/* 家庭AI学习中枢 V1.0 · 全局样式（孩子端：简单/大字体/明显反馈） */
* { margin: 0; padding: 0; box-sizing: border-box; -webkit-tap-highlight-color: transparent; }
body {
  font-family: "PingFang SC", "Microsoft YaHei", sans-serif;
  background: linear-gradient(160deg, #eef5ff 0%, #fdf3ff 100%);
  min-height: 100vh; color: #2b3a55;
}
.container { max-width: 960px; margin: 0 auto; padding: 24px 16px 48px; }

/* 首页 */
.home-header { text-align: center; padding: 32px 0 8px; }
.home-header h1 { font-size: 34px; letter-spacing: 2px; }
.home-header p { color: #7b8aa5; margin-top: 8px; font-size: 15px; }
.student-cards { display: flex; gap: 24px; justify-content: center; margin-top: 36px; flex-wrap: wrap; }
.student-card {
  width: 300px; border-radius: 24px; padding: 40px 24px; text-align: center; cursor: pointer;
  color: #fff; transition: transform .15s, box-shadow .15s; border: none; outline: none;
}
.student-card:hover { transform: translateY(-6px); box-shadow: 0 16px 32px rgba(43,58,85,.18); }
.student-card .avatar { font-size: 72px; }
.student-card h2 { font-size: 30px; margin-top: 12px; }
.student-card .grade { font-size: 18px; opacity: .9; margin-top: 6px; }
.card-boy { background: linear-gradient(150deg, #4facfe, #2b6ef2); }
.card-girl { background: linear-gradient(150deg, #f78fb3, #e0579b); }
.demo-tip { text-align: center; margin-top: 28px; color: #98a5bd; font-size: 13px; }

/* 学生首页 */
.topbar {
  display: flex; align-items: center; justify-content: space-between;
  padding: 16px 20px; border-radius: 20px; color: #fff; margin-bottom: 24px;
}
.topbar .back { background: rgba(255,255,255,.25); border: none; color: #fff; padding: 8px 16px; border-radius: 12px; font-size: 15px; cursor: pointer; }
.topbar h1 { font-size: 24px; }
.topbar .sub { opacity: .9; font-size: 14px; }
.grid { display: grid; gap: 16px; }
.grid.cols-2 { grid-template-columns: repeat(2, 1fr); }
.grid.cols-3 { grid-template-columns: repeat(3, 1fr); }
.feature {
  background: #fff; border-radius: 20px; padding: 22px 12px; text-align: center; cursor: pointer;
  text-decoration: none; color: #2b3a55; box-shadow: 0 4px 14px rgba(43,58,85,.08);
  transition: transform .15s; display: block;
}
.feature:hover { transform: translateY(-4px); }
.feature .icon { font-size: 40px; }
.feature .label { font-size: 17px; font-weight: 600; margin-top: 8px; }
.feature.disabled { opacity: .45; cursor: not-allowed; }
.feature .badge { display: inline-block; font-size: 11px; background: #ffe3b3; color: #a06a00; border-radius: 8px; padding: 2px 8px; margin-top: 6px; }
.g2 .feature .label { font-size: 19px; }

/* AI老师页 */
.ai-shell { max-width: 720px; margin: 0 auto; }
.ai-header { display: flex; align-items: center; gap: 12px; padding: 16px 20px; background: #fff; border-radius: 20px; box-shadow: 0 4px 14px rgba(43,58,85,.08); margin-bottom: 16px; }
.ai-header .ai-avatar { font-size: 36px; }
.ai-header h1 { font-size: 20px; }
.ai-header .kp { font-size: 13px; color: #7b8aa5; margin-top: 2px; }
.ai-header select { margin-left: auto; padding: 8px 12px; border-radius: 12px; border: 1px solid #d8e0ee; font-size: 15px; }
.chat-box { background: #fff; border-radius: 20px; padding: 20px; min-height: 380px; max-height: 55vh; overflow-y: auto; box-shadow: 0 4px 14px rgba(43,58,85,.08); display: flex; flex-direction: column; gap: 14px; }
.msg { max-width: 82%; padding: 14px 16px; border-radius: 18px; font-size: 17px; line-height: 1.7; white-space: pre-wrap; }
.msg.ai { background: #eef3ff; border-bottom-left-radius: 4px; align-self: flex-start; }
.msg.kid { background: linear-gradient(150deg, #ffd875, #ffb347); color: #5a3a00; border-bottom-right-radius: 4px; align-self: flex-end; }
.msg .role-tag { display: block; font-size: 11px; color: #98a5bd; margin-bottom: 4px; }
.chat-input { display: flex; gap: 10px; margin-top: 16px; }
.chat-input textarea { flex: 1; border: 2px solid #d8e0ee; border-radius: 16px; padding: 12px 16px; font-size: 17px; resize: none; height: 56px; font-family: inherit; }
.chat-input button { border: none; border-radius: 16px; padding: 0 26px; font-size: 17px; font-weight: 700; color: #fff; cursor: pointer; background: linear-gradient(150deg, #4facfe, #2b6ef2); }
.chat-input button:disabled { opacity: .5; }
.grading-panel { background: #fff; border-radius: 16px; padding: 14px 18px; font-size: 14px; box-shadow: 0 4px 14px rgba(43,58,85,.08); margin-top: 16px; }
.grading-panel h3 { font-size: 15px; margin-bottom: 8px; }
.grading-panel code { font-size: 12px; color: #556; word-break: break-all; }

