/* Mathbility 视觉改版 R1 ·「清爽纸面 / 轻线条」
   加载在最后：只覆盖表现层，不改结构、脚本与数据。
   四套品牌主题色值保持 theme-orb154.js 原定义，本表只改用法：
   发丝线边框、单层环境影、分段式导航、幽灵按钮与更清晰的字体层级。
   链接任何状态都无下划线，也不用底边框模拟；键盘焦点保持清晰可见。 */
@media screen {
  :root {
    --vr-line: color-mix(in srgb, var(--brand-ink) 10%, var(--brand-bg));
    --vr-line-strong: color-mix(in srgb, var(--brand-ink) 18%, var(--brand-bg));
    --vr-ink-shadow: color-mix(in srgb, var(--brand-ink) 5%, transparent);
    --vr-shadow-sm: 0 1px 2px color-mix(in srgb, var(--brand-ink) 4%, transparent), 0 6px 18px color-mix(in srgb, var(--brand-ink) 4%, transparent);
    --vr-shadow-md: 0 2px 4px color-mix(in srgb, var(--brand-ink) 5%, transparent), 0 14px 36px color-mix(in srgb, var(--brand-ink) 7%, transparent);
    --vr-focus: 0 0 0 3px color-mix(in srgb, var(--brand-primary) 16%, transparent);
    --vr-radius-s: 10px;
    --vr-radius-m: 14px;
    --vr-radius-l: 18px;
  }

  /* ---------- 页面底色与顶栏 ---------- */
  body {
    background-color: var(--brand-bg);
    background-image: radial-gradient(ellipse 120% 60% at 50% -8%, color-mix(in srgb, var(--brand-surface, #fff) 80%, transparent), transparent 62%);
  }
  body > header {
    border: 1px solid var(--vr-line);
    border-bottom-width: 1px;
    border-radius: var(--vr-radius-l);
    background: color-mix(in srgb, var(--brand-surface, #fff) 92%, transparent);
    box-shadow: var(--vr-shadow-sm);
    padding-block: 14px;
  }
  .brand-icon { width: 42px; height: 42px; }
  #identity { font-size: 13px; font-weight: 600; color: var(--brand-ink); }
  #themeSelect {
    min-height: 40px;
    border: 1px solid var(--vr-line);
    border-radius: var(--vr-radius-s);
    background: var(--brand-surface, #fff);
    font-size: 12px;
    font-weight: 600;
    box-shadow: none;
  }

  /* ---------- 字体层级 ---------- */
  h1 { font-weight: 700; letter-spacing: -.03em; }
  h2 { font-size: 25px; font-weight: 700; letter-spacing: -.01em; }
  h3 { font-size: 19px; font-weight: 650; }
  .eyebrow { font-size: 11px; letter-spacing: .16em; color: var(--brand-primary); font-weight: 700; }
  .muted { font-size: 13px; }
  .small { font-size: 12px; }
  label { font-size: 13px; font-weight: 600; }

  /* ---------- 卡片：发丝线 + 单层环境影 ---------- */
  .panel, .access-card, .membership-plan, .membership-order, .globe-progress {
    border: 1px solid var(--vr-line);
    border-radius: var(--vr-radius-l);
    background: var(--brand-surface, #fff);
    box-shadow: var(--vr-shadow-sm);
  }
  .panel { padding: 28px 30px; }
  dialog {
    border: 1px solid var(--vr-line);
    border-radius: var(--vr-radius-l);
    background: var(--brand-surface, #fff);
    box-shadow: var(--vr-shadow-md);
  }

