/* ==========================================================================
   香柏树单词 Cedar Words · 官网样式
   品牌主色取自品牌字标 #006450，无外部字体 / 无第三方依赖
   ========================================================================== */

:root {
  --brand: #006450;
  --brand-deep: #00463a;
  --brand-mid: #0f7f68;
  --brand-bright: #17a47f;
  --brand-wash: #f0f7f5;
  --brand-wash-2: #e2f0ec;

  --ink: #14201d;
  --ink-2: #4c5c58;
  --ink-3: #7d8b87;
  --line: #e4ecea;
  --line-soft: #eff5f3;
  --white: #ffffff;

  --radius-sm: 10px;
  --radius: 16px;
  --radius-lg: 22px;
  --radius-xl: 30px;

  --shadow-sm: 0 1px 2px rgba(20, 32, 29, 0.04), 0 2px 8px rgba(20, 32, 29, 0.04);
  --shadow: 0 2px 6px rgba(20, 32, 29, 0.05), 0 12px 28px rgba(20, 32, 29, 0.07);
  --shadow-lg: 0 8px 20px rgba(0, 100, 80, 0.08), 0 30px 60px rgba(20, 32, 29, 0.1);

  --max: 1120px;
  --gutter: 24px;

  --font: -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans GB",
    "Microsoft YaHei", "Helvetica Neue", Helvetica, Arial, sans-serif;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  font-family: var(--font);
  color: var(--ink);
  background: var(--white);
  font-size: 16px;
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

img {
  max-width: 100%;
  display: block;
}

a {
  color: var(--brand);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

h1,
h2,
h3,
h4 {
  margin: 0;
  line-height: 1.3;
  letter-spacing: -0.01em;
}

p {
  margin: 0;
}

ul {
  margin: 0;
  padding: 0;
  list-style: none;
}

/* ---------- 布局工具 ---------- */

.wrap {
  width: 100%;
  max-width: var(--max);
  margin: 0 auto;
  padding: 0 var(--gutter);
}

.section {
  padding: 88px 0;
}

/* 锚点跳转时避免标题被吸顶导航遮住 */
[id] {
  scroll-margin-top: 88px;
}

.section--tight {
  padding: 64px 0;
}

.section--wash {
  background: var(--brand-wash);
}

.center {
  text-align: center;
}

.eyebrow {
  display: inline-block;
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.08em;
  color: var(--brand-mid);
  background: var(--brand-wash-2);
  border-radius: 999px;
  padding: 5px 14px;
  margin-bottom: 18px;
}

.section-title {
  font-size: clamp(26px, 3.4vw, 36px);
  font-weight: 700;
  margin-bottom: 14px;
}

.section-sub {
  color: var(--ink-2);
  font-size: 16px;
  max-width: 640px;
}

.center .section-sub {
  margin-left: auto;
  margin-right: auto;
}

/* ---------- 按钮 ---------- */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  font-size: 15px;
  font-weight: 600;
  padding: 13px 26px;
  border-radius: 14px;
  border: 1px solid transparent;
  cursor: pointer;
  transition: transform 0.16s ease, box-shadow 0.16s ease, background 0.16s ease,
    color 0.16s ease;
  white-space: nowrap;
  font-family: inherit;
}

.btn:hover {
  text-decoration: none;
  transform: translateY(-1px);
}

.btn:active {
  transform: translateY(0);
}

.btn--primary {
  background: var(--brand);
  color: #fff;
  box-shadow: 0 6px 16px rgba(0, 100, 80, 0.22);
}

.btn--primary:hover {
  background: var(--brand-deep);
  color: #fff;
}

.btn--ghost {
  background: #fff;
  color: var(--brand);
  border-color: var(--line);
  box-shadow: var(--shadow-sm);
}

.btn--ghost:hover {
  border-color: var(--brand-bright);
  color: var(--brand-deep);
}

.btn--sm {
  padding: 9px 18px;
  font-size: 14px;
  border-radius: 11px;
}

/* ---------- 顶部导航 ---------- */

.nav {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(255, 255, 255, 0.86);
  backdrop-filter: saturate(180%) blur(14px);
  -webkit-backdrop-filter: saturate(180%) blur(14px);
  border-bottom: 1px solid var(--line-soft);
}

