-light);
            font-size: 0.95rem;
        }
        .result-placeholder svg {
            width: 44px;
            height: 44px;
            margin-bottom: 0.5rem;
            opacity: 0.3;
        }
        .loan-summary {
            display: flex;
            flex-wrap: wrap;
            gap: 1.2rem;
            padding: 0.6rem 0;
            margin-bottom: 1rem;
            border-bottom: 1px dashed var(--border);
            font-size: 0.95rem;
        }
        .loan-summary strong { margin-left: 2px; }

        .compare-cols { display: flex; gap: 1rem; margin-bottom: 1rem; }
        .compare-col {
            flex: 1;
            border: 1px solid var(--border);
            border-radius: 3px;
            padding: 0.9rem 1rem;
        }
        .col-title {
            font-size: 1rem;
            font-weight: 600;
            margin-bottom: 0.5rem;
            padding-bottom: 0.4rem;
            border-bottom: 1px solid var(--border);
        }
        .col-item {
            display: flex;
            justify-content: space-between;
            align-items: baseline;
            padding: 0.3rem 0;
            font-size: 0.92rem;
        }
        .col-label { color: var(--text-light); }
        .col-value { font-weight: 600; text-align: right; }
        .col-value.primary { color: #c2410c; font-size: 1.15rem; }
        .col-value.success { color: #15803d; }

        .compare-tip {
            border-left: 3px solid var(--primary);
            background: #eef2ff;
            padding: 0.6rem 0.9rem;
            font-size: 0.9rem;
            line-height: 1.6;
        }
        @media (max-width: 640px) {
            .compare-cols { flex-direction: column; gap: 0.75rem; }
            .loan-summary { flex-direction: column; gap: 0.2rem; }
        }

        /* ===== 还款计划表 ===== */
        .schedule-section { margin-top: 1.25rem; }
        .schedule-header {
            display: flex;
            justify-content: space-between;
            align-items: center;
            flex-wrap: wrap;
            gap: 0.5rem;
            margin-bottom: 0.75rem;
        }
        .schedule-mode-tabs { display: inline-flex; gap: 0.4rem; }
        .schedule-mode-tab {
            padding: 0.4rem 1rem;
            font-size: 0.9rem;
            border: 1px solid var(--border);
            background: var(--card);
            cursor: pointer;
            color: var(--text);
        }
        .schedule-mode-tab.active {
            background: var(--primary);
            border-color: var(--primary);
            color: #fff;
        }
        .toggle-btn {
            background: var(--bg);
            border: 1px solid var(--border);
            padding: 0.4rem 0.9rem;
            cursor: pointer;
            font-size: 0.9rem;
        }
        .toggle-btn:hover { background: #e8e8e8; }

        .schedule-wrapper {
            max-height: 400px;
            overflow-y: auto;
            border: 1px solid var(--border);
        }
        table { width: 100%; border-collapse: collapse; font-size: 0.85rem; }
        th, td {
            padding: 0.55rem 0.5rem;
            text-align: center;
            border-bottom: 1px solid var(--border);
        }
        th { background: #f0f0f0; font-weight: 600; position: sticky; top: 0; }
        tr:hover { background: #fafafa; }
        @media (max-width: 640px) {
            .schedule-wrapper { font-size: 0.75rem; }
            th, td { padding: 0.4rem 0.2rem; }
        }

        /* ===== 概念介绍区 ===== */
        .intro-section {
            margin-top: 2.5rem;
            padding-top: 1.5rem;
            border-top: 1px solid var(--border);
        }
        .intro-section h2 { margin-top: 1.5rem; }
        .intro-section p { color: var(--text); line-height: 1.8; }
        .source-note {
            font-size: 0.8rem;
            color: var(--text-light);
            border-top: 1px dashed var(--border);
            padding-top: 0.75rem;
            margin-top: 1.5rem;
        }

        /* ===== FAQ（原生 details/summary 折叠） ===== */
        .faq-list {
            border: 1px solid var(--border);
            background: var(--card);
            border-radius: 3px;
        }
        .faq-item { border-bottom: 1px solid var(--border); }
        .faq-item:last-child { border-bottom: none; }
        .faq-question {
            display: flex;
            justify-content: space-between;
            align-items: center;
            gap: 0.5rem;
            padding: 0.85rem 1rem;
            cursor: pointer;
            font-weight: 600;
            font-size: 0.98rem;
            list-style: none;
        }
        .faq-question::-webkit-details-marker { display: none; }
        .faq-icon { font-size: 0.75rem; color: #999; }
        .faq-answer {
            padding: 0 1rem 0.9rem;
            color: var(--text-light);
            line-height: 1.8;
            font-size: 0.92rem;
        }
        .faq-answer p { margin-bottom: 0.5rem; }
        .faq-answer p:last-child { margin-bottom: 0; }

        /* ===== 文章区 ===== */
        .section-title {
            font-size: 1.25rem;
            margin: 2.5rem 0 1rem;
            padding-bottom: 0.5rem;
            border-bottom: 2px solid var(--primary);
            display: inline-block;
        }
        .articles-grid {
            display: grid;
            grid-template-columns: repeat(3, 1fr);
            gap: 1rem;
            margin-bottom: 2rem;
        }
        .article-card {
            display: block;
            background: var(--card);
            border: 1px solid var(--border);
            border-radius: 3px;
            padding: 1rem;
        }
        .article-card:hover { border-color: var(--primary); text-decoration: none; }
        .article-card h3 {
            font-size: 0.95rem;
            margin-bottom: 0.4rem;
            color: var(--text);
            line-height: 1.5;
        }
        .article-card:hover h3 { color: var(--primary); }
        .article-card p { font-size: 0.85rem; color: var(--text-light); line-height: 1.6; margin: 0; }
        .article-card time {
            display: block;
            font-size: 0.8rem;
            color: #999;
            margin-top: 0.5rem;
        }
        @media (max-width: 768px) { .articles-grid { grid-template-columns: 1fr; } }

        /* ===== 页脚 ===== */
        footer {
            background: var(--card);
            border-top: 1px solid var(--border);
            margin-top: 2rem;
            padding: 1.5rem 1rem;
        }
        .footer-content {
            max-width: 1200px;
            margin: 0 auto;
            display: flex;
            justify-content: space-between;
            align-items: center;
            flex-wrap: wrap;
            gap: 0.8rem;
        }
        .footer-links { display: flex; gap: 1.2rem; flex-wrap: wrap; }
        .footer-links a { color: var(--text-light); font-size: 0.9rem; }
        .footer-links a:hover { color: var(--primary); }
        .copyright { color: var(--text-light); font-size: 0.9rem; }
        @media (max-width: 640px) { .footer-content { flex-direction: column; text-align: center; } }