/* ============================================================
   分子语堂 · 设计系统
   美学方向：工程图纸手册 — 网格纸、墨绿黑、铁锈橙、硬阴影
   ============================================================ */

:root {
  --paper: #f4f0e4;
  --paper-deep: #ebe6d6;
  --card: #fbf9f2;
  --ink: #1f2d27;
  --ink-2: #55645c;
  --ink-3: #8b968f;
  --rust: #c24914;
  --rust-deep: #9a3810;
  --rust-soft: #f6e3d8;
  --teal: #0e6e63;
  --teal-deep: #0a5249;
  --teal-soft: #ddeae6;
  --blue: #20558a;
  --blue-soft: #e0e9f2;
  --gold: #a8813a;
  --grid: rgba(31, 45, 39, 0.055);
  --grid-strong: rgba(31, 45, 39, 0.12);
  --line: #d9d2bf;
  --shadow: 5px 5px 0 rgba(31, 45, 39, 0.92);
  --shadow-sm: 3px 3px 0 rgba(31, 45, 39, 0.9);
  --shadow-rust: 5px 5px 0 rgba(194, 73, 20, 0.35);

  --serif: "Noto Serif SC", "Source Han Serif SC", "Songti SC", "STZhongsong", "SimSun", serif;
  --sans: "Noto Sans SC", "Source Han Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
  --mono: "Cascadia Code", "JetBrains Mono", "Fira Code", "Consolas", "Courier New", monospace;

  --radius: 2px;
  --nav-h: 66px;
}

* { margin: 0; padding: 0; box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  font-family: var(--sans);
  color: var(--ink);
  background-color: var(--paper);
  background-image:
    linear-gradient(var(--grid) 1px, transparent 1px),
    linear-gradient(90deg, var(--grid) 1px, transparent 1px);
  background-size: 30px 30px;
  font-size: 16px;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

::selection { background: var(--rust); color: var(--card); }

a { color: inherit; text-decoration: none; }
img { max-width: 100%; display: block; }
button { font-family: inherit; cursor: pointer; }

/* ---------- 滚动条 ---------- */
::-webkit-scrollbar { width: 10px; height: 10px; }
::-webkit-scrollbar-track { background: var(--paper-deep); }
::-webkit-scrollbar-thumb { background: var(--ink-2); border: 2px solid var(--paper-deep); }
::-webkit-scrollbar-thumb:hover { background: var(--rust); }

/* ============================================================
   顶部导航
   ============================================================ */
.nav {
  position: sticky;
  top: 0;
  z-index: 100;
  height: var(--nav-h);
  background: var(--paper);
  border-bottom: 2px solid var(--ink);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 clamp(16px, 4vw, 48px);
}

.nav-brand {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-shrink: 0;
}

.nav-logo {
  width: 42px;
  height: 42px;
  flex-shrink: 0;
}

.nav-title { display: flex; flex-direction: column; line-height: 1.15; }
.nav-title .zh {
  font-family: var(--serif);
  font-weight: 900;
  font-size: 21px;
  letter-spacing: 2px;
}
.nav-title .en {
  font-family: var(--mono);
  font-size: 9.5px;
  letter-spacing: 2.2px;
  color: var(--ink-2);
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 4px;
}

.nav-links a {
  font-size: 14.5px;
  font-weight: 600;
  padding: 8px 14px;
  position: relative;
  color: var(--ink-2);
  transition: color 0.18s;
}

.nav-links a::after {
  content: "";
  position: absolute;
  left: 14px;
  right: 14px;
  bottom: 3px;
  height: 2px;
  background: var(--rust);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.22s cubic-bezier(0.2, 0.9, 0.3, 1);
}

.nav-links a:hover { color: var(--ink); }
.nav-links a:hover::after { transform: scaleX(1); }

.nav-links a.active { color: var(--rust); }
.nav-links a.active::after { transform: scaleX(1); }

.nav-cta {
  margin-left: 12px;
  background: var(--ink);
  color: var(--paper) !important;
  padding: 9px 18px !important;
  font-size: 13.5px !important;
  border: 2px solid var(--ink);
  box-shadow: var(--shadow-sm);
  transition: transform 0.15s, box-shadow 0.15s;
}
.nav-cta:hover { transform: translate(-2px, -2px); box-shadow: 5px 5px 0 rgba(31,45,39,0.92); }
.nav-cta::after { display: none; }

.nav-burger {
  display: none;
  background: none;
  border: 2px solid var(--ink);
  width: 42px;
  height: 42px;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 5px;
  box-shadow: var(--shadow-sm);
}
.nav-burger span {
  display: block;
  width: 20px;
  height: 2px;
  background: var(--ink);
}

/* ============================================================
   通用版式
   ============================================================ */
.wrap { max-width: 1200px; margin: 0 auto; padding: 0 clamp(16px, 4vw, 40px); }

.sec { padding: clamp(48px, 8vw, 88px) 0; position: relative; }

.sec-head { display: flex; align-items: baseline; gap: 18px; margin-bottom: 14px; flex-wrap: wrap; }
.sec-index {
  font-family: var(--mono);
  font-size: 13px;
  font-weight: 700;
  color: var(--rust);
  letter-spacing: 1.5px;
  white-space: nowrap;
}
.sec-title {
  font-family: var(--serif);
  font-weight: 900;
  font-size: clamp(26px, 4vw, 38px);
  letter-spacing: 1px;
  line-height: 1.2;
}
.sec-sub {
  font-family: var(--mono);
  font-size: 12px;
  color: var(--ink-3);
  letter-spacing: 2px;
  margin-top: 6px;
}
.sec-desc { color: var(--ink-2); max-width: 720px; margin-top: 10px; }

.rule {
  height: 3px;
  background: var(--ink);
  margin: 18px 0 0;
  position: relative;
}
.rule::after {
  content: "";
  position: absolute;
  right: 0;
  top: 0;
  height: 3px;
  width: 90px;
  background: var(--rust);
}

.hazard {
  height: 12px;
  background: repeating-linear-gradient(-45deg, var(--rust) 0 14px, var(--ink) 14px 28px);
  border-top: 2px solid var(--ink);
  border-bottom: 2px solid var(--ink);
}

