/* ============================================================
   我爱学 · 统一设计系统 (app.css)
   视觉方向：暖调"晨曦" —— 青绿主色 + 橙调点缀，告别旧蓝紫
   独立文件，不改动旧 style.css，避免波及现有 17 个页面
   ============================================================ */

:root {
  /* —— 中性色（暖调，非冷灰）—— */
  --bg: #FBFAF7;
  --surface: #FFFFFF;
  --surface-2: #F4F1EA;
  --border: #ECE6DB;
  --border-strong: #DBD2C2;
  --text: #211C16;
  --text-2: #5C554A;
  --text-3: #938A7C;

  /* —— 主色：青绿（成长 / 专注）—— */
  --primary: #0F7669;
  --primary-600: #0D9488;
  --primary-700: #115E59;
  --primary-50: #E6F4F1;
  --primary-100: #CCEBDD;

  /* —— 点缀：暖橙（活力 / 鼓励）—— */
  --accent: #EA580C;
  --accent-600: #D97706;
  --accent-50: #FFF1E6;
  --accent-100: #FFE0C7;

  /* —— 语义色 —— */
  --danger: #DC2626;
  --success: #16A34A;
  --warning: #B45309;

  /* —— 圆角 —— */
  --r-sm: 10px;
  --r-md: 16px;
  --r-lg: 22px;
  --r-pill: 999px;

  /* —— 阴影（暖调、低饱和）—— */
  --sh-sm: 0 1px 2px rgba(40,33,24,.04), 0 2px 6px rgba(40,33,24,.05);
  --sh-md: 0 6px 20px rgba(40,33,24,.07), 0 2px 8px rgba(40,33,24,.04);
  --sh-lg: 0 18px 50px rgba(40,33,24,.12), 0 4px 12px rgba(40,33,24,.05);

  /* —— 字体 —— */
  --font: "PingFang SC", "Microsoft YaHei", "Hiragino Sans GB", system-ui, -apple-system, sans-serif;

  /* —— 布局 —— */
  --maxw: 880px;
  --header-h: 60px;
  --tab-h: 64px;
}

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

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

body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  min-height: 100dvh;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  /* 氛围：极淡的青绿/橙调光晕，替代纯色块 */
  background-image:
    radial-gradient(120% 80% at 12% -8%, rgba(15,118,105,.07), transparent 55%),
    radial-gradient(100% 70% at 100% 0%, rgba(234,88,12,.05), transparent 50%);
  background-attachment: fixed;
}

h1, h2, h3, h4 { font-weight: 600; letter-spacing: -.01em; line-height: 1.3; }
a { color: inherit; text-decoration: none; }

/* ============================================================
   页面容器
   ============================================================ */
.page {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: calc(var(--header-h) + 20px) 16px calc(var(--tab-h) + 28px);
}
.page-narrow { padding-left: 16px; padding-right: 16px; }

/* 入场动画：错峰上浮 */
@keyframes rise {
  from { opacity: 0; transform: translateY(14px); }
  to   { opacity: 1; transform: translateY(0); }
}
.rise {
  opacity: 0;
  animation: rise .55s cubic-bezier(.16,1,.3,1) forwards;
  animation-delay: calc(var(--i, 0) * 70ms);
}

/* ============================================================
   统一外壳 · 顶栏
   ============================================================ */
.app-header {
  position: fixed; top: 0; left: 0; right: 0;
  height: var(--header-h);
  display: flex; align-items: center; justify-content: space-between;
  padding: 0 16px;
  background: rgba(255,255,255,.72);
  backdrop-filter: saturate(160%) blur(16px);
  -webkit-backdrop-filter: saturate(160%) blur(16px);
  border-bottom: 1px solid var(--border);
  z-index: 200;
}
.app-header .brand { display: flex; align-items: center; gap: 10px; }
.app-header .brand img { height: 32px; width: auto; border-radius: 9px; }
.app-header .brand .name {
  font-size: 17px; font-weight: 700; letter-spacing: .02em;
  background: linear-gradient(120deg, var(--primary-700), var(--accent));
  -webkit-background-clip: text; background-clip: text;
  -webkit-text-fill-color: transparent;
}
.app-header .user {
  display: flex; align-items: center; gap: 10px; font-size: 14px; color: var(--text-2);
}
.app-header .avatar {
  width: 34px; height: 34px; border-radius: var(--r-pill);
  display: grid; place-items: center;
  background: var(--primary-50); color: var(--primary-700);
  font-weight: 700; font-size: 14px; border: 1px solid var(--primary-100);
}
.app-header .btn-ghost {
  font-size: 13px; padding: 7px 14px; border-radius: var(--r-pill);
  border: 1px solid var(--border); color: var(--text-2); background: var(--surface);
  cursor: pointer; transition: all .2s;
}
.app-header .btn-ghost:hover { border-color: var(--primary-100); color: var(--primary-700); }

