/* 正文：思源黑体 / 标题：思源宋体（Bunny CDN，国内更稳） */
@import url('https://fonts.bunny.net/css?family=noto-sans-sc:400,500,600,700|noto-serif-sc:600,700&display=swap');

:root {
  --ink: #0f1c24;
  --ink-soft: #3a4a54;
  --paper: #f3f6f4;
  --surface: #ffffff;
  --line: #d5e0d9;
  --accent: #0d7a5f;
  --accent-deep: #085544;
  --accent-soft: #e6f4ef;
  --amber: #c47a12;
  --amber-soft: #fff4e3;
  --sky: #1a6b8a;
  --sky-soft: #e5f3f8;
  --danger: #a33b2c;
  --shadow: 0 12px 40px rgba(15, 28, 36, 0.08);
  --radius: 14px;
  --font-sans: "Noto Sans SC", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", sans-serif;
  --font-display: "Noto Serif SC", "Source Han Serif SC", "Songti SC", "STSong", serif;
  --max: 1180px;
  --sidebar: 280px;
}

*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; text-size-adjust: 100%; }
body {
  margin: 0;
  font-family: var(--font-sans);
  font-weight: 400;
  font-size: 16px;
  color: var(--ink);
  background:
    radial-gradient(ellipse 80% 50% at 10% -10%, #d8efe6 0%, transparent 55%),
    radial-gradient(ellipse 60% 40% at 100% 0%, #dcecf2 0%, transparent 50%),
    linear-gradient(180deg, #eef3f0 0%, var(--paper) 40%, #e8eeea 100%);
  min-height: 100vh;
  line-height: 1.75;
  letter-spacing: 0.01em;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

h1, h2, h3, .section-title, .hero h1, .quest-head h1, .level-hero h1,
.module-quest-card .mq-num, .module-item .num {
  font-family: var(--font-display);
  font-weight: 700;
  letter-spacing: 0.02em;
  line-height: 1.35;
}

a { color: var(--accent-deep); text-decoration: none; }
a:hover { text-decoration: underline; }
img, svg { max-width: 100%; height: auto; display: block; }

.container { width: min(100% - 2rem, var(--max)); margin-inline: auto; }

/* —— Top nav —— */
.topbar {
  position: sticky; top: 0; z-index: 50;
  backdrop-filter: blur(12px);
  background: rgba(243, 246, 244, 0.88);
  border-bottom: 1px solid var(--line);
}
.topbar-inner {
  display: flex; align-items: center; justify-content: space-between;
  gap: 1rem; padding: 0.75rem 0; width: min(100% - 2rem, var(--max)); margin-inline: auto;
}
.brand {
  display: flex; align-items: center; gap: 0.65rem;
  font-weight: 700; color: var(--ink); text-decoration: none;
}
.brand:hover { text-decoration: none; }
.brand-mark {
  width: 36px; height: 36px; border-radius: 10px;
  background: linear-gradient(135deg, var(--accent), var(--sky));
  display: grid; place-items: center; color: #fff; font-size: 0.85rem; font-weight: 900;
}
.brand-logo {
  width: 36px; height: 36px; border-radius: 10px; display: block;
  object-fit: contain; flex-shrink: 0;
}
.nav-links { display: flex; flex-wrap: wrap; gap: 0.35rem 1rem; align-items: center; }
.nav-links a {
  color: var(--ink-soft); font-size: 0.92rem; font-weight: 500; text-decoration: none;
}
.nav-links a:hover, .nav-links a.active { color: var(--accent-deep); }

.auth-bar {
  display: flex; align-items: center; gap: 0.45rem; margin-left: auto; flex-shrink: 0;
}
.auth-user {
  font-size: 0.85rem; color: var(--ink-soft); max-width: 9rem;
  overflow: hidden; text-overflow: ellipsis; white-space: nowrap;
}
.auth-badge {
  font-size: 0.72rem; font-weight: 600; color: var(--accent-deep);
  background: var(--accent-soft); border-radius: 999px; padding: 0.2rem 0.55rem;
}
.auth-btn {
  appearance: none; border: 1px solid var(--accent); background: var(--accent); color: #fff;
  border-radius: 8px; padding: 0.35rem 0.7rem; font-size: 0.82rem; cursor: pointer;
}
.auth-btn:hover { background: var(--accent-deep); border-color: var(--accent-deep); }
.auth-btn--ghost {
  background: transparent; color: var(--accent-deep); border-color: var(--line);
}
.auth-btn--ghost:hover { background: var(--accent-soft); }