/* ---------- 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-family: var(--mono);
  font-weight: 700;
  font-size: 14px;
  letter-spacing: 0.5px;
  padding: 12px 22px;
  border: 2px solid var(--ink);
  background: var(--card);
  color: var(--ink);
  box-shadow: var(--shadow-sm);
  transition: transform 0.15s, box-shadow 0.15s, background 0.15s;
  user-select: none;
}
.btn:hover { transform: translate(-2px, -2px); box-shadow: 5px 5px 0 rgba(31, 45, 39, 0.92); }
.btn:active { transform: translate(1px, 1px); box-shadow: 2px 2px 0 rgba(31, 45, 39, 0.92); }
.btn.primary { background: var(--rust); color: #fff; }
.btn.dark { background: var(--ink); color: var(--paper); }
.btn.teal { background: var(--teal); color: #fff; }
.btn.sm { padding: 8px 14px; font-size: 12.5px; }
.btn svg { width: 16px; height: 16px; }
.btn:disabled { opacity: 0.45; cursor: not-allowed; transform: none; }

/* ---------- 卡片 ---------- */
.card {
  background: var(--card);
  border: 2px solid var(--ink);
  box-shadow: var(--shadow);
  padding: 26px;
  position: relative;
}

.card-tag {
  position: absolute;
  top: -2px;
  right: -2px;
  font-family: var(--mono);
  font-size: 10.5px;
  font-weight: 700;
  letter-spacing: 1.5px;
  background: var(--ink);
  color: var(--paper);
  padding: 4px 12px;
}
.card-tag.rust { background: var(--rust); }
.card-tag.teal { background: var(--teal); }
.card-tag.gold { background: var(--gold); }
.card-tag.blue { background: var(--blue); }

/* ---------- 周期表元素卡 ---------- */
.elem {
  border: 2.5px solid var(--ink);
  background: var(--card);
  box-shadow: var(--shadow);
  padding: 20px 22px;
  position: relative;
  display: block;
  transition: transform 0.2s cubic-bezier(0.2, 0.9, 0.3, 1.4), box-shadow 0.2s;
  overflow: hidden;
}
.elem::before {
  content: "";
  position: absolute;
  inset: 6px;
  border: 1px solid var(--grid-strong);
  pointer-events: none;
}
.elem:hover { transform: translate(-3px, -3px) rotate(-0.4deg); box-shadow: 8px 8px 0 rgba(31, 45, 39, 0.92); }
.elem .num { font-family: var(--mono); font-size: 12px; color: var(--rust); font-weight: 700; letter-spacing: 1px; }
.elem .sym {
  font-family: var(--serif);
  font-size: clamp(44px, 6vw, 64px);
  font-weight: 900;
  line-height: 1.05;
}
.elem .sym small { font-size: 0.42em; vertical-align: 0.55em; margin-left: 4px; font-weight: 700; }
.elem .ename { font-family: var(--mono); font-size: 11px; letter-spacing: 1.8px; color: var(--ink-2); text-transform: uppercase; }
.elem .edesc { font-size: 13px; color: var(--ink-2); margin-top: 10px; line-height: 1.6; }
.elem .e-meta {
  margin-top: 14px;
  padding-top: 12px;
  border-top: 1px dashed var(--grid-strong);
  font-family: var(--mono);
  font-size: 11px;
  color: var(--ink-3);
  display: flex;
  justify-content: space-between;
  letter-spacing: 0.5px;
}
.elem.accent-rust { background: linear-gradient(135deg, var(--card) 60%, var(--rust-soft)); }
.elem.accent-teal { background: linear-gradient(135deg, var(--card) 60%, var(--teal-soft)); }

/* ============================================================
   首页 Hero
   ============================================================ */
.hero {
  position: relative;
  padding: clamp(56px, 9vw, 110px) 0 clamp(48px, 7vw, 80px);
  overflow: hidden;
}
.hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background:
    radial-gradient(ellipse 700px 480px at 88% 12%, rgba(14, 110, 99, 0.1), transparent 65%),
    radial-gradient(ellipse 640px 420px at 6% 90%, rgba(194, 73, 20, 0.09), transparent 60%);
  pointer-events: none;
}

.hero-grid {
  display: grid;
  grid-template-columns: 1.25fr 0.75fr;
  gap: clamp(24px, 5vw, 64px);
  align-items: center;
  position: relative;
}

.hero-kicker {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-family: var(--mono);
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 2.5px;
  color: var(--teal);
  border: 1.5px solid var(--teal);
  padding: 6px 14px;
  background: rgba(14, 110, 99, 0.06);
  margin-bottom: 26px;
}
.hero-kicker .dot { width: 8px; height: 8px; background: var(--rust); border-radius: 50%; animation: blink 2.2s infinite; }
@keyframes blink { 0%, 100% { opacity: 1; } 50% { opacity: 0.25; } }

.hero h1 {
  font-family: var(--serif);
  font-weight: 900;
  font-size: clamp(40px, 7vw, 74px);
  line-height: 1.12;
  letter-spacing: 2px;
}
.hero h1 .hl {
  color: var(--rust);
  position: relative;
  white-space: nowrap;
}
.hero h1 .hl::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 6px;
  height: 10px;
  background: repeating-linear-gradient(-45deg, rgba(194,73,20,0.22) 0 8px, transparent 8px 16px);
  z-index: -1;
}
.hero-en {
  font-family: var(--mono);
  font-size: clamp(12px, 1.4vw, 15px);
  letter-spacing: 4px;
  color: var(--ink-2);
  margin-top: 18px;
  text-transform: uppercase;
}
.hero-desc {
  font-size: 16.5px;
  color: var(--ink-2);
  max-width: 560px;
  margin-top: 22px;
}
.hero-desc b { color: var(--ink); border-bottom: 2px solid var(--rust); padding-bottom: 1px; }

.hero-actions { display: flex; gap: 14px; margin-top: 34px; flex-wrap: wrap; }

.hero-stats {
  display: flex;
  gap: clamp(20px, 4vw, 52px);
  margin-top: 44px;
  padding-top: 24px;
  border-top: 2px solid var(--ink);
  flex-wrap: wrap;
}
.hstat .v { font-family: var(--serif); font-size: 30px; font-weight: 900; color: var(--ink); }
.hstat .v em { font-style: normal; color: var(--rust); }
.hstat .k { font-family: var(--mono); font-size: 11px; letter-spacing: 2px; color: var(--ink-3); margin-top: 2px; }

/* Hero 右侧：分子图 + 印章 */
.hero-visual { position: relative; display: flex; align-items: center; justify-content: center; min-height: 380px; }
.molecule {
  width: min(420px, 100%);
  filter: drop-shadow(6px 6px 0 rgba(31, 45, 39, 0.15));
  animation: floaty 7s ease-in-out infinite;
}
@keyframes floaty { 0%, 100% { transform: translateY(0) rotate(0deg); } 50% { transform: translateY(-14px) rotate(2deg); } }

