/* ===== 溺水知识小助手 — 全局样式（科技清新·淡蓝主题） ===== */

/* --- CSS 自定义属性 --- */
:root {
  --color-primary: #60a5fa;
  --color-primary-hover: #93c5fd;
  --color-primary-glow: rgba(96, 165, 250, 0.25);
  --color-accent: #67e8f9;
  --color-bg-start: #0a1628;
  --color-bg-end: #1a2a4a;
  --color-card-bg: rgba(15, 30, 60, 0.75);
  --color-card-border: rgba(96, 165, 250, 0.2);
  --color-card-hover: rgba(20, 40, 75, 0.85);
  --color-text: #cbd5e1;
  --color-text-dim: #64748b;
  --color-text-bright: #f1f5f9;
  --color-danger: #f87171;
  --color-success: #6ee7b7;
  --color-warning: #fbbf24;
  --radius-card: 20px;
  --radius-btn: 14px;
  --radius-sm: 10px;
  --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --shadow-card: 0 4px 20px rgba(96, 165, 250, 0.12);
  --shadow-card-hover: 0 12px 36px rgba(96, 165, 250, 0.2);
  --shadow-btn: 0 4px 16px rgba(96, 165, 250, 0.2);
  --shadow-btn-hover: 0 6px 24px rgba(96, 165, 250, 0.35);
}

/* --- 基础重置 --- */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "PingFang SC",
               "Microsoft YaHei", "Helvetica Neue", sans-serif;
  background: linear-gradient(160deg, #0a1628, #1a2a4a, #0d1f3c);
  color: #e2e8f0;
  min-height: 100vh;
  line-height: 1.8;
  padding: 0 20px 48px;
  position: relative;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* 选中文字高亮 */
::selection {
  background: rgba(96, 165, 250, 0.3);
  color: #f1f5f9;
}

/* ===== 下雨背景（Canvas 动画） ===== */
#rain-canvas {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: 0;
  pointer-events: none;
  opacity: 0.35;
}

/* 所有内容在 rain canvas 之上 */
header, nav, main, footer, .cover-content {
  position: relative;
  z-index: 1;
}

/* ===== 封面页专用 ===== */
.cover-page {
  padding: 0;
  margin: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
  background: linear-gradient(160deg, #0a1628, #1a2a4a, #0d1f3c);
  overflow: hidden;
}

.cover-content {
  text-align: center;
  z-index: 2;
  padding: 20px;
  max-width: 600px;
  width: 100%;
}

.cover-title {
  font-size: clamp(2rem, 6vw, 3.2rem);
  font-weight: 800;
  background: linear-gradient(135deg, #60a5fa, #67e8f9, #a7f3d0);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  margin-bottom: 8px;
  letter-spacing: 2px;
  text-shadow: 0 0 40px rgba(96, 165, 250, 0.3);
}

.cover-sub {
  font-size: clamp(0.9rem, 2.5vw, 1.1rem);
  color: rgba(148, 163, 184, 0.9);
  margin-bottom: 32px;
}

/* 封面场景（小河 + 救生圈 + 救生人员） */
.cover-scene {
  position: relative;
  width: 100%;
  max-width: 480px;
  height: 200px;
  margin: 0 auto 32px;
  border-radius: var(--radius-card);
  overflow: hidden;
  background: linear-gradient(180deg, rgba(96,165,250,0.08), rgba(103,232,249,0.12));
  border: 1px solid rgba(96,165,250,0.15);
}

/* 小河 */
.cover-river {
  position: absolute;
  bottom: 0;
  left: 0;
  width: 100%;
  height: 80px;
  background: linear-gradient(180deg, rgba(103,232,249,0.3), rgba(96,165,250,0.4));
  border-radius: 50% 50% 0 0 / 100% 100% 0 0;
  animation: riverFlow 3s ease-in-out infinite alternate;
}

@keyframes riverFlow {
  0% { transform: scaleY(1) translateY(0); }
  100% { transform: scaleY(1.05) translateY(4px); }
}

/* 救生圈 */
.cover-ring {
  position: absolute;
  bottom: 50px;
  left: 20%;
  width: 56px;
  height: 56px;
  border: 6px solid #67e8f9;
  border-radius: 50%;
  background: rgba(255,255,255,0.1);
  box-shadow: 0 0 20px rgba(103,232,249,0.3);
  animation: floatRing 2.5s ease-in-out infinite;
}

.cover-ring::after {
  content: '';
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 20px;
  height: 20px;
  border: 3px solid rgba(255,255,255,0.3);
  border-radius: 50%;
}

@keyframes floatRing {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-8px); }
}

