/* ============================================================
   Weight Tracker — Apple Design System
   SF Pro Display / SF Pro Text, Action Blue #0066cc
   ============================================================ */

/* --- CSS Variables (Dark default) --- */
:root {
  --primary: #0066cc;
  --primary-focus: #0071e3;
  --primary-on-dark: #2997ff;
  --ink: #1d1d1f;
  --ink-muted-80: #333333;
  --ink-muted-48: #7a7a7a;
  --body-muted: #cccccc;
  --canvas: #ffffff;
  --canvas-parchment: #f5f5f7;
  --surface-pearl: #fafafc;
  --surface-tile-1: #272729;
  --surface-tile-2: #2a2a2c;
  --surface-black: #000000;
  --hairline: #e0e0e0;
  --divider-soft: #f0f0f0;
  --on-primary: #ffffff;
  --on-dark: #ffffff;

  /* Semantic */
  --bg: var(--surface-tile-1);
  --bg-card: var(--surface-tile-2);
  --bg-hover: #333335;
  --text-primary: var(--on-dark);
  --text-secondary: var(--body-muted);
  --text-muted: var(--ink-muted-48);
  --border: #3a3a3c;
  --accent: var(--primary-on-dark);
  --accent-hover: #40a9ff;
  --green: #34c759;
  --red: #ff3b30;
  --chart-line: var(--primary-on-dark);
  --chart-avg: rgba(41,151,255,0.4);
  --chart-goal: rgba(255,255,255,0.3);
  --chart-grid: rgba(255,255,255,0.08);
  --chart-fill: rgba(41,151,255,0.1);
}

[data-theme="light"] {
  --bg: var(--canvas-parchment);
  --bg-card: var(--canvas);
  --bg-hover: #e8e8ed;
  --text-primary: var(--ink);
  --text-secondary: var(--ink-muted-80);
  --text-muted: var(--ink-muted-48);
  --border: var(--hairline);
  --accent: var(--primary);
  --accent-hover: var(--primary-focus);
  --chart-line: var(--primary);
  --chart-avg: rgba(0,102,204,0.35);
  --chart-goal: rgba(0,0,0,0.2);
  --chart-grid: rgba(0,0,0,0.06);
  --chart-fill: rgba(0,102,204,0.08);
}

/* --- Reset & Base --- */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html { scroll-behavior: smooth; }

body {
  font-family: "SF Pro Text", system-ui, -apple-system, BlinkMacSystemFont, "Inter", sans-serif;
  font-size: 17px;
  line-height: 1.47;
  letter-spacing: -0.374px;
  color: var(--text-primary);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

a { color: var(--accent); text-decoration: none; }
a:hover { color: var(--accent-hover); }

img { max-width: 100%; height: auto; }

/* --- Global Header --- */
.global-header {
  background: var(--surface-black);
  height: 44px;
  padding: 0 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  position: sticky;
  top: 0;
  z-index: 100;
}

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

.logo {
  font-family: "SF Pro Display", system-ui, -apple-system, sans-serif;
  font-size: 14px;
  font-weight: 600;
  color: var(--on-dark);
  letter-spacing: -0.12px;
}
.logo:hover { color: var(--on-dark); opacity: 0.8; }

.breadcrumb { font-size: 12px; color: rgba(255,255,255,0.6); letter-spacing: -0.12px; }
.breadcrumb a { color: rgba(255,255,255,0.6); }
.breadcrumb a:hover { color: var(--on-dark); }
.breadcrumb .sep { margin: 0 4px; }

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

.back-to-hub {
  font-size: 12px;
  color: rgba(255,255,255,0.8);
  letter-spacing: -0.12px;
}
.back-to-hub:hover { color: var(--on-dark); }

.theme-toggle {
  background: none;
  border: none;
  color: rgba(255,255,255,0.8);
  cursor: pointer;
  font-size: 16px;
  padding: 4px;
  line-height: 1;
}
.theme-toggle:hover { color: var(--on-dark); }

/* --- Layout --- */
.layout {
  display: grid;
  grid-template-columns: 180px 1fr 320px;
  gap: 24px;
  max-width: 1440px;
  margin: 0 auto;
  padding: 24px;
}

.sidebar { position: relative; }
.sidebar--left .ad-slot,
.sidebar--right .ad-slot { position: sticky; top: 68px; }

.main-content { min-width: 0; }

/* --- Hero --- */
.hero-section {
  text-align: center;
  padding: 48px 0 24px;
}

