/* ============================================================================
   童学视 应用门户（app.tongxueshi.com）—— 样式表
   ----------------------------------------------------------------------------
   沿用企业官网 site/assets/css/main.css 的设计约定：
     · 白底 + 克制配色；全站无卡片、无阴影，层级只靠字号、字重、间距与分隔线
     · 唯一的「表演」在首屏 .hero：品牌标识由虚到实的一次性入场，其余位置一律克制
     · 字体只用系统中文无衬线栈，**不引 webfont**
     · 零 JS
   本文件独立自包含（门户根路径下 access 不到 site/ 的样式），改配色时两处需同步。
   ============================================================================ */

:root {
  --paper:   #ffffff;
  --wash:    #eef6f7;
  --ink:     #16292f;
  --ink-2:   #556a70;
  --line:    #e2eaeb;
  --line-brand: #cfe0e2;
  --brand:   #0a6c77;
  --brand-d: #07505a;
  --wrap:    1080px;
  --sans: "PingFang SC", "HarmonyOS Sans SC", "Microsoft YaHei", "Hiragino Sans GB",
          "Source Han Sans SC", "Noto Sans CJK SC", "WenQuanYi Micro Hei",
          -apple-system, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

/* ---------- 基础 ---------- */

*, *::before, *::after { box-sizing: border-box; }

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: 76px;
}

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 17px;
  line-height: 1.95;
  -webkit-font-smoothing: antialiased;
}

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

a { color: var(--brand); text-underline-offset: .25em; }
a:hover { color: var(--brand-d); }

p { margin: 0 0 1.15em; }
p:last-child { margin-bottom: 0; }

:focus-visible { outline: 2px solid var(--brand); outline-offset: 3px; border-radius: 2px; }

.wrap { width: min(var(--wrap), calc(100% - 48px)); margin-inline: auto; }

.skip {
  position: absolute; left: -9999px; top: 0; z-index: 10;
  background: var(--brand); color: #fff;
  padding: 10px 18px; text-decoration: none;
}
.skip:focus { left: 12px; top: 12px; color: #fff; }

/* ---------- 顶栏 ---------- */

.topbar {
  position: sticky; top: 0; z-index: 5;
  background: var(--paper);
  border-bottom: 1px solid var(--line);
}

.topbar-inner {
  display: flex; align-items: center; justify-content: space-between;
  gap: 12px 24px; flex-wrap: wrap;
  padding-block: 14px;
}

.brand { display: inline-flex; align-items: center; text-decoration: none; }
.brand-logo { width: auto; height: 30px; }

.nav { display: flex; gap: 26px; font-size: 15px; }
.nav a {
  color: var(--ink-2); text-decoration: none;
  padding-block: 4px;
  border-bottom: 1px solid transparent;
}
.nav a:hover, .nav a:focus-visible { color: var(--brand); border-bottom-color: var(--brand); }

/* ---------- 首屏 ---------- */

.hero {
  padding: clamp(64px, 12vh, 116px) 0 clamp(44px, 6.5vh, 72px);
  text-align: center;
  background: linear-gradient(to bottom, #e9f4f5 0%, #f8fcfc 58%, #ffffff 100%);
}

.hero-mark { margin: 0 0 .34em; animation: focus-in 1.6s cubic-bezier(.22, .61, .36, 1) both; }
.hero-mark img { width: clamp(228px, 45vw, 500px); margin-inline: auto; }

.hero-lead {
  display: flex; flex-wrap: wrap; justify-content: center;
  gap: clamp(12px, 2.6vw, 32px);
  margin: 0 0 .7em;
  font-size: clamp(20px, 3.2vw, 32px);
  font-weight: 700;
  line-height: 1.5;
  letter-spacing: .04em;
  animation: focus-in 1.6s cubic-bezier(.22, .61, .36, 1) .28s both;
}

.hero-sub {
  max-width: 32em; margin: 0 auto 2.3em;
  color: var(--ink-2); font-size: 17px;
  text-wrap: balance;
  animation: focus-in 1.6s cubic-bezier(.22, .61, .36, 1) .46s both;
}

.hero-actions {
  display: flex; flex-wrap: wrap; justify-content: center; gap: 14px;
  animation: focus-in 1.6s cubic-bezier(.22, .61, .36, 1) .62s both;
}

.btn {
  display: inline-block;
  padding: 13px 32px;
  background: var(--brand); color: #fff;
  font-size: 16px; letter-spacing: .05em; text-decoration: none;
  border: 1px solid var(--brand);
  border-radius: 2px;
  transition: background-color .2s ease, color .2s ease;
}
.btn:hover, .btn:focus-visible { background: var(--brand-d); color: #fff; }

