/* 防止语言切换闪烁 */
html:not([data-i18n-ready]) [data-i18n] {
  visibility: hidden;
}

html[data-i18n-ready] [data-i18n] {
  visibility: visible;
}

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

:root {
  --primary-1: #667eea;
  --primary-2: #764ba2;
  --bg-gradient: linear-gradient(135deg, var(--primary-1) 0%, var(--primary-2) 100%);
  --text-1: #1f2937;
  --text-2: #4b5563;
  --text-3: #6b7280;
  --border: #e5e7eb;
  --card-bg: #ffffff;
  --muted-bg: #f8f9ff;
  --success: #22c55e;
  --error: #ef4444;
}

html, body {
  min-height: 100%;
}

body {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  color: var(--text-1);
  background: var(--bg-gradient);
  line-height: 1.6;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

header.site-header {
  background: var(--bg-gradient);
  color: #fff;
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 18px 0;
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
}

.brand .logo {
  width: 36px;
  height: 36px;
}

.brand .title {
  font-weight: 700;
  font-size: 20px;
}

nav.main-nav a {
  color: #fff;
  text-decoration: none;
  margin: 0 12px;
  font-weight: 600;
  opacity: 0.9;
}

nav.main-nav a.active {
  opacity: 1;
  border-bottom: 2px solid rgba(255,255,255,0.9);
}

.lang-switcher {
  display: flex;
  align-items: center;
}

.lang-switcher select {
  padding: 6px 10px;
  border-radius: 6px;
  border: 1px solid rgba(255,255,255,0.5);
  background: rgba(255,255,255,0.1);
  color: #fff;
  font-size: 14px;
  cursor: pointer;
  transition: all 0.3s ease;
}

.lang-switcher select:hover {
  background: rgba(255,255,255,0.2);
  border-color: rgba(255,255,255,0.8);
}

.lang-switcher select option {
  background: #333;
  color: #fff;
}

.hero {
  background: transparent;
  color: #fff;
  padding: 48px 0 8px 0;
}

.hero h1 {
  font-size: 40px;
  margin-bottom: 10px;
}

.hero p {
  font-size: 18px;
  opacity: 0.95;
}

main {
  background: #fff;
  border-radius: 16px 16px 0 0;
  padding: 32px 0 48px 0;
  box-shadow: 0 -2px 30px rgba(0,0,0,0.08);
}

.section {
  max-width: 1200px;
  margin: 24px auto;
}

.card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 24px;
  box-shadow: 0 10px 20px rgba(0,0,0,0.05);
}

h2.section-title {
  font-size: 26px;
  margin-bottom: 14px;
}

.form-group {
  margin-bottom: 16px;
}

label {
  display: block;
  margin-bottom: 8px;
  font-weight: 600;
  color: var(--text-2);
}

input[type="file"],
select,
input[type="text"] {
  width: 100%;
  padding: 12px;
  border: 2px solid #ddd;
  border-radius: 8px;
  font-size: 16px;
  transition: border-color 0.2s ease;
}

input[type="text"]:focus,
select:focus {
  outline: none;
  border-color: var(--primary-1);
}

.btn {
  background: var(--bg-gradient);
  color: white;
  border: none;
  padding: 12px 22px;
  border-radius: 8px;
  font-size: 16px;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s ease;
  margin-right: 10px;
  margin-bottom: 10px;
}

.btn:hover { opacity: 0.95; transform: translateY(-1px); }
.btn:disabled { opacity: 0.6; cursor: not-allowed; transform: none; }

.progress { display: none; margin-top: 16px; }
.progress-bar { width: 100%; height: 20px; background: #f0f0f0; border-radius: 10px; overflow: hidden; }
.progress-fill { height: 100%; background: linear-gradient(90deg, var(--primary-1), var(--primary-2)); width: 0%; transition: width 0.3s ease; animation: pulse 2s infinite; }

@keyframes pulse { 0%, 100% { opacity: 1; } 50% { opacity: 0.7; } }

.result { margin-top: 16px; padding: 16px; border-radius: 8px; border-left: 5px solid var(--primary-1); background: var(--muted-bg); }
.result.success { border-left-color: var(--success); background: #f0fff4; }
.result.error { border-left-color: var(--error); background: #fff5f5; }

.download-link { display: inline-block; background: var(--success); color: white; padding: 10px 20px; border-radius: 6px; text-decoration: none; margin-top: 10px; }
.download-link:hover { filter: brightness(0.95); }

/* 转换器样式 */
.converter-card { background: var(--card-bg); border-radius: 16px; padding: 32px; box-shadow: 0 20px 40px rgba(0,0,0,0.08); border: 1px solid var(--border); }
.converter-header { text-align: center; margin-bottom: 24px; }
.converter-subtitle { color: var(--text-2); font-size: 16px; margin-top: 8px; }

