:root {
    --bg: #f4f6fb;
    --card: #ffffff;
    --ink: #1f2733;
    --muted: #6b7785;
    --primary: #3b6ef5;
    --primary-d: #2f59c7;
    --ok: #1f9d55;
    --bad: #e2483a;
    --line: #e6eaf0;
    --shadow: 0 1px 3px rgba(20, 30, 50, .08), 0 6px 18px rgba(20, 30, 50, .05);
}

* { box-sizing: border-box; }

body {
    margin: 0;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
    background: var(--bg);
    color: var(--ink);
    line-height: 1.6;
    /* 窄屏时顶栏导航较长，禁止横向滚动，避免登录卡片被挤出视口 */
    overflow-x: hidden;
    /* 内容不足一屏时（如 404 / 登录页）把页脚压到底部 */
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

main.container { flex: 1 0 auto; }
.footer { flex: none; }

/* 顶栏 */
.topbar {
    background: linear-gradient(120deg, #3b6ef5, #6a8bff);
    color: #fff;
    box-shadow: var(--shadow);
}
.topbar-inner {
    max-width: 1240px;
    margin: 0 auto;
    padding: 14px 20px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 12px;
    flex-wrap: wrap;
}
.brand { color: #fff; font-weight: 700; font-size: 18px; text-decoration: none; white-space: nowrap; }
/* 新增多个一级厂商下拉后，导航项允许自动换行，避免挤压其它菜单 */
.nav { display: flex; flex-wrap: wrap; align-items: center; justify-content: flex-end; min-width: 0; }
.nav a { color: #eaf0ff; text-decoration: none; margin-left: 12px; font-size: 14px; white-space: nowrap; }
.nav a:hover { color: #fff; text-decoration: underline; }

/* body 是 flex 纵向容器，横向的 auto margin 会覆盖 align-items:stretch，
   使 main 收缩到「内容宽度」而不是撑满（题干短时整页只有 480px 宽）。
   显式 width:100% 固定交叉轴尺寸，再由 max-width 收敛并居中。 */
.container { width: 100%; max-width: 1200px; margin: 0 auto; padding: 24px 20px 60px; }

/* 标题 */
.page-title { font-size: 24px; margin: 0 0 6px; }
.section-title { font-size: 18px; margin: 28px 0 12px; border-left: 4px solid var(--primary); padding-left: 10px; }
.muted { color: var(--muted); }
.warn { color: #b7791f; }
.ok { color: var(--ok); font-weight: 600; }
.err { color: var(--bad); }

/* 卡片 */
.card-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 16px; margin-top: 16px; }
.card { background: var(--card); border-radius: 12px; padding: 18px; box-shadow: var(--shadow); }
.card h2 { margin: 0 0 10px; font-size: 16px; }
.hint { margin-top: 24px; }
.hint pre { background: #0f172a; color: #e2e8f0; padding: 14px; border-radius: 8px; overflow-x: auto; font-size: 13px; }

/* 按钮 */
.btn {
    display: inline-block; background: var(--primary); color: #fff; border: none;
    padding: 9px 16px; border-radius: 8px; text-decoration: none; cursor: pointer;
    font-size: 14px; transition: .15s;
}
.btn:hover { background: var(--primary-d); }
.btn-ghost { background: #fff; color: var(--primary); border: 1px solid var(--primary); }
.btn-ghost:hover { background: #eef3ff; }
.btn-danger { background: var(--bad); }
.btn-danger:hover { background: #c1382c; }
.btn-sm { padding: 5px 10px; font-size: 12px; margin-left: 10px; }
.btn-lg { padding: 13px 28px; font-size: 16px; }
.btn-primary { background: var(--primary); color: #fff; font-weight: 600; }
.btn-primary:hover { background: var(--primary-d); }

.btn-row { display: flex; gap: 12px; flex-wrap: wrap; margin-top: 14px; }

/* 普通用户首页：聚焦答题的主区域 */
.answer-hero {
    border: 1px solid var(--line);
    box-shadow: 0 6px 22px rgba(59, 110, 245, .10);
}
.answer-hero h2 { margin-top: 0; }

