/* ============================================================
 * 公瑾AI技术笔记 — 通用样式
 * ============================================================ */

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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC',
    'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
  background: var(--color-bg);
  color: var(--color-text);
  min-height: 100vh;
  font-size: var(--font-md);
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--gap-md) env(safe-area-inset-bottom);
  -webkit-font-smoothing: antialiased;
}

/* ============ Header ============ */
.page-header {
  position: relative;
  background: var(--header-bg);
  padding: 36px 24px 28px;
  text-align: center;
  color: var(--header-text);
  min-height: 20vh;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  overflow: hidden;
  margin: 0 calc(-1 * var(--gap-md)) var(--gap-md);
}
.page-header h1 {
  font-size: var(--font-2xl);
  font-weight: 700;
  letter-spacing: 2px;
  margin-bottom: 6px;
  position: relative;
  z-index: 1;
  text-shadow: 0 2px 12px rgba(0, 0, 0, 0.3);
}
.page-header p {
  font-size: var(--font-sm);
  opacity: 0.85;
}
.page-header .sub {
  font-size: var(--font-xs);
  opacity: 0.6;
  margin-top: 4px;
}

.back-link {
  display: inline-block;
  margin: 10px 0;
  color: var(--color-primary);
  font-size: var(--font-sm);
  text-decoration: none;
  background: var(--color-primary-bg);
  padding: 6px 16px;
  border-radius: 20px;
}

/* ============ Card ============ */
.card {
  background: var(--color-bg-card);
  border-radius: var(--radius-lg);
  padding: 22px 18px;
  box-shadow: var(--shadow-card);
  margin-bottom: var(--gap-md);
}

.card-title {
  font-size: var(--font-lg);
  font-weight: 700;
  color: var(--color-primary);
  margin-bottom: 14px;
  display: flex;
  align-items: center;
  gap: 6px;
}

/* ============ Button ============ */
.btn {
  display: inline-block;
  padding: 10px 18px;
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius-md);
  background: var(--color-bg-card);
  color: var(--color-text);
  font-size: var(--font-sm);
  cursor: pointer;
  text-decoration: none;
  text-align: center;
  transition: all 0.15s;
}
.btn:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
}
.btn:active {
  transform: scale(0.97);
}
.btn-primary {
  background: linear-gradient(135deg, var(--color-primary), var(--color-primary-light));
  color: #fff;
  border-color: var(--color-primary);
  box-shadow: var(--shadow-button);
}
.btn-block {
  display: block;
  width: 100%;
  height: 48px;
  line-height: 48px;
  font-size: var(--font-lg);
  font-weight: 600;
  letter-spacing: 1px;
  padding: 0;
}

/* ============ Input ============ */
.input {
  width: 100%;
  height: 48px;
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 0 14px;
  font-size: var(--font-md);
  color: var(--color-text);
  background: var(--color-bg-input);
  outline: none;
  transition: border-color 0.2s;
}
.input:focus {
  border-color: var(--color-primary);
  background: var(--color-bg-card);
}
.input::placeholder {
  color: var(--color-text-placeholder);
}

/* ============ Tab Bar (首页底部) ============ */
.tab-bar {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  background: var(--color-bg-card);
  border-top: 1px solid var(--color-border);
  display: flex;
  z-index: 100;
  padding-bottom: env(safe-area-inset-bottom);
  box-shadow: 0 -2px 10px rgba(0, 0, 0, 0.06);
}
.tab-item {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 6px 0 8px;
  text-decoration: none;
  color: var(--color-text-muted);
}
.tab-item .ti {
  width: 24px;
  height: 24px;
  margin-bottom: 2px;
}
.tab-item .tt {
  font-size: 10px;
  font-weight: 500;
}
.tab-item.on {
  color: var(--color-primary);
}
.tab-item.on .tt {
  font-weight: 700;
}

/* ============ Theme Switcher (右上角) ============ */
.theme-toggle {
  position: fixed;
  top: 14px;
  right: 14px;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  border: none;
  background: rgba(255, 255, 255, 0.2);
  color: #fff;
  font-size: 20px;
  cursor: pointer;
  z-index: 200;
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: transform 0.15s;
}
.theme-toggle:hover {
  transform: scale(1.1);
}
.theme-toggle:active {
  transform: scale(0.95);
}

/* ============ Toast ============ */
.toast {
  position: fixed;
  bottom: 90px;
  left: 50%;
  transform: translateX(-50%);
  background: rgba(0, 0, 0, 0.75);
  color: #fff;
  padding: 8px 18px;
  border-radius: 18px;
  font-size: var(--font-sm);
  z-index: 99;
  opacity: 0;
  transition: opacity 0.3s;
  pointer-events: none;
}
.toast.show {
  opacity: 1;
}

/* ============ Footer ============ */
.ft {
  text-align: center;
  padding: 24px 14px 80px;
  color: var(--color-text-muted);
  font-size: var(--font-sm);
}
.ft .contact {
  display: flex;
  justify-content: center;
  gap: 16px;
  margin: 8px 0;
  font-size: var(--font-md);
}
.ft .contact a,
.ft .contact span {
  color: var(--color-primary);
  text-decoration: none;
  cursor: pointer;
}
.ft .brand {
  font-size: var(--font-md);
  color: var(--color-text-soft);
  font-weight: 500;
  margin-bottom: 10px;
  line-height: 1.6;
}

/* ============ Responsive ============ */
@media (max-width: 380px) {
  .page-header h1 {
    font-size: 22px;
  }
  .card {
    padding: 16px 14px;
  }
}

/* ============ Utility ============ */
.text-center { text-align: center; }
.text-muted { color: var(--color-text-muted); }
.text-primary { color: var(--color-primary); }
.mb-sm { margin-bottom: var(--gap-sm); }
.mb-md { margin-bottom: var(--gap-md); }
.mb-lg { margin-bottom: var(--gap-lg); }
.mt-sm { margin-top: var(--gap-sm); }
.mt-md { margin-top: var(--gap-md); }


/* === Page Header Hero（带图片背景） === */
.page-header-hero {
  background: linear-gradient(90deg, rgba(15, 25, 50, 0.55) 0%, rgba(15, 25, 50, 0.25) 60%, rgba(15, 25, 50, 0) 100%), var(--hero-img) center right/cover no-repeat !important;
  color: #fff !important;
  min-height: 220px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: flex-start;
  position: relative;
  overflow: hidden;
  padding-left: 24px;
  padding-right: 24px;
  text-align: left;
}
.page-header-hero h1,
.page-header-hero p,
.page-header-hero .sub {
  color: #fff;
  text-shadow: 0 2px 8px rgba(0, 0, 0, 0.45);
}
.page-header-hero .sub {
  opacity: 0.92;
}