.stamp {
  position: absolute;
  right: 0;
  bottom: 12px;
  width: 118px;
  height: 118px;
  border: 2.5px solid var(--rust);
  border-radius: 50%;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  color: var(--rust);
  transform: rotate(-12deg);
  background: rgba(251, 249, 242, 0.85);
  animation: floaty 8s ease-in-out infinite reverse;
}
.stamp::before {
  content: "";
  position: absolute;
  inset: 7px;
  border: 1.5px dashed var(--rust);
  border-radius: 50%;
}
.stamp .s1 { font-family: var(--serif); font-weight: 900; font-size: 22px; letter-spacing: 3px; }
.stamp .s2 { font-family: var(--mono); font-size: 9px; letter-spacing: 1.5px; margin-top: 3px; }

/* ============================================================
   模块总览 / 通用网格
   ============================================================ */
.grid-2 { display: grid; grid-template-columns: repeat(2, 1fr); gap: 26px; }
.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
.grid-4 { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; }

/* ============================================================
   首页路线图
   ============================================================ */
.path {
  border: 2px solid var(--ink);
  background: var(--paper-deep);
  box-shadow: var(--shadow);
  padding: clamp(20px, 4vw, 40px);
}
.path-row {
  display: grid;
  grid-template-columns: 120px 1fr;
  gap: 20px;
  padding: 20px 0;
  border-bottom: 1px dashed var(--grid-strong);
  align-items: start;
}
.path-row:last-child { border-bottom: none; }
.path-stage {
  font-family: var(--mono);
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 1.5px;
  color: var(--paper);
  background: var(--ink);
  padding: 5px 10px;
  display: inline-block;
}
.path-row:hover .path-stage { background: var(--rust); }
.path-name { font-family: var(--serif); font-weight: 700; font-size: 18px; }
.path-desc { font-size: 14px; color: var(--ink-2); margin-top: 4px; }

/* ============================================================
   页脚
   ============================================================ */
.footer {
  border-top: 2px solid var(--ink);
  background: var(--ink);
  color: #c9d2cc;
  margin-top: 0;
}
.footer-inner {
  max-width: 1200px;
  margin: 0 auto;
  padding: 44px clamp(16px, 4vw, 40px) 30px;
  display: grid;
  grid-template-columns: 1.4fr 1fr 1fr;
  gap: 36px;
}
.footer .f-brand { display: flex; align-items: center; gap: 12px; }
.footer .f-brand svg { width: 38px; height: 38px; }
.footer .f-zh { font-family: var(--serif); font-size: 19px; font-weight: 900; color: var(--paper); letter-spacing: 2px; }
.footer .f-en { font-family: var(--mono); font-size: 9px; letter-spacing: 2px; color: #8b968f; }
.footer p { font-size: 13px; color: #8b968f; margin-top: 14px; max-width: 340px; }
.footer h4 {
  font-family: var(--mono);
  font-size: 12px;
  letter-spacing: 2px;
  color: var(--rust);
  margin-bottom: 14px;
  text-transform: uppercase;
}
.footer ul { list-style: none; }
.footer li { margin-bottom: 9px; }
.footer li a { font-size: 13.5px; color: #c9d2cc; transition: color 0.15s; }
.footer li a:hover { color: var(--rust); text-decoration: underline; text-underline-offset: 3px; }
.footer-bottom {
  border-top: 1px solid rgba(244, 240, 228, 0.15);
  padding: 16px clamp(16px, 4vw, 40px);
  max-width: 1200px;
  margin: 0 auto;
  font-family: var(--mono);
  font-size: 11px;
  color: #8b968f;
  display: flex;
  justify-content: space-between;
  gap: 12px;
  flex-wrap: wrap;
}

/* ============================================================
   内容页顶部横幅
   ============================================================ */
.page-hero {
  padding: clamp(44px, 7vw, 76px) 0 clamp(30px, 5vw, 44px);
  position: relative;
  overflow: hidden;
}
.page-hero .ph-kicker {
  font-family: var(--mono);
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 3px;
  color: var(--rust);
}
.page-hero h1 {
  font-family: var(--serif);
  font-weight: 900;
  font-size: clamp(34px, 5.5vw, 56px);
  letter-spacing: 2px;
  margin-top: 10px;
  line-height: 1.15;
}
.page-hero .ph-en {
  font-family: var(--mono);
  font-size: 12px;
  letter-spacing: 3px;
  color: var(--ink-3);
  margin-top: 10px;
  text-transform: uppercase;
}
.page-hero .ph-desc { max-width: 700px; color: var(--ink-2); margin-top: 16px; font-size: 15.5px; }

/* ============================================================
   化工/英语内容组件
   ============================================================ */

/* 章节手风琴 */
.unit {
  border: 2px solid var(--ink);
  background: var(--card);
  box-shadow: var(--shadow-sm);
  margin-bottom: 22px;
}
.unit-head {
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 18px 22px;
  cursor: pointer;
  user-select: none;
  transition: background 0.15s;
}
.unit-head:hover { background: var(--paper-deep); }
.unit-no {
  font-family: var(--mono);
  font-weight: 700;
  font-size: 13px;
  letter-spacing: 1px;
  color: var(--paper);
  background: var(--ink);
  padding: 4px 10px;
  flex-shrink: 0;
}
.unit.open .unit-no { background: var(--rust); }
.unit-title { font-family: var(--serif); font-weight: 900; font-size: 19px; flex: 1; letter-spacing: 1px; }
.unit-meta { font-family: var(--mono); font-size: 11px; color: var(--ink-3); letter-spacing: 1px; }
.unit-arrow { transition: transform 0.25s; flex-shrink: 0; }
.unit.open .unit-arrow { transform: rotate(180deg); }
.unit-body {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.4s cubic-bezier(0.2, 0.9, 0.3, 1);
}
.unit.open .unit-body { max-height: 3200px; }
.unit-body-inner { padding: 6px 26px 26px; border-top: 1px dashed var(--grid-strong); }

/* 知识条目 */
.kp {
  padding: 16px 0;
  border-bottom: 1px dashed var(--grid-strong);
}
.kp:last-child { border-bottom: none; }
.kp-title {
  font-weight: 700;
  font-size: 16px;
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
}
.kp-title .en-term {
  font-family: var(--mono);
  font-size: 11px;
  font-weight: 600;
  color: var(--teal);
  background: var(--teal-soft);
  padding: 2px 8px;
  letter-spacing: 0.5px;
}
.kp-body { font-size: 14.5px; color: var(--ink-2); margin-top: 8px; }
.kp-body b { color: var(--ink); }
.kp-body ul { margin: 8px 0 0 20px; }
.kp-body li { margin-bottom: 4px; }