/* Flash */
.flash { padding: 12px 14px; border-radius: 8px; margin: 14px 0; font-size: 14px; }
.flash-success, .flash-ok { background: #e7f7ee; color: #1f7a45; border: 1px solid #b7e6c8; }
.flash-error { background: #fdeceb; color: #b23226; border: 1px solid #f3c2bd; }

/* 表格 */
.table { width: 100%; border-collapse: collapse; background: var(--card); border-radius: 12px; overflow: hidden; box-shadow: var(--shadow); }
.table th, .table td { padding: 11px 14px; text-align: left; border-bottom: 1px solid var(--line); font-size: 14px; }
.table th { background: #f7f9fc; color: var(--muted); font-weight: 600; }
.table tr:last-child td { border-bottom: none; }
.row-actions a { margin-right: 12px; color: var(--primary); text-decoration: none; }
.row-actions a:hover { text-decoration: underline; }

/* 标签 */
.tag { display: inline-block; padding: 2px 10px; border-radius: 999px; background: #eef1f6; color: var(--muted); font-size: 12px; }
.tag-ok { background: #e7f7ee; color: var(--ok); }

/* 统计 */
.stat-row { display: flex; flex-wrap: wrap; gap: 12px; margin: 16px 0; }
.stat { flex: 1; min-width: 110px; background: var(--card); border-radius: 12px; padding: 16px; text-align: center; box-shadow: var(--shadow); }
.stat-num { font-size: 26px; font-weight: 700; }
.stat-label { color: var(--muted); font-size: 13px; margin-top: 4px; }
.stat-ok .stat-num { color: var(--ok); }
.stat-bad .stat-num { color: var(--bad); }

/* 表单 */
.form { background: var(--card); border-radius: 12px; padding: 20px; box-shadow: var(--shadow); margin-top: 14px; }
.form-row { margin-bottom: 16px; }
.form-row label { display: block; font-weight: 600; margin-bottom: 6px; font-size: 14px; }
/* 统一文本类输入框（含 password！此前遗漏导致密码框还是浏览器默认窄样式） */
.form-row input[type=date],
.form-row input[type=text],
.form-row input[type=password],
.form-row input[type=email],
.form-row input[type=number],
.form-row input[type=tel],
.form-row input[type=search],
.form-row input[type=url],
.form-row textarea {
    width: 100%;
    height: 42px;
    padding: 0 12px;
    border: 1px solid var(--line);
    border-radius: 8px;
    font-size: 14px;
    font-family: inherit;
    color: var(--ink);
    background: #fff;
    line-height: 1.4;
    transition: border-color .15s, box-shadow .15s, background .15s;
}
.form-row textarea { height: auto; padding: 10px 12px; }
.form-row input:focus,
.form-row select:focus,
.form-row textarea:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(59, 110, 245, .14);
}
.form-row input::placeholder,
.form-row textarea::placeholder { color: #a8b2c0; }
.form-row input:disabled,
.form-row textarea:disabled { background: #f5f7fa; color: var(--muted); cursor: not-allowed; }
textarea { resize: vertical; }

/* 答题 */
.quiz-sticky {
    position: sticky; top: 0; z-index: 20; background: var(--card);
    display: flex; align-items: center; gap: 14px; padding: 10px 14px;
    border-radius: 10px; box-shadow: var(--shadow); margin: 14px 0;
}
.quiz-sticky-right { margin-left: auto; color: var(--muted); font-size: 14px; }
.quiz-progress { flex: 1; height: 8px; background: #eef1f6; border-radius: 999px; overflow: hidden; }
.quiz-progress-bar { height: 100%; width: 0; background: var(--primary); transition: width .2s; }