  /* ---------- 按钮与输入 ---------- */
  .primary, .secondary, .tabs button, .domain, .node, .knowledge-link, .practice-course-button {
    transition: background-color 150ms ease, border-color 150ms ease, box-shadow 150ms ease, color 150ms ease, transform 150ms ease;
  }
  .primary {
    min-height: 46px;
    padding: 12px 22px;
    border: 1px solid var(--brand-primary);
    border-radius: 12px;
    font-size: 14px;
    font-weight: 700;
    box-shadow: 0 2px 6px color-mix(in srgb, var(--brand-primary) 18%, transparent);
  }
  .primary:hover:not(:disabled) { background: var(--brand-hover); box-shadow: 0 4px 12px color-mix(in srgb, var(--brand-primary) 22%, transparent); transform: none; }
  .primary:active:not(:disabled) { transform: translateY(1px); box-shadow: none; }
  .secondary {
    min-height: 42px;
    border: 1px solid var(--vr-line-strong);
    border-radius: 11px;
    background: var(--brand-surface, #fff);
    color: var(--brand-ink);
    font-size: 13px;
    font-weight: 600;
    box-shadow: none;
  }
  .secondary:hover:not(:disabled) { background: var(--brand-tint); border-color: var(--brand-primary); color: var(--brand-primary); }
  .secondary:active:not(:disabled) { transform: none; box-shadow: none; }
  .header-actions .secondary { min-height: 40px; font-size: 12px; }
  button:disabled { box-shadow: none; transform: none; }
  input:not([type="checkbox"]):not([type="range"]):not([type="file"]), textarea, select {
    border: 1px solid var(--vr-line-strong);
    border-radius: var(--vr-radius-s);
    background: var(--brand-surface, #fff);
    box-shadow: none;
  }
  input:focus, textarea:focus, select:focus {
    border-color: var(--brand-primary);
    box-shadow: var(--vr-focus);
    outline: 0;
  }
  button:focus-visible, a:focus-visible, summary:focus-visible, canvas:focus-visible {
    outline: 3px solid var(--brand-primary);
    outline-offset: 3px;
  }

  /* ---------- 工作区导航：分段式 ---------- */
  body[data-session="active"] .tabs {
    gap: 4px;
    padding: 5px;
    margin: 20px 0 24px;
    border: 1px solid var(--vr-line);
    border-radius: var(--vr-radius-m);
    background: color-mix(in srgb, var(--brand-tint) 55%, var(--brand-surface, #fff));
    box-shadow: none;
  }
  .tabs button {
    min-height: 44px;
    padding: 10px 18px;
    border: 1px solid transparent;
    border-radius: var(--vr-radius-s);
    color: var(--brand-muted);
    font-size: 12px;
    font-weight: 600;
    transition: background-color 150ms ease, color 150ms ease, box-shadow 150ms ease;
  }
  .tabs button:hover:not(.active) { background: color-mix(in srgb, var(--brand-tint) 80%, #fff); color: var(--brand-primary); }
  .tabs button.active {
    background: var(--brand-primary);
    color: #fff;
    box-shadow: 0 2px 8px color-mix(in srgb, var(--brand-primary) 22%, transparent);
  }
  .tabs button span { font-size: 14px; font-weight: 650; margin-left: 8px; }
  .tabs button.active span { color: #fff; }
  .tabs button:focus-visible { outline-offset: 1px; }

  /* 章节标题：短强调条 + 主题色眉题 */
  .section-heading {
    margin-bottom: 22px;
    padding: 2px 0 2px 14px;
    border-left: 3px solid var(--brand-primary);
    border-radius: 2px;
  }
  .section-heading h2 { letter-spacing: -.01em; }
  .section-heading > .muted { font-size: 13px; }

  /* ---------- 首页 ---------- */
  .hero { padding: 56px 16px 40px; gap: 48px; }
  .hero h1 { font-size: clamp(44px, 4.6vw, 60px); line-height: 1.26; }
  .hero .intro { font-size: 15px; line-height: 2.05; }
  .hero-art { width: 288px; margin-right: 24px; }
  .hero-art .math-orb {
    width: 252px;
    border-radius: 50%;
    background: radial-gradient(circle, color-mix(in srgb, var(--brand-tint) 80%, transparent), transparent 68%);
    filter: none;
  }
  .hero-art span { font-size: 11px; letter-spacing: .18em; color: var(--brand-muted); }
  .desktop-use-note { color: var(--brand-muted); }
  .notice {
    border: 1px solid var(--vr-line);
    border-radius: var(--vr-radius-s);
    background: color-mix(in srgb, var(--brand-tint) 70%, var(--brand-surface, #fff));
  }