/* 标志牌（预防溺水） */
.cover-sign {
  position: absolute;
  bottom: 62px;
  right: 8%;
  font-size: 0.72rem;
  font-weight: 700;
  color: #94a3b8;
  background: linear-gradient(180deg, rgba(30,58,95,0.9), rgba(15,30,60,0.9));
  padding: 6px 10px;
  border-radius: 4px;
  text-align: center;
  line-height: 1.3;
  box-shadow: 0 2px 8px rgba(96,165,250,0.2);
  border: 2px solid #60a5fa;
  animation: floatSign 3.5s ease-in-out infinite 1s;
  letter-spacing: 0.5px;
}

.cover-sign::before {
  content: '';
  position: absolute;
  bottom: -14px;
  left: 50%;
  transform: translateX(-50%);
  width: 4px;
  height: 14px;
  background: #60a5fa;
  border-radius: 0 0 2px 2px;
}

@keyframes floatSign {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-5px); }
}

/* 救生人员（emoji 人 + 救生衣） */
.cover-guard {
  position: absolute;
  bottom: 55px;
  right: 42%;
  font-size: 2.4rem;
  animation: floatGuard 3s ease-in-out infinite 0.5s;
  filter: drop-shadow(0 2px 8px rgba(96,165,250,0.3));
}

@keyframes floatGuard {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-6px); }
}

/* 开始学习按钮 */
.cover-btn {
  display: inline-block;
  padding: 14px 48px;
  border-radius: 50px;
  background: linear-gradient(135deg, #3b82f6, #60a5fa);
  color: #ffffff;
  text-decoration: none;
  font-weight: 700;
  font-size: 1.15rem;
  border: none;
  cursor: pointer;
  transition: var(--transition);
  box-shadow: 0 4px 24px rgba(96, 165, 250, 0.3);
  letter-spacing: 1px;
}

.cover-btn:hover {
  transform: translateY(-3px) scale(1.03);
  box-shadow: 0 8px 32px rgba(96, 165, 250, 0.45);
}

.cover-btn:active {
  transform: translateY(0) scale(0.98);
}

/* ===== 渐变标题 ===== */
.gradient-title {
  font-size: clamp(1.6rem, 4vw, 2.6rem);
  font-weight: 800;
  background: linear-gradient(135deg, #60a5fa, #67e8f9, #a7f3d0);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  text-align: center;
  margin: 32px 0 8px;
  letter-spacing: 1px;
}

.gradient-sub {
  font-size: clamp(0.9rem, 2.5vw, 1.1rem);
  color: #94a3b8;
  text-align: center;
  margin-bottom: 32px;
  font-weight: 400;
  letter-spacing: 0.5px;
}

/* ===== 导航栏 ===== */
.nav-bar {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  justify-content: center;
  padding: 20px 0 12px;
  max-width: 800px;
  margin: 0 auto;
}

.nav-bar a {
  color: #94a3b8;
  text-decoration: none;
  font-size: 0.85rem;
  padding: 7px 18px;
  border-radius: 20px;
  background: rgba(15, 30, 60, 0.5);
  border: 1px solid rgba(96, 165, 250, 0.15);
  transition: var(--transition);
  font-weight: 500;
  letter-spacing: 0.3px;
}

.nav-bar a:hover {
  color: var(--color-text-bright);
  background: rgba(96, 165, 250, 0.15);
  border-color: rgba(96, 165, 250, 0.3);
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(96,165,250,0.15);
}

.nav-bar a.active {
  color: #93c5fd;
  border-color: #60a5fa;
  background: rgba(96, 165, 250, 0.15);
  box-shadow: 0 0 20px rgba(96,165,250,0.1);
}

/* ===== 卡片网格 ===== */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 20px;
  max-width: 960px;
  margin: 0 auto;
  padding: 8px 0;
}

.card {
  background: var(--color-card-bg);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: 1px solid var(--color-card-border);
  border-radius: var(--radius-card);
  padding: 32px 26px;
  text-decoration: none;
  color: var(--color-text);
  transition: var(--transition);
  cursor: pointer;
  display: block;
  box-shadow: var(--shadow-card);
  position: relative;
  overflow: hidden;
}

/* 卡片顶部光晕 */
.card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 2px;
  background: linear-gradient(90deg, transparent, #60a5fa, transparent);
  opacity: 0.4;
  transition: var(--transition);
}

.card:hover::before {
  opacity: 1;
  height: 3px;
}

.card:hover {
  background: var(--color-card-hover);
  border-color: rgba(96, 165, 250, 0.3);
  transform: translateY(-6px);
  box-shadow: var(--shadow-card-hover);
}

.card:active {
  transform: translateY(-2px);
}

.card-icon {
  font-size: 2.6rem;
  margin-bottom: 14px;
  display: block;
  transition: var(--transition);
}