.quiz-set { background: var(--card); border-radius: 12px; padding: 16px 18px; margin-bottom: 16px; box-shadow: var(--shadow); }
.set-title { font-size: 17px; margin: 0 0 12px; color: var(--primary-d); }

.question { padding: 12px 0; border-bottom: 1px dashed var(--line); }
.question:last-child { border-bottom: none; }
.q-head { margin: 0 0 10px; display: flex; gap: 8px; align-items: baseline; }
.q-text { font-weight: 600; }
.q-type { font-size: 12px; padding: 2px 8px; border-radius: 6px; color: #fff; background: #7a8aa0; white-space: nowrap; }
.q-type-single { background: #3b6ef5; }
.q-type-multiple { background: #9b51e0; }
.q-type-judge { background: #1f9d55; }

.options { display: flex; flex-direction: column; gap: 8px; }
.option { display: flex; align-items: center; gap: 10px; padding: 10px 12px; border: 1px solid var(--line); border-radius: 8px; cursor: pointer; transition: .12s; }
.option:hover { background: #f5f8ff; border-color: #c7d6ff; }
.option input { width: 18px; height: 18px; accent-color: var(--primary); }
.option-static.option-correct { background: #e7f7ee; border-color: #b7e6c8; }

.answer-line { margin: 8px 0 0; color: var(--ok); font-size: 14px; }
.answer-line b { font-size: 15px; }

.submit-bar { text-align: center; margin: 24px 0; }

/* 错题 */
.wrong-item { background: var(--card); border-radius: 10px; padding: 12px 16px; margin-bottom: 10px; box-shadow: var(--shadow); }
.err-line { color: var(--bad); margin: 4px 0; }
.ok-line { color: var(--ok); margin: 4px 0; }

/* 题目解析（显示在答案下方） */
.explanation {
    margin-top: 10px; padding: 12px 14px;
    background: #f7f9ff; border: 1px solid #dfe7ff;
    border-left: 3px solid var(--primary); border-radius: 8px;
}
.exp-title { font-weight: 700; color: var(--primary-d); font-size: 14px; margin-bottom: 6px; }
.exp-body { color: var(--ink); font-size: 13.5px; line-height: 1.9; word-break: break-word; }
.exp-line { display: inline; }
.explanation strong { color: #24406e; }

.footer { text-align: center; color: var(--muted); font-size: 13px; padding: 24px; }

/* 顶栏用户与角色徽标 */
.nav-user { margin-left: 18px; display: inline-flex; align-items: center; gap: 8px; color: #eaf0ff; font-size: 14px; }
.nav-user b { color: #fff; }
/* 用户名即个人中心入口：整块可点，hover 有一层浅色底 */
.nav-user-link {
    display: inline-flex; align-items: center; gap: 8px;
    margin-left: 0 !important; padding: 3px 9px 3px 4px; border-radius: 999px;
    color: #fff; text-decoration: none; line-height: 1.4;
}
.nav-user-link:hover, .nav-user-link:focus-visible {
    background: rgba(255, 255, 255, .18); color: #fff; text-decoration: none;
}
.nav-user-link.is-current { background: rgba(255, 255, 255, .24); }
.nav-logout { color: #cfe0ff !important; margin-left: 4px; }
.role-badge { display: inline-block; padding: 1px 8px; border-radius: 999px; font-size: 12px; font-weight: 600; }
.role-badge.role-admin { background: #ffd9a8; color: #8a4b00; }
.role-badge.role-user { background: #d7e3ff; color: #234; }

/* 登录 / 注册 居中卡片 */
.auth-wrap { max-width: 420px; margin: 40px auto; }
.auth-card { background: var(--card); border-radius: 14px; padding: 30px 28px 24px; box-shadow: var(--shadow); }
.auth-card h1 { font-size: 22px; margin: 0 0 6px; line-height: 1.35; }
.auth-card .sub { color: var(--muted); font-size: 14px; line-height: 1.7; margin: 0 0 22px; }
.auth-card .form-row { margin-bottom: 16px; }
.auth-card .form-row label { margin-bottom: 7px; }
.forgot-link {
    display: inline-block; margin-top: 9px; font-size: 13px;
    color: var(--primary); text-decoration: none;
}
.forgot-link:hover { text-decoration: underline; }
.auth-card .btn { width: 100%; height: 42px; padding: 0 16px; font-size: 15px; margin-top: 4px; }
.auth-foot { text-align: center; margin: 18px 0 0; font-size: 14px; color: var(--muted); }
.auth-foot a { color: var(--primary); text-decoration: none; }