/* ============================================================
   V1.0.1 · 三端自适应基线（手机 / 平板 / 电脑）
   原则：只加不改 —— 以上原有规则一字未动，全部用断点覆盖
   断点：手机 ≤600px ｜ 平板 601–1023px ｜ 电脑 ≥1024px
   ============================================================ */

/* ---------- 电脑 ≥1024：用足大屏，横向舒展 ---------- */
@media (min-width: 1024px) {
  .container { max-width: 1120px; padding: 32px 32px 64px; }
  .home-header { padding: 48px 0 8px; }
  .home-header h1 { font-size: 40px; }
  .student-cards { gap: 28px; margin-top: 44px; }
  .student-card { width: 256px; padding: 36px 20px; }
  .grid { gap: 20px; }
  .feature { padding: 26px 14px; }
  .feature .icon { font-size: 44px; }
  .feature .label { font-size: 18px; }
  .ai-shell { max-width: 900px; }
  .chat-box { min-height: 460px; max-height: 68vh; }
  .msg { max-width: 72%; }
  .chat-input textarea { height: 60px; }
}

/* ---------- 平板 601–1023：中间态 ---------- */
@media (min-width: 601px) and (max-width: 1023px) {
  .container { max-width: 100%; padding: 24px 24px 48px; }
  .student-card { width: 276px; }
  .ai-shell { max-width: 760px; }
  .chat-box { max-height: 62vh; }
}

/* ---------- 手机 ≤600：单列、紧凑、防挤出屏幕 ---------- */
@media (max-width: 600px) {
  .container { padding: 16px 12px 40px; }
  .home-header { padding: 24px 0 4px; }
  .home-header h1 { font-size: 26px; letter-spacing: 1px; }
  .home-header p { font-size: 14px; }
  .student-cards { gap: 16px; margin-top: 24px; }
  .student-card { width: 100%; max-width: 340px; padding: 28px 18px; border-radius: 20px; }
  .student-card .avatar { font-size: 56px; }
  .student-card h2 { font-size: 24px; }
  .student-card .grade { font-size: 16px; }

  .topbar { padding: 12px 14px; border-radius: 16px; margin-bottom: 16px; }
  .topbar h1 { font-size: 18px; }
  .topbar .sub { font-size: 12px; }
  .topbar .back { padding: 6px 10px; font-size: 13px; border-radius: 10px; }
  /* topbar 两侧的固定宽度占位块在窄屏收窄，否则标题被挤爆 */
  .topbar > div[style*="width:72px"] { width: 46px !important; }
  .topbar > div[style*="width:64px"] { width: 42px !important; }

  .grid { gap: 12px; }
  .grid.cols-3 { grid-template-columns: repeat(2, 1fr); }
  .feature { padding: 18px 8px; border-radius: 16px; }
  .feature .icon { font-size: 34px; }
  .feature .label { font-size: 15px; }
  .g2 .feature .label { font-size: 17px; }

  .ai-header { padding: 12px 14px; gap: 8px; border-radius: 16px; }
  .ai-header .ai-avatar { font-size: 28px; }
  .ai-header h1 { font-size: 17px; }
  .ai-header .kp { font-size: 12px; }
  .ai-header select { margin-left: 0; padding: 6px 8px; font-size: 13px; }
  .chat-box { padding: 14px; min-height: 320px; border-radius: 16px; }
  .msg { max-width: 88%; font-size: 16px; padding: 12px 14px; }
  .chat-input textarea { height: 52px; font-size: 16px; }
  .chat-input button { padding: 0 18px; font-size: 16px; }
}

/* ---------- 超窄机 ≤380：再收一档，保证不横向滚动 ---------- */
@media (max-width: 380px) {
  .home-header h1 { font-size: 22px; }
  .topbar h1 { font-size: 16px; }
  .feature .icon { font-size: 30px; }
  .feature .label { font-size: 14px; }
  .msg { max-width: 92%; }
}