  /* ---------- 登录 / 注册 / 版本选择 ---------- */
  .login {
    max-width: 480px;
    padding: 32px 36px;
    border-top: 1px solid var(--vr-line);
  }
  .login h2 { font-size: 26px; }
  .login input { min-height: 48px; }
  #authNotice {
    margin: 0 0 18px;
    padding: 11px 14px;
    border: 1px solid var(--vr-line);
    border-radius: var(--vr-radius-s);
    background: var(--brand-tint);
    color: var(--brand-ink);
    font-size: 13px;
    line-height: 1.7;
  }
  .auth-tabs {
    gap: 4px;
    padding: 4px;
    border: 1px solid var(--vr-line);
    border-radius: 12px;
    background: color-mix(in srgb, var(--brand-tint) 55%, var(--brand-surface, #fff));
  }
  .login .auth-tabs button { border-radius: 9px; font-size: 13px; font-weight: 600; color: var(--brand-muted); box-shadow: none; }
  .login .auth-tabs button.active { background: var(--brand-primary); color: #fff; box-shadow: 0 2px 6px color-mix(in srgb, var(--brand-primary) 20%, transparent); }
  .login .auth-switch { color: var(--brand-primary); font-weight: 600; }
  .login .guest-entry { background: var(--brand-tint); border-color: var(--vr-line); color: var(--brand-primary); }
  .access-card { padding: 28px; border-top: 1px solid var(--vr-line); }
  .access-card.member { border-color: color-mix(in srgb, var(--brand-primary) 35%, var(--vr-line)); background: color-mix(in srgb, var(--brand-tint) 65%, var(--brand-surface, #fff)); }
  .access-card .access-price { font-weight: 700; }

  /* ---------- 训练：课程与板块 ---------- */
  .practice-course-controls {
    gap: 14px;
    padding: 18px 20px;
    border: 1px solid var(--vr-line);
    border-radius: var(--vr-radius-m);
    background: var(--brand-surface, #fff);
    box-shadow: var(--vr-shadow-sm);
  }
  .practice-course-button {
    min-height: 44px;
    border: 1px solid var(--vr-line);
    border-radius: var(--vr-radius-s);
    background: var(--brand-bg);
    font-size: 13px;
    font-weight: 600;
  }
  .practice-course-button:hover { background: var(--brand-tint); border-color: var(--brand-primary); }
  .practice-course-button[aria-pressed=true] {
    background: var(--brand-primary);
    border-color: var(--brand-primary);
    color: #fff;
    box-shadow: 0 2px 6px color-mix(in srgb, var(--brand-primary) 20%, transparent);
  }
  .practice-course-aux .practice-course-button { background: transparent; }
  .practice-course-aux .practice-course-button[aria-pressed=true] {
    background: var(--brand-tint);
    color: var(--brand-primary);
    box-shadow: none;
  }
  .practice-domain-summary { font-size: 12px; }

  body[data-session="active"] .domain {
    min-height: 100px;
    padding: 18px 20px;
    gap: 16px;
    border: 1px solid var(--vr-line);
    border-radius: var(--vr-radius-m);
    background: var(--brand-surface, #fff);
    box-shadow: none;
  }
  .domain .symbol {
    width: 50px;
    height: 50px;
    border: 1px solid var(--vr-line);
    border-radius: 13px;
    background: color-mix(in srgb, var(--brand-tint) 75%, var(--brand-surface, #fff));
    font-size: 28px;
  }
  .domain strong { font-size: 15px; font-weight: 700; }
  .domain small { font-size: 12px; }
  body[data-session="active"] .domain:hover { border-color: var(--brand-primary); box-shadow: var(--vr-shadow-sm); transform: none; }
  body[data-session="active"] .domain.active {
    background: color-mix(in srgb, var(--brand-tint) 80%, var(--brand-surface, #fff));
    border-color: var(--brand-primary);
    box-shadow: var(--vr-shadow-sm);
  }
  .domain.active .symbol { background: var(--brand-primary); border-color: var(--brand-primary); color: #fff; }
  .domain .arrow { color: var(--brand-primary); }