.nav__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 68px;
  gap: 20px;
}

.nav__brand {
  display: flex;
  align-items: center;
  gap: 11px;
  flex-shrink: 0;
}

.nav__brand:hover {
  text-decoration: none;
}

.nav__mark {
  width: 34px;
  height: 34px;
  border-radius: 9px;
  flex-shrink: 0;
  border: 1px solid rgba(0, 0, 0, 0.07);
}

.nav__wordmark {
  height: 19px;
  width: auto;
}

.nav__links {
  display: flex;
  align-items: center;
  gap: 28px;
  font-size: 15px;
  color: var(--ink-2);
}

.nav__links a {
  color: var(--ink-2);
}

.nav__links a:hover {
  color: var(--brand);
  text-decoration: none;
}

/* ---------- Hero ---------- */

.hero {
  position: relative;
  overflow: hidden;
  padding: 72px 0 84px;
  background: linear-gradient(180deg, var(--brand-wash) 0%, #fff 78%);
}

.hero__grid {
  display: grid;
  grid-template-columns: minmax(0, 1.05fr) minmax(0, 0.95fr);
  gap: 56px;
  align-items: center;
}

.hero h1 {
  font-size: clamp(32px, 4.6vw, 52px);
  font-weight: 800;
  letter-spacing: -0.02em;
  margin-bottom: 20px;
}

.hero h1 em {
  font-style: normal;
  color: var(--brand);
}

.hero__lead {
  font-size: 17px;
  color: var(--ink-2);
  max-width: 500px;
  margin-bottom: 30px;
}

.hero__cta {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  align-items: center;
  margin-bottom: 18px;
}

.hero__meta {
  font-size: 13.5px;
  color: var(--ink-3);
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
}

.dot {
  width: 4px;
  height: 4px;
  border-radius: 50%;
  background: var(--ink-3);
  opacity: 0.5;
  flex-shrink: 0;
}

/* ---------- 手机 mockup ---------- */

.hero__media {
  display: flex;
  justify-content: center;
}

.phone {
  width: 270px;
  margin: 0 auto;
  background: #101a18;
  border-radius: 40px;
  padding: 9px;
  box-shadow: var(--shadow-lg);
  position: relative;
}

.phone::after {
  content: "";
  position: absolute;
  top: 20px;
  left: 50%;
  transform: translateX(-50%);
  width: 76px;
  height: 20px;
  background: #101a18;
  border-radius: 999px;
  z-index: 3;
}

.phone__screen {
  border-radius: 32px;
  overflow: hidden;
  background: linear-gradient(170deg, #0b6d59 0%, #00463a 55%, #06302a 100%);
  min-height: 540px;
  padding: 46px 18px 20px;
  color: #fff;
  position: relative;
}

.phone__screen--light {
  background: linear-gradient(170deg, #f4fbf9 0%, #e8f4f0 100%);
  color: var(--ink);
}

.mock-status {
  display: flex;
  justify-content: space-between;
  font-size: 10.5px;
  font-weight: 600;
  opacity: 0.75;
  margin-bottom: 26px;
}

.mock-label {
  font-size: 11px;
  letter-spacing: 0.1em;
  opacity: 0.62;
  margin-bottom: 10px;
  font-weight: 600;
}

.mock-word {
  font-size: 30px;
  font-weight: 700;
  letter-spacing: -0.01em;
  margin-bottom: 6px;
}

.mock-phonetic {
  font-size: 13px;
  opacity: 0.72;
  margin-bottom: 16px;
  font-family: "SF Mono", ui-monospace, Menlo, monospace;
}

.mock-def {
  font-size: 15px;
  line-height: 1.6;
  opacity: 0.95;
  margin-bottom: 8px;
}

.mock-line {
  height: 1px;
  background: currentColor;
  opacity: 0.16;
  margin: 18px 0;
}

.mock-sentence {
  font-size: 13px;
  opacity: 0.72;
  line-height: 1.7;
}

.mock-pill {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 11.5px;
  font-weight: 600;
  padding: 5px 11px;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.16);
  border: 1px solid rgba(255, 255, 255, 0.22);
}