/* 用户下拉菜单 */
.app-menu {
  position: fixed; top: calc(var(--header-h) + 8px); right: 16px;
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--r-md); box-shadow: var(--sh-md);
  padding: 6px; min-width: 168px; z-index: 300; display: none;
}
.app-menu.open { display: block; animation: rise .2s ease forwards; }
.app-menu a, .app-menu button {
  display: flex; align-items: center; gap: 8px; width: 100%;
  padding: 10px 12px; border: 0; background: none; cursor: pointer;
  font-size: 14px; color: var(--text); border-radius: var(--r-sm); font-family: var(--font);
  text-align: left;
}
.app-menu a:hover, .app-menu button:hover { background: var(--surface-2); }

/* ============================================================
   统一外壳 · 底部标签栏
   ============================================================ */
.app-tabbar {
  position: fixed; left: 50%; transform: translateX(-50%);
  bottom: 0; width: 100%; max-width: var(--maxw);
  height: var(--tab-h);
  display: flex; align-items: stretch;
  background: rgba(255,255,255,.82);
  backdrop-filter: saturate(160%) blur(18px);
  -webkit-backdrop-filter: saturate(160%) blur(18px);
  border-top: 1px solid var(--border);
  z-index: 200; padding-bottom: env(safe-area-inset-bottom, 0);
}
.app-tab {
  flex: 1; display: flex; flex-direction: column; align-items: center; justify-content: center;
  gap: 3px; color: var(--text-3); font-size: 11px; cursor: pointer;
  position: relative; transition: color .2s; -webkit-tap-highlight-color: transparent;
}
.app-tab svg { width: 22px; height: 22px; }
.app-tab.active { color: var(--primary-700); }
.app-tab.active::before {
  content: ""; position: absolute; top: 7px; width: 26px; height: 3px;
  border-radius: 3px; background: var(--primary); 
}

/* ============================================================
   组件 · 卡片 / 按钮
   ============================================================ */
.card {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--r-lg); box-shadow: var(--sh-sm); padding: 20px;
}
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  padding: 12px 20px; border-radius: var(--r-pill); border: 1px solid transparent;
  font-family: var(--font); font-size: 15px; font-weight: 600; cursor: pointer;
  transition: transform .15s, box-shadow .2s, background .2s;
}
.btn-primary { background: var(--primary); color: #fff; box-shadow: 0 6px 16px rgba(15,118,105,.28); }
.btn-primary:hover { background: var(--primary-600); transform: translateY(-1px); }
.btn-ghost { background: var(--surface); border-color: var(--border); color: var(--text); }
.btn-ghost:hover { border-color: var(--primary-100); color: var(--primary-700); }
.btn-sm { padding: 8px 14px; font-size: 13px; }

/* ============================================================
   组件 · 区块标题 / 年级栏
   ============================================================ */
.section-title {
  font-size: 17px; font-weight: 700; margin: 26px 4px 14px;
  display: flex; align-items: center; gap: 8px;
}
.section-title .dot { width: 9px; height: 9px; border-radius: 3px; background: var(--primary); }

.grade-bar {
  display: flex; align-items: center; gap: 12px; margin: 4px 0 8px;
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--r-md); padding: 14px 16px; box-shadow: var(--sh-sm);
}
.grade-bar .label { font-size: 14px; color: var(--text-2); font-weight: 500; white-space: nowrap; }
.grade-bar select {
  flex: 1; appearance: none; border: 0; background: var(--surface-2);
  border-radius: var(--r-sm); padding: 11px 38px 11px 14px; font-size: 15px;
  color: var(--text); font-family: var(--font); cursor: pointer;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' fill='%23938A7C' viewBox='0 0 16 16'%3E%3Cpath d='M8 11L3 6h10l-5 5z'/%3E%3C/svg%3E");
  background-repeat: no-repeat; background-position: right 14px center;
}
.grade-bar select:focus { outline: 2px solid var(--primary); outline-offset: 2px; }

/* ============================================================
   组件 · 核心双卡
   ============================================================ */
.core-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; margin-top: 6px; }
.core-card {
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--r-lg);
  padding: 22px 18px; box-shadow: var(--sh-sm); cursor: pointer;
  display: flex; flex-direction: column; gap: 8px; transition: transform .18s, box-shadow .25s, border-color .25s;
}
.core-card:hover { transform: translateY(-3px); box-shadow: var(--sh-md); border-color: var(--primary-100); }
.core-card .ic {
  width: 50px; height: 50px; border-radius: 14px; display: grid; place-items: center;
}
.core-card .ic svg { width: 26px; height: 26px; }
.core-card h3 { font-size: 17px; }
.core-card p { font-size: 13px; color: var(--text-2); }

