/* ============================================
   Global Styles — Reset, Layout, Components
   Physics Animation Teaching Platform
   ============================================ */

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

body {
  font-family: var(--font-sans);
  background: var(--color-bg);
  color: var(--color-text-primary);
  line-height: 1.6;
  overflow-x: hidden;
}

/* ----- Navigation Bar ----- */
.top-nav {
  height: var(--nav-height);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 var(--spacing-lg);
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  -webkit-backdrop-filter: blur(20px);
  backdrop-filter: blur(20px);
  position: sticky;
  top: 0;
  z-index: 100;
}

.nav-title {
  font-size: var(--font-size-base);
  font-weight: 600;
  text-align: center;
  flex: 0 1 auto;
  min-width: 0;
}

/* Site brand (injected by layout.js) */
.nav-brand {
  display: inline-flex;
  align-items: center;
  font-size: var(--font-size-base);
  font-weight: 700;
  color: var(--color-text-primary);
  letter-spacing: 0.02em;
  white-space: nowrap;
}

.nav-brand-en {
  margin-left: 6px;
  font-size: var(--font-size-s);
  font-weight: 600;
  color: var(--color-accent);
  letter-spacing: 0.08em;
}

/* 首页左侧品牌区：与右侧 .nav-actions 等宽，保证中间标题严格居中 */
.nav-home-brand {
  flex: 1 1 0;
  min-width: 0;
}

/* 导航品牌 Logo（SVG 矢量） */
.nav-logo {
  height: 22px;
  width: auto;
  margin-right: 7px;
  flex: none;
  vertical-align: middle;
}

.nav-feedback,
.nav-download {
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  text-decoration: none;
  cursor: pointer;
  white-space: nowrap;
}

/* 详情页左侧占位区：只负责等宽，保证标题居中，不参与点击 */
.nav-left {
  display: flex;
  align-items: center;
  flex: 1 1 0;
  min-width: 0;
}

.nav-back {
  display: inline-flex;
  align-items: center;
  gap: 0;
  text-decoration: none;
  cursor: pointer;
}

.nav-back:hover,
.nav-feedback:hover,
.nav-download:hover {
  color: var(--color-accent);
}

/* 导航右侧操作区（下载 + 反馈）：flex:1 与左侧 .nav-back 等宽，保证标题严格居中 */
.nav-actions {
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-md);
  flex: 1 1 0;
  justify-content: flex-end;
  min-width: 0;
}

.nav-download {
  padding: 3px 10px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  white-space: nowrap;
  transition: color var(--transition-fast), border-color var(--transition-fast);
}

.nav-download:hover {
  border-color: var(--color-accent);
}

.nav-download.nav-disabled,
.nav-screenshot.nav-disabled {
  opacity: 0.45;
  cursor: not-allowed;
  border-color: var(--color-border);
  color: var(--color-text-secondary);
}

/* 导航登录入口 */
.nav-auth {
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  cursor: pointer;
  padding: 3px 12px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  white-space: nowrap;
  transition: color var(--transition-fast), border-color var(--transition-fast);
}

.nav-auth:hover {
  color: var(--color-accent);
  border-color: var(--color-accent);
}

/* 导航“关于我们”链接 */
.nav-about {
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  text-decoration: none;
  cursor: pointer;
  white-space: nowrap;
  transition: color var(--transition-fast);
}

.nav-about:hover {
  color: var(--color-accent);
}

/* 详情页状态徽标 */
.nav-status {
  white-space: nowrap;
}

.status-badge {
  font-size: var(--font-size-xs);
  font-weight: 600;
  padding: 2px 10px;
  border-radius: 10px;
  line-height: 1.6;
}

.status-online { color: #10B981; background: rgba(16, 185, 129, 0.12); }
.status-offline { color: #F87171; background: rgba(248, 113, 113, 0.12); }
.status-coming_soon { color: #38BDF8; background: rgba(56, 189, 248, 0.12); }
.status-updating { color: #F59E0B; background: rgba(245, 158, 11, 0.12); }
.status-draft { color: #94A3B8; background: rgba(148, 163, 184, 0.14); }
.status-deleted { color: #EF4444; background: rgba(239, 68, 68, 0.12); }

body.page-status-offline .animation-layout,
body.page-status-draft .animation-layout,
body.page-status-deleted .animation-layout {
  opacity: 0.45;
  pointer-events: none;
  user-select: none;
}

.nav-priority {
  white-space: nowrap;
  font-size: var(--font-size-xs);
  font-weight: 600;
  padding: 2px 10px;
  border-radius: 10px;
  line-height: 1.6;
}
.nav-priority.p1 { color: #EF4444; background: rgba(239, 68, 68, 0.12); }
.nav-priority.p2 { color: #F59E0B; background: rgba(245, 158, 11, 0.12); }
.nav-priority.p3 { color: #10B981; background: rgba(16, 185, 129, 0.12); }