.upload-zone { 
  border: 3px dashed #d1d5db; 
  border-radius: 16px; 
  padding: 48px 24px; 
  text-align: center; 
  background: #fafbff; 
  transition: all 0.3s ease; 
  cursor: pointer; 
  margin-bottom: 24px;
}
.upload-zone:hover { border-color: var(--primary-1); background: #f0f4ff; }
.upload-zone.dragover { border-color: var(--primary-1); background: #e6f0ff; transform: scale(1.02); }
.upload-icon { font-size: 48px; margin-bottom: 16px; }
.upload-zone h3 { color: var(--text-1); margin-bottom: 8px; }
.upload-link { color: var(--primary-1); font-weight: 600; cursor: pointer; text-decoration: underline; }
.upload-hint { color: var(--text-3); font-size: 14px; margin-top: 8px; }

.converter-options { display: flex; flex-direction: column; gap: 20px; }
.format-selector label { font-weight: 600; color: var(--text-1); margin-bottom: 12px; display: block; }
.format-buttons { display: flex; flex-wrap: wrap; gap: 8px; }
.format-btn { 
  padding: 12px 20px; 
  border: 2px solid var(--border); 
  background: #fff; 
  border-radius: 8px; 
  font-weight: 600; 
  cursor: pointer; 
  transition: all 0.2s ease;
}
.format-btn:hover { border-color: var(--primary-1); color: var(--primary-1); }
.format-btn.active { background: var(--bg-gradient); color: #fff; border-color: transparent; }

.form-row { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }

.btn-primary { 
  background: var(--bg-gradient); 
  color: #fff; 
  border: none; 
  padding: 16px 32px; 
  border-radius: 12px; 
  font-size: 18px; 
  font-weight: 600; 
  cursor: pointer; 
  transition: all 0.3s ease; 
  display: flex; 
  align-items: center; 
  justify-content: center; 
  gap: 8px; 
  min-height: 56px;
}
.btn-primary:hover { transform: translateY(-2px); box-shadow: 0 12px 24px rgba(102, 126, 234, 0.3); }
.btn-primary:disabled { opacity: 0.6; cursor: not-allowed; transform: none; }
.btn-icon { font-size: 20px; }

/* 格式展示区 */
.formats-showcase { text-align: center; }
.formats-grid { display: grid; grid-template-columns: 1fr auto 1fr; gap: 32px; align-items: center; margin-top: 32px; }
.format-category h3 { margin-bottom: 16px; color: var(--text-1); }
.format-tags { display: flex; flex-wrap: wrap; gap: 8px; justify-content: center; }
.format-tag { 
  background: #f0f4ff; 
  border: 2px solid #e0e7ff; 
  padding: 8px 16px; 
  border-radius: 20px; 
  font-size: 14px; 
  font-weight: 600; 
  color: var(--primary-1);
  transition: all 0.2s ease;
}
.format-tag.popular { background: var(--bg-gradient); color: #fff; border-color: transparent; }
.format-tag:hover { transform: translateY(-2px); box-shadow: 0 4px 8px rgba(102, 126, 234, 0.2); }
.format-arrow { font-size: 32px; color: var(--primary-1); }

/* 增强特性卡片 */
.features-grid-enhanced { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; margin-top: 32px; }
.feature-card-enhanced { 
  background: #fff; 
  border: 1px solid var(--border); 
  border-radius: 16px; 
  padding: 24px; 
  text-align: center; 
  transition: all 0.3s ease; 
  position: relative; 
  overflow: hidden;
}
.feature-card-enhanced:hover { 
  transform: translateY(-8px); 
  box-shadow: 0 20px 40px rgba(0,0,0,0.1); 
  border-color: var(--primary-1);
}
.feature-icon { 
  font-size: 48px; 
  margin-bottom: 16px; 
  display: block;
}
.feature-card-enhanced h3 { 
  font-size: 20px; 
  margin-bottom: 12px; 
  color: var(--text-1);
}
.feature-card-enhanced p { 
  color: var(--text-2); 
  margin-bottom: 16px; 
  line-height: 1.6;
}
.feature-stats { 
  background: var(--muted-bg); 
  border-radius: 8px; 
  padding: 12px; 
  margin-top: 16px;
}
.stat { 
  font-size: 18px; 
  font-weight: 700; 
  color: var(--primary-1); 
  display: block;
}
.stat-label { 
  font-size: 12px; 
  color: var(--text-3); 
  margin-top: 4px;
}

/* 统计区域 */
.stats-section { text-align: center; }
.stats-grid { 
  display: grid; 
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); 
  gap: 24px; 
  margin-top: 32px;
}
.stat-card { 
  background: var(--bg-gradient); 
  color: #fff; 
  padding: 32px 24px; 
  border-radius: 16px; 
  text-align: center;
}
.stat-number { 
  font-size: 32px; 
  font-weight: 700; 
  margin-bottom: 8px;
}
.stat-label { 
  font-size: 14px; 
  opacity: 0.9;
}

