/* Simple and Beautiful Cat Avatar Styles */
.cute-cat-container {
  position: fixed;
  top: 20px;
  right: 20px;
  z-index: 10000;
}

.cute-cat {
  width: 70px;
  height: 70px;
  cursor: pointer;
  transition: transform 0.3s ease;
  position: relative;
}

.cute-cat:hover {
  transform: scale(1.1) rotate(2deg);
}

.cat-head {
  position: relative;
  width: 60px;
  height: 60px;
  background: linear-gradient(135deg, #FFB366 0%, #FF8E53 100%);
  border-radius: 50%;
  margin: 0 auto;
  box-shadow: 0 4px 20px rgba(255, 107, 53, 0.3);
  z-index: 2;
}

/* Simple cat ears */
.cat-ear {
  position: absolute;
  width: 16px;
  height: 20px;
  background: linear-gradient(135deg, #FFB366 0%, #FF8E53 100%);
  border-radius: 50% 50% 50% 0;
  top: -8px;
  z-index: 1;
}

.cat-ear-left {
  left: 12px;
  transform: rotate(-30deg);
}

.cat-ear-right {
  right: 12px;
  transform: rotate(30deg);
}

.ear-inner {
  position: absolute;
  width: 8px;
  height: 12px;
  background: #FFE5D9;
  border-radius: 50% 50% 50% 0;
  top: 3px;
  left: 4px;
}

/* Simple cat face */
.cat-face {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  z-index: 3;
}

/* Simple eyes */

.cat-eye {
  position: absolute;
  width: 14px;
  height: 14px;
  top: -6px;
}

.eye-left {
  left: -16px;
}

.eye-right {
  right: -16px;
}

.eyeball {
  width: 14px;
  height: 14px;
  background: white;
  border-radius: 50%;
  position: relative;
  border: 1px solid #E0E0E0;


}

.pupil {
  position: absolute;
  width: 6px;
  height: 6px;
  background: #2C3E50;
  border-radius: 50%;
  top: 4px;
  left: 4px;
  transition: transform 0.3s ease;
}

.eye-shine {
  position: absolute;
  width: 3px;
  height: 3px;
  background: white;
  border-radius: 50%;
  top: 2px;
  left: 2px;
  z-index: 5;
}

/* Simple nose */
.cat-nose {
  position: absolute;
  width: 6px;
  height: 5px;
  background: #FF69B4;
  border-radius: 50% 50% 50% 50% / 60% 60% 40% 40%;
  top: 2px;
  left: -3px;
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.1);
}

/* Simple mouth */
.cat-mouth {
  position: absolute;
  top: 8px;
  left: -8px;
}

.mouth-line {
  position: absolute;
  width: 8px;
  height: 2px;
  border: 1.5px solid #2C3E50;
  border-top: none;
  border-radius: 0 0 8px 8px;
}

.mouth-left {
  left: 0.1px;
  transform: rotate(-15deg);
}

.mouth-right {
  left: 8px;
  transform: rotate(15deg);
}

/* Simple whiskers */
.cat-whiskers {
  position: absolute;
  top: 6px;
  left: -25px;
  width: 50px;
  height: 15px;
}

.whisker {
  position: absolute;
  height: 1px;
  background: #2C3E50;
  border-radius: 1px;
}

.whisker-left-1 {
  left: 0;
  top: 3px;
  width: 12px;
  transform: rotate(-10deg);
}

.whisker-left-2 {
  left: 2px;
  top: 7px;
  width: 10px;
  transform: rotate(-5deg);
}

.whisker-right-1 {
  right: 0;
  top: 3px;
  width: 12px;
  transform: rotate(10deg);
}

.whisker-right-2 {
  right: 2px;
  top: 7px;
  width: 10px;
  transform: rotate(5deg);
}

/* Simple cheeks */
.cat-cheeks {
  position: absolute;
  top: 8px;
  left: -20px;
  width: 40px;
}

.cheek {
  position: absolute;
  width: 8px;
  height: 6px;
  background: rgba(255, 182, 193, 0.6);
  border-radius: 50%;
}