/* —— Hero / portal —— */
.hero {
  padding: 3.5rem 0 2.5rem;
  position: relative;
  overflow: hidden;
}
.hero-grid {
  display: grid; grid-template-columns: 1.15fr 0.85fr; gap: 2.5rem; align-items: center;
}
.eyebrow {
  display: inline-block; font-size: 0.82rem; letter-spacing: 0.08em;
  text-transform: uppercase; color: var(--accent); font-weight: 700; margin-bottom: 0.75rem;
}
.hero h1 {
  font-family: var(--font-display);
  font-size: clamp(2rem, 4.6vw, 3rem);
  line-height: 1.25; margin: 0 0 1rem; font-weight: 700;
  letter-spacing: 0.03em;
}
.hero-lead { font-size: 1.08rem; color: var(--ink-soft); max-width: 36rem; margin: 0 0 1.75rem; }
.cta-row { display: flex; flex-wrap: wrap; gap: 0.75rem; }
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 0.4rem;
  padding: 0.75rem 1.25rem; border-radius: 999px; font-weight: 600; font-size: 0.95rem;
  border: 1.5px solid transparent; cursor: pointer; text-decoration: none;
  transition: transform 0.15s ease, box-shadow 0.15s ease, background 0.15s;
}
.btn:hover { text-decoration: none; transform: translateY(-1px); }
.btn-primary { background: var(--accent); color: #fff; box-shadow: 0 8px 24px rgba(13, 122, 95, 0.28); }
.btn-primary:hover { background: var(--accent-deep); color: #fff; }
.btn-secondary { background: var(--surface); color: var(--ink); border-color: var(--line); }
.btn-ghost { background: transparent; color: var(--accent-deep); border-color: var(--accent); }

.hero-visual {
  position: relative; border-radius: 20px; overflow: hidden;
  background: linear-gradient(160deg, #0d5c4a 0%, #1a6b8a 55%, #0f1c24 100%);
  min-height: 320px; box-shadow: var(--shadow);
  padding: 1.25rem; color: #e8f5f1;
}
.hero-visual img,
.hero-visual svg {
  width: 100%; height: auto; display: block; opacity: 1;
  border-radius: 12px;
}
.hero-stat {
  position: absolute; bottom: 1.25rem; left: 1.25rem; right: 1.25rem;
  display: flex; gap: 1rem; flex-wrap: wrap;
}
.hero-stat span {
  background: rgba(255,255,255,0.12); backdrop-filter: blur(6px);
  padding: 0.45rem 0.85rem; border-radius: 10px; font-size: 0.85rem;
}

/* —— Sections —— */
.section { padding: 2.5rem 0; }
.section-title {
  font-family: var(--font-display); font-size: 1.65rem; margin: 0 0 0.5rem; font-weight: 700;
}
.section-desc { color: var(--ink-soft); margin: 0 0 1.5rem; max-width: 40rem; }

.card-grid {
  display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 1rem;
}
.card {
  background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 1.25rem 1.35rem; box-shadow: 0 4px 16px rgba(15,28,36,0.04);
}
.card h3 { margin: 0 0 0.5rem; font-size: 1.05rem; }
.card p { margin: 0; color: var(--ink-soft); font-size: 0.94rem; }
.card-num {
  width: 2rem; height: 2rem; border-radius: 8px; background: var(--accent-soft);
  color: var(--accent-deep); display: grid; place-items: center; font-weight: 800;
  font-size: 0.85rem; margin-bottom: 0.75rem;
}