.card:hover .card-icon {
  transform: scale(1.1);
}

.card h3 {
  font-size: 1.15rem;
  font-weight: 700;
  margin-bottom: 10px;
  color: var(--color-text-bright);
  letter-spacing: 0.5px;
}

.card p {
  font-size: 0.88rem;
  color: var(--color-text-dim);
  line-height: 1.6;
}

/* ===== 内容卡片 ===== */
.content-card {
  background: var(--color-card-bg);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: 1px solid var(--color-card-border);
  border-radius: var(--radius-card);
  padding: 32px 28px;
  max-width: 720px;
  margin: 20px auto;
  box-shadow: var(--shadow-card);
}

.content-card h2 {
  font-size: 1.35rem;
  color: #93c5fd;
  margin-bottom: 16px;
  display: flex;
  align-items: center;
  gap: 8px;
  letter-spacing: 0.5px;
}

.content-card p,
.content-card li {
  font-size: 0.93rem;
  color: var(--color-text);
  line-height: 1.8;
  margin-bottom: 8px;
}

.content-card ul,
.content-card ol {
  padding-left: 24px;
  margin: 8px 0 16px;
}

.content-card li {
  margin-bottom: 8px;
  padding-left: 4px;
}

.content-card li::marker {
  color: #60a5fa;
}

/* ===== 提示框 ===== */
.tip {
  border-left: 4px solid #60a5fa;
  background: rgba(96, 165, 250, 0.08);
  padding: 14px 18px;
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  margin: 16px 0;
  font-size: 0.88rem;
  line-height: 1.6;
}

.tip.warning {
  border-left-color: var(--color-warning);
  background: rgba(252, 211, 77, 0.08);
}

.tip.danger {
  border-left-color: var(--color-danger);
  background: rgba(96,165,250,0.08);
}

.tip.success {
  border-left-color: var(--color-success);
  background: rgba(110, 231, 183, 0.08);
}

/* ===== 按钮 ===== */
.btn {
  display: inline-block;
  padding: 11px 30px;
  border-radius: var(--radius-btn);
  background: linear-gradient(135deg, #3b82f6, #60a5fa);
  color: #ffffff;
  text-decoration: none;
  font-weight: 600;
  font-size: 0.93rem;
  border: none;
  cursor: pointer;
  transition: var(--transition);
  box-shadow: var(--shadow-btn);
  letter-spacing: 0.5px;
}

.btn:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-btn-hover);
}

.btn:active {
  transform: translateY(0) scale(0.98);
}

.btn-outline {
  background: transparent;
  border: 1.5px solid #60a5fa;
  color: #60a5fa;
  box-shadow: none;
}

.btn-outline:hover {
  background: rgba(96, 165, 250, 0.1);
  box-shadow: none;
}

/* ===== 统计图 ===== */
.chart-container {
  max-width: 720px;
  margin: 20px auto;
  background: var(--color-card-bg);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: 1px solid var(--color-card-border);
  border-radius: var(--radius-card);
  padding: 32px 28px;
  box-shadow: var(--shadow-card);
}

.chart-container h2 {
  font-size: 1.2rem;
  color: #93c5fd;
  margin-bottom: 24px;
  text-align: center;
  letter-spacing: 0.5px;
}

.chart-bars {
  display: flex;
  align-items: flex-end;
  gap: 12px;
  height: 220px;
  padding: 0 8px;
  border-bottom: 2px solid rgba(96,165,250,0.15);
}

.chart-bar-wrap {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  height: 100%;
  justify-content: flex-end;
}

.chart-bar {
  width: 100%;
  max-width: 48px;
  border-radius: 6px 6px 0 0;
  background: linear-gradient(180deg, #3b82f6, #60a5fa);
  transition: height 0.8s cubic-bezier(0.4, 0, 0.2, 1);
  min-height: 4px;
  position: relative;
  cursor: pointer;
  box-shadow: 0 -2px 12px rgba(96,165,250,0.2);
}

.chart-bar:hover {
  opacity: 0.85;
  transform: scaleX(1.08);
}

.chart-bar-label {
  font-size: 0.75rem;
  color: var(--color-text-dim);
  margin-top: 8px;
  text-align: center;
  font-weight: 500;
}

.chart-bar-value {
  font-size: 0.7rem;
  color: var(--color-text-bright);
  margin-bottom: 4px;
  font-weight: 700;
}

/* ===== 游戏页 ===== */
.game-container {
  max-width: 640px;
  margin: 20px auto;
  text-align: center;
}

.game-question {
  background: var(--color-card-bg);
  backdrop-filter: blur(16px);
  border: 1px solid var(--color-card-border);
  border-radius: var(--radius-card);
  padding: 32px 28px;
  margin-bottom: 20px;
  box-shadow: var(--shadow-card);
}