.cheek-left {
  left: 0;
}

.cheek-right {
  right: 0;
}

/* Simple breathing animation */
.cute-cat {
  animation: simpleBreathe 3s ease-in-out infinite;
}

@keyframes simpleBreathe {
  0%, 100% { transform: scale(1); }
  50% { transform: scale(1.02); }
}

/* Simple hover effects */
.cute-cat:hover .pupil {
  transform: scale(1.1);
}

.cute-cat:hover .cheek {
  background: rgba(255, 182, 193, 0.8);
}

/* Bounce animation for clicks */
@keyframes catBounce {
  0%, 100% { transform: translateY(0) scale(1); }
  25% { transform: translateY(-5px) scale(1.05); }
  50% { transform: translateY(-3px) scale(1.08); }
  75% { transform: translateY(-4px) scale(1.05); }
}

@media (max-width: 768px) {
  .cute-cat-container {
    top: 15px;
    right: 15px;
  }
  
  .cute-cat {
    width: 60px;
    height: 60px;
  }
  
  .cat-head {
    width: 50px;
    height: 50px;
  }
}

/* Decorative stars - SVG style */
.cat-stars {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
  z-index: 1;
}

.star {
  position: absolute;
  width: 8px;
  height: 8px;
  opacity: 0.8;
}

.star::before,
.star::after {
  content: '';
  position: absolute;
  width: 8px;
  height: 2px;
  background: currentColor;
  border-radius: 1px;
  top: 3px;
  left: 0;
}

.star::after {
  transform: rotate(90deg);
}

.star-1 {
  color: #F39C12;
  top: 15px;
  left: 5px;
  animation: starTwinkle 3s ease-in-out infinite;
}

.star-2 {
  color: #E74C3C;
  top: 25px;
  right: 10px;
  animation: starTwinkle 3s ease-in-out infinite 0.5s;
}

.star-3 {
  color: #3498DB;
  bottom: 30px;
  left: 8px;
  animation: starTwinkle 3s ease-in-out infinite 1s;
}

.star-4 {
  color: #2ECC71;
  bottom: 20px;
  right: 5px;
  animation: starTwinkle 3s ease-in-out infinite 1.5s;
}

@keyframes starTwinkle {
  0%, 100% { opacity: 0.8; transform: scale(1); }
  50% { opacity: 1; transform: scale(1.2); }
}

/* Breathing animation - enhanced */
.cute-cat {
  animation: catBreathe 4s ease-in-out infinite;
}

@keyframes catBreathe {
  0%, 100% { transform: scale(1); }
  50% { transform: scale(1.03); }
}

/* Ear twitching animation */
.cat-ear {
  animation: earTwitch 8s ease-in-out infinite;
}

.cat-ear-left {
  animation-delay: 1s;
}

.cat-ear-right {
  animation-delay: 3s;
}

@keyframes earTwitch {
  0%, 95%, 100% { transform: rotate(var(--ear-rotation, 0deg)); }
  2%, 4% { transform: rotate(var(--ear-rotation, 0deg)) scale(1.1); }
}

.cat-ear-left {
  --ear-rotation: -25deg;
}

.cat-ear-right {
  --ear-rotation: 25deg;
}

/* Cat body - SVG style */
.cat-body {
  position: relative;
  width: 70px;
  height: 35px;
  margin: 0 auto;
}

.cat-chest {
  width: 60px;
  height: 25px;
  background: linear-gradient(135deg, #FFEECC 0%, #FFE5B4 100%);
  border-radius: 50% 50% 40% 40%;
  position: relative;
  left: 5px;
  border: 1px solid rgba(255, 179, 102, 0.3);
  top: 5px;
}

/* Collar - SVG style */
.cat-collar {
  position: absolute;
  width: 55px;
  height: 8px;
  background: #E74C3C;
  border-radius: 4px;
  top: 8px;
  left: 7.5px;
  border: 1px solid #C0392B;
}

.collar-inner {
  position: absolute;
  width: 50px;
  height: 6px;
  background: #C0392B;
  border-radius: 3px;
  top: 1px;
  left: 2.5px;
}