  #questionPicker {
    padding: 18px 22px;
    margin-block: 18px 24px;
    border: 1px solid var(--vr-line);
    border-radius: var(--vr-radius-m);
    background: var(--brand-surface, #fff);
    box-shadow: var(--vr-shadow-sm);
  }
  .difficulty-track input::-webkit-slider-runnable-track { height: 6px; }
  .difficulty-track input::-webkit-slider-thumb { width: 22px; height: 22px; margin-top: -8px; border-width: 3px; }

  /* ---------- 题目阅读页 ---------- */
  body[data-session="active"] .question {
    padding: 0 34px 32px;
    border: 1px solid var(--vr-line);
    border-top: 1px solid var(--vr-line);
    border-radius: var(--vr-radius-l);
  }
  .question-top {
    margin: 0 -34px 26px;
    padding: 15px 34px;
    border-bottom: 1px solid var(--vr-line);
    border-radius: var(--vr-radius-l) var(--vr-radius-l) 0 0;
    background: color-mix(in srgb, var(--brand-tint) 62%, var(--brand-surface, #fff));
    font-size: 12px;
  }
  .question-top #progress { color: var(--brand-primary); font-weight: 700; }
  .math-content { font-size: 18px; line-height: 2.05; }
  #stem { padding: 2px 2px 10px; }
  #stem .question-text-flow { gap: 18px; }
  #stem .question-equation-number { color: var(--brand-muted); }
  .math-content .katex-display { padding-block: 8px; }

  #answerForm {
    margin-top: 30px;
    padding: 22px 24px;
    border: 1px solid var(--vr-line);
    border-radius: var(--vr-radius-m);
    background: var(--brand-surface, #fff);
    box-shadow: none;
  }
  #answerForm > label { font-size: 15px; margin-bottom: 12px; }
  #answer {
    border: 1px solid var(--vr-line);
    border-radius: var(--vr-radius-s);
    padding: 12px 16px;
    background-color: var(--brand-bg);
    background-image: repeating-linear-gradient(transparent 0, transparent 31px, var(--vr-line) 31px, var(--vr-line) 32px);
    font-size: 16px;
    line-height: 32px;
    box-shadow: none;
  }
  #answer:focus { border-color: var(--brand-primary); box-shadow: var(--vr-focus); }
  #answerForm:has(#answer:focus) { border-color: var(--brand-primary); box-shadow: none; }
  #answerForm .actions { border-top-color: var(--vr-line); }
  .upload-trigger {
    border: 1px solid var(--vr-line-strong);
    border-radius: var(--vr-radius-s);
    background: var(--brand-surface, #fff);
    box-shadow: none;
  }
  .upload-trigger:hover { background: var(--brand-tint); border-color: var(--brand-primary); }
  .handwriting-panel { border-top-color: var(--vr-line); }
  #handwriting { border-color: var(--vr-line-strong); border-radius: var(--vr-radius-s); }
  .ink-toolbar .secondary { font-size: 12px; min-height: 38px; }
  .attachment-row { border-radius: var(--vr-radius-s); }

  /* 教学面板：白底 + 左侧强调条，不再整版填充 */
  .teaching-panel {
    margin: 26px 0;
    padding: 24px 26px;
    border: 1px solid var(--vr-line);
    border-left: 3px solid var(--brand-primary);
    border-radius: var(--vr-radius-m);
    background: var(--brand-surface, #fff);
    box-shadow: var(--vr-shadow-sm);
  }
  .teaching-heading h3 { font-size: 20px; }
  .teaching-detail { border-top-color: var(--vr-line); }
  .knowledge-link {
    border: 1px solid var(--vr-line);
    border-radius: var(--vr-radius-s);
    background: var(--brand-surface, #fff);
    box-shadow: none;
  }
  .knowledge-link:hover { border-color: var(--brand-primary); background: var(--brand-tint); }
  .hint-step {
    padding: 12px 18px;
    border-left: 3px solid var(--brand-primary);
    border-radius: 0 var(--vr-radius-s) var(--vr-radius-s) 0;
    background: color-mix(in srgb, var(--brand-tint) 70%, var(--brand-surface, #fff));
  }
  .self-report { border-top-color: var(--vr-line); }
  .report-options button { min-height: 38px; font-size: 12px; }
  .secondary.selected, .report-options button.selected {
    background: var(--brand-primary);
    border-color: var(--brand-primary);
    color: #fff;
  }