/* 公式块 */
.formula {
  font-family: var(--mono);
  background: var(--ink);
  color: #f0ead6;
  padding: 16px 20px;
  margin: 14px 0;
  font-size: 15px;
  letter-spacing: 0.5px;
  overflow-x: auto;
  position: relative;
  border: 2px solid var(--ink);
}
.formula::before {
  content: "FORMULA";
  position: absolute;
  top: -2px;
  right: -2px;
  background: var(--rust);
  color: #fff;
  font-size: 9px;
  font-weight: 700;
  letter-spacing: 1.5px;
  padding: 2px 8px;
}
.formula i { font-style: italic; color: #f5c98a; }
.formula .sub { font-size: 0.7em; vertical-align: -0.25em; }

/* 术语表 */
.term-table { width: 100%; border-collapse: collapse; font-size: 14px; }
.term-table th {
  font-family: var(--mono);
  font-size: 11.5px;
  letter-spacing: 1.5px;
  text-align: left;
  background: var(--ink);
  color: var(--paper);
  padding: 10px 14px;
}
.term-table td { padding: 10px 14px; border-bottom: 1px solid var(--grid-strong); }
.term-table tr:nth-child(even) td { background: rgba(31, 45, 39, 0.03); }
.term-table td:first-child { font-weight: 700; white-space: nowrap; }
.term-table td:nth-child(2) { font-family: var(--mono); font-size: 13px; color: var(--teal); }
.term-table tr:hover td { background: var(--rust-soft); }

/* ============================================================
   闪卡
   ============================================================ */
.flash-zone { display: flex; flex-direction: column; align-items: center; gap: 22px; }
.flashcard {
  width: min(560px, 100%);
  min-height: 260px;
  border: 2.5px solid var(--ink);
  box-shadow: var(--shadow);
  cursor: pointer;
  position: relative;
  transform-style: preserve-3d;
  transition: transform 0.55s cubic-bezier(0.3, 0.9, 0.3, 1);
  background: var(--card);
}
.flashcard.flipped { transform: rotateY(180deg); }
.flash-face {
  position: absolute;
  inset: 0;
  backface-visibility: hidden;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 30px;
  text-align: center;
}
.flash-face.back { transform: rotateY(180deg); background: var(--teal-soft); }
.flash-word { font-family: var(--serif); font-size: clamp(30px, 5vw, 42px); font-weight: 900; letter-spacing: 1px; }
.flash-phon { font-family: var(--mono); color: var(--ink-3); font-size: 15px; margin-top: 8px; }
.flash-hint { font-family: var(--mono); font-size: 11px; color: var(--ink-3); letter-spacing: 2px; position: absolute; bottom: 16px; }
.flash-def { font-size: 17px; font-weight: 600; }
.flash-ex { font-size: 14px; color: var(--ink-2); margin-top: 14px; font-style: italic; line-height: 1.8; }
.flash-ex b { color: var(--rust); font-style: normal; }
.flash-cat {
  position: absolute;
  top: 14px;
  left: 14px;
  font-family: var(--mono);
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 1.5px;
  background: var(--ink);
  color: var(--paper);
  padding: 3px 10px;
}
.flash-nav { display: flex; align-items: center; gap: 18px; }
.flash-count { font-family: var(--mono); font-size: 13px; color: var(--ink-2); letter-spacing: 1px; min-width: 70px; text-align: center; }

.chip-row { display: flex; gap: 10px; flex-wrap: wrap; }
.chip {
  font-family: var(--mono);
  font-size: 12.5px;
  font-weight: 600;
  padding: 7px 16px;
  border: 1.5px solid var(--ink-2);
  background: var(--card);
  color: var(--ink-2);
  letter-spacing: 0.5px;
  transition: all 0.15s;
}
.chip:hover { border-color: var(--ink); color: var(--ink); }
.chip.on { background: var(--ink); color: var(--paper); border-color: var(--ink); }

/* ============================================================
   测验
   ============================================================ */
.quiz-q {
  border: 2px solid var(--ink);
  background: var(--card);
  box-shadow: var(--shadow-sm);
  padding: 22px 26px;
  margin-bottom: 18px;
}
.quiz-q .q-title { font-weight: 700; font-size: 16px; display: flex; gap: 12px; }
.quiz-q .q-no { font-family: var(--mono); color: var(--rust); flex-shrink: 0; }
.quiz-opts { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; margin-top: 16px; }
.quiz-opt {
  border: 1.5px solid var(--ink-2);
  background: var(--paper);
  padding: 10px 14px;
  text-align: left;
  font-size: 14px;
  display: flex;
  align-items: center;
  gap: 10px;
  transition: all 0.15s;
}
.quiz-opt .opt-key {
  font-family: var(--mono);
  font-size: 11px;
  font-weight: 700;
  width: 22px;
  height: 22px;
  border: 1.5px solid currentColor;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}
.quiz-opt:hover { border-color: var(--ink); background: var(--card); }
.quiz-opt.right { background: var(--teal); border-color: var(--teal-deep); color: #fff; }
.quiz-opt.right .opt-key { border-color: #fff; }
.quiz-opt.wrong { background: var(--rust-soft); border-color: var(--rust); color: var(--rust-deep); }
.quiz-opt.wrong .opt-key { border-color: var(--rust-deep); }
.quiz-opt:disabled { cursor: default; opacity: 0.85; }
.quiz-explain {
  margin-top: 14px;
  padding: 12px 16px;
  background: var(--blue-soft);
  border-left: 3px solid var(--blue);
  font-size: 13.5px;
  color: var(--ink-2);
  display: none;
}
.quiz-explain.show { display: block; }

/* ============================================================
   AI 问答页（全屏）
   ============================================================ */
body.qa-body { display: flex; flex-direction: column; height: 100vh; overflow: hidden; }

.qa-shell {
  flex: 1;
  display: grid;
  grid-template-columns: 290px 1fr;
  min-height: 0;
}