/* 登录 / 注册：表单校验提示、图形验证码、按钮 loading */
.form-alert {
    background: #fdeceb; border: 1px solid #f3c2bd; color: #b23226;
    border-radius: 8px; padding: 10px 12px; font-size: 13.5px; margin: 0 0 16px;
}
.field-msg { margin: 6px 0 0; font-size: 12.5px; line-height: 1.6; min-height: 18px; color: var(--muted); }
.field-msg.is-ok { color: #1a7f4b; }
.field-msg.is-err { color: #c1382c; }
.field-msg.is-loading { color: #5b6b85; }
.field-hint { display: block; margin-top: 6px; color: var(--muted); font-size: 12px; line-height: 1.6; }
.label-optional { font-weight: 400; color: var(--muted); font-size: 12px; margin-left: 4px; }
.auth-card input.is-ok { border-color: #1a7f4b; box-shadow: 0 0 0 2px rgba(26, 127, 75, .12); }
.auth-card input.is-err { border-color: #c1382c; box-shadow: 0 0 0 2px rgba(193, 56, 44, .12); }
.auth-card .btn[disabled] { opacity: .68; cursor: not-allowed; }

.captcha-row { display: flex; align-items: center; gap: 10px; }
.captcha-row input { flex: 1 1 auto; min-width: 0; }
.captcha-img {
    flex: 0 0 auto; width: 120px; height: 40px; border-radius: 8px;
    border: 1px solid var(--line); background: #f2f5fb; cursor: pointer;
    user-select: none; -webkit-user-drag: none;
}
.captcha-foot { display: flex; align-items: center; justify-content: space-between; gap: 10px; }
.captcha-foot .field-hint { margin-top: 6px; }
.link-btn {
    border: 0; background: none; padding: 6px 0 0; margin: 0;
    font: inherit; font-size: 13px; color: var(--primary); cursor: pointer;
}
.link-btn:hover { text-decoration: underline; }

@media (max-width: 420px) {
    .captcha-img { width: 104px; height: 38px; }
}


/* 后台统计卡 */
.kpi-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(160px, 1fr)); gap: 14px; margin: 16px 0; }
.kpi { background: var(--card); border-radius: 12px; padding: 18px; text-align: center; box-shadow: var(--shadow); }
.kpi-num { font-size: 28px; font-weight: 700; color: var(--primary-d); }
.kpi-label { color: var(--muted); font-size: 13px; margin-top: 4px; }
.admin-section { background: var(--card); border-radius: 12px; padding: 18px; box-shadow: var(--shadow); margin-top: 18px; }
.btn-tiny { padding: 4px 10px; font-size: 12px; margin-left: 8px; }

/* 文件上传 */
.file-input { padding: 8px 0; font-size: 14px; }
.field-tip { display: block; margin-top: 6px; color: var(--muted); font-size: 12px; }
.hint h4 { margin: 14px 0 6px; font-size: 14px; color: var(--ink); }

/* 管理员：题库编辑 / 删除确认 */
.admin-section { overflow-x: auto; }
.row-actions a.btn-danger { color: #fff; }
.row-actions a.btn-danger:hover { text-decoration: none; background: #c1382c; }

.notice-box {
    background: #fff8ec; border: 1px solid #ffe2b8; color: #8a4b00;
    border-radius: 8px; padding: 12px 14px; font-size: 13px; margin: 14px 0;
}
.danger-box {
    background: #fdeceb; border: 1px solid #f3c2bd; color: #b23226;
    border-radius: 8px; padding: 14px 16px; font-size: 14px; margin: 16px 0;
}