.hero-section h1 {
  font-family: "SF Pro Display", system-ui, -apple-system, sans-serif;
  font-size: 48px;
  font-weight: 600;
  line-height: 1.07;
  letter-spacing: -0.28px;
  margin-bottom: 8px;
}

.subtitle {
  font-size: 17px;
  color: var(--text-secondary);
  max-width: 600px;
  margin: 0 auto;
}

/* --- Controls Bar --- */
.controls-bar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 12px 0;
  margin-bottom: 16px;
  flex-wrap: wrap;
  gap: 12px;
}

.unit-selector {
  display: flex;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 9999px;
  overflow: hidden;
}

.unit-btn {
  background: none;
  border: none;
  color: var(--text-secondary);
  font-family: inherit;
  font-size: 14px;
  font-weight: 600;
  padding: 6px 16px;
  cursor: pointer;
  letter-spacing: -0.224px;
  transition: background 0.2s, color 0.2s;
}

.unit-btn.active {
  background: var(--accent);
  color: var(--on-primary);
}

.btn-login {
  display: flex;
  align-items: center;
  gap: 8px;
  background: var(--accent);
  color: var(--on-primary);
  border: none;
  border-radius: 9999px;
  padding: 8px 18px;
  font-family: inherit;
  font-size: 14px;
  font-weight: 400;
  cursor: pointer;
  letter-spacing: -0.224px;
  transition: transform 0.1s;
}
.btn-login:active { transform: scale(0.95); }

.user-info {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 14px;
  color: var(--text-secondary);
}

.user-avatar {
  width: 28px;
  height: 28px;
  border-radius: 50%;
  object-fit: cover;
}

.btn-logout {
  background: none;
  border: 1px solid var(--border);
  border-radius: 9999px;
  color: var(--text-secondary);
  font-family: inherit;
  font-size: 12px;
  padding: 4px 12px;
  cursor: pointer;
  letter-spacing: -0.12px;
}
.btn-logout:hover { color: var(--text-primary); border-color: var(--text-muted); }

/* --- Cards --- */
.card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 18px;
  padding: 24px;
  margin-bottom: 16px;
}

.card-title {
  font-family: "SF Pro Display", system-ui, -apple-system, sans-serif;
  font-size: 21px;
  font-weight: 600;
  line-height: 1.19;
  letter-spacing: 0.231px;
  margin-bottom: 16px;
}

/* --- Entry Form --- */
.entry-form .form-row,
.goal-form .form-row {
  display: flex;
  gap: 12px;
  align-items: flex-end;
  flex-wrap: wrap;
}

.form-group {
  flex: 1;
  min-width: 120px;
}

.form-group label {
  display: block;
  font-size: 14px;
  font-weight: 600;
  color: var(--text-secondary);
  margin-bottom: 6px;
  letter-spacing: -0.224px;
}

.form-group input,
.form-group select {
  width: 100%;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  color: var(--text-primary);
  font-family: inherit;
  font-size: 17px;
  padding: 10px 14px;
  letter-spacing: -0.374px;
  transition: border-color 0.2s;
}

.form-group input:focus,
.form-group select:focus {
  outline: none;
  border-color: var(--accent);
}

.height-input-group {
  display: flex;
  gap: 8px;
}

.height-input-group input { flex: 1; }
.height-input-group select { width: 60px; flex: none; }

/* --- Buttons --- */
.btn-primary {
  background: var(--accent);
  color: var(--on-primary);
  border: none;
  border-radius: 9999px;
  padding: 11px 22px;
  font-family: inherit;
  font-size: 17px;
  font-weight: 400;
  cursor: pointer;
  letter-spacing: -0.374px;
  white-space: nowrap;
  transition: transform 0.1s;
}
.btn-primary:active { transform: scale(0.95); }

.btn-secondary {
  background: transparent;
  color: var(--accent);
  border: 1px solid var(--accent);
  border-radius: 9999px;
  padding: 10px 22px;
  font-family: inherit;
  font-size: 17px;
  font-weight: 400;
  cursor: pointer;
  letter-spacing: -0.374px;
  white-space: nowrap;
  transition: transform 0.1s;
}
.btn-secondary:active { transform: scale(0.95); }

.btn-text {
  background: none;
  border: none;
  color: var(--accent);
  font-family: inherit;
  font-size: 14px;
  cursor: pointer;
  letter-spacing: -0.224px;
}
.btn-text:hover { color: var(--accent-hover); }

.btn-link {
  display: inline-block;
  font-size: 17px;
  font-weight: 400;
  color: var(--accent);
  margin-top: 12px;
}

