/* 脑力乐园 · 墨水屏(Kindle)优化样式
   目标：高对比黑白、无动画无过渡(防残影)、不依赖颜色传达信息、
   不使用 CSS 变量 / Grid / 阴影等老旧内核不支持的特性、单列大字。 */

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: #ffffff;
  color: #000000;
}

body {
  font-family: "PingFang SC", "Heiti SC", "Microsoft YaHei", "Noto Sans CJK SC", sans-serif;
  font-size: 18px;
  line-height: 1.6;
  padding: 0 14px 40px;
  -webkit-text-size-adjust: 100%;
}

/* ---------- 顶部 ---------- */
.site-header {
  max-width: 760px;
  margin: 0 auto;
  padding: 16px 0 10px;
  border-bottom: 3px solid #000;
  display: block;
  text-align: center;
}
.brand { display: block; }
.brand-emoji { display: none; } /* 墨水屏可能不渲染彩色 emoji，隐藏装饰 */
.brand-text h1 { margin: 0; font-size: 28px; font-weight: 800; letter-spacing: 1px; }
.tagline { margin: 4px 0 0; font-size: 15px; color: #000; }

.score-badge {
  display: inline-block;
  margin-top: 10px;
  border: 3px solid #000;
  padding: 6px 18px;
  font-size: 20px;
  font-weight: 800;
}
.score-badge .star { font-weight: 800; }

/* ---------- 分类 ---------- */
.cats {
  max-width: 760px;
  margin: 12px auto 0;
  text-align: center;
}
.cat-btn {
  display: inline-block;
  border: 2px solid #000;
  background: #fff;
  color: #000;
  padding: 10px 16px;
  margin: 4px;
  font-size: 17px;
  font-weight: 700;
  cursor: pointer;
}
.cat-btn.active {
  background: #000;
  color: #fff;
}

/* ---------- 难度 ---------- */
.levels {
  max-width: 760px;
  margin: 10px auto 0;
  text-align: center;
}
.levels-label {
  font-size: 17px;
  font-weight: 800;
  margin-right: 4px;
}

/* ---------- 工具栏 ---------- */
.toolbar {
  max-width: 760px;
  margin: 16px auto 0;
  text-align: center;
}
.btn-primary {
  display: inline-block;
  background: #000;
  color: #fff;
  border: 3px solid #000;
  padding: 16px 30px;
  font-size: 22px;
  font-weight: 800;
  cursor: pointer;
}
.read-toggle {
  display: block;
  margin-top: 12px;
  font-size: 15px;
  color: #000;
}
.read-toggle input { width: 20px; height: 20px; vertical-align: middle; }

.hint {
  max-width: 760px;
  margin: 14px auto 0;
  font-size: 16px;
  color: #000;
  border: 2px dashed #000;
  padding: 10px 12px;
}

/* ---------- 卡片（单列） ---------- */
.card-list {
  max-width: 760px;
  margin: 14px auto 0;
  display: block;
}
.card {
  background: #fff;
  border: 2px solid #000;
  border-top: 8px solid #000;
  padding: 16px;
  margin-bottom: 18px;
  display: block;
}

.card-top { margin-bottom: 8px; }
.card-tag {
  display: inline-block;
  font-size: 14px;
  font-weight: 800;
  color: #fff;
  background: #000;
  padding: 3px 12px;
}
.card-num { float: right; font-size: 14px; font-weight: 700; color: #000; }

.card-emoji { font-size: 30px; line-height: 1.2; }
.card-prompt { font-size: 21px; font-weight: 800; line-height: 1.5; margin: 6px 0; }
.card-visual {
  font-size: 32px;
  line-height: 1.5;
  letter-spacing: 3px;
  word-break: break-word;
  white-space: pre-line;
  border: 2px solid #000;
  padding: 10px 12px;
  margin: 8px 0;
}
.card-know { font-size: 16px; color: #000; }

.story-body {
  font-size: 18px;
  line-height: 1.8;
  color: #000;
  border-left: 6px solid #000;
  padding: 8px 14px;
  margin: 8px 0;
}
.story-q { font-size: 19px; font-weight: 800; margin: 8px 0 0; }

/* ---------- 选项 ---------- */
.options { margin-top: 10px; }
.opt-btn {
  display: block;
  width: 100%;
  border: 2px solid #000;
  background: #fff;
  color: #000;
  padding: 14px 12px;
  margin: 8px 0;
  font-size: 20px;
  font-weight: 700;
  text-align: center;
  cursor: pointer;
}
.opt-btn:disabled { cursor: default; }
/* 墨水屏无彩色，用“填黑/删除线”强对比区分对错 */
.opt-btn.correct {
  background: #000;
  color: #fff;
  border: 3px solid #000;
}
.opt-btn.correct:before { content: "✓ "; font-weight: 800; }
.opt-btn.wrong {
  background: #fff;
  color: #000;
  border: 3px dashed #000;
  text-decoration: line-through;
}
.opt-btn.wrong:before { content: "✗ "; text-decoration: none; }

/* ---------- 反馈与讲解 ---------- */
.card-actions { margin-top: 10px; }
.mini-btn {
  display: inline-block;
  border: 2px solid #000;
  background: #fff;
  color: #000;
  padding: 10px 16px;
  margin: 6px 6px 0 0;
  font-size: 16px;
  font-weight: 700;
  cursor: pointer;
}
.mini-btn.solid { background: #000; color: #fff; }
.mini-btn.done { background: #000; color: #fff; border: 2px solid #000; }

.feedback {
  font-size: 18px;
  font-weight: 800;
  min-height: 1.2em;
  margin-top: 10px;
}
/* 不用颜色区分，仅用加粗文字；类名保留以兼容脚本 */
.feedback.good { color: #000; }
.feedback.bad { color: #000; }

.explain {
  font-size: 16px;
  color: #000;
  line-height: 1.6;
  border: 2px solid #000;
  padding: 10px 12px;
  margin-top: 8px;
}
.tip {
  font-size: 18px;
  color: #000;
  line-height: 1.7;
  border: 2px solid #000;
  padding: 12px 14px;
  margin-top: 8px;
}

.site-footer {
  max-width: 760px;
  margin: 26px auto 0;
  text-align: center;
  color: #000;
  font-size: 14px;
  border-top: 2px solid #000;
  padding-top: 12px;
}
.hidden { display: none !important; }