/* ----- Three-Column Layout ----- */
.animation-layout {
  display: grid;
  grid-template-columns: var(--panel-width) 1fr var(--info-width);
  gap: var(--spacing-md);
  padding: var(--spacing-md);
  height: calc(100vh - var(--nav-height));
}

/* ----- Frosted Glass Panel ----- */
.glass-panel {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  -webkit-backdrop-filter: blur(20px);
  backdrop-filter: blur(20px);
  padding: var(--spacing-md);
}

/* ----- Canvas Container ----- */
.canvas-container {
  background: var(--color-canvas-bg);
  border-radius: var(--radius-md);
  overflow: hidden;
  position: relative;
}

canvas {
  display: block;
  width: 100%;
  height: 100%;
}

/* ----- Playback Bar (通用播放控制条) ----- */
.playback-bar {
  position: absolute;
  left: 50%;
  bottom: var(--spacing-md);
  transform: translateX(-50%);
  display: flex;
  align-items: center;
  gap: var(--spacing-xs);
  padding: 6px 10px;
  background: rgba(16, 24, 43, 0.85);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  box-shadow: 0 4px 18px rgba(0, 0, 0, 0.35);
  z-index: 5;
  user-select: none;
}

.playback-bar .pb-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 34px;
  height: 34px;
  border: none;
  border-radius: var(--radius-sm);
  background: transparent;
  color: var(--color-text-primary);
  font-size: 1rem;
  cursor: pointer;
  transition: background var(--transition-fast), color var(--transition-fast);
}

.playback-bar .pb-btn:hover {
  background: var(--color-surface);
  color: var(--color-accent);
}

.playback-bar .pb-btn-main {
  width: 40px;
  height: 40px;
  font-size: 1.15rem;
  background: var(--color-accent);
  color: #0F172A;
}

.playback-bar .pb-btn-main:hover {
  background: var(--color-accent);
  filter: brightness(1.12);
  color: #0F172A;
}

.playback-bar .pb-speeds {
  display: flex;
  align-items: center;
  gap: 2px;
  margin-left: var(--spacing-xs);
  padding-left: var(--spacing-sm);
  border-left: 1px solid var(--color-border);
}

.playback-bar .pb-speed {
  border: none;
  border-radius: var(--radius-sm);
  background: transparent;
  color: var(--color-text-secondary);
  font-family: var(--font-mono);
  font-size: var(--font-size-xs);
  padding: 4px 7px;
  cursor: pointer;
  transition: color var(--transition-fast), background var(--transition-fast);
}

.playback-bar .pb-speed:hover {
  color: var(--color-text-primary);
}

.playback-bar .pb-speed.active {
  background: var(--color-surface);
  color: var(--color-accent);
  font-weight: 600;
}

/* 窄屏下播放条限宽并允许换行 */
@media (max-width: 600px) {
  .playback-bar {
    max-width: calc(100% - var(--spacing-md) * 2);
    flex-wrap: nowrap;
    justify-content: center;
    padding: 3px 5px;
    gap: 2px;
  }
  .playback-bar .pb-btn {
    width: 17px;
    height: 17px;
    font-size: 0.5rem;
  }
  .playback-bar .pb-btn-main {
    width: 20px;
    height: 20px;
    font-size: 0.5625rem;
  }
  .playback-bar .pb-speeds {
    gap: 1px;
    margin-left: 2px;
    padding-left: 4px;
  }
  .playback-bar .pb-speed {
    font-size: 0.375rem;
    padding: 2px 4px;
  }
}

/* ----- Buttons ----- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-xs);
  padding: var(--spacing-sm) var(--spacing-md);
  border-radius: var(--radius-sm);
  border: 1px solid var(--color-border);
  background: var(--color-surface);
  color: var(--color-text-primary);
  cursor: pointer;
  font-size: var(--font-size-sm);
  font-family: var(--font-sans);
  transition: transform var(--transition-fast), box-shadow var(--transition-fast);
}

.btn:hover {
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
}

.btn:active {
  transform: scale(0.96);
  filter: brightness(1.2);
}

.btn-primary {
  background: var(--color-accent);
  color: #0F172A;
  border-color: var(--color-accent);
  font-weight: 600;
}

/* ----- Button Variants ----- */
.btn-secondary {
  background: var(--color-surface);
  color: var(--color-text-primary);
  border-color: var(--color-border);
}
.btn-secondary:hover {
  background: rgba(255, 255, 255, 0.1);
}

