/* ===== 全局重置 & CSS 变量 ===== */
* { margin: 0; padding: 0; box-sizing: border-box; }
:root {
    --primary: #4f46e5;
    --primary-hover: #4338ca;
    --primary-light: #eef2ff;
    --success: #22c55e;
    --success-hover: #16a34a;
    --warning: #f59e0b;
    --warning-hover: #d97706;
    --gray-50: #f8fafc;
    --gray-100: #f1f5f9;
    --gray-200: #e2e8f0;
    --gray-300: #cbd5e1;
    --gray-500: #64748b;
    --gray-700: #334155;
    --gray-900: #0f172a;
    --radius: 16px;
    --shadow: 0 4px 24px rgba(0, 0, 0, 0.06);
}
body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "PingFang SC", "Microsoft YaHei", sans-serif;
    background: var(--gray-50);
    color: var(--gray-900);
    line-height: 1.6;
    padding: 20px;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
}
.container {
    max-width: 1100px;
    width: 100%;
    margin: 0 auto;
    background: #ffffff;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 28px 32px;
    transition: all 0.3s;
}
@media (max-width: 768px) { body { padding: 12px; } .container { padding: 18px 16px; } }
@media (max-width: 480px) { body { padding: 8px; } .container { padding: 14px 12px; } }

/* ===== 顶部标题区 ===== */
.page-header { margin-bottom: 28px; }
.page-header h1 {
    font-size: clamp(24px, 4vw, 32px);
    font-weight: 800;
    border-left: 5px solid var(--primary);
    padding-left: 18px;
    line-height: 1.3;
    color: var(--gray-900);
}
.page-header .sub {
    color: var(--gray-500);
    padding-left: 23px;
    margin-top: 4px;
    font-size: 15px;
}

/* ===== 工具组件 ===== */
.input-group, .output-group { display: flex; flex-direction: column; gap: 6px; margin-bottom: 16px; }
.input-group label, .output-group label { font-weight: 600; color: var(--gray-700); font-size: 14px; }
.input-group .hint, .output-group .hint { font-weight: 400; color: var(--gray-500); font-size: 13px; }
textarea, input[type="number"], input[type="text"], input[type="file"], input[type="range"] {
    width: 100%;
    padding: 12px 16px;
    font-size: 15px;
    font-family: 'JetBrains Mono', 'Courier New', Consolas, monospace;
    border: 2px solid var(--gray-200);
    border-radius: 12px;
    transition: all 0.25s;
    background: var(--gray-50);
    color: var(--gray-900);
}
input[type="range"] { padding: 4px 0; background: transparent; }
textarea { height: 140px; resize: vertical; line-height: 1.7; }
textarea:focus, input:focus { outline: none; border-color: var(--primary); box-shadow: 0 0 0 4px rgba(79,70,229,0.1); background: #ffffff; }
.output-group textarea { background: var(--gray-100); }

/* ===== 按钮 ===== */
.button-group { display: flex; flex-wrap: wrap; gap: 10px; margin: 4px 0 20px; }
.btn {
    padding: 10px 24px;
    border: none;
    border-radius: 10px;
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.25s ease;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 6px;
    flex: 1 0 auto;
    min-width: 100px;
    background: var(--gray-100);
    color: var(--gray-700);
}
.btn:hover { transform: translateY(-2px); }
.btn-primary { background: var(--primary); color: #fff; box-shadow: 0 4px 12px rgba(79,70,229,0.3); }
.btn-primary:hover { background: var(--primary-hover); }
.btn-success { background: var(--success); color: #fff; box-shadow: 0 4px 12px rgba(34,197,94,0.3); }
.btn-success:hover { background: var(--success-hover); }
.btn-warning { background: var(--warning); color: #fff; box-shadow: 0 4px 12px rgba(245,158,11,0.3); }
.btn-warning:hover { background: var(--warning-hover); }
.btn-outline { background: transparent; border: 2px solid var(--gray-200); color: var(--gray-700); }
.btn-outline:hover { border-color: var(--gray-500); background: var(--gray-50); }
.btn-danger { background: #ef4444; color: #fff; }
.btn-danger:hover { background: #dc2626; }
.btn-purple { background: #8b5cf6; color: #fff; box-shadow: 0 4px 12px rgba(139,92,246,0.3); }
.btn-purple:hover { background: #7c3aed; }
@media (max-width: 600px) { .btn { flex: 1 1 45%; min-width: 70px; padding: 10px 14px; font-size: 13px; } }
@media (max-width: 400px) { .btn { flex: 1 1 100%; } }