/* 次级按钮：描边而非填充，避免与主按钮争夺注意力 */
.btn-ghost { background: transparent; color: var(--brand); }
.btn-ghost:hover, .btn-ghost:focus-visible { background: var(--brand); color: #fff; }

.btn-sm { padding: 10px 24px; font-size: 15px; }

@keyframes focus-in {
  from { opacity: 0; filter: blur(10px); transform: translateY(8px); }
  to   { opacity: 1; filter: blur(0);    transform: none; }
}

/* ---------- 通用区块 ---------- */

.band { padding: clamp(64px, 9vw, 120px) 0; border-top: 1px solid var(--line); }
.band-alt { background: var(--wash); }

.section-title {
  margin: 0 0 .5em;
  font-size: clamp(24px, 3vw, 30px);
  font-weight: 700; line-height: 1.5; letter-spacing: .02em;
}

.section-lead { max-width: 34em; margin: 0 0 2.8em; color: var(--ink-2); }

/* 两件产品并列：竖分隔线区分，不用卡片和阴影 */
.columns {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
}
.columns > article {
  padding: 0 40px;
  border-left: 1px solid var(--line-brand);
}
.columns > article:first-child { padding-left: 0; border-left: 0; }
.columns > article:last-child  { padding-right: 0; }

.columns h3 {
  margin: 0 0 .2em;
  font-size: 21px; font-weight: 700; line-height: 1.6;
  letter-spacing: .01em;
}
.columns p { margin: 0 0 1em; color: var(--ink-2); font-size: 16px; }

/* 产品类型小标：区分「网页端 / 小程序」，放在标题下方而非做成标签 */
.product-sub {
  margin-bottom: 1.2em !important;
  font-size: 14px !important;
  letter-spacing: .08em;
  color: var(--brand) !important;
}

.product-actions { margin-top: 1.6em !important; }

/* 小程序暂无网页入口，用说明文字代替按钮，避免出现「点了没反应」的假按钮 */
.hint { font-size: 15px; color: var(--ink-2); }

.note {
  max-width: 40em; margin-top: 2.8em;
  font-size: 14.5px; color: var(--ink-2);
}

/* ---------- 关于 ---------- */

.prose { max-width: 34em; }
.prose p { color: var(--ink-2); }
.prose-lead { font-size: 19px; color: var(--ink) !important; }

/* ---------- 联系方式 ---------- */

.contact {
  display: grid; grid-template-columns: auto 1fr;
  gap: 14px 44px;
  max-width: 34em; margin: 0;
}
.contact dt { color: var(--ink-2); }
.contact dd { margin: 0; color: var(--ink); }

/* ---------- 页脚 ---------- */

.footer {
  border-top: 1px solid var(--line);
  padding: 56px 0 64px;
}

.footer-inner {
  display: flex; flex-direction: column; align-items: center; gap: 12px;
  text-align: center;
}
.footer-inner p { margin: 0; }
.footer-logo { width: min(210px, 68vw); height: auto; }
.footer-copy { font-size: 14px; color: var(--ink-2); }

.footer-beian {
  display: flex; flex-wrap: wrap; justify-content: center;
  align-items: center; gap: 6px 20px;
  font-size: 14px; color: var(--ink-2);
}
.footer-icp, .footer-police { display: inline-flex; align-items: center; gap: 5px; }
.footer-police img { width: 20px; height: 20px; }

.footer-note { font-size: 13.5px; color: var(--ink-2); }
.footer-inner a { color: var(--ink-2); text-decoration: none; }
.footer-inner a:hover, .footer-inner a:focus-visible { color: var(--brand); text-decoration: underline; }

/* ---------- 响应式 ---------- */

@media (max-width: 820px) {
  .columns { grid-template-columns: 1fr; gap: 0; }
  .columns > article {
    padding: 32px 0 0;
    border-left: 0;
    border-top: 1px solid var(--line-brand);
  }
  .columns > article:first-child { padding-top: 0; border-top: 0; }
  .columns > article:last-child { padding-bottom: 0; }
}

@media (max-width: 560px) {
  body { font-size: 16.5px; }
  .topbar-inner { padding-block: 12px; }
  .nav { gap: 18px; font-size: 14.5px; }
  .contact { gap: 12px 24px; }
  .hero-actions .btn { width: 100%; text-align: center; }
}

/* ---------- 尊重系统的「减少动态效果」 ---------- */

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation-duration: .001ms !important;
    animation-delay: 0ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: .001ms !important;
  }
}