.btn-danger {
  background: var(--color-physics-red);
  color: #fff;
  border-color: var(--color-physics-red);
}

/* ----- Slider ----- */
.slider-group {
  margin-bottom: var(--spacing-md);
}

.slider-group label {
  display: block;
  font-size: var(--font-size-sm);
  margin-bottom: var(--spacing-xs);
  color: var(--color-text-secondary);
}

.slider-group input[type="range"] {
  width: 100%;
}

/* ----- Custom Range Slider (WebKit + Firefox) ----- */
input[type="range"] {
  -webkit-appearance: none;
  appearance: none;
  width: 100%;
  height: 18px;
  background: transparent;
  cursor: pointer;
  --range-fill: 50%;
}

/* Track — WebKit */
input[type="range"]::-webkit-slider-runnable-track {
  height: 6px;
  border-radius: var(--radius-sm);
  background: linear-gradient(
    to right,
    var(--color-accent) 0%,
    var(--color-accent) var(--range-fill),
    rgba(255, 255, 255, 0.12) var(--range-fill),
    rgba(255, 255, 255, 0.12) 100%
  );
}

/* Thumb — WebKit */
input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 16px;
  height: 16px;
  margin-top: -5px; /* (6px track - 16px thumb) / 2 */
  border-radius: 50%;
  background: var(--color-accent);
  border: 2px solid #fff;
  box-shadow: 0 1px 4px rgba(0, 0, 0, 0.4);
  transition: transform var(--transition-fast), box-shadow var(--transition-fast);
}
input[type="range"]::-webkit-slider-thumb:hover {
  transform: scale(1.2);
  box-shadow: 0 0 0 5px rgba(245, 158, 11, 0.22);
}
input[type="range"]:active::-webkit-slider-thumb {
  transform: scale(1.1);
}

/* Track — Firefox */
input[type="range"]::-moz-range-track {
  height: 6px;
  border-radius: var(--radius-sm);
  background: rgba(255, 255, 255, 0.12);
}
input[type="range"]::-moz-range-progress {
  height: 6px;
  border-radius: var(--radius-sm);
  background: var(--color-accent);
}

/* Thumb — Firefox */
input[type="range"]::-moz-range-thumb {
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: var(--color-accent);
  border: 2px solid #fff;
  box-shadow: 0 1px 4px rgba(0, 0, 0, 0.4);
  transition: transform var(--transition-fast), box-shadow var(--transition-fast);
}
input[type="range"]::-moz-range-thumb:hover {
  transform: scale(1.2);
  box-shadow: 0 0 0 5px rgba(245, 158, 11, 0.22);
}

/* Focus */
input[type="range"]:focus-visible {
  outline: none;
  box-shadow: 0 0 0 3px rgba(245, 158, 11, 0.3);
  border-radius: var(--radius-sm);
}

.slider-value {
  font-family: var(--font-mono);
  font-size: var(--font-size-sm);
  color: var(--color-accent);
}

/* ----- Checkbox ----- */
.checkbox-group {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  margin-bottom: var(--spacing-sm);
  cursor: pointer;
}

.checkbox-group input[type="checkbox"] {
  accent-color: var(--color-accent);
}

/* ----- Radio Group ----- */
.radio-group {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-sm);
  margin-bottom: var(--spacing-md);
}

.radio-group-label {
  display: flex;
  align-items: center;
  gap: var(--spacing-xs);
  cursor: pointer;
  font-size: var(--font-size-sm);
}

.radio-group-label input[type="radio"] {
  accent-color: var(--color-accent);
}

/* ----- Teaching Footer ----- */
.teaching-footer {
  background: var(--color-surface);
  border-top: 1px solid var(--color-border);
  padding: var(--spacing-md) var(--spacing-lg);
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  line-height: 1.8;
}

/* ----- Select Dropdown ----- */
.select-group {
  margin-bottom: var(--spacing-md);
}

.select-group select {
  width: 100%;
  padding: var(--spacing-sm);
  border-radius: var(--radius-sm);
  border: 1px solid var(--color-border);
  background: #172139;
  color: var(--color-text-primary);
  font-family: var(--font-sans);
  font-size: var(--font-size-sm);
  cursor: pointer;
}

/* 下拉展开的选项列表：深色背景 + 浅色字（避免白底看不清） */
.select-group select option {
  background: #172139;
  color: #E2E8F0;
}

.select-group select:focus {
  outline: none;
  border-color: var(--color-accent);
}

.select-group .control-label {
  margin-bottom: var(--spacing-xs);
}

/* ----- Control Utilities ----- */
.control-label {
  display: block;
  font-size: var(--font-size-sm);
  margin-bottom: var(--spacing-xs);
  color: var(--color-text-secondary);
}