.editor-basic { display: grid; grid-template-columns: 220px 1fr; gap: 16px; }
@media (max-width: 640px) { .editor-basic { grid-template-columns: 1fr; } }

.form-row select {
    width: 100%; height: 42px; padding: 0 12px; border: 1px solid var(--line);
    border-radius: 8px; font-size: 14px; font-family: inherit; background: #fff;
    color: var(--ink); transition: border-color .15s, box-shadow .15s;
}
.form-row input.confirm-input { max-width: 260px; }

.editor-card {
    background: var(--card); border: 1px solid var(--line); border-radius: 12px;
    padding: 16px 18px; margin: 14px 0; box-shadow: var(--shadow);
    transition: opacity .15s, border-color .15s;
}
.editor-card.marked-delete { opacity: .5; border-color: var(--bad); }
.editor-card-head {
    display: flex; align-items: center; justify-content: space-between;
    border-bottom: 1px solid var(--line); padding-bottom: 10px; margin-bottom: 14px;
}
.editor-card-head h2 { font-size: 16px; margin: 0; }
.del-check { font-size: 13px; color: var(--bad); cursor: pointer; white-space: nowrap; }
.del-check input { accent-color: var(--bad); }

.option-edit-row { display: flex; align-items: center; gap: 10px; margin-bottom: 8px; }
.option-letter { width: 22px; font-weight: 700; color: var(--primary-d); flex: none; }
.option-edit-row input[type=text] { flex: 1; }

/* 排行榜 */
.lb-tabs { display: flex; gap: 10px; flex-wrap: wrap; margin: 18px 0 12px; }
.lb-tab {
    padding: 8px 20px; border: 1px solid var(--line); border-radius: 8px;
    background: var(--card); color: var(--primary); text-decoration: none; font-size: 14px;
}
.lb-tab:hover { background: #eef3ff; }
.lb-tab.active { background: var(--primary); border-color: var(--primary); color: #fff; font-weight: 600; }
.lb-period-nav {
    display: flex; align-items: center; gap: 16px; flex-wrap: wrap;
    margin: 12px 0 18px; font-size: 14px;
}
.lb-period-nav a { color: var(--primary); text-decoration: none; }
.lb-period-nav a:hover { text-decoration: underline; }
.lb-me-card { border-left: 4px solid var(--primary); margin-bottom: 16px; }
.lb-table td, .lb-table th { vertical-align: middle; }
.lb-points { font-weight: 700; color: var(--primary-d); font-size: 15px; }
.lb-rank { display: inline-block; min-width: 26px; text-align: center; font-weight: 700; color: var(--muted); }
.lb-medal { color: #fff; border-radius: 999px; padding: 2px 8px; }
.lb-medal-1 { background: #d9a520; }
.lb-medal-2 { background: #8d9aab; }
.lb-medal-3 { background: #b97748; }
.lb-top-1 { background: #fffaf0; }
.lb-top-2 { background: #f8fafc; }
.lb-top-3 { background: #fff7f2; }
.lb-me-row { box-shadow: inset 3px 0 0 var(--primary); }