.module-list { display: grid; gap: 0.75rem; }
.module-item {
  display: grid; grid-template-columns: auto 1fr auto; gap: 1rem; align-items: center;
  background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 1rem 1.25rem; text-decoration: none; color: inherit;
  transition: border-color 0.15s, box-shadow 0.15s, transform 0.15s;
}
.module-item:hover {
  border-color: var(--accent); box-shadow: var(--shadow); text-decoration: none;
  transform: translateX(4px);
}
.module-item .num {
  font-family: var(--font-display); font-size: 1.5rem; color: var(--accent);
  min-width: 2.2rem;
}
.module-item h3 { margin: 0; font-size: 1.05rem; }
.module-item p { margin: 0.2rem 0 0; font-size: 0.88rem; color: var(--ink-soft); }
.module-item .hours {
  font-size: 0.82rem; color: var(--amber); background: var(--amber-soft);
  padding: 0.3rem 0.65rem; border-radius: 999px; white-space: nowrap; font-weight: 600;
}

.entry-cards { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1rem; }
.entry-card {
  display: block; padding: 1.5rem; border-radius: var(--radius); text-decoration: none;
  color: #fff; min-height: 160px; position: relative; overflow: hidden;
  transition: transform 0.15s;
}
.entry-card:hover { transform: translateY(-3px); text-decoration: none; color: #fff; }
.entry-card h3 { margin: 0 0 0.5rem; font-size: 1.2rem; }
.entry-card p { margin: 0; opacity: 0.9; font-size: 0.92rem; }
.entry-card.video { background: linear-gradient(135deg, #1a6b8a, #0d4a62); }
.entry-card.book { background: linear-gradient(135deg, #0d7a5f, #085544); }
.entry-card.notes { background: linear-gradient(135deg, #c47a12, #8a5508); }

.footer {
  margin-top: 3rem; padding: 2rem 0; border-top: 1px solid var(--line);
  color: var(--ink-soft); font-size: 0.88rem; text-align: center;
}

/* —— Lesson layout —— */
.lesson-shell { display: grid; grid-template-columns: var(--sidebar) 1fr; min-height: calc(100vh - 58px); }
.sidebar {
  background: rgba(255,255,255,0.72); border-right: 1px solid var(--line);
  padding: 1.25rem 1rem; position: sticky; top: 58px; height: calc(100vh - 58px); overflow-y: auto;
}
.sidebar h2 { font-size: 0.78rem; text-transform: uppercase; letter-spacing: 0.06em; color: var(--ink-soft); margin: 0 0 0.75rem; }
.side-module { margin-bottom: 1rem; }
.side-module > a {
  display: block; font-weight: 700; font-size: 0.9rem; color: var(--ink);
  padding: 0.35rem 0.5rem; border-radius: 8px; text-decoration: none;
}
.side-module > a:hover, .side-module > a.active { background: var(--accent-soft); color: var(--accent-deep); text-decoration: none; }
.side-sections { list-style: none; margin: 0.25rem 0 0; padding: 0 0 0 0.5rem; }
.side-sections a {
  display: block; padding: 0.3rem 0.5rem; font-size: 0.84rem; color: var(--ink-soft);
  border-radius: 6px; text-decoration: none;
}
.side-sections a:hover, .side-sections a.active { background: #fff; color: var(--accent-deep); text-decoration: none; }
.progress-wrap { margin-top: 1.25rem; padding-top: 1rem; border-top: 1px solid var(--line); }
.progress-bar { height: 6px; background: var(--line); border-radius: 99px; overflow: hidden; }
.progress-bar > span { display: block; height: 100%; background: var(--accent); width: 0%; transition: width 0.3s; }
.progress-label { font-size: 0.78rem; color: var(--ink-soft); margin-top: 0.4rem; }

.lesson-main { padding: 1.75rem 1.5rem 3rem; max-width: 820px; }
.lesson-meta { display: flex; flex-wrap: wrap; gap: 0.5rem; margin-bottom: 0.75rem; }
.tag {
  font-size: 0.78rem; font-weight: 600; padding: 0.25rem 0.65rem; border-radius: 999px;
  background: var(--accent-soft); color: var(--accent-deep);
}
.tag.amber { background: var(--amber-soft); color: var(--amber); }
.lesson-main h1 {
  font-family: var(--font-display); font-size: clamp(1.6rem, 3vw, 2.1rem);
  margin: 0 0 1rem; line-height: 1.25; font-weight: 700;
}
.lesson-main h2 {
  font-size: 1.25rem; margin: 2rem 0 0.75rem; padding-bottom: 0.4rem;
  border-bottom: 2px solid var(--accent-soft); color: var(--accent-deep);
}
.lesson-main h3 { font-size: 1.05rem; margin: 1.5rem 0 0.5rem; }
.lesson-main p { margin: 0 0 1rem; color: var(--ink); }
.lesson-main ul, .lesson-main ol { margin: 0 0 1rem; padding-left: 1.35rem; color: var(--ink-soft); }
.lesson-main li { margin-bottom: 0.35rem; }