  .method-card {
    border: 1px solid #cfdef0;
    border-radius: var(--vr-radius-m);
    background: #f0f5fc;
    box-shadow: none;
  }
  .solution-steps { gap: 12px; }
  .solution-step {
    padding: 18px 20px;
    border: 1px solid var(--vr-line);
    border-radius: var(--vr-radius-m);
    background: var(--brand-surface, #fff);
    box-shadow: none;
  }
  .step-label > span {
    width: 32px;
    height: 32px;
    border: 1px solid var(--vr-line);
    border-radius: 9px;
    background: var(--brand-tint);
    font-weight: 700;
  }
  .step-reason {
    border: 1px solid #e7dcc3;
    border-radius: var(--vr-radius-s);
    background: #faf6ec;
  }
  .solution-conclusion {
    border: 1px solid #c8e0d3;
    border-radius: var(--vr-radius-m);
    background: #f0f8f3;
    box-shadow: none;
  }
  .rubric-card { border-radius: var(--vr-radius-m); box-shadow: none; }
  .points-badge { border-radius: 8px; }
  .exam-context {
    border: 1px solid var(--vr-line);
    border-radius: var(--vr-radius-m);
    background: color-mix(in srgb, var(--brand-tint) 70%, var(--brand-surface, #fff));
  }
  .exam-relation { border-color: var(--vr-line-strong); }
  .question-feedback { border-top-color: var(--vr-line); }
  .question-feedback summary { color: var(--brand-ink); }
  .mapping-notice {
    border: 1px solid var(--vr-line);
    border-radius: var(--vr-radius-s);
    background: var(--brand-tint);
  }
  .coordinate-metrics strong { font-weight: 700; }
  .compact-item, .node-item-group .compact-item {
    border: 1px solid var(--vr-line);
    border-radius: var(--vr-radius-s);
    background: var(--brand-surface, #fff);
    box-shadow: none;
  }
  .compact-item:hover { border-color: var(--brand-primary); }

  /* ---------- 知识球 ---------- */
  .globe-progress {
    padding: 20px 24px;
    border-radius: var(--vr-radius-m);
    box-shadow: var(--vr-shadow-sm);
  }
  .globe-progress strong { font-size: 32px; font-weight: 700; letter-spacing: -.03em; }
  .globe-progress progress { height: 8px; }
  .graph-layout aside, .graph-layout article { padding: 22px; }
  #nodeSearch { font-size: 14px; }
  #nodeList .node { border-radius: var(--vr-radius-s); }
  #nodeList .node.selected { box-shadow: inset 0 0 0 2px var(--brand-primary); }
  #network {
    border: 1px solid var(--vr-line);
    border-radius: var(--vr-radius-m);
    background: var(--brand-surface, #fff);
  }
  .globe-tools .secondary { min-height: 38px; font-size: 12px; }
  .globe-position {
    border: 1px solid var(--vr-line);
    border-radius: var(--vr-radius-s);
    background: var(--brand-tint);
  }
  .globe-learning-actions button[aria-pressed=true] { box-shadow: 0 2px 6px color-mix(in srgb, var(--brand-primary) 20%, transparent); }
  #nodeDetail h3 { font-size: 22px; }

  /* ---------- 个人中心（紧凑版继承新语言） ---------- */
  #account .panel:not(.admin-management) {
    border: 1px solid var(--vr-line);
    border-radius: var(--vr-radius-l);
    box-shadow: var(--vr-shadow-sm);
  }
  #account .account-status {
    border: 1px solid var(--vr-line);
    border-radius: var(--vr-radius-m);
    background: color-mix(in srgb, var(--brand-tint) 68%, var(--brand-surface, #fff));
  }
  #account .account-access-label { border: 1px solid var(--vr-line); background: var(--brand-surface, #fff); }
  #account .membership-plan {
    border: 1px solid var(--vr-line);
    border-radius: var(--vr-radius-m);
    box-shadow: none;
  }
  #account .membership-plan:hover { border-color: var(--brand-primary); }
  #account .membership-order {
    border: 1px solid var(--vr-line);
    border-radius: var(--vr-radius-m);
    box-shadow: none;
  }
  #account .account-recent-works { border-top-color: var(--vr-line); }
  .membership-result-icon { border-color: var(--vr-line-strong); }
  .membership-next-step { border-radius: var(--vr-radius-s); }
  .feedback-queue { border-color: var(--vr-line); border-radius: var(--vr-radius-s); }
  .feedback-detail { border-color: var(--vr-line); border-radius: var(--vr-radius-s); }