/* ===== 首页卡片 ===== */
.tools-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 18px; margin: 28px 0 10px; }
.tool-card {
    background: var(--gray-50);
    padding: 20px 16px 16px;
    border-radius: var(--radius);
    text-decoration: none;
    color: var(--gray-900);
    border: 1.5px solid transparent;
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
}
.tool-card::before { content: ''; position: absolute; top: 0; left: 0; right: 0; height: 4px; background: var(--primary); opacity: 0; transition: opacity 0.3s; }
.tool-card:hover { border-color: var(--primary); transform: translateY(-4px); box-shadow: 0 12px 40px rgba(79,70,229,0.12); }
.tool-card:hover::before { opacity: 1; }
.tool-card .icon { font-size: 2rem; display: block; margin-bottom: 8px; }
.tool-card h2 { font-size: 1rem; font-weight: 700; margin-bottom: 4px; }
.tool-card p { color: var(--gray-500); font-size: 0.82rem; line-height: 1.5; }
.tool-card .tag { display: inline-block; margin-top: 10px; background: var(--primary-light); color: var(--primary); font-size: 0.65rem; font-weight: 600; padding: 2px 12px; border-radius: 20px; }

/* ===== 底部导航链接 ===== */
.footer-nav {
    margin-top: 40px;
    padding-top: 24px;
    border-top: 2px solid var(--gray-100);
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 6px 16px;
}
.footer-nav a {
    color: var(--gray-500);
    text-decoration: none;
    font-size: 13px;
    transition: color 0.2s;
    padding: 4px 8px;
    border-radius: 6px;
}
.footer-nav a:hover { color: var(--primary); background: var(--primary-light); }
.footer-nav .current-footer { color: var(--primary); font-weight: 600; background: var(--primary-light); padding: 4px 8px; border-radius: 6px; }

.site-footer {
    margin-top: 16px;
    padding-top: 16px;
    text-align: center;
    color: var(--gray-500);
    font-size: 14px;
}
.site-footer a { color: var(--primary); text-decoration: none; }

/* ===== SEO 内容区 ===== */
.info-section { margin-top: 36px; padding-top: 28px; border-top: 2px solid var(--gray-100); }
.info-section h2 { font-size: clamp(20px, 2.8vw, 26px); font-weight: 700; margin-bottom: 12px; color: var(--gray-900); }
.info-section h3 { font-size: clamp(17px, 2vw, 20px); font-weight: 600; margin: 24px 0 10px; color: var(--gray-900); }
.info-section p { color: var(--gray-700); line-height: 1.9; font-size: 15px; margin-bottom: 12px; }
.info-section ul, .info-section ol { padding-left: 24px; margin: 8px 0 16px; }
.info-section li { color: var(--gray-700); line-height: 1.8; font-size: 15px; margin-bottom: 4px; }
.info-section code { background: var(--gray-100); padding: 2px 10px; border-radius: 6px; font-family: monospace; font-size: 14px; color: var(--primary); }
.info-card { background: var(--primary-light); padding: 18px 24px; border-radius: 12px; border-left: 4px solid var(--primary); margin: 18px 0; }
.example-box { background: var(--gray-50); border: 1px solid var(--gray-200); border-radius: 10px; padding: 16px 20px; font-family: monospace; font-size: 14px; margin: 12px 0; }
.example-box span { background: #ffffff; padding: 2px 12px; border-radius: 4px; margin: 0 4px; border: 1px solid var(--gray-200); }