.mock-pill--light {
  background: rgba(0, 100, 80, 0.08);
  border-color: rgba(0, 100, 80, 0.16);
  color: var(--brand);
}

.mock-row {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
}

.mock-progress {
  height: 5px;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.2);
  overflow: hidden;
  margin: 22px 0 8px;
}

.mock-progress span {
  display: block;
  height: 100%;
  border-radius: 999px;
  background: #7ee0bb;
}

.mock-progress--light {
  background: rgba(0, 100, 80, 0.14);
}

.mock-progress--light span {
  background: var(--brand);
}

.mock-actions {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 7px;
  margin-top: 20px;
}

.mock-action {
  border-radius: 12px;
  padding: 11px 4px;
  text-align: center;
  font-size: 10.5px;
  font-weight: 600;
  background: rgba(255, 255, 255, 0.13);
  border: 1px solid rgba(255, 255, 255, 0.18);
  line-height: 1.35;
}

.mock-action b {
  display: block;
  font-size: 14px;
  margin-bottom: 1px;
}

.mock-action--known {
  background: rgba(126, 224, 187, 0.22);
  border-color: rgba(126, 224, 187, 0.42);
}

.mock-action--unknown {
  background: rgba(255, 178, 168, 0.18);
  border-color: rgba(255, 178, 168, 0.38);
}

/* 打卡日历 */
.mock-cal {
  display: grid;
  grid-template-columns: repeat(7, 1fr);
  gap: 5px;
  margin-top: 14px;
}

.mock-cal i {
  aspect-ratio: 1;
  border-radius: 6px;
  background: rgba(255, 255, 255, 0.12);
  display: block;
}

.mock-cal i.on {
  background: #7ee0bb;
}

.mock-cal i.half {
  background: rgba(126, 224, 187, 0.42);
}

.mock-stat-row {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 9px;
  margin-top: 18px;
}

.mock-stat {
  background: rgba(255, 255, 255, 0.12);
  border: 1px solid rgba(255, 255, 255, 0.16);
  border-radius: 13px;
  padding: 11px 8px;
  text-align: center;
}

.mock-stat b {
  display: block;
  font-size: 19px;
  font-weight: 700;
}

.mock-stat span {
  font-size: 10px;
  opacity: 0.7;
}

/* ---------- 数据条 ---------- */

.figures {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 18px;
  padding: 30px 0;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.figure {
  text-align: center;
}

.figure b {
  display: block;
  font-size: 26px;
  font-weight: 800;
  color: var(--brand);
  letter-spacing: -0.02em;
}

.figure span {
  font-size: 13.5px;
  color: var(--ink-3);
}

/* ---------- 功能卡 ---------- */

.grid-3 {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 20px;
  margin-top: 46px;
}

.grid-2 {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 20px;
  margin-top: 46px;
}

.card {
  background: #fff;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  padding: 28px;
  transition: border-color 0.18s ease, box-shadow 0.18s ease, transform 0.18s ease;
}

.card:hover {
  border-color: var(--brand-wash-2);
  box-shadow: var(--shadow);
  transform: translateY(-2px);
}

.card__icon {
  width: 44px;
  height: 44px;
  border-radius: 13px;
  background: var(--brand-wash);
  color: var(--brand);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 18px;
}

.card__icon svg {
  width: 22px;
  height: 22px;
}

.card h3 {
  font-size: 17.5px;
  font-weight: 700;
  margin-bottom: 9px;
}

.card p {
  font-size: 14.5px;
  color: var(--ink-2);
  line-height: 1.75;
}

/* ---------- 交错特性区块 ---------- */

.feature {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
  gap: 60px;
  align-items: center;
  padding: 46px 0;
}

.feature--flip .feature__media {
  order: -1;
}

.feature__body h3 {
  font-size: clamp(22px, 2.6vw, 28px);
  font-weight: 700;
  margin-bottom: 14px;
}

.feature__body > p {
  color: var(--ink-2);
  font-size: 15.5px;
  margin-bottom: 22px;
}