.collar-tag {
  position: absolute;
  width: 14px;
  height: 10px;
  background: #F39C12;
  border-radius: 50%;
  top: -1px;
  left: 20.5px;
  font-size: 7px;
  color: white;
  text-align: center;
  line-height: 10px;
  font-weight: bold;
  border: 1px solid #E67E22;
  z-index: 5;
}

.collar-tag::before {
  content: '';
  position: absolute;
  width: 10px;
  height: 8px;
  background: #E67E22;
  border-radius: 50%;
  top: 1px;
  left: 2px;
  z-index: -1;
}

/* Bow tie - SVG style */
.cat-bowtie {
  position: absolute;
  top: 20px;
  left: 50%;
  transform: translateX(-50%);
  z-index: 4;
}

.bowtie-left {
  position: absolute;
  width: 12px;
  height: 10px;
  background: #8E44AD;
  border-radius: 2px 0 2px 2px;
  left: -8px;
  top: 0;
  transform: skew(-10deg);
}

.bowtie-right {
  position: absolute;
  width: 12px;
  height: 10px;
  background: #8E44AD;
  border-radius: 0 2px 2px 2px;
  right: -8px;
  top: 0;
  transform: skew(10deg);
}

.bowtie-center {
  position: absolute;
  width: 8px;
  height: 10px;
  background: #9B59B6;
  border-radius: 2px;
  left: -4px;
  top: 0;
  border: 1px solid #8E44AD;
}

.bowtie-knot {
  position: absolute;
  width: 6px;
  height: 8px;
  background: #8E44AD;
  border-radius: 1px;
  left: -3px;
  top: 1px;
}

/* Breathing animation */
.cute-cat {
  animation: catBreathe 3s ease-in-out infinite;
}

@keyframes catBreathe {
  0%, 100% { transform: scale(1); }
  50% { transform: scale(1.02); }
}

/* Bounce animation for clicks */
@keyframes catBounce {
  0%, 100% { transform: translateY(0) scale(1); }
  25% { transform: translateY(-10px) scale(1.03); }
  50% { transform: translateY(-5px) scale(1.05); }
  75% { transform: translateY(-8px) scale(1.03); }
}

/* Hover effects */
.cute-cat:hover .pupil {
  transform: scale(1.2);
}

.cute-cat:hover .cheek {
  background: rgba(255, 182, 193, 0.8);
}

.cute-cat:hover .ear-inner {
  background: #FFD6CC;
}

@media (max-width: 768px) {
  .cute-cat-container {
    top: 15px;
    right: 15px;
  }
  
  .cute-cat {
    width: 75px;
    height: 100px;
  }
  
  .cat-head {
    width: 58px;
    height: 55px;
  }
  
  .lens {
    width: 18px;
    height: 18px;
    border-width: 2px;
  }
  
  .cat-hat {
    top: -12px;
  }
  
  .hat-base {
    width: 40px;
  }
  
  .hat-top {
    width: 30px;
    height: 10px;
  }
  
  .star {
    width: 6px;
    height: 6px;
  }
}

/* Intro Text Mobile Styles */
@media (max-width: 480px) {
  .intro-text .btn.page-scroll {
    font-size: 13px !important;
    padding: 6px 12px !important;
    margin: 10px 4px 0 4px !important;
    min-width: 120px;
    display: inline-block;
    white-space: nowrap;
  }

  .intro-text {
    display: flex;
    flex-direction: column;
    align-items: center;
  }

  .intro-text .btn-group {
    display: flex;
    flex-direction: row;
    flex-wrap: nowrap;
    justify-content: center;
    gap: 8px;
    width: 100%;
  }
}

/* White button styles for intro section */
.intro .btn-default {
  color: white !important;
  border-color: white !important;
  background: transparent !important;
}

.intro .btn-default:hover,
.intro .btn-default:focus {
  color: #2c3e50 !important;
  background-color: white !important;
  border-color: white !important;
}

.intro .btn-default:active {
  color: #2c3e50 !important;
  background-color: rgba(255, 255, 255, 0.9) !important;
  border-color: white !important;
}