.goals-box {
  background: var(--sky-soft); border-left: 4px solid var(--sky);
  padding: 1rem 1.15rem; border-radius: 0 var(--radius) var(--radius) 0; margin: 0 0 1.5rem;
}
.goals-box strong { display: block; margin-bottom: 0.4rem; color: var(--sky); }
.goals-box ul { margin: 0; padding-left: 1.2rem; color: var(--ink); }

.figure {
  margin: 1.5rem 0; background: var(--surface); border: 1px solid var(--line);
  border-radius: var(--radius); padding: 1.25rem; overflow: hidden;
}
.figure figcaption {
  margin-top: 0.75rem; font-size: 0.82rem; color: var(--ink-soft); text-align: center;
}

.interact {
  margin: 1.5rem 0; border-radius: var(--radius); padding: 1.15rem 1.25rem; border: 1px solid transparent;
}
.interact h4 { margin: 0 0 0.5rem; font-size: 0.95rem; display: flex; align-items: center; gap: 0.4rem; }
.interact.think { background: var(--amber-soft); border-color: #f0d9a8; }
.interact.discuss { background: var(--sky-soft); border-color: #b8d9e6; }
.interact.try { background: var(--accent-soft); border-color: #a8d9c8; }
.interact.note { background: #f5f0eb; border-color: #e0d4c6; }
.interact textarea, .interact input[type="text"] {
  width: 100%; margin-top: 0.5rem; padding: 0.65rem 0.75rem; border: 1px solid var(--line);
  border-radius: 10px; font-family: inherit; font-size: 0.92rem; resize: vertical; min-height: 80px;
  background: #fff;
}
.interact .actions { margin-top: 0.65rem; display: flex; flex-wrap: wrap; gap: 0.5rem; }
.interact .hint { font-size: 0.85rem; color: var(--ink-soft); margin-top: 0.5rem; }
.chat-sim {
  margin-top: 0.75rem; background: #fff; border: 1px solid var(--line); border-radius: 12px;
  padding: 0.85rem; max-height: 280px; overflow-y: auto;
}
.chat-sim .msg { margin-bottom: 0.65rem; font-size: 0.9rem; }
.chat-sim .msg.user { color: var(--accent-deep); white-space: pre-wrap; }
.chat-sim .msg.bot { color: var(--ink-soft); padding: 0.5rem 0.65rem; background: var(--paper); border-radius: 8px; }
.chat-sim .msg .msg-role { font-weight: 600; margin-bottom: 0.25rem; color: var(--ink); }
.chat-sim .msg-md { line-height: 1.55; overflow-wrap: anywhere; }
.chat-sim .msg-md > *:first-child { margin-top: 0; }
.chat-sim .msg-md > *:last-child { margin-bottom: 0; }
.chat-sim .msg-md p { margin: 0.4rem 0; }
.chat-sim .msg-md h1,
.chat-sim .msg-md h2,
.chat-sim .msg-md h3,
.chat-sim .msg-md h4 { margin: 0.65rem 0 0.35rem; font-size: 1rem; line-height: 1.35; color: var(--ink); }
.chat-sim .msg-md ul,
.chat-sim .msg-md ol { margin: 0.35rem 0 0.35rem 1.2rem; padding: 0; }
.chat-sim .msg-md li { margin: 0.15rem 0; }
.chat-sim .msg-md code {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 0.85em; background: rgba(0,0,0,0.06); padding: 0.05em 0.3em; border-radius: 4px;
}
.chat-sim .msg-md pre {
  margin: 0.45rem 0; padding: 0.55rem 0.7rem; overflow: auto;
  background: rgba(0,0,0,0.06); border-radius: 8px; font-size: 0.82rem;
}
.chat-sim .msg-md pre code { background: none; padding: 0; }
.chat-sim .msg-md table { width: 100%; border-collapse: collapse; margin: 0.45rem 0; font-size: 0.85rem; }
.chat-sim .msg-md th,
.chat-sim .msg-md td { border: 1px solid var(--line); padding: 0.3rem 0.45rem; text-align: left; }
.chat-sim .msg-md blockquote {
  margin: 0.45rem 0; padding: 0.25rem 0.65rem; border-left: 3px solid var(--accent);
  color: var(--ink-soft); background: rgba(255,255,255,0.5);
}
.chat-sim .msg-md a { color: var(--sky); }