.game-question h2 {
  font-size: 1.2rem;
  color: var(--color-text-bright);
  margin-bottom: 20px;
  line-height: 1.6;
}

.game-options {
  display: flex;
  flex-direction: column;
  gap: 12px;
  max-width: 400px;
  margin: 0 auto;
}

.game-option {
  padding: 14px 20px;
  border-radius: var(--radius-btn);
  background: rgba(15, 30, 60, 0.5);
  border: 1px solid rgba(96, 165, 250, 0.15);
  color: var(--color-text);
  font-size: 0.95rem;
  cursor: pointer;
  transition: var(--transition);
  text-align: left;
  line-height: 1.5;
}

.game-option:hover {
  background: rgba(96, 165, 250, 0.1);
  border-color: #60a5fa;
  transform: translateX(4px);
}

.game-option.correct {
  background: rgba(110,231,183,0.15);
  border-color: var(--color-success);
  box-shadow: 0 0 16px rgba(96,165,250,0.15);
}

.game-option.wrong {
  background: rgba(96,165,250,0.15);
  border-color: var(--color-danger);
}

.game-option:disabled {
  cursor: default;
  opacity: 0.7;
}

.game-score {
  font-size: 1rem;
  color: var(--color-text-dim);
  margin-top: 20px;
  font-weight: 500;
}

.game-result {
  font-size: 1.1rem;
  margin-top: 16px;
  min-height: 28px;
  line-height: 1.6;
}

/* ===== 徽章页 ===== */
.badge-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 20px;
  max-width: 800px;
  margin: 0 auto;
  padding: 8px 0;
}

.badge-card {
  background: var(--color-card-bg);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: 1px solid var(--color-card-border);
  border-radius: var(--radius-card);
  padding: 32px 20px;
  text-align: center;
  transition: var(--transition);
  box-shadow: var(--shadow-card);
}

.badge-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-card-hover);
}

.badge-card.badge-locked {
  opacity: 0.45;
  filter: grayscale(0.6);
}

.badge-icon {
  font-size: 3rem;
  margin-bottom: 14px;
  display: block;
}

.badge-name {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--color-text-bright);
  margin-bottom: 8px;
  letter-spacing: 0.5px;
}

.badge-desc {
  font-size: 0.82rem;
  color: var(--color-text-dim);
  line-height: 1.5;
}

/* ===== 徽章弹窗 ===== */
.badge-popup-overlay {
  position: fixed;
  top: 0; left: 0; width: 100%; height: 100%;
  background: rgba(0,0,0,0.6);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 999;
  animation: fadeIn 0.3s ease;
}

.badge-popup {
  background: linear-gradient(160deg, #0a1628, #1a2a4a);
  border: 2px solid rgba(96,165,250,0.3);
  border-radius: 20px;
  padding: 32px 28px;
  max-width: 340px;
  width: 90%;
  text-align: center;
  animation: popUp 0.4s cubic-bezier(0.34, 1.56, 0.64, 1);
}

.badge-popup-icon {
  font-size: 3.5rem;
  margin-bottom: 8px;
}

.badge-popup-title {
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--color-text-bright);
  margin-bottom: 16px;
}

.badge-popup-item {
  font-size: 1.5rem;
  font-weight: 700;
  color: #93c5fd;
  margin: 8px 0 4px;
}

.badge-popup-desc {
  font-size: 0.85rem;
  color: var(--color-text-dim);
  margin-bottom: 12px;
}

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

@keyframes popUp {
  from { transform: scale(0.7); opacity: 0; }
  to { transform: scale(1); opacity: 1; }
}

/* ===== 页脚 ===== */
footer {
  text-align: center;
  color: #64748b;
  font-size: 0.78rem;
  padding: 40px 0 16px;
  border-top: 1px solid rgba(96, 165, 250, 0.1);
  margin-top: 48px;
  letter-spacing: 0.3px;
}

/* ===== 响应式 ===== */
@media (max-width: 600px) {
  body {
    padding: 0 12px 36px;
  }
  .card-grid {
    grid-template-columns: 1fr;
    gap: 16px;
  }
  .content-card,
  .chart-container {
    padding: 24px 18px;
  }
  .nav-bar {
    gap: 6px;
  }
  .nav-bar a {
    font-size: 0.78rem;
    padding: 5px 10px;
  }
  .chart-bars {
    height: 160px;
    gap: 6px;
  }
  .cover-scene {
    height: 150px;
  }
  .badge-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: 12px;
  }
  .game-question {
    padding: 24px 18px;
  }
  .game-option {
    padding: 12px 16px;
    font-size: 0.9rem;
  }
  .card {
    padding: 24px 20px;
  }
}