.qa-side {
  border-right: 2px solid var(--ink);
  background: var(--paper-deep);
  display: flex;
  flex-direction: column;
  min-height: 0;
}
.qa-side-head { padding: 18px; border-bottom: 2px solid var(--ink); }
.qa-side-head .t { font-family: var(--serif); font-weight: 900; font-size: 17px; letter-spacing: 1px; }
.qa-side-head .s { font-family: var(--mono); font-size: 10px; letter-spacing: 1.5px; color: var(--ink-3); margin-top: 2px; }
.qa-new {
  margin: 16px;
  width: calc(100% - 32px);
  justify-content: center;
}
.qa-sessions { flex: 1; overflow-y: auto; padding: 0 16px 16px; }
.qa-session {
  border: 1.5px solid transparent;
  padding: 10px 12px;
  font-size: 13px;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 8px;
  color: var(--ink-2);
  margin-bottom: 4px;
}
.qa-session:hover { background: rgba(31, 45, 39, 0.06); }
.qa-session.on { border-color: var(--ink); background: var(--card); color: var(--ink); box-shadow: var(--shadow-sm); }
.qa-session .s-title { flex: 1; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.qa-session .s-del { opacity: 0; border: none; background: none; color: var(--rust); font-size: 15px; line-height: 1; padding: 2px; }
.qa-session:hover .s-del { opacity: 1; }
.qa-side-foot { border-top: 2px solid var(--ink); padding: 14px 16px; }
.model-chip {
  display: flex;
  align-items: center;
  gap: 10px;
  border: 2px solid var(--ink);
  background: var(--card);
  box-shadow: var(--shadow-sm);
  padding: 10px 14px;
  cursor: pointer;
  width: 100%;
  text-align: left;
  transition: transform 0.15s;
}
.model-chip:hover { transform: translate(-2px, -2px); }
.model-chip .m-dot { width: 9px; height: 9px; border-radius: 50%; background: var(--teal); flex-shrink: 0; }
.model-chip .m-dot.off { background: var(--rust); }
.model-chip .m-name { font-family: var(--mono); font-size: 12px; font-weight: 700; flex: 1; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.model-chip .m-cfg { font-family: var(--mono); font-size: 16px; }

.qa-main { display: flex; flex-direction: column; min-width: 0; min-height: 0; }
.qa-topbar {
  height: 58px;
  border-bottom: 2px solid var(--ink);
  background: var(--paper);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 20px;
  gap: 14px;
  flex-shrink: 0;
}
.qa-topbar .t { font-family: var(--serif); font-weight: 900; font-size: 16px; letter-spacing: 1px; white-space: nowrap; }
.qa-topbar .t small { font-family: var(--mono); font-size: 10px; color: var(--ink-3); letter-spacing: 1.5px; display: block; font-weight: 400; }
.qa-topbar-actions { display: flex; gap: 10px; }

.qa-msgs { flex: 1; overflow-y: auto; padding: 28px clamp(14px, 3vw, 34px); scroll-behavior: smooth; }
.qa-msgs-inner { max-width: 860px; margin: 0 auto; }

.msg { display: flex; gap: 14px; margin-bottom: 26px; animation: msgIn 0.3s ease both; }
@keyframes msgIn { from { opacity: 0; transform: translateY(10px); } to { opacity: 1; transform: none; } }
.msg-ava {
  width: 38px;
  height: 38px;
  border: 2px solid var(--ink);
  background: var(--teal);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  font-family: var(--serif);
  font-weight: 900;
  font-size: 16px;
}
.msg.user .msg-ava { background: var(--rust); }
.msg-ava svg { width: 20px; height: 20px; }
.msg-body { min-width: 0; flex: 1; }
.msg-name { font-family: var(--mono); font-size: 10.5px; font-weight: 700; letter-spacing: 1.5px; color: var(--ink-3); margin-bottom: 6px; text-transform: uppercase; }
.msg.user .msg-name { color: var(--rust); }
.msg-content {
  border: 2px solid var(--ink);
  background: var(--card);
  padding: 14px 18px;
  font-size: 14.5px;
  line-height: 1.85;
  box-shadow: var(--shadow-sm);
  overflow-wrap: break-word;
}
.msg.user .msg-content { background: var(--rust-soft); }

/* AI markdown 输出样式 */
.msg-content h1, .msg-content h2, .msg-content h3 {
  font-family: var(--serif);
  font-weight: 900;
  margin: 14px 0 8px;
  line-height: 1.3;
}
.msg-content h1 { font-size: 19px; }
.msg-content h2 { font-size: 17px; }
.msg-content h3 { font-size: 15.5px; }
.msg-content p { margin: 8px 0; }
.msg-content ul, .msg-content ol { margin: 8px 0 8px 22px; }
.msg-content li { margin-bottom: 4px; }
.msg-content code {
  font-family: var(--mono);
  font-size: 12.5px;
  background: rgba(31, 45, 39, 0.08);
  padding: 1px 6px;
}
.msg-content pre {
  background: var(--ink);
  color: #e9e4d3;
  padding: 14px 16px;
  overflow-x: auto;
  margin: 12px 0;
  font-family: var(--mono);
  font-size: 13px;
  line-height: 1.7;
}
.msg-content pre code { background: none; padding: 0; color: inherit; }
.msg-content table { border-collapse: collapse; margin: 12px 0; font-size: 13px; width: 100%; }
.msg-content th, .msg-content td { border: 1px solid var(--ink-2); padding: 7px 12px; text-align: left; }
.msg-content th { background: var(--paper-deep); font-family: var(--mono); font-size: 12px; }
.msg-content blockquote { border-left: 3px solid var(--rust); padding-left: 14px; color: var(--ink-2); margin: 10px 0; }
.msg-content strong { font-weight: 700; }
.msg-content .cursor-blink { display: inline-block; width: 8px; height: 15px; background: var(--rust); vertical-align: -2px; animation: blink 1s infinite; }

.msg-error { border-left: 4px solid var(--rust); background: var(--rust-soft); }

.qa-empty { text-align: center; padding: 48px 20px 20px; }
.qa-empty .big {
  font-family: var(--serif);
  font-weight: 900;
  font-size: clamp(24px, 3.6vw, 32px);
  letter-spacing: 2px;
}
.qa-empty .sub { font-family: var(--mono); font-size: 11.5px; color: var(--ink-3); letter-spacing: 2px; margin-top: 8px; }
.qa-suggests { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; margin-top: 34px; }
.qa-suggest {
  border: 2px solid var(--ink);
  background: var(--card);
  box-shadow: var(--shadow-sm);
  padding: 16px 18px;
  text-align: left;
  transition: transform 0.15s, box-shadow 0.15s;
}
.qa-suggest:hover { transform: translate(-2px, -2px); box-shadow: 5px 5px 0 rgba(31, 45, 39, 0.92); }
.qa-suggest .sg-tag { font-family: var(--mono); font-size: 10px; font-weight: 700; letter-spacing: 1.5px; color: var(--paper); background: var(--teal); display: inline-block; padding: 2px 8px; margin-bottom: 8px; }
.qa-suggest.chem .sg-tag { background: var(--rust); }
.qa-suggest .sg-t { font-weight: 700; font-size: 14.5px; line-height: 1.5; }