.nav-pager {
  display: flex; justify-content: space-between; gap: 1rem; margin-top: 2.5rem;
  padding-top: 1.25rem; border-top: 1px solid var(--line); flex-wrap: wrap;
}
.nav-pager a {
  display: inline-flex; align-items: center; gap: 0.35rem; padding: 0.6rem 1rem;
  background: var(--surface); border: 1px solid var(--line); border-radius: 10px;
  color: var(--ink); font-weight: 500; text-decoration: none; font-size: 0.9rem;
}
.nav-pager a:hover { border-color: var(--accent); color: var(--accent-deep); }

.embed-frame {
  width: 100%; min-height: 75vh; border: 0; border-radius: var(--radius);
  background: #111; box-shadow: var(--shadow);
}
.video-wrap {
  background: var(--surface); border-radius: var(--radius); padding: 1.25rem 1.25rem 1.5rem;
  border: 1px solid var(--line); text-align: center;
  max-width: 960px; /* 与常见在线播放器画幅接近，避免被拉伸发糊 */
  margin-inline: auto;
}
.video-frame {
  position: relative;
  width: 100%;
  max-width: 960px;
  margin: 0.75rem auto 0;
  aspect-ratio: 16 / 9;
  background: #000;
  border-radius: 12px;
  overflow: hidden;
  box-shadow: 0 8px 28px rgba(15, 28, 36, 0.18);
}
.video-frame iframe {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  border: 0;
  display: block;
  background: #000;
}
@media (max-width: 640px) {
  .video-wrap { padding: 1rem; }
}


.media-slot {
  margin: 1.25rem 0; padding: 1.25rem; border-radius: var(--radius);
  border: 1.5px dashed var(--sky); background: linear-gradient(135deg, #e5f3f8, #f7faf8);
  text-align: center;
}
.media-slot strong { display: block; color: var(--sky); margin-bottom: 0.35rem; }
.media-slot p { margin: 0 0 0.75rem; color: var(--ink-soft); font-size: 0.9rem; }

.menu-toggle {
  display: none; border: 1px solid var(--line); background: #fff; border-radius: 8px;
  padding: 0.4rem 0.7rem; font-size: 0.9rem; cursor: pointer;
}

@media (max-width: 900px) {
  .hero-grid, .entry-cards { grid-template-columns: 1fr; }
  .lesson-shell { grid-template-columns: 1fr; }
  .sidebar {
    position: fixed; left: 0; top: 58px; bottom: 0; width: min(86vw, 300px);
    z-index: 40; transform: translateX(-105%); transition: transform 0.2s;
    box-shadow: var(--shadow);
  }
  .sidebar.open { transform: translateX(0); }
  .menu-toggle { display: inline-flex; }
  .module-item { grid-template-columns: auto 1fr; }
  .module-item .hours { grid-column: 2; justify-self: start; }
}

/* Motion */
@keyframes fadeUp {
  from { opacity: 0; transform: translateY(12px); }
  to { opacity: 1; transform: translateY(0); }
}
.hero-grid > *, .entry-card, .module-item {
  animation: fadeUp 0.55s ease both;
}
.entry-card:nth-child(2) { animation-delay: 0.08s; }
.entry-card:nth-child(3) { animation-delay: 0.16s; }
.module-item:nth-child(n) { animation-delay: calc(0.04s * var(--i, 1)); }

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