.back-to-top {
  position: fixed;
  bottom: 30px;
  right: 30px;
  width: 60px;
  height: 60px;
  background: linear-gradient(135deg, #E87E04 0%, #CC6600 100%);
  color: white;
  border: none;
  border-radius: 50%;
  cursor: pointer;
  font-size: 16px;
  display: none;
  z-index: 9999;
  transition: all 0.3s ease;
  box-shadow: 0 4px 12px rgba(232, 126, 4, 0.3);
  padding: 0 !important;
  margin: 0 !important;
  overflow: hidden !important;
}

.back-to-top-content {
  width: 100%;
  height: 100%;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
}

.back-to-top i {
  font-size: 18px;
  display: block;
  line-height: 1;
  margin: 0 auto;
  padding: 0;
  text-align: center;
  width: 100%;
}

.back-to-top-text {
  font-size: 10px;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  display: block;
  width: 100%;
  text-align: center;
  line-height: 1;
  padding: 0;
  margin: 2px auto 0;
  -webkit-text-size-adjust: 100%; /* 防止iOS上的字体大小自动调整 */
  -webkit-transform: translateZ(0); /* 启用硬件加速，防止iOS渲染问题 */
  transform: translateZ(0);
  position: relative;
  left: 0;
  right: 0;
}

/* Design tokens for consistent cross-device styling */
:root { 
  --btn-radius: 8px; 
  --btn-font-size: 12px; 
  --btn-pad-y: 6px; 
  --btn-pad-x: 12px; 
  --btn-transition: .18s ease;
  --btn-shadow: 0 2px 8px rgba(0,0,0,0.1);
  --btn-shadow-hover: 0 4px 12px rgba(0,0,0,0.15);
  
  /* Unified color scheme */
  --btn-primary: #E87E04;
  --btn-primary-hover: #CC6600;
  --btn-secondary: #2C3E50;
  --btn-secondary-hover: #34495E;
  --btn-outline-color: #E87E04;
  --btn-outline-hover-bg: #E87E04;
  --btn-outline-hover-text: white;
  --btn-text-color: #2C3E50;
}

/* Unified button base styles */
.btn, .btn-default, .btn-resource, .btn-outline, button {
  border-radius: var(--btn-radius) !important;
  font-weight: 600;
  line-height: 1.25;
  transition: all var(--btn-transition);
  border: 2px solid transparent;
  box-shadow: var(--btn-shadow);
  text-decoration: none !important;
  display: inline-block;
  cursor: pointer;
  font-family: inherit;
}

/* Unified button hover effects */
.btn:hover, .btn-default:hover, .btn-resource:hover, .btn-outline:hover, button:hover {
  transform: translateY(-1px);
  box-shadow: var(--btn-shadow-hover);
  text-decoration: none !important;
}

/* Primary buttons (main navigation) */
.btn-default, .intro .btn-default {
  padding: 10px 22px !important;
  font-size: 16px !important;
  line-height: 1.3 !important;
  background: transparent !important;
  color: white !important;
  border-color: white !important;
}

.btn-default:hover, .btn-default:focus, .intro .btn-default:hover, .intro .btn-default:focus {
  background: white !important;
  color: var(--btn-secondary) !important;
  border-color: white !important;
}

/* Outline buttons (filters, controls) */
.btn-outline {
  padding: var(--btn-pad-y) var(--btn-pad-x) !important;
  font-size: var(--btn-font-size) !important;
  background: transparent !important;
  color: var(--btn-outline-color) !important;
  border-color: var(--btn-outline-color) !important;
}

.btn-outline:hover, .btn-outline:focus {
  background: var(--btn-outline-hover-bg) !important;
  color: var(--btn-outline-hover-text) !important;
  border-color: var(--btn-outline-hover-bg) !important;
}

.btn-outline.active {
  background: var(--btn-outline-color) !important;
  color: white !important;
  border-color: var(--btn-outline-color) !important;
}

/* Resource buttons (papers, code, etc.) */
.btn-resource {
  padding: var(--btn-pad-y) var(--btn-pad-x) !important;
  font-size: var(--btn-font-size) !important;
  line-height: 1.2 !important;
  vertical-align: middle;
  margin: 2px 3px;
  background: var(--btn-primary) !important;
  color: white !important;
  border-color: var(--btn-primary) !important;
}