.qa-inputbar {
  border-top: 2px solid var(--ink);
  background: var(--paper);
  padding: 16px clamp(14px, 3vw, 34px) 20px;
  flex-shrink: 0;
}
.qa-inputbar-inner { max-width: 860px; margin: 0 auto; }
.qa-input-box {
  display: flex;
  align-items: flex-end;
  gap: 12px;
  border: 2px solid var(--ink);
  background: var(--card);
  box-shadow: var(--shadow-sm);
  padding: 10px 12px;
}
.qa-input-box:focus-within { box-shadow: 5px 5px 0 rgba(194, 73, 20, 0.4); }
.qa-input-box textarea {
  flex: 1;
  border: none;
  outline: none;
  resize: none;
  background: none;
  font-family: var(--sans);
  font-size: 15px;
  line-height: 1.6;
  max-height: 160px;
  min-height: 26px;
  color: var(--ink);
}
.qa-send {
  background: var(--rust);
  color: #fff;
  border: 2px solid var(--ink);
  width: 44px;
  height: 44px;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  box-shadow: 2px 2px 0 rgba(31, 45, 39, 0.9);
  transition: transform 0.12s;
}
.qa-send:hover { transform: translate(-1px, -1px); }
.qa-send:disabled { opacity: 0.4; }
.qa-send svg { width: 18px; height: 18px; }
.qa-foot-hint {
  font-family: var(--mono);
  font-size: 10.5px;
  color: var(--ink-3);
  text-align: center;
  margin-top: 10px;
  letter-spacing: 0.5px;
}

/* 模型配置弹窗 */
.modal-mask {
  position: fixed;
  inset: 0;
  background: rgba(31, 45, 39, 0.55);
  z-index: 200;
  display: none;
  align-items: center;
  justify-content: center;
  padding: 20px;
  backdrop-filter: blur(2px);
}
.modal-mask.show { display: flex; }
.modal {
  background: var(--paper);
  border: 2.5px solid var(--ink);
  box-shadow: 8px 8px 0 rgba(31, 45, 39, 0.9);
  width: min(620px, 100%);
  max-height: 88vh;
  overflow-y: auto;
  animation: modalIn 0.25s cubic-bezier(0.2, 0.9, 0.3, 1.2);
}
@keyframes modalIn { from { opacity: 0; transform: translateY(24px) scale(0.97); } to { opacity: 1; transform: none; } }
.modal-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 18px 22px;
  border-bottom: 2px solid var(--ink);
  position: sticky;
  top: 0;
  background: var(--paper);
  z-index: 2;
}
.modal-head .t { font-family: var(--serif); font-weight: 900; font-size: 18px; letter-spacing: 1px; }
.modal-head .s { font-family: var(--mono); font-size: 10px; letter-spacing: 1.5px; color: var(--ink-3); display: block; margin-top: 2px; }
.modal-close { background: none; border: 2px solid var(--ink); width: 34px; height: 34px; font-size: 16px; font-weight: 700; box-shadow: var(--shadow-sm); }
.modal-close:hover { background: var(--rust); color: #fff; }
.modal-body { padding: 22px; }

.field { margin-bottom: 18px; }
.field label {
  display: block;
  font-family: var(--mono);
  font-size: 11.5px;
  font-weight: 700;
  letter-spacing: 1.5px;
  color: var(--ink-2);
  margin-bottom: 7px;
  text-transform: uppercase;
}
.field input, .field select {
  width: 100%;
  border: 2px solid var(--ink);
  background: var(--card);
  padding: 11px 14px;
  font-family: var(--mono);
  font-size: 13.5px;
  outline: none;
  color: var(--ink);
}
.field input:focus, .field select:focus { box-shadow: 3px 3px 0 rgba(14, 110, 99, 0.5); }
.field .hint { font-size: 11.5px; color: var(--ink-3); margin-top: 6px; line-height: 1.6; }
.field .hint a { color: var(--blue); text-decoration: underline; text-underline-offset: 2px; }

.provider-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; }
.provider {
  border: 2px solid var(--ink-2);
  background: var(--card);
  padding: 12px 14px;
  text-align: left;
  display: flex;
  flex-direction: column;
  gap: 4px;
  transition: all 0.15s;
}
.provider:hover { border-color: var(--ink); }
.provider.on { border-color: var(--rust); background: var(--rust-soft); box-shadow: var(--shadow-sm); }
.provider .p-name { font-weight: 700; font-size: 14px; display: flex; align-items: center; gap: 8px; }
.provider .p-free {
  font-family: var(--mono);
  font-size: 9.5px;
  background: var(--teal);
  color: #fff;
  padding: 1px 7px;
  letter-spacing: 1px;
}
.provider .p-desc { font-size: 11.5px; color: var(--ink-3); line-height: 1.5; }

.modal-foot {
  display: flex;
  gap: 12px;
  justify-content: flex-end;
  padding: 16px 22px 22px;
  border-top: 1px dashed var(--grid-strong);
  margin-top: 6px;
}

/* ============================================================
   工具下载页
   ============================================================ */
.tool-card {
  border: 2px solid var(--ink);
  background: var(--card);
  box-shadow: var(--shadow);
  padding: 24px;
  display: flex;
  flex-direction: column;
  gap: 12px;
  transition: transform 0.18s, box-shadow 0.18s;
}
.tool-card:hover { transform: translate(-3px, -3px); box-shadow: 8px 8px 0 rgba(31, 45, 39, 0.92); }
.tool-head { display: flex; align-items: center; gap: 14px; }
.tool-icon {
  width: 52px;
  height: 52px;
  border: 2px solid var(--ink);
  background: var(--paper-deep);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}
.tool-icon svg { width: 26px; height: 26px; }
.tool-name { font-family: var(--serif); font-weight: 900; font-size: 18px; letter-spacing: 0.5px; }
.tool-fmt {
  font-family: var(--mono);
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 1px;
  color: var(--paper);
  background: var(--teal);
  padding: 2px 8px;
  display: inline-block;
  margin-top: 3px;
}
.tool-fmt.rust { background: var(--rust); }
.tool-desc { font-size: 13.5px; color: var(--ink-2); flex: 1; }
.tool-list { font-size: 12.5px; color: var(--ink-3); list-style: none; }
.tool-list li::before { content: "▸ "; color: var(--rust); }