  /* 个人中心内的管理工作台入口卡（管理员可见） */
  .admin-console-entry {
    margin-top: 8px;
    padding: 18px 20px;
    border: 1px solid var(--vr-line);
    border-radius: var(--vr-radius-m);
    background: color-mix(in srgb, var(--brand-tint) 55%, var(--brand-surface, #fff));
  }
  .admin-console-entry > p { margin: 4px 0 14px; }
  .admin-console-entry .admin-console-entry-link { display: inline-flex; align-items: center; min-height: 42px; padding: 10px 20px; border-radius: 11px; font-size: 13px; }
  .admin-console-entry .muted { margin: 14px 0 0; }
  .admin-console-entry code { font: 11px/1.5 ui-monospace, Consolas, monospace; }

  /* ---------- 全景 iframe / 页脚 ---------- */
  .atlas-frame {
    border: 1px solid var(--vr-line);
    border-radius: var(--vr-radius-l);
    box-shadow: var(--vr-shadow-sm);
  }
  footer {
    border-top: 1px solid var(--vr-line);
    padding-top: 22px;
  }
  .error { border-radius: var(--vr-radius-s); }

  /* ---------- 链接下划线最终防线（任何状态、含链接式按钮） ---------- */
  a, a:hover, a:focus, a:active, a:visited,
  .text-button, .auth-switch, .membership-back { text-decoration: none !important; }

  /* ---------- 窄屏 ---------- */
  @media (max-width: 800px) {
    .panel { padding: 20px; border-radius: var(--vr-radius-m); }
    .hero { padding: 34px 0 26px; gap: 24px; }
    .hero h1 { font-size: clamp(34px, 6vw, 46px); }
    h2 { font-size: 23px; }
    h3 { font-size: 18px; }
    .login { padding: 26px 22px; }
    body[data-session="active"] .tabs { gap: 3px; padding: 4px; margin: 14px 0 18px; }
    .tabs button { min-height: 42px; padding: 8px 10px; }
    .tabs button span { font-size: 12px; margin-left: 5px; }
    .section-heading { margin-bottom: 18px; padding-left: 12px; }
    body[data-session="active"] .domain { min-height: 88px; padding: 14px 16px; gap: 12px; }
    .domain .symbol { width: 44px; height: 44px; border-radius: 11px; font-size: 25px; }
    #questionPicker { padding: 14px 16px; margin-block: 14px 20px; }
    body[data-session="active"] .question { padding: 0 18px 22px; border-radius: var(--vr-radius-m); }
    .question-top { margin-inline: -18px; padding: 12px 18px; font-size: 11px; border-radius: var(--vr-radius-m) var(--vr-radius-m) 0 0; }
    .math-content { font-size: 16px; line-height: 2; }
    #answerForm { padding: 16px; margin-top: 24px; }
    #answerForm > label { font-size: 14px; }
    #answer { min-height: 150px; font-size: 15px; }
    .teaching-panel { padding: 18px; }
    .teaching-heading h3 { font-size: 18px; }
    .solution-step, .method-card, .rubric-card, .solution-conclusion { padding: 16px; }
    .globe-progress { padding: 18px; }
    .globe-progress strong { font-size: 26px; }
    .graph-layout aside, .graph-layout article { padding: 18px; }
    .access-card { padding: 22px; }
    dialog { padding: 24px; }
  }

  @media (prefers-reduced-motion: reduce) {
    .primary, .secondary, .tabs button, .domain, .node, .knowledge-link, .practice-course-button { transition: none; }
    .primary:active:not(:disabled), .secondary:active:not(:disabled) { transform: none; }
  }
}