/* ============================================================
   组件 · 百宝箱工具行
   ============================================================ */
.tool-list { display: flex; flex-direction: column; gap: 10px; }
.tool-row {
  display: flex; align-items: center; gap: 14px;
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--r-md); padding: 14px 16px; box-shadow: var(--sh-sm);
  cursor: pointer; transition: transform .16s, box-shadow .25s, border-color .25s;
}
.tool-row:hover { transform: translateY(-2px); box-shadow: var(--sh-md); border-color: var(--primary-100); }
.tool-ic {
  width: 46px; height: 46px; border-radius: 13px; flex: none;
  display: grid; place-items: center; font-size: 20px; font-weight: 700; color: #fff;
}
.tool-ic svg { width: 24px; height: 24px; }
/* 图标底色变体 */
.t-teal   { background: linear-gradient(135deg, #0F7669, #115E59); }
.t-orange { background: linear-gradient(135deg, #EA580C, #D97706); }
.t-amber  { background: linear-gradient(135deg, #D97706, #B45309); }
.t-sky    { background: linear-gradient(135deg, #0E7490, #155E75); }
.t-rose   { background: linear-gradient(135deg, #BE123C, #9F1239); }
.t-lime   { background: linear-gradient(135deg, #4D7C0F, #3F6212); }
.t-indigo { background: linear-gradient(135deg, #4F46E5, #3730A3); }
.t-slate  { background: linear-gradient(135deg, #475569, #334155); }

.tool-info { flex: 1; min-width: 0; }
.tool-info h4 { font-size: 15px; font-weight: 600; }
.tool-info p { font-size: 12.5px; color: var(--text-2); margin-top: 2px;
  overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.tool-arrow { color: var(--text-3); font-size: 20px; flex: none; transition: transform .2s; }
.tool-row:hover .tool-arrow { transform: translateX(3px); color: var(--primary); }

/* ============================================================
   组件 · 徽标 / 输入
   ============================================================ */
.badge {
  display: inline-flex; align-items: center; gap: 5px; font-size: 12px; font-weight: 600;
  padding: 4px 10px; border-radius: var(--r-pill); background: var(--primary-50); color: var(--primary-700);
}
.input, .select {
  width: 100%; border: 1px solid var(--border); border-radius: var(--r-sm);
  padding: 11px 14px; font-size: 15px; font-family: var(--font); color: var(--text);
  background: var(--surface); transition: border-color .2s, box-shadow .2s;
}
.input:focus, .select:focus { outline: none; border-color: var(--primary); box-shadow: 0 0 0 3px var(--primary-100); }
.label { display: block; font-size: 13px; font-weight: 500; color: var(--text-2); margin: 12px 0 6px; }

/* 空状态 */
.empty { text-align: center; color: var(--text-3); padding: 40px 20px; font-size: 14px; }

/* ============================================================
   响应式 & 降级
   ============================================================ */
@media (max-width: 420px) {
  .core-grid { grid-template-columns: 1fr; }
}
@media (prefers-reduced-motion: reduce) {
  .rise { animation: none; opacity: 1; }
  .core-card:hover, .tool-row:hover { transform: none; }
  * { scroll-behavior: auto !important; }
}

/* ============================================================
   外壳补充 · 品牌标记 / 历史按钮 / 用户菜单头 / 页脚
   ============================================================ */
.app-header .brand svg.brand-mark { height: 32px; width: 32px; border-radius: 9px; display: block; }
.app-header .h-btn {
  width: 36px; height: 36px; border-radius: var(--r-pill);
  display: grid; place-items: center; cursor: pointer;
  border: 1px solid var(--border); background: var(--surface); color: var(--text-2);
  transition: all .2s;
}
.app-header .h-btn:hover { border-color: var(--primary-100); color: var(--primary-700); }
.app-header .h-btn svg { width: 18px; height: 18px; }

/* 用户下拉菜单头部 */
.app-menu-head {
  display: flex; align-items: center; gap: 10px;
  padding: 10px 12px; border-bottom: 1px solid var(--border); margin-bottom: 4px;
}
.app-menu-head .mm-avatar {
  width: 40px; height: 40px; border-radius: var(--r-pill); flex: none;
  display: grid; place-items: center; background: var(--primary); color: #fff; font-weight: 700; font-size: 16px;
}
.app-menu-head .mm-name { font-size: 14px; font-weight: 600; }
.app-menu-head .mm-role { font-size: 12px; color: var(--text-3); }

/* 页脚 */
.site-footer { text-align: center; padding: 24px 16px 8px; font-size: 12px; color: var(--text-3); }
.site-footer a { color: var(--text-3); border-bottom: 1px dashed var(--border-strong); }
.site-footer a:hover { color: var(--primary-700); }