/* 阿里云认证：三级下拉菜单
   仅作用于 .nav-dropdown / .nav-submenu 内部，沿用顶栏配色与卡片变量，
   不改动上方 .nav a 等既有规则，其它一级菜单保持原样。 */
.nav-dropdown { position: relative; display: inline-flex; align-items: center; vertical-align: middle; margin-left: 12px; }
/* 一级菜单与下拉面板之间有 8px 的视觉间隙（见 .nav-submenu 的 margin-top）。
   这段空隙不属于任何元素，鼠标向下移动时 :hover 会瞬间丢失、面板闪退，
   导致根本点不到二级菜单。用一条透明的伪元素把空隙“桥”起来，视觉零变化。 */
.nav-dropdown::after {
    content: "";
    position: absolute;
    top: 100%;
    left: -10px;
    right: -14px;
    height: 12px; /* 略大于 8px 间隙，并盖住面板顶边 2px，保证无缝衔接 */
    background: transparent;
}
.nav-dropdown > .nav-link { margin-left: 0; color: #eaf0ff; text-decoration: none; font-size: 14px; white-space: nowrap; }
.nav-dropdown.is-current > .nav-link { color: #fff; font-weight: 600; }
.nav-toggle {
    background: transparent; border: 0; padding: 0 2px; margin-left: 4px;
    color: inherit; cursor: pointer; font-size: 13px; line-height: 1;
}
.nav-submenu {
    display: none; position: absolute; top: 100%; left: 0; z-index: 30;
    min-width: 190px; margin: 8px 0 0; padding: 6px 0; list-style: none;
    background: var(--card); border: 1px solid var(--line);
    border-radius: 10px; box-shadow: var(--shadow);
}
/* 桌面 hover / 键盘 focus / 触屏点击（.open 由 nav.js 切换）均可展开 */
[data-nav-dropdown]:hover > .nav-submenu,
[data-nav-dropdown]:focus-within > .nav-submenu,
[data-nav-dropdown].open > .nav-submenu { display: block; }
/* 三级菜单：悬停 / 点击展开 */
.nav-submenu li.has-children:hover > .nav-submenu,
.nav-submenu li.has-children:focus-within > .nav-submenu,
.nav-submenu li.has-children.open > .nav-submenu { display: block; }
.nav-submenu li.has-children > .nav-toggle { position: absolute; top: 8px; right: 8px; margin: 0; color: var(--muted); }
/* 顶栏当前栏目高亮 */
.nav > a.is-current { color: #fff; font-weight: 600; }
.nav-submenu li { position: relative; }
.nav-level-3 { top: -7px; left: 100%; margin-top: 0; }
.nav .nav-submenu a {
    display: block; margin: 0; padding: 8px 14px; color: var(--ink);
    font-size: 14px; text-decoration: none; white-space: nowrap;
}
.nav .nav-submenu a:hover,
.nav .nav-submenu a.is-active { color: var(--primary-d); background: #eef3ff; text-decoration: none; }
.nav .nav-submenu a.is-active { font-weight: 600; }
.nav-submenu .has-children > a { padding-right: 30px; }
.nav-submenu .has-children > .nav-toggle {
    position: absolute; top: 7px; right: 8px; margin: 0; color: var(--muted);
}

/* 认证栏目介绍页 */
.breadcrumb { font-size: 13px; margin-bottom: 14px; }
.breadcrumb a { color: var(--primary); text-decoration: none; }
.breadcrumb a:hover { text-decoration: underline; }
.breadcrumb-sep { color: var(--muted); margin: 0 8px; }
.cert-intro { font-size: 15px; margin: 6px 0 4px; }
.card h2 a { color: var(--ink); text-decoration: none; }
.card h2 a:hover { color: var(--primary-d); }

@media (max-width: 640px) {
    .nav-dropdown { display: block; margin: 8px 0 0 18px; }
    .nav-submenu, .nav-level-3 { position: static; box-shadow: none; margin: 4px 0 0; }
    .nav-level-3 { margin-left: 12px; }
    /* 折叠态下二级面板是静态排版，桥接层会盖住第一条菜单，直接关掉 */
    .nav-dropdown::after { display: none; }
}

/* 三级栏目选择器（题目导入页 / 题库编辑页共用） */
.required-mark { color: #c0392b; font-weight: 700; }
.category-picker-row { display: flex; flex-wrap: wrap; gap: 10px; }
.category-picker-row .cat-level { flex: 1 1 180px; min-width: 160px; }
.cat-level.is-hidden { display: none; }
.category-picker-hint { display: block; margin-top: 8px; }
.category-picker-hint.is-error { color: #c0392b; font-weight: 600; }