.btn-resource:hover, .btn-resource:focus {
  background: var(--btn-primary-hover) !important;
  color: white !important;
  border-color: var(--btn-primary-hover) !important;
}

/* Special resource button types - 优化后的颜色方案 */
.btn-res-pdf { 
  background: #E53E3E !important; 
  border-color: #E53E3E !important; 
  color: white !important;
}
.btn-res-pdf:hover { 
  background: #C53030 !important; 
  border-color: #C53030 !important; 
  color: white !important;
}

.btn-res-code { 
  background: #38A169 !important; 
  border-color: #38A169 !important; 
  color: white !important;
}
.btn-res-code:hover { 
  background: #2F855A !important; 
  border-color: #2F855A !important; 
  color: white !important;
}

.btn-res-poster, .btn-res-slides { 
  background: #3182CE !important; 
  border-color: #3182CE !important; 
  color: white !important;
}
.btn-res-poster:hover, .btn-res-slides:hover { 
  background: #2C5282 !important; 
  border-color: #2C5282 !important; 
  color: white !important;
}

.btn-res-blog { 
  background: #805AD5 !important; 
  border-color: #805AD5 !important; 
  color: white !important;
}
.btn-res-blog:hover { 
  background: #6B46C1 !important; 
  border-color: #6B46C1 !important; 
  color: white !important;
}

.btn-res-news { 
  background: #F56500 !important; 
  border-color: #F56500 !important; 
  color: white !important;
}
.btn-res-news:hover { 
  background: #DD6B20 !important; 
  border-color: #DD6B20 !important; 
  color: white !important;
}

.btn-res-bibtex { 
  background: #718096 !important; 
  border-color: #718096 !important; 
  color: white !important;
}
.btn-res-bibtex:hover { 
  background: #4A5568 !important; 
  border-color: #4A5568 !important; 
  color: white !important;
}

.btn-res-video, .btn-res-audio { 
  background: #D53F8C !important; 
  border-color: #D53F8C !important; 
  color: white !important;
}
.btn-res-video:hover, .btn-res-audio:hover { 
  background: #B83280 !important; 
  border-color: #B83280 !important; 
  color: white !important;
}

.btn-res-external { 
  background: #4299E1 !important; 
  border-color: #4299E1 !important; 
  color: white !important;
}
.btn-res-external:hover { 
  background: #3182CE !important; 
  border-color: #3182CE !important; 
  color: white !important;
}

.btn-res-internal { 
  background: #48BB78 !important; 
  border-color: #48BB78 !important; 
  color: white !important;
}
.btn-res-internal:hover { 
  background: #38A169 !important; 
  border-color: #38A169 !important; 
  color: white !important;
}

.btn-res-paper { 
  background: #ED8936 !important; 
  border-color: #ED8936 !important; 
  color: white !important;
}
.btn-res-paper:hover { 
  background: #DD6B20 !important; 
  border-color: #DD6B20 !important; 
  color: white !important;
}

/* Navigation toggle button */
.navbar-toggle {
  background-color: transparent !important;
  border: 2px solid var(--btn-outline-color) !important;
  border-radius: var(--btn-radius) !important;
  padding: 6px 10px !important;
  margin-top: 8px !important;
  margin-bottom: 8px !important;
  transition: all var(--btn-transition) !important;
}

.navbar-toggle:hover, .navbar-toggle:focus {
  background-color: rgba(232, 126, 4, 0.1) !important;
  transform: translateY(-1px);
  box-shadow: var(--btn-shadow);
}

.navbar-toggle .icon-bars {
  color: var(--btn-outline-color) !important;
  font-size: 18px !important;
}

/* Back to top button */
.back-to-top { 
  position: fixed;
  bottom: 20px;
  right: 20px;
  width: 60px;
  height: 60px;
  border-radius: var(--btn-radius) !important;
  background: linear-gradient(135deg, var(--btn-primary) 0%, var(--btn-primary-hover) 100%) !important;
  border: none !important;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 0;
  text-align: center;
}