.checklist li {
  display: flex;
  gap: 11px;
  font-size: 14.5px;
  color: var(--ink-2);
  padding: 7px 0;
  line-height: 1.7;
}

.checklist svg {
  width: 19px;
  height: 19px;
  flex-shrink: 0;
  margin-top: 4px;
  color: var(--brand-bright);
}

.feature__media {
  display: flex;
  justify-content: center;
}

/* ---------- 学习科学 ---------- */

.science {
  display: grid;
  grid-template-columns: minmax(0, 0.95fr) minmax(0, 1.05fr);
  gap: 60px;
  align-items: center;
}

.curve-card {
  background: #fff;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  padding: 26px;
  box-shadow: var(--shadow-sm);
}

.curve-legend {
  display: flex;
  gap: 20px;
  font-size: 12.5px;
  color: var(--ink-3);
  margin-top: 14px;
  flex-wrap: wrap;
}

.curve-legend i {
  display: inline-block;
  width: 10px;
  height: 10px;
  border-radius: 3px;
  margin-right: 6px;
  vertical-align: -1px;
}

/* ---------- 战队 / 下载 / FAQ ---------- */

.quote-card {
  background: linear-gradient(150deg, var(--brand) 0%, var(--brand-deep) 100%);
  color: #fff;
  border-radius: var(--radius-xl);
  padding: 52px;
  text-align: center;
  box-shadow: var(--shadow-lg);
}

.quote-card h2 {
  font-size: clamp(24px, 3vw, 32px);
  font-weight: 700;
  margin-bottom: 14px;
}

.quote-card p {
  color: rgba(255, 255, 255, 0.82);
  max-width: 560px;
  margin: 0 auto 26px;
  font-size: 16px;
}

.quote-card .hero__meta {
  color: rgba(255, 255, 255, 0.68);
  justify-content: center;
  margin-top: 16px;
}

.download {
  display: grid;
  grid-template-columns: minmax(0, 1.1fr) minmax(0, 0.9fr);
  gap: 56px;
  align-items: center;
}

.download__card {
  background: #fff;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  padding: 26px;
  box-shadow: var(--shadow);
  text-align: center;
}

.download__card img {
  width: 148px;
  margin: 0 auto 16px;
  border-radius: 22px;
  box-shadow: var(--shadow);
  border: 1px solid var(--line);
}

.qr {
  width: 148px;
  height: 148px;
  margin: 0 auto 14px;
  border-radius: 14px;
  border: 1px dashed var(--line);
  background: var(--brand-wash);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--ink-3);
  font-size: 12px;
  text-align: center;
  padding: 14px;
  line-height: 1.6;
}

.faq {
  max-width: 780px;
  margin: 46px auto 0;
}

.faq details {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 18px 22px;
  margin-bottom: 12px;
  background: #fff;
}

.faq details[open] {
  border-color: var(--brand-wash-2);
  box-shadow: var(--shadow-sm);
}

.faq summary {
  cursor: pointer;
  font-weight: 600;
  font-size: 15.5px;
  list-style: none;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
}

.faq summary::-webkit-details-marker {
  display: none;
}

.faq summary::after {
  content: "+";
  font-size: 20px;
  color: var(--brand);
  font-weight: 400;
  flex-shrink: 0;
}

.faq details[open] summary::after {
  content: "–";
}

.faq p {
  margin-top: 12px;
  font-size: 14.5px;
  color: var(--ink-2);
  line-height: 1.8;
}

/* ---------- 页脚 ---------- */

.footer {
  background: #0b1a16;
  color: rgba(255, 255, 255, 0.66);
  padding: 56px 0 30px;
  font-size: 13.5px;
}

.footer a {
  color: rgba(255, 255, 255, 0.78);
}

.footer a:hover {
  color: #fff;
}

.footer__grid {
  display: grid;
  grid-template-columns: minmax(0, 1.4fr) repeat(3, minmax(0, 1fr));
  gap: 40px;
  padding-bottom: 36px;
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.footer__brand {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 14px;
}

