/* ====== GLOBAL RESET ====== */
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: "Inter", Arial, sans-serif;
  line-height: 1.6;
  color: #222;
  background-color: #f8f9fa;
}

/* ====== HEADER ====== */
header {
  background-color: #000;
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1rem 2rem;
  flex-wrap: wrap;
}

header .logo {
  font-size: 1.5rem;
  font-weight: 700;
  color: #81c00c;
  text-decoration: none;
}

header nav a {
  color: #fff;
  margin-left: 1.2rem;
  text-decoration: none;
  font-weight: 500;
}

header nav a:hover {
  color: #81c00c;
}

/* ====== MAIN CONTENT ====== */
main {
  max-width: 900px;
  margin: 2rem auto;
  padding: 1rem;
  background: #fff;
  border-radius: 12px;
  box-shadow: 0 4px 12px rgba(0,0,0,0.05);
}

h1, h2, h3 {
  color: #000;
  margin-bottom: 1rem;
}

p {
  margin-bottom: 1rem;
}

/* ====== FORM SECTION ====== */
.calc-container {
  display: flex;
  flex-wrap: wrap;
  gap: 2rem;
  align-items: flex-start;
}

form {
  flex: 1 1 320px;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

label {
  font-weight: 600;
}

input, select {
  padding: 0.5rem;
  border: 1px solid #ccc;
  border-radius: 6px;
  font-size: 1rem;
  width: 100%;
}

button {
  background-color: #81c00c;
  color: #fff;
  border: none;
  padding: 0.75rem;
  font-size: 1rem;
  border-radius: 6px;
  cursor: pointer;
  transition: background-color 0.2s;
}

button:hover {
  background-color: #6da70a;
}

/* ====== AD BOX ====== */
.ad-box {
  flex: 1 1 250px;
  border: 2px dashed #ccc;
  padding: 1rem;
  text-align: center;
  background: #f9f9f9;
  color: #666;
  border-radius: 8px;
}

/* ====== RESULT PAGE ====== */
#results {
  background: #f4f7f2;
  border-left: 4px solid #81c00c;
  padding: 1rem 1.5rem;
  border-radius: 8px;
  margin-bottom: 1.5rem;
}

#aboutTDEE {
  background: #f9f9f9;
  padding: 1rem 1.5rem;
  border-radius: 8px;
}

.button {
  display: inline-block;
  margin-top: 1.5rem;
  padding: 0.75rem 1.2rem;
  background-color: #81c00c;
  color: #fff;
  border-radius: 6px;
  text-decoration: none;
}

.button:hover {
  background-color: #6da70a;
}

/* ====== FOOTER ====== */
footer {
  text-align: center;
  padding: 1.5rem 0;
  background-color: #000;
  color: #aaa;
  margin-top: 3rem;
}

footer a {
  color: #81c00c;
  text-decoration: none;
}

footer a:hover {
  text-decoration: underline;
}

/* ====== RESPONSIVE ====== */
@media (max-width: 768px) {
  header {
    flex-direction: column;
    align-items: flex-start;
  }
  
  header nav {
    margin-top: 0.5rem;
  }

  .calc-container {
    flex-direction: column;
  }

  .ad-box {
    order: -1;
  }
  
  /* 减小移动设备上计算器下方信息部分的上边距 */
  .info-section {
    margin-top: 0.5rem !important;
    padding-top: 1rem !important;
  }
  
  /* 确保main容器在移动设备上有适当的内边距 */
  main {
    padding: 0.75rem 1rem;
  }
}
/* ====== UNIFIED HEADER LAYOUT ====== */
header {
  justify-content: center;  /* 居中整个 header 内容 */
  padding: 1rem 0;          /* 上下留白一致 */
}

header .header-inner {
  max-width: 900px;         /* 与 main 对齐 */
  width: 100%;
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0 2rem;          /* 保留边距避免贴边 */
  box-sizing: border-box;
}

/* LOGO 与导航保持平衡间距 */
header .logo {
  margin-left: 0;
}

header nav {
  margin-right: 0;
}

header nav a {
  margin-left: 1.5rem;
}

/* 响应式导航在手机端居中堆叠 */
@media (max-width: 768px) {
  header .header-inner {
    flex-direction: column;
    align-items: flex-start;
    padding: 0 1.5rem;
  }

  header nav {
    margin-top: 0.75rem;
  }

  header nav a {
    margin: 0 1rem 0.5rem 0;
  }
}