/* Mobile specific overrides */
@media (max-width: 768px) {
  .intro .btn-default {
    color: #FFFFFF !important;
    border-color: #FFFFFF !important;
    background: rgba(255,255,255,0) !important;
    padding: 10px 22px; /* maintain same sizing for consistency */
  }
  .intro .btn-default:active,
  .intro .btn-default:focus,
  .intro .btn-default:hover {
    background: #FFFFFF !important;
    color: #2c3e50 !important;
    border-color: #FFFFFF !important;
  }
  .btn-resource { min-width: 66px; }
  .achievement-box .btn-resource { display: inline-block; }
  .back-to-top {
    font-size: 14px;
  }
  
  /* Enhanced mobile navigation */
  .navbar-toggle {
    background-color: transparent !important;
    border: 2px solid #FFA500 !important;
    border-radius: 4px !important;
    padding: 6px 10px !important;
    margin-top: 8px !important;
    margin-bottom: 8px !important;
  }
  
  .navbar-toggle:hover,
  .navbar-toggle:focus {
    background-color: rgba(255, 165, 0, 0.1) !important;
  }
  
  .navbar-toggle .icon-bars {
    color: #FFA500 !important;
    font-size: 18px !important;
  }
  
  .navbar-collapse {
    border-top: 1px solid rgba(255, 165, 0, 0.3) !important;
    margin-top: 10px !important;
  }
  
  .navbar-nav {
    margin: 7.5px 0 !important;
  }
  
  .navbar-nav li a {
    padding: 12px 15px !important;
    font-size: 16px !important;
    border-bottom: 1px solid rgba(255, 255, 255, 0.1) !important;
  }
}

.back-to-top:hover {
  background: linear-gradient(135deg, #CC6600 0%, #B85C00 100%);
  transform: translateY(-2px);
  box-shadow: 0 6px 16px rgba(232, 126, 4, 0.4);
}

.back-to-top:focus {
  outline: 2px solid #E87E04;
  outline-offset: 2px;
}

.back-to-top.show {
  display: flex !important;
  animation: fadeInUp 0.3s ease;
}


.audio-control {
  position: fixed;
  bottom: 30px;
  left: 30px;
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px 20px;
  border-radius: 999px;
  background: linear-gradient(135deg, rgba(35, 22, 75, 0.9) 0%, rgba(57, 26, 96, 0.9) 100%);
  color: #ffffff;
  box-shadow: 0 12px 28px rgba(32, 23, 70, 0.35);
  z-index: 9999;
  backdrop-filter: blur(10px);
  border: 1px solid rgba(255, 255, 255, 0.18);
}

.audio-toggle {
  background: linear-gradient(135deg, #ff97d0 0%, #ff6b9a 100%);
  border: none;
  color: #ffffff;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: transform 0.2s ease, box-shadow 0.25s ease, background 0.25s ease;
}

.audio-toggle:hover {
  transform: translateY(-2px);
  box-shadow: 0 12px 24px rgba(255, 107, 154, 0.35);
}

.audio-toggle:focus {
  outline: 2px solid rgba(255, 151, 208, 0.6);
  outline-offset: 3px;
}

.audio-toggle.is-paused {
  background: linear-gradient(135deg, #8f9bff 0%, #6f7ad9 100%);
  box-shadow: 0 6px 18px rgba(111, 122, 217, 0.35);
}

.audio-icon {
  line-height: 1;
  display: inline-flex;
  align-items: center;
  justify-content: center;
}

.audio-icon svg {
  width: 22px;
  height: 22px;
  display: block;
}

.audio-toggle.is-paused .icon-note {
  display: none;
}

.audio-toggle:not(.is-paused) .icon-note-off {
  display: none;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  border: 0;
}

@keyframes fadeInUp {
  from { opacity: 0; transform: translateY(20px); }
  to { opacity: 1; transform: translateY(0); }
}

@keyframes catBounce {
  0%, 100% { transform: translateY(0) scale(1); }
  25% { transform: translateY(-10px) scale(1.05); }
  50% { transform: translateY(-5px) scale(1.1); }
  75% { transform: translateY(-8px) scale(1.05); }
}

@media (max-width: 768px) {
  .back-to-top {
    bottom: 20px;
    right: 20px;
    width: 50px;
    height: 50px;
    padding: 0 !important;
  }
  