/* 计算器 */
.calc-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; }
.calc-panel { border: 2px solid var(--ink); background: var(--card); box-shadow: var(--shadow-sm); padding: 20px; }
.calc-panel h4 {
  font-family: var(--serif);
  font-weight: 900;
  font-size: 16px;
  letter-spacing: 1px;
  padding-bottom: 10px;
  border-bottom: 2px solid var(--ink);
  margin-bottom: 16px;
  display: flex;
  align-items: center;
  gap: 8px;
}
.calc-panel h4 .mono-tag { font-family: var(--mono); font-size: 9px; color: var(--paper); background: var(--teal); padding: 2px 6px; letter-spacing: 1px; font-weight: 700; }
.calc-row { display: flex; align-items: center; gap: 10px; margin-bottom: 12px; }
.calc-row label { font-size: 13px; font-weight: 600; white-space: nowrap; min-width: 64px; }
.calc-row input, .calc-row select {
  flex: 1;
  border: 2px solid var(--ink);
  background: var(--paper);
  padding: 8px 10px;
  font-family: var(--mono);
  font-size: 13px;
  outline: none;
  min-width: 0;
}
.calc-result {
  margin-top: 14px;
  font-family: var(--mono);
  background: var(--ink);
  color: #f0ead6;
  padding: 12px 16px;
  font-size: 14.5px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
}
.calc-result b { color: #f5c98a; font-size: 17px; }

/* ============================================================
   动效
   ============================================================ */
.reveal { opacity: 0; transform: translateY(26px); transition: opacity 0.7s ease, transform 0.7s cubic-bezier(0.2, 0.8, 0.3, 1); }
.reveal.in { opacity: 1; transform: none; }
.reveal.d1 { transition-delay: 0.08s; }
.reveal.d2 { transition-delay: 0.16s; }
.reveal.d3 { transition-delay: 0.24s; }

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation: none !important; transition: none !important; }
  .reveal { opacity: 1; transform: none; }
}

/* ============================================================
   响应式
   ============================================================ */
@media (max-width: 1020px) {
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
  .calc-grid { grid-template-columns: 1fr; }
  .footer-inner { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 860px) {
  .nav-links {
    position: absolute;
    top: var(--nav-h);
    left: 0;
    right: 0;
    background: var(--paper);
    border-bottom: 2px solid var(--ink);
    flex-direction: column;
    align-items: stretch;
    padding: 10px 16px 16px;
    gap: 2px;
    display: none;
    box-shadow: 0 12px 24px rgba(31, 45, 39, 0.15);
  }
  .nav-links.open { display: flex; }
  .nav-links a { padding: 12px 10px; border-bottom: 1px dashed var(--grid-strong); }
  .nav-links a::after { display: none; }
  .nav-links a.active { color: var(--rust); }
  .nav-cta { margin: 10px 0 0; text-align: center; justify-content: center; }
  .nav-burger { display: flex; }

  .hero-grid { grid-template-columns: 1fr; }
  .hero-visual { min-height: 300px; }
  .grid-2, .grid-3 { grid-template-columns: 1fr; }
  .qa-suggests { grid-template-columns: 1fr; }
  .path-row { grid-template-columns: 1fr; gap: 8px; }

  .qa-shell { grid-template-columns: 1fr; }
  .qa-side { display: none; }
  .qa-side.mobile-open { display: flex; position: fixed; inset: var(--nav-h) 0 0 0; z-index: 90; background: var(--paper); }
  .quiz-opts { grid-template-columns: 1fr; }
}

@media (max-width: 560px) {
  .grid-4 { grid-template-columns: 1fr; }
  .provider-grid { grid-template-columns: 1fr; }
  .footer-inner { grid-template-columns: 1fr; }
  .hero-stats { gap: 18px 28px; }
  .stamp { width: 92px; height: 92px; }
  .stamp .s1 { font-size: 17px; }
}

/* ============================================================
   每日学习仪表盘（首页）
   ============================================================ */
.dash-hero { padding: clamp(40px, 6vw, 72px) 0 clamp(24px, 4vw, 40px); position: relative; overflow: hidden; }
.dash-hero::before {
  content: "";
  position: absolute; inset: 0;
  background:
    radial-gradient(ellipse 640px 420px at 92% 8%, rgba(194, 73, 20, 0.08), transparent 62%),
    radial-gradient(ellipse 560px 380px at 4% 92%, rgba(14, 110, 99, 0.08), transparent 60%);
  pointer-events: none;
}
.dash-top { display: grid; grid-template-columns: 1.3fr 0.7fr; gap: 26px; align-items: stretch; position: relative; }
.dash-kicker {
  display: inline-flex; align-items: center; gap: 10px;
  font-family: var(--mono); font-size: 12px; font-weight: 700; letter-spacing: 2px;
  color: var(--teal); border: 1.5px solid var(--teal); padding: 6px 14px;
  background: rgba(14, 110, 99, 0.06); margin-bottom: 18px; flex-wrap: wrap;
}
.dash-kicker .dot { width: 8px; height: 8px; background: var(--rust); border-radius: 50%; animation: blink 2.2s infinite; }
.dash-date { font-family: var(--mono); font-size: 13px; color: var(--ink-2); letter-spacing: 1px; }
.dash-hero h1 { font-family: var(--serif); font-weight: 900; font-size: clamp(30px, 4.6vw, 46px); letter-spacing: 2px; margin-top: 12px; line-height: 1.2; }
.dash-hero h1 .hl { color: var(--rust); }

.countdown-card {
  border: 2px solid var(--ink); background: var(--ink); color: #e9e4d3;
  box-shadow: var(--shadow); padding: 24px; text-align: center;
  position: relative; display: flex; flex-direction: column; justify-content: center;
}
.countdown-card .cd-label { font-family: var(--mono); font-size: 11px; letter-spacing: 2px; color: #8b968f; }
.countdown-card .cd-num { font-family: var(--serif); font-size: clamp(52px, 7vw, 76px); font-weight: 900; color: #f5c98a; line-height: 1.1; }
.countdown-card .cd-days { font-family: var(--mono); font-size: 13px; letter-spacing: 3px; }
.countdown-card .cd-date { font-family: var(--mono); font-size: 11.5px; color: #8b968f; margin-top: 10px; letter-spacing: 1px; }
.cd-edit {
  position: absolute; top: 10px; right: 10px; background: none; color: #8b968f;
  border: 1px solid #55645c; font-family: var(--mono); font-size: 10px; padding: 3px 8px; letter-spacing: 1px;
}
.cd-edit:hover { color: #f5c98a; border-color: #f5c98a; }