/* ===== 认证栏目详情页：首屏认证介绍 + 本栏目试题列表 ===== */
.cert-intro-card { border-left: 4px solid var(--primary); margin-top: 16px; }
.cert-intro-head { display: flex; align-items: center; gap: 10px; flex-wrap: wrap; }
.cert-intro-head h2 { margin: 0; font-size: 17px; }
.cert-intro-text { font-size: 15px; line-height: 1.85; margin: 12px 0 6px; }
.cert-source { font-size: 12px; margin: 0; }
.section-count { font-size: 13px; font-weight: 400; }
.q-list { display: flex; flex-direction: column; gap: 10px; }
.q-item { background: var(--card); border: 1px solid var(--line); border-radius: 10px;
          padding: 12px 16px; box-shadow: var(--shadow); }
.q-item summary { cursor: pointer; font-size: 14px; }
.q-title { font-weight: 600; }
.q-meta { font-size: 12px; }
.q-body { border-top: 1px solid var(--line); margin-top: 12px; padding-top: 10px; font-size: 14px; }
.q-options { margin: 0 0 10px; padding-left: 20px; }
.q-options li { margin: 4px 0; }
.q-answer { margin: 6px 0; }
.q-exp { background: #f7f9fc; border-radius: 8px; padding: 10px 12px; margin-top: 8px; }
.exp-block { margin-top: 6px; line-height: 1.75; }
.exp-line { display: inline-block; }

/* ===== 每日答题练习：三级联动 + 随机 10 题 ===== */
.practice-picker { margin-top: 8px; }
.picker-row { display: flex; flex-wrap: wrap; gap: 12px; }
.picker-row > div { flex: 1 1 200px; min-width: 170px; }
.picker-row label { font-size: 13px; font-weight: 600; display: block; margin-bottom: 6px; }
.picker-row select { width: 100%; padding: 9px 10px; border: 1px solid var(--line);
                     border-radius: 8px; font-size: 14px; background: #fff; }
.practice-intro { margin-top: 16px; padding: 14px 16px; background: #f2f6ff;
                  border-radius: 10px; border-left: 4px solid var(--primary); }
.practice-intro h3 { margin: 0 0 8px; font-size: 15px; }
.practice-intro p { margin: 4px 0; font-size: 14px; }
.q-card { margin-top: 14px; }
.q-card h3 { margin: 0 0 10px; font-size: 15px; }
.q-stem { font-size: 15px; margin: 0 0 12px; font-weight: 500; }
.q-choices { display: flex; flex-direction: column; gap: 8px; }
.q-choice { display: flex; align-items: flex-start; gap: 8px; padding: 8px 10px;
            border: 1px solid var(--line); border-radius: 8px; cursor: pointer; font-size: 14px; }
.q-choice:hover { background: #f7f9fc; }
.q-choice input { margin-top: 4px; }
.q-feedback { margin-top: 10px; }
.q-result { padding: 10px 12px; border-radius: 8px; font-size: 14px; }
.q-result.ok { background: #e7f7ee; border: 1px solid #b7e6c8; }
.q-result.err { background: #fdeceb; border: 1px solid #f3c2bd; }
.q-result p { margin: 6px 0; }
.q-card.q-right { border-left: 4px solid var(--ok); }
.q-card.q-wrong { border-left: 4px solid var(--bad); }
.practice-score { margin-top: 18px; }


/* ===== 窄屏适配：顶栏换行 + 登录/注册卡片不溢出 ===== */
@media (max-width: 720px) {
    .topbar-inner { padding: 12px 16px; gap: 8px; }
    .brand { font-size: 17px; }
    .nav { width: 100%; justify-content: flex-start; }
    .nav a { margin: 2px 14px 2px 0; }
    .container { padding: 18px 16px 48px; }
    .auth-wrap { margin: 22px auto; max-width: 100%; }
    .auth-card { padding: 24px 20px 20px; border-radius: 12px; }
    .auth-card h1 { font-size: 20px; }
}