/* ===== 各工具特有样式 ===== */
.calc-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 30px; margin: 20px 0; }
.calc-form { background: var(--gray-50); padding: 24px; border-radius: var(--radius); }
.calc-form .field { margin-bottom: 16px; }
.calc-form label { display: block; font-weight: 600; font-size: 14px; margin-bottom: 4px; color: var(--gray-700); }
.calc-form .hint { font-weight: 400; color: var(--gray-500); font-size: 13px; }
.calc-result { background: var(--primary-light); padding: 24px; border-radius: var(--radius); display: flex; flex-direction: column; justify-content: center; }
.calc-result .amount { font-size: 2.2rem; font-weight: 800; color: var(--primary); margin: 8px 0; }
.calc-result .sub-amount { font-size: 1.2rem; font-weight: 600; color: var(--gray-700); }
.calc-result .detail { margin-top: 16px; border-top: 1px solid rgba(79,70,229,0.15); padding-top: 16px; font-size: 14px; color: var(--gray-700); }
.calc-result .detail span { font-weight: 600; }
@media (max-width: 768px) { .calc-grid { grid-template-columns: 1fr; } }

.upload-zone {
    border: 3px dashed var(--gray-300);
    border-radius: var(--radius);
    padding: 40px 20px;
    text-align: center;
    cursor: pointer;
    transition: 0.3s;
    background: var(--gray-50);
    margin: 16px 0;
}
.upload-zone:hover, .upload-zone.dragover { border-color: var(--primary); background: var(--primary-light); }
.upload-zone .icon { font-size: 3.6rem; display: block; margin-bottom: 8px; }
.preview-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; margin: 16px 0; }
.preview-box { background: var(--gray-50); padding: 16px; border-radius: var(--radius); text-align: center; }
.preview-box img { max-width: 100%; max-height: 200px; border-radius: 8px; }
@media (max-width: 600px) { .preview-grid { grid-template-columns: 1fr; } }

.rounder-controls { display: flex; flex-wrap: wrap; gap: 16px 24px; align-items: center; background: var(--gray-50); padding: 18px 22px; border-radius: var(--radius); margin: 16px 0; }
.rounder-controls .control-group { display: flex; align-items: center; gap: 8px; flex-wrap: wrap; }
.rounder-controls label { font-weight: 600; font-size: 14px; color: var(--gray-700); white-space: nowrap; }
.rounder-controls input[type="range"] { width: 140px; padding: 0; }
.rounder-controls input[type="number"] { width: 80px; padding: 6px 10px; border: 2px solid var(--gray-200); border-radius: 8px; font-size: 14px; text-align: center; }
.rounder-controls input[type="color"] { width: 44px; height: 36px; padding: 2px; border: 2px solid var(--gray-200); border-radius: 8px; cursor: pointer; background: transparent; }
.rounder-controls .transparent-btn { padding: 6px 16px; border: 2px solid var(--gray-200); border-radius: 8px; background: var(--gray-50); cursor: pointer; font-size: 13px; font-weight: 500; transition: 0.2s; color: var(--gray-700); }
.rounder-controls .transparent-btn.active { border-color: var(--primary); background: var(--primary-light); color: var(--primary); }
.preview-area { display: flex; flex-wrap: wrap; gap: 30px; justify-content: center; align-items: center; margin: 16px 0; }
.preview-area .box { text-align: center; }
.preview-area .box h4 { font-size: 14px; color: var(--gray-500); margin-bottom: 8px; }
.preview-area canvas { border: 2px solid var(--gray-200); border-radius: 12px; max-width: 200px; max-height: 200px; background: #fff; }
.preview-area canvas.transparent-bg { background: repeating-conic-gradient(#e8e8e8 0% 25%, #ffffff 0% 50%) 0 0 / 20px 20px; }
.download-row { text-align: center; margin-top: 12px; }