/* --- Stats Grid --- */
.stats-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
  margin-bottom: 16px;
}

.stat-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 18px;
  padding: 16px;
  text-align: center;
}

.stat-label {
  display: block;
  font-size: 12px;
  font-weight: 400;
  color: var(--text-muted);
  letter-spacing: -0.12px;
  margin-bottom: 4px;
  text-transform: uppercase;
}

.stat-value {
  display: block;
  font-family: "SF Pro Display", system-ui, -apple-system, sans-serif;
  font-size: 24px;
  font-weight: 600;
  line-height: 1.1;
  letter-spacing: 0;
}

.stat-value.positive { color: var(--green); }
.stat-value.negative { color: var(--red); }

/* --- Progress Card --- */
.progress-bar-container {
  background: var(--bg);
  border-radius: 9999px;
  height: 8px;
  overflow: hidden;
  margin-bottom: 8px;
}

.progress-bar {
  height: 100%;
  background: var(--accent);
  border-radius: 9999px;
  transition: width 0.4s ease;
}

.progress-text {
  font-size: 14px;
  color: var(--text-secondary);
  letter-spacing: -0.224px;
}

/* --- Chart --- */
.chart-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 16px;
}
.chart-header .card-title { margin-bottom: 0; }

.chart-filters {
  display: flex;
  background: var(--bg);
  border-radius: 9999px;
  overflow: hidden;
  border: 1px solid var(--border);
}

.filter-btn {
  background: none;
  border: none;
  color: var(--text-secondary);
  font-family: inherit;
  font-size: 14px;
  font-weight: 600;
  padding: 6px 14px;
  cursor: pointer;
  letter-spacing: -0.224px;
  transition: background 0.2s, color 0.2s;
}

.filter-btn.active {
  background: var(--accent);
  color: var(--on-primary);
}

.chart-container { position: relative; }

#weightChart { width: 100%; height: 350px; display: block; }

.chart-empty {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 14px;
  color: var(--text-muted);
  pointer-events: none;
}

/* --- Log Table --- */
.log-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 16px;
}
.log-header .card-title { margin-bottom: 0; }
.log-actions { display: flex; gap: 12px; align-items: center; }

.table-wrapper { overflow-x: auto; }

.log-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 14px;
  letter-spacing: -0.224px;
}

.log-table th {
  text-align: left;
  color: var(--text-muted);
  font-weight: 400;
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  padding: 8px 12px;
  border-bottom: 1px solid var(--border);
}

.log-table td {
  padding: 10px 12px;
  border-bottom: 1px solid var(--border);
  color: var(--text-primary);
}

.log-table tbody tr:hover { background: var(--bg-hover); }

.table-empty {
  text-align: center;
  color: var(--text-muted);
  padding: 32px 12px;
}

.change-positive { color: var(--red); }
.change-negative { color: var(--green); }
.change-zero { color: var(--text-muted); }

.action-btn {
  background: none;
  border: none;
  color: var(--text-muted);
  cursor: pointer;
  font-size: 14px;
  padding: 4px 6px;
  border-radius: 4px;
  transition: color 0.2s;
}
.action-btn:hover { color: var(--red); }

/* --- BMI Card --- */
.bmi-result {
  display: flex;
  align-items: baseline;
  gap: 12px;
  margin-bottom: 8px;
}

.bmi-value {
  font-family: "SF Pro Display", system-ui, -apple-system, sans-serif;
  font-size: 40px;
  font-weight: 600;
  line-height: 1.1;
}

.bmi-category {
  font-size: 17px;
  color: var(--text-secondary);
}

.bmi-desc {
  font-size: 14px;
  color: var(--text-muted);
  letter-spacing: -0.224px;
}

/* --- Ad Slots --- */
.ad-slot {
  display: flex;
  justify-content: center;
  align-items: center;
  background: transparent;
  border-radius: 4px;
  overflow: hidden;
}

.ad-slot--inline {
  margin: 24px 0;
}

.ad-slot--bottom {
  margin: 24px 0 0;
}

/* --- Content / Educational --- */
.content-section {
  margin: 32px 0;
}

.content-section h2 {
  font-family: "SF Pro Display", system-ui, -apple-system, sans-serif;
  font-size: 28px;
  font-weight: 600;
  line-height: 1.14;
  letter-spacing: 0.196px;
  margin: 40px 0 16px;
}