  .audio-control {
    bottom: 20px;
    left: 20px;
    padding: 10px 16px;
    gap: 10px;
  }
  
  .audio-toggle {
    width: 36px;
    height: 36px;
  }
  
  .back-to-top-content {
    width: 100%;
    height: 100%;
  }
  
  .back-to-top i {
    font-size: 16px;
    font-size: 16px;
    display: block;
    line-height: 1;
    margin: 0 auto;
    padding: 0;
  }
  
  .back-to-top-text {
    font-size: 8px;
    display: block;
    text-align: center;
    line-height: 1;
    margin: 1px auto 0;
    width: 100%;
    padding: 0;
    -webkit-text-size-adjust: 100%; /* 防止iOS上的字体大小自动调整 */
    -webkit-transform: translateZ(0);
    transform: translateZ(0);
    position: relative;
    left: 0;
    right: 0;
  }
}

/* Research Interests optimization */
.service { position: relative; }
.about-box {
  background:#fff;
  border:1px solid #e5e7eb;
  padding:28px 28px 24px 28px;
  box-shadow:0 2px 6px rgba(0,0,0,0.05);
  border-radius:12px;
  font-size:14.5px;
  line-height:1.55;
  color:#2c3e50;
}
.about-box h3.about-heading { margin-top:0; font-size:20px; font-weight:600; margin-bottom:14px; }
.about-box p { margin-bottom:14px; }
.about-box .about-metrics-text { margin-bottom:18px; }
/* Unified section spacing */
.site-section { padding:55px 0 50px 0; position:relative; }
/* Tighten sections that already have inner visual blocks (e.g., achievements list) */
#achievements.site-section { padding-top:45px; }
#contact.site-section { padding-top:45px; padding-bottom:40px; }
/* Remove top padding for first section to avoid excess gap below header */
#about.site-section { padding-top:40px; }
/* Optional subtle divider between sections (commented out) */
/* .site-section:after { content:""; position:absolute; left:0; right:0; bottom:0; height:1px; background:linear-gradient(to right,transparent,#e5e7eb,transparent);} */
@media (max-width:768px){
  .site-section { padding:42px 0 40px 0; }
  #about.site-section { padding-top:34px; }
  #achievements.site-section { padding-top:35px; }
  #contact.site-section { padding-top:35px; }
}
.metric-label, .metric-value { display:none; }
.about-contact { font-size:14px; margin-top:4px; }
/* Contact card */
.contact-card { background:#fff; border:1px solid #e5e7eb; border-radius:12px; padding:26px 28px 22px 28px; box-shadow:0 2px 6px rgba(0,0,0,0.05); text-align:left; }
.contact-item { display:flex; align-items:flex-start; gap:14px; margin-bottom:18px; }
.contact-item:last-of-type { margin-bottom:14px; }
.contact-item i { font-size:30px; color:#2c3e50; line-height:1; margin-top:2px; }
.contact-info { flex:1; min-width:0; }
.contact-label { display:block; font-size:11px; letter-spacing:.6px; text-transform:uppercase; color:#64748b; margin-bottom:2px; }
.contact-value, .contact-link { font-size:15px; font-weight:500; color:#1e293b; word-break:break-all; }
.contact-link { text-decoration:none; border-bottom:1px solid transparent; transition:color .18s, border-color .18s; }
.contact-link:hover, .contact-link:focus { color:#0f172a; border-color:#94a3b8; }
.contact-note { font-size:13px; color:#475569; margin-top:4px; line-height:1.4; }
#copyEmail.btn { padding:4px 10px !important; font-size:11.5px !important; }
.copy-feedback { font-size:12px; margin-top:8px; min-height:16px; color:#2563eb; }
@media (max-width:768px){
  .contact-card { padding:22px 20px 20px 20px; }
  .contact-item { margin-bottom:16px; }
  .contact-value, .contact-link { font-size:14px; }
}
@media (max-width:768px){
  .about-box { padding:22px 18px 18px 18px; font-size:14px; }
  .about-box h3.about-heading { font-size:18px; }
  .metric-value { font-size:15px; }
}