/* 房贷明细表 */
.mortgage-input { background: var(--gray-50); padding: 24px; border-radius: var(--radius); }
.mortgage-input .row { display: grid; grid-template-columns: 1fr 1fr 1fr; gap: 16px; }
.mortgage-input .field label { display: block; font-weight: 600; font-size: 14px; margin-bottom: 4px; color: var(--gray-700); }
.mortgage-input .field input { width: 100%; padding: 10px 14px; border: 2px solid var(--gray-200); border-radius: 10px; font-size: 15px; transition: 0.2s; }
.mortgage-input .field input:focus { outline: none; border-color: var(--primary); box-shadow: 0 0 0 4px rgba(79,70,229,0.1); }
.mortgage-btn-group { display: flex; gap: 12px; margin-top: 16px; flex-wrap: wrap; }
.result-grid { display: grid; grid-template-columns: 1fr 1fr 1fr 1fr; gap: 16px; margin: 20px 0; }
.result-card { background: var(--gray-50); padding: 16px 20px; border-radius: var(--radius); text-align: center; }
.result-card .label { font-size: 13px; color: var(--gray-500); }
.result-card .value { font-size: 1.6rem; font-weight: 700; color: var(--primary); margin-top: 4px; }
.detail-table-wrap { margin-top: 24px; max-height: 400px; overflow-y: auto; border: 1px solid var(--gray-200); border-radius: var(--radius); }
.detail-table { width: 100%; border-collapse: collapse; font-size: 14px; }
.detail-table th { background: var(--gray-100); padding: 10px 12px; text-align: center; position: sticky; top: 0; z-index: 2; font-weight: 600; color: var(--gray-700); }
.detail-table td { padding: 8px 12px; text-align: center; border-bottom: 1px solid var(--gray-100); }
.detail-table tr:nth-child(even) { background: var(--gray-50); }
.detail-table tr:hover { background: var(--primary-light); }
.detail-table .total-row { font-weight: 700; background: var(--gray-200) !important; }
@media (max-width: 768px) { .mortgage-input .row { grid-template-columns: 1fr; } .result-grid { grid-template-columns: 1fr 1fr; } }
@media (max-width: 480px) { .result-grid { grid-template-columns: 1fr; } }

/* 公式查询 */
.formula-category { margin-bottom: 28px; }
.formula-category h3 { background: var(--gray-100); padding: 10px 18px; border-radius: 10px; font-size: 16px; margin-bottom: 10px; display: flex; align-items: center; gap: 12px; flex-wrap: wrap; }
.formula-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); gap: 10px; }
.formula-item { background: var(--gray-50); padding: 10px 14px; border-radius: 8px; border-left: 3px solid var(--primary); }
.formula-item .name { font-weight: 600; font-size: 14px; display: flex; align-items: center; gap: 8px; flex-wrap: wrap; }
.formula-item .expr { font-family: 'Courier New', monospace; font-size: 14px; color: var(--gray-700); margin-top: 2px; }
.level-tag { display: inline-block; font-size: 11px; background: var(--primary-light); color: var(--primary); padding: 1px 10px; border-radius: 12px; font-weight: 400; }
@media (max-width: 600px) { .formula-grid { grid-template-columns: 1fr; } }

/* 科学家 */
.scientist-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); gap: 20px; margin: 20px 0; }
.scientist-card { background: var(--gray-50); padding: 20px; border-radius: var(--radius); border-top: 4px solid var(--primary); }
.scientist-card .name { font-size: 1.2rem; font-weight: 700; }
.scientist-card .field { color: var(--primary); font-weight: 600; font-size: 14px; }
.scientist-card .years { color: var(--gray-500); font-size: 13px; }
.scientist-card .bio { color: var(--gray-700); font-size: 14px; line-height: 1.7; margin-top: 8px; }
.scientist-card .contribution { background: #ffffff; padding: 12px 16px; border-radius: 8px; margin-top: 10px; font-size: 14px; border-left: 3px solid var(--warning); }

/* TTS */
.tts-controls { display: flex; flex-wrap: wrap; gap: 16px; align-items: center; background: var(--gray-50); padding: 16px 20px; border-radius: var(--radius); margin: 12px 0; }
.tts-controls label { font-weight: 600; white-space: nowrap; }
.tts-controls input[type="range"] { width: 150px; }