.dash-actions { display: flex; gap: 12px; margin-top: 22px; flex-wrap: wrap; align-items: center; }
.streak-badge {
  display: inline-flex; align-items: center; gap: 8px;
  font-family: var(--mono); font-weight: 700; font-size: 13px;
  background: var(--rust); color: #fff; border: 2px solid var(--ink);
  padding: 8px 14px; box-shadow: var(--shadow-sm);
}
.streak-badge .fire { font-size: 15px; }

.progress-shell { border: 2px solid var(--ink); background: var(--card); box-shadow: var(--shadow); padding: 18px 22px; margin-top: 26px; }
.progress-top { display: flex; justify-content: space-between; align-items: baseline; gap: 12px; margin-bottom: 10px; flex-wrap: wrap; }
.progress-top .pt { font-family: var(--serif); font-weight: 900; font-size: 16px; letter-spacing: 1px; }
.progress-top .pn { font-family: var(--mono); font-size: 13px; font-weight: 700; color: var(--rust); }
.progress-bar { height: 16px; border: 2px solid var(--ink); background: var(--paper); position: relative; overflow: hidden; }
.progress-fill {
  height: 100%; width: 0;
  background: repeating-linear-gradient(-45deg, var(--rust) 0 10px, var(--rust-deep) 10px 20px);
  transition: width 0.5s cubic-bezier(0.2, 0.9, 0.3, 1);
}
.progress-note { font-family: var(--mono); font-size: 10.5px; color: var(--ink-3); margin-top: 8px; letter-spacing: 0.5px; }

.task-card {
  border: 2px solid var(--ink); background: var(--card); box-shadow: var(--shadow-sm);
  padding: 18px 20px; position: relative; transition: background 0.2s;
}
.task-card.done { background: var(--teal-soft); }
.task-card.done::after {
  content: "✓ DONE"; position: absolute; top: -2px; right: -2px;
  font-family: var(--mono); font-size: 9.5px; font-weight: 700; letter-spacing: 1px;
  background: var(--teal); color: #fff; padding: 3px 10px;
}
.task-top { display: flex; justify-content: space-between; align-items: center; gap: 10px; margin-bottom: 10px; }
.task-tag {
  font-family: var(--mono); font-size: 10px; font-weight: 700; letter-spacing: 1.5px;
  background: var(--teal); color: #fff; padding: 3px 10px; display: inline-block;
}
.task-tag.rust { background: var(--rust); }
.task-tag.gold { background: var(--gold); }
.task-check-wrap { display: inline-flex; align-items: center; gap: 7px; font-size: 12.5px; color: var(--ink-2); cursor: pointer; user-select: none; }
.task-check {
  appearance: none; -webkit-appearance: none; width: 20px; height: 20px;
  border: 2px solid var(--ink); background: var(--card); cursor: pointer; position: relative; flex-shrink: 0;
}
.task-check:checked::after {
  content: "✓"; position: absolute; inset: 0; display: flex; align-items: center; justify-content: center;
  font-weight: 900; color: var(--rust-deep); font-size: 15px;
}
.word-big { font-family: var(--serif); font-size: 30px; font-weight: 900; letter-spacing: 0.5px; line-height: 1.2; }
.word-phon { font-family: var(--mono); color: var(--ink-3); font-size: 14px; margin-top: 4px; }
.word-mean { font-size: 14px; font-weight: 600; margin-top: 10px; }
.word-ex { font-size: 13px; color: var(--ink-2); margin-top: 10px; font-style: italic; line-height: 1.75; border-top: 1px dashed var(--grid-strong); padding-top: 10px; }
.word-ex b { color: var(--rust); font-style: normal; }
.chem-t { font-family: var(--serif); font-size: 20px; font-weight: 900; letter-spacing: 1px; line-height: 1.3; }
.chem-en { font-family: var(--mono); font-size: 11px; font-weight: 400; color: var(--teal); letter-spacing: 0.5px; margin-left: 10px; }
.chem-d { font-size: 13.5px; color: var(--ink-2); margin-top: 8px; line-height: 1.8; }

.review-zone { display: flex; gap: 8px; flex-wrap: wrap; }
.review-chip {
  display: inline-block; border: 1.5px dashed var(--ink-2); padding: 4px 12px;
  font-family: var(--mono); font-size: 12.5px; color: var(--ink-2); cursor: help; background: var(--card);
}
.review-chip:hover { border-style: solid; border-color: var(--rust); color: var(--rust-deep); }

.sync-row { display: flex; gap: 10px; flex-wrap: wrap; margin-top: 18px; }
.install-hint { font-family: var(--mono); font-size: 10.5px; color: var(--ink-3); margin-top: 8px; letter-spacing: 0.5px; }

/* ============================================================
   求职中心 / 六级页补充
   ============================================================ */
.duty-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 22px; }
.check-list { list-style: none; }
.check-list li {
  padding: 9px 0 9px 30px; border-bottom: 1px dashed var(--grid-strong);
  position: relative; font-size: 14px; color: var(--ink-2);
}
.check-list li::before {
  content: "□"; position: absolute; left: 4px; top: 7px;
  font-family: var(--mono); font-weight: 700; color: var(--rust); font-size: 15px;
}
.check-list li b { color: var(--ink); }
.star-line { border-left: 3px solid var(--teal); padding: 8px 14px; background: var(--teal-soft); margin: 8px 0; font-size: 13.5px; }
.star-line b { color: var(--teal-deep); }
.salary-tag {
  font-family: var(--mono); font-size: 11px; font-weight: 700;
  background: var(--rust); color: #fff; padding: 2px 8px; margin-left: 8px; white-space: nowrap;
}

/* ============================================================
   六级备考中心 · 词汇卡
   ============================================================ */
.vcard { transition: transform 0.18s ease, box-shadow 0.18s ease; }
.vcard:hover { transform: translateY(-3px); box-shadow: var(--shadow); }
.vcard.vunknown { border-color: var(--rust); background: var(--rust-soft); }
.expr-topic-bar { display: flex; gap: 10px; flex-wrap: wrap; }

@media (max-width: 1080px) {
  .nav-links { display: none; }
  .nav-links.open { display: flex; }
  .nav-burger { display: flex; }
  .nav-links { position: absolute; top: var(--nav-h); left: 0; right: 0; background: var(--paper); border-bottom: 2px solid var(--ink); flex-direction: column; align-items: stretch; padding: 10px 16px 16px; gap: 2px; box-shadow: 0 12px 24px rgba(31, 45, 39, 0.15); }
}
@media (max-width: 860px) {
  .dash-top { grid-template-columns: 1fr; }
  .duty-grid { grid-template-columns: 1fr; }
}