/* 步骤指南 */
.guide-section { text-align: center; }
.guide-steps { 
  display: flex; 
  align-items: center; 
  justify-content: center; 
  gap: 24px; 
  margin-top: 32px; 
  flex-wrap: wrap;
}
.step { 
  display: flex; 
  flex-direction: column; 
  align-items: center; 
  max-width: 200px;
}
.step-number { 
  width: 60px; 
  height: 60px; 
  background: var(--bg-gradient); 
  color: #fff; 
  border-radius: 50%; 
  display: flex; 
  align-items: center; 
  justify-content: center; 
  font-size: 24px; 
  font-weight: 700; 
  margin-bottom: 16px;
}
.step-content h3 { 
  font-size: 18px; 
  margin-bottom: 8px; 
  color: var(--text-1);
}
.step-content p { 
  color: var(--text-2); 
  font-size: 14px;
}
.step-arrow { 
  font-size: 24px; 
  color: var(--primary-1); 
  margin: 0 16px;
}

/* 通用样式 */
.text-center { text-align: center; }
.section-subtitle { 
  color: var(--text-2); 
  font-size: 18px; 
  margin-top: 8px; 
  max-width: 600px; 
  margin-left: auto; 
  margin-right: auto;
}

.features-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 16px; }
.feature-card { background: #f8f9ff; border: 1px solid var(--border); border-radius: 10px; padding: 16px; }
.feature-card h3 { margin-bottom: 8px; font-size: 18px; }

footer.site-footer { padding: 20px 0 40px 0; color: var(--text-3); background: #fff; }
.footer-top { display: grid; grid-template-columns: repeat(auto-fit, minmax(160px, 1fr)); gap: 24px; padding: 24px 0; border-top: 1px solid var(--border); }
.footer-col h4 { margin-bottom: 10px; color: var(--text-1); }
.footer-col a { display: block; color: var(--text-2); text-decoration: none; margin: 4px 0; }
.footer-bottom { display: flex; align-items: center; justify-content: space-between; border-top: 1px solid var(--border); padding-top: 16px; font-size: 14px; }

.code { background: #f8f9fa; padding: 12px; border-radius: 6px; border-left: 4px solid var(--primary-1); overflow-x: auto; }

@media (max-width: 768px) {
  .header-inner { flex-direction: column; align-items: flex-start; gap: 12px; }
  nav.main-nav { display: flex; flex-wrap: wrap; gap: 10px; margin: 6px 0; }
  .hero h1 { font-size: 28px; }
  
  /* 移动端转换器优化 */
  .converter-card { padding: 20px; margin: 0 -4px; }
  .upload-zone { padding: 32px 16px; }
  .upload-icon { font-size: 36px; }
  .format-buttons { justify-content: center; }
  .format-btn { font-size: 14px; padding: 10px 16px; }
  .form-row { grid-template-columns: 1fr; gap: 12px; }
  .btn-primary { font-size: 16px; padding: 14px 24px; }
  
  /* 移动端格式展示优化 */
  .formats-grid { grid-template-columns: 1fr; gap: 20px; text-align: center; }
  .format-arrow { transform: rotate(90deg); margin: 16px 0; }
  .format-tags { justify-content: center; }
  .format-tag { font-size: 12px; padding: 6px 12px; }
  
  /* 移动端特性卡片优化 */
  .features-grid-enhanced { grid-template-columns: 1fr; gap: 16px; }
  .feature-card-enhanced { padding: 20px; }
  .feature-icon { font-size: 36px; }
  .feature-card-enhanced h3 { font-size: 18px; }
  
  /* 移动端统计优化 */
  .stats-grid { grid-template-columns: repeat(2, 1fr); gap: 16px; }
  .stat-card { padding: 24px 16px; }
  .stat-number { font-size: 24px; }
  
  /* 移动端步骤优化 */
  .guide-steps { flex-direction: column; gap: 16px; }
  .step-arrow { transform: rotate(90deg); margin: 8px 0; }
  .step { max-width: 100%; }
  .step-number { width: 50px; height: 50px; font-size: 20px; }
  
  /* 移动端通用优化 */
  .section-title { font-size: 22px; }
  .section-subtitle { font-size: 16px; padding: 0 16px; }
  .container { padding: 0 16px; }
  .section { margin: 16px 0; }
}

@media (max-width: 480px) {
  .hero h1 { font-size: 24px; }
  .hero p { font-size: 16px; }
  
  .converter-card { padding: 16px; border-radius: 12px; }
  .upload-zone { padding: 24px 12px; }
  .format-buttons { gap: 6px; }
  .format-btn { padding: 8px 12px; font-size: 13px; }
  
  .stats-grid { grid-template-columns: 1fr; }
  .stat-card { padding: 20px 16px; }
  
  .feature-card-enhanced { padding: 16px; }
  .section-title { font-size: 20px; }
  .section-subtitle { font-size: 15px; }
}