.control-separator {
  border: none;
  border-top: 1px solid var(--color-border);
  margin: var(--spacing-md) 0;
}

/* ----- Formula (本地轻量排版，零外链) ----- */
/* 核心公式：放大、突出、居中（需求 V4.3 第3条） */
.formula-core {
  margin: var(--spacing-sm) 0;
  padding: var(--spacing-sm) var(--spacing-md);
  text-align: center;
  color: var(--color-accent);
  background: rgba(245, 158, 11, 0.08);
  border-radius: var(--radius-sm);
  overflow-x: auto;
}
.formula-core .f-math { font-size: 1.35em; }

/* 普通块级公式 */
.formula-block {
  margin: var(--spacing-xs) 0;
  text-align: center;
  overflow-x: auto;
  color: var(--color-text-primary);
}
.formula-block .f-math { font-size: 1.05em; }

/* 行内公式 */
.formula-inline { color: var(--color-text-primary); }

/* 解析失败降级为纯文本时的等宽字体呈现 */
.formula-core:not(:has(.f-math)),
.formula-block:not(:has(.f-math)) {
  font-family: var(--font-mono);
}

/* ----- Responsive（移动端适配，需求 V4.3 第4条） ----- */

/* 平板及以下：画布置顶占满整行，控件/资讯双栏并排 */
@media (max-width: 1024px) {
  .animation-layout {
    grid-template-columns: 1fr 1fr;
    grid-auto-flow: dense;
    height: auto;
    min-height: calc(100vh - var(--nav-height));
  }
  .canvas-container {
    order: -1;
    grid-column: 1 / -1;
    min-height: 50vh;
  }
}

/* 手机：三栏堆叠，画布优先并保证可见高度，页面自然滚动 */
@media (max-width: 768px) {
  :root {
    --panel-width: 100%;
    --info-width: 100%;
    --nav-height: 52px;
  }

  .animation-layout {
    grid-template-columns: 1fr;
    grid-template-rows: auto;
    height: auto;                 /* 取消固定高度，避免画布被挤出可视区 */
    min-height: calc(100vh - var(--nav-height));
    gap: var(--spacing-sm);
    padding: var(--spacing-sm);
  }

  /* 画布置顶 + 最小可见高度 */
  .canvas-container {
    order: -1;
    grid-column: auto;
    min-height: 56vh;
    width: 100%;
  }

  #controls-panel { order: 2; }
  #info-panel { order: 3; }

  .glass-panel { width: 100%; }

  /* 导航栏紧凑化，标题超出省略 */
  .top-nav {
    display: grid;
    grid-template-columns: auto 1fr auto;
    align-items: center;
    padding: 0 var(--spacing-md);
    gap: var(--spacing-sm);
  }
  .nav-left,
  .nav-home-brand {
    justify-self: start;
    min-width: 0;
  }
  .nav-actions {
    justify-self: end;
    min-width: 0;
  }
  .nav-title {
    justify-self: stretch;
    font-size: var(--font-size-sm);
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
    min-width: 0;
  }
  /* 手机导航：禁止任何文字折行；左侧只保留 Logo，右侧次要操作图标化 */
  .nav-left,
  .nav-brand,
  .nav-back,
  .nav-actions,
  .nav-auth,
  .nav-about,
  .nav-download,
  .nav-feedback {
    white-space: nowrap;
  }
  .nav-brand-text,
  .nav-brand-en {
    display: none;
  }
  .nav-logo {
    height: 20px;
    margin-right: 0;
  }
  .nav-actions {
    gap: 6px;
  }
  .nav-about {
    display: none;
  }
  .nav-auth {
    max-width: 96px;
    overflow: hidden;
    text-overflow: ellipsis;
    padding: 3px 8px;
    font-size: 13px;
  }
  .nav-download,
  .nav-feedback {
    border: 0;
    padding: 4px 2px;
    font-size: 17px;
    line-height: 1;
  }
  .nav-btn-label {
    display: none;
  }
  .nav-status {
    display: none;
  }
  .teaching-footer { font-size: var(--font-size-xs); }
}

/* ----- Site Footer（首页 / 关于页通用）----- */
.home-footer {
  text-align: center;
  padding: var(--spacing-lg);
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  border-top: 1px solid var(--color-border);
  background: var(--color-surface);
}
.btn.selected {
  background: var(--color-accent) !important;
  color: #0F172A !important;
  border-color: var(--color-accent) !important;
  font-weight: 700;
  box-shadow: 0 0 10px rgba(245, 158, 11, 0.4);
}

.btn.selected:hover {
  filter: brightness(1.1);
}

/* ----- Button Variants ----- */