:root {
  --bg: #f6f7f8;
  --card: #ffffff;
  --text: #1f2933;
  --muted: #6b7280;
  --green: #5fa36a;
  --green-dark: #4b8f58;
  --border: #e5e7eb;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  color: var(--text);
  background: var(--bg);
}

.container {
  max-width: 1400px;
  margin: 0 auto;
  padding: 0 24px;
}

.site-header {
  background: var(--card);
  border-bottom: 1px solid var(--border);
}

.site-header .container {
  display: flex;
  align-items:end;
  justify-content: space-between;
  height: 64px;
  padding-bottom: 18px;
}

.logo {
  font-weight: 600;
  font-size: 24px;
}

nav a {
  margin-left: 20px;
  color: var(--muted);
  visibility: hidden;
}

nav a:hover {
  color: var(--text);
}

.hero {
  padding: 20px 0;
}

.hero-grid {
  display: grid;
  grid-template-columns: 500px 1fr;
  gap: 48px;
  align-items:start;
}

.hero h1 {
  font-size: 42px;
  margin-bottom: 16px;
}


.hero-image img {
  width: 100%;
  border-radius: 4px;
  box-shadow: 0 8px 16px rgba(0,0,0,0.2);
}

.conversion-process {
  display: flex;
  justify-content: space-between; /* 平均分布 */
  align-items: flex-start;
  margin-bottom: 40px;
  gap: 32px; /* 图片之间间隔 */
  position: relative;
  flex-wrap: wrap;
}
.process-step {
  flex: 1 1; 
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  position: relative;
  z-index: 1; /* 高于连线 */
}

.process-step img {
  width: 100%;    /* 占容器全部宽度 */
  height: auto;   /* 等比缩放 */
  border-radius: 4px; /* 可选，圆角 */
  box-shadow: 0 4px 12px rgba(0,0,0,0.15); /* 可选，浮起效果 */
  margin-bottom: 12px;
  transition: transform 0.3s ease;
}

.process-step span {
  font-weight: 600;
  color: var(--text);
  font-size: 16px;
}
.process-step:hover img {
  transform: scale(1.05);
  box-shadow: 0 10px 24px rgba(0,0,0,0.18);
}

.process-step:hover .step-arrow {
  transform: translateX(4px) rotate(45deg);
  color: #4b5563;
}

.step-arrow {
  position: absolute;
  right: -30px;
  top: 40%;
  width: 16px;
  height: 16px;
  border-top: 3px solid var(--muted);
  border-right: 3px solid var(--muted);
  transform: rotate(45deg);
  margin: 0 12px;
}

/* 响应式：屏幕小于768px自动堆叠 */
@media(max-width:768px) {
  .conversion-process {
    flex-direction: column;
  }

  .process-step {
    flex: 1 1 100%;
    margin-bottom: 24px;
  }

  .process-step>span:nth-of-type(1) {
    position: absolute;
    top : -30px
  }
  .process-step img {
    width: 80%;
  }
  .step-arrow {
    display: none; /* 小屏幕隐藏箭头 */
  }
}


.subtitle {
  font-size: 18px;
  color: var(--muted);
}

.hero-actions {
  margin-top: 32px;
}

.btn-primary {
  display: inline-block;
  background: var(--green);
  color: #fff;
  padding: 14px 22px;
  border-radius: 10px;
  text-decoration: none;
  font-weight: 600;
}

.btn-primary:hover {
  background: var(--green-dark);
}

.btn-primary.large {
  font-size: 18px;
  padding: 16px 28px;
}


.note {
  display: block;
  margin-top: 10px;
  font-size: 13px;
  color: var(--muted);
}

.section {
  padding: 20px 0;
}

.section h2 {
  width: 100%;
  font-size: 32px;
  margin-bottom: 32px;
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 24px;
}

.feature-card {
  background: var(--card);
  padding: 24px;
  border-radius: 14px;
  border: 1px solid var(--border);
}

.feature-card h3{
  font-size: 24px;
}

.formats {
  font-size: 18px;
  color: var(--muted);
}

.download-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 40px;
}

.donate-box {
  background: var(--card);
  border-radius: 16px;
  padding: 28px;
  border: 1px solid var(--border);  
  box-shadow: 0 2px 4px rgba(0,0,0,0.2);
}
.donate-box .btn-secondary {
  font-size: 18px;
  display: inline-block;
  background: #f3f4f6;
  color: var(--text);
  padding: 12px 18px;
  border-radius: 10px;
  text-decoration: none;
  font-weight: 500;
  border: 1px solid var(--border);
}

.donate-box .btn-secondary:hover {
  background: #e5e7eb;
}

.donate-box h3{
  font-size: 24px;
}

.donate-note {
  margin-top: 12px;
  font-size: 13px;
  color: var(--muted);
}

.site-footer {
  border-top: 1px solid var(--border);
  padding: 24px 0;
  font-size: 16px;
  color: var(--muted);
}

.site-footer .container {
  display: flex;
  justify-content: space-between;
}