.footer__brand img {
  width: 30px;
  height: 30px;
  border-radius: 8px;
}

.footer__brand strong {
  color: #fff;
  font-size: 15px;
}

.footer__col h4 {
  color: #fff;
  font-size: 14px;
  font-weight: 600;
  margin-bottom: 14px;
}

.footer__col li {
  margin-bottom: 9px;
}

.footer__bottom {
  padding-top: 24px;
  display: flex;
  justify-content: space-between;
  gap: 20px;
  flex-wrap: wrap;
  align-items: center;
  font-size: 12.5px;
  color: rgba(255, 255, 255, 0.5);
}

.footer__bottom a {
  color: rgba(255, 255, 255, 0.6);
}

/* ---------- 协议等长文页面 ---------- */

.doc {
  max-width: 820px;
  margin: 0 auto;
  padding: 56px 0 88px;
}

.doc h1 {
  font-size: clamp(26px, 3.4vw, 34px);
  font-weight: 700;
  margin-bottom: 10px;
}

.doc__meta {
  font-size: 13.5px;
  color: var(--ink-3);
  padding-bottom: 26px;
  margin-bottom: 34px;
  border-bottom: 1px solid var(--line);
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
}

.doc h2 {
  font-size: 17.5px;
  font-weight: 700;
  margin: 34px 0 12px;
  color: var(--brand-deep);
}

.doc p,
.doc li {
  font-size: 15px;
  color: var(--ink-2);
  line-height: 1.9;
}

.doc p {
  margin-bottom: 12px;
}

.doc ol,
.doc ul {
  padding-left: 22px;
  margin: 0 0 12px;
  list-style: disc;
}

.doc ol {
  list-style: decimal;
}

.doc li {
  margin-bottom: 8px;
}

.doc .callout {
  background: #fff8ed;
  border: 1px solid #f6e3c8;
  border-left: 4px solid #e8992a;
  border-radius: 10px;
  padding: 16px 20px;
  margin-bottom: 20px;
}

.doc .callout p {
  color: #7a5214;
  margin: 0;
  font-size: 14.5px;
}

.doc .callout p + p {
  margin-top: 10px;
}

.doc table {
  width: 100%;
  border-collapse: collapse;
  margin: 16px 0 20px;
  font-size: 14px;
}

.doc th,
.doc td {
  border: 1px solid var(--line);
  padding: 11px 14px;
  text-align: left;
  vertical-align: top;
  color: var(--ink-2);
  line-height: 1.7;
}

.doc th {
  background: var(--brand-wash);
  font-weight: 600;
  color: var(--ink);
  white-space: nowrap;
}

.doc-nav {
  display: flex;
  gap: 12px;
  margin-top: 44px;
  padding-top: 28px;
  border-top: 1px solid var(--line);
  flex-wrap: wrap;
}

.back-home {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  font-size: 14px;
  color: var(--ink-3);
  margin-bottom: 26px;
}

.back-home:hover {
  color: var(--brand);
  text-decoration: none;
}

/* ---------- 响应式 ---------- */

@media (max-width: 940px) {
  .nav__links {
    display: none;
  }

  .hero {
    padding: 48px 0 64px;
  }

  .hero__grid,
  .feature,
  .science,
  .download {
    grid-template-columns: minmax(0, 1fr);
    gap: 40px;
  }

  .feature--flip .feature__media {
    order: 0;
  }

  .grid-3,
  .grid-2 {
    grid-template-columns: minmax(0, 1fr);
  }

  .figures {
    grid-template-columns: repeat(2, 1fr);
    gap: 24px 18px;
  }

  .footer__grid {
    grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
    gap: 30px;
  }

  .section {
    padding: 62px 0;
  }

  .quote-card {
    padding: 38px 24px;
  }
}

@media (max-width: 560px) {
  .wrap {
    padding: 0 18px;
  }

  .phone {
    width: 250px;
  }

  .footer__grid {
    grid-template-columns: minmax(0, 1fr);
  }

  .hero__cta .btn {
    flex: 1 1 auto;
  }

  .hero__cta {
    flex-direction: column;
    align-items: stretch;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  .btn:hover,
  .card:hover {
    transform: none;
  }
}