.content-section h2:first-child { margin-top: 0; }

.content-section p {
  color: var(--text-secondary);
  margin-bottom: 16px;
}

.content-section ul {
  color: var(--text-secondary);
  margin: 0 0 16px 24px;
}

.content-section li { margin-bottom: 8px; }
.content-section li strong { color: var(--text-primary); }

/* --- FAQ --- */
.faq-section details {
  border: 1px solid var(--border);
  border-radius: 11px;
  margin-bottom: 8px;
  overflow: hidden;
}

.faq-section summary {
  font-size: 17px;
  font-weight: 600;
  padding: 16px 20px;
  cursor: pointer;
  list-style: none;
  position: relative;
  letter-spacing: -0.374px;
}

.faq-section summary::-webkit-details-marker { display: none; }

.faq-section summary::after {
  content: "+";
  position: absolute;
  right: 20px;
  top: 50%;
  transform: translateY(-50%);
  font-size: 20px;
  font-weight: 300;
  color: var(--text-muted);
}

.faq-section details[open] summary::after { content: "\2212"; }

.faq-answer {
  padding: 0 20px 16px;
}

.faq-answer p { margin-bottom: 8px; }
.faq-answer p:last-child { margin-bottom: 0; }

/* --- Cross-Links --- */
.cross-links {
  padding: 48px 0;
  border-top: 1px solid var(--border);
  margin-top: 16px;
}

.cross-links h2 {
  font-family: "SF Pro Display", system-ui, -apple-system, sans-serif;
  font-size: 24px;
  font-weight: 600;
  margin-bottom: 20px;
}

.cross-links-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 16px;
}

.cross-link-card {
  display: flex;
  flex-direction: column;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 18px;
  padding: 20px;
  color: var(--text-primary);
  transition: background 0.2s;
}
.cross-link-card:hover { background: var(--bg-hover); color: var(--text-primary); }

.cross-link-icon { font-size: 28px; margin-bottom: 8px; }
.cross-link-name { font-size: 17px; font-weight: 600; margin-bottom: 4px; letter-spacing: -0.374px; }
.cross-link-desc { font-size: 14px; color: var(--text-secondary); letter-spacing: -0.224px; }

/* --- Footer --- */
.global-footer {
  background: var(--canvas-parchment);
  border-top: 1px solid var(--border);
  padding: 32px;
  text-align: center;
}

.footer-links { margin-bottom: 12px; }
.footer-links a {
  color: var(--ink-muted-80);
  font-size: 12px;
  margin: 0 12px;
  letter-spacing: -0.12px;
}
.footer-links a:hover { color: var(--ink); }

.footer-copyright {
  font-size: 12px;
  color: var(--ink-muted-48);
  letter-spacing: -0.12px;
}

/* --- Modal --- */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.5);
  z-index: 200;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px;
}

.modal {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 18px;
  padding: 32px;
  max-width: 420px;
  width: 100%;
}

.modal h3 {
  font-family: "SF Pro Display", system-ui, -apple-system, sans-serif;
  font-size: 21px;
  font-weight: 600;
  margin-bottom: 12px;
}

.modal p {
  font-size: 14px;
  color: var(--text-secondary);
  margin-bottom: 20px;
  line-height: 1.47;
}

.modal-actions {
  display: flex;
  gap: 12px;
  justify-content: flex-end;
}

/* --- Responsive --- */
@media (max-width: 1100px) {
  .layout {
    grid-template-columns: 1fr 320px;
  }
  .sidebar--left { display: none; }
}

@media (max-width: 768px) {
  .layout {
    grid-template-columns: 1fr;
    padding: 12px;
    gap: 0;
  }

  .sidebar--left,
  .sidebar--right { display: none; }

  .global-header { padding: 0 16px; }
  .breadcrumb { display: none; }

  .hero-section {
    padding: 32px 0 16px;
  }

  .hero-section h1 {
    font-size: 34px;
    letter-spacing: -0.374px;
  }

  .stats-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .entry-form .form-row,
  .goal-form .form-row {
    flex-direction: column;
  }

  .form-group { min-width: 100%; }

  .btn-primary,
  .btn-secondary {
    width: 100%;
    text-align: center;
  }

  #weightChart { height: 250px; }

  .cross-links-grid {
    grid-template-columns: 1fr;
  }

  .content-section h2 {
    font-size: 24px;
  }
}

@media (max-width: 420px) {
  .hero-section h1 {
    font-size: 28px;
  }

  .stats-grid {
    grid-template-columns: 1fr 1fr;
    gap: 8px;
  }

  .stat-card { padding: 12px; }
  .stat-value { font-size: 20px; }
}