/* ============================================================
   Glow UI - Online Whiteboard
   Dark mode default, light mode via [data-theme="light"]
   ============================================================ */

:root {
  --bg: #121212;
  --bg-card: #181818;
  --bg-hover: #282828;
  --border: #404040;
  --text-muted: #535353;
  --text-secondary: #B3B3B3;
  --text-primary: #FFFFFF;
  --green: #1DB954;
  --green-hover: #1ed760;
  --red: #C0392B;
  --font: 'Inter', sans-serif;
}

[data-theme="light"] {
  --bg: #FFFFFF;
  --bg-card: #F5F5F5;
  --bg-hover: #E8E8E8;
  --border: #D0D0D0;
  --text-muted: #999999;
  --text-secondary: #666666;
  --text-primary: #121212;
  --green: #1DB954;
  --green-hover: #17a349;
}

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

html { scroll-behavior: smooth; }

body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text-primary);
  min-height: 100vh;
  line-height: 1.6;
  transition: background 0.2s, color 0.2s;
}

/* ---- Header ---- */
.header {
  background: rgba(18, 18, 18, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  height: 64px;
  position: sticky;
  top: 0;
  z-index: 100;
  border-bottom: 1px solid var(--border);
}

[data-theme="light"] .header {
  background: rgba(255, 255, 255, 0.9);
}

.header-inner {
  max-width: 1440px;
  margin: 0 auto;
  padding: 0 24px;
  height: 100%;
  display: flex;
  align-items: center;
  gap: 24px;
}

.logo {
  color: var(--green);
  font-weight: 800;
  font-size: 20px;
  text-decoration: none;
  white-space: nowrap;
  flex-shrink: 0;
}

.header-nav {
  display: flex;
  gap: 8px;
  flex: 1;
}

.header-nav a {
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 14px;
  font-weight: 500;
  padding: 6px 12px;
  border-radius: 4px;
  transition: color 0.15s;
}

.header-nav a:hover,
.header-nav a.active {
  color: var(--text-primary);
}

.theme-toggle {
  background: var(--bg-card);
  border: 1px solid var(--border);
  color: var(--text-secondary);
  width: 36px;
  height: 36px;
  border-radius: 50%;
  cursor: pointer;
  font-size: 16px;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  transition: background 0.15s, color 0.15s;
}

.theme-toggle:hover {
  background: var(--bg-hover);
  color: var(--text-primary);
}

/* ---- 3-column layout ---- */
.layout-3col {
  display: grid;
  grid-template-columns: 180px 1fr 300px;
  gap: 24px;
  max-width: 1440px;
  margin: 0 auto;
  padding: 32px 24px;
  align-items: start;
}

.sidebar {
  position: sticky;
  top: 88px;
}

/* ---- Main content ---- */
.main-content {
  min-width: 0;
}

.page-header {
  margin-bottom: 24px;
}

.page-header h1 {
  font-size: 36px;
  font-weight: 800;
  color: var(--text-primary);
  line-height: 1.2;
  margin-bottom: 8px;
}

.page-subtitle {
  font-size: 15px;
  color: var(--text-secondary);
}

/* ---- Toolbar ---- */
.wb-toolbar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 16px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 10px 12px;
  margin-bottom: 12px;
}

.wb-tool-group {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 6px;
}

.wb-tool-group + .wb-tool-group {
  border-left: 1px solid var(--border);
  padding-left: 16px;
}

.wb-tool-btn {
  background: transparent;
  border: 1px solid var(--border);
  color: var(--text-secondary);
  width: 38px;
  height: 38px;
  border-radius: 6px;
  cursor: pointer;
  font-size: 16px;
  font-weight: 700;
  font-family: var(--font);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background 0.12s, color 0.12s, border-color 0.12s;
}

.wb-tool-btn:hover {
  background: var(--bg-hover);
  color: var(--text-primary);
  border-color: var(--green);
}

.wb-tool-btn.is-active {
  background: var(--green);
  color: #000000;
  border-color: var(--green);
}

.wb-props {
  flex: 1;
  flex-wrap: wrap;
  justify-content: flex-end;
  gap: 14px;
}

.wb-prop {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 13px;
  color: var(--text-secondary);
  cursor: pointer;
}

.wb-prop-label {
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  font-size: 11px;
  color: var(--text-secondary);
}

.wb-prop input[type="color"] {
  width: 36px;
  height: 32px;
  border: 1px solid var(--border);
  border-radius: 6px;
  background: transparent;
  padding: 2px;
  cursor: pointer;
}

.wb-prop--slider {
  min-width: 160px;
}

.wb-prop input[type="range"] {
  flex: 1;
  accent-color: var(--green);
  cursor: pointer;
}

.wb-prop-value {
  width: 24px;
  text-align: right;
  font-variant-numeric: tabular-nums;
  color: var(--text-primary);
  font-weight: 600;
}

.wb-prop--checkbox input {
  accent-color: var(--green);
  cursor: pointer;
  width: 16px;
  height: 16px;
}

/* ---- Canvas wrap ---- */
.wb-canvas-wrap {
  position: relative;
  width: 100%;
  aspect-ratio: 4 / 3;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 8px;
  overflow: hidden;
  box-shadow: 0 4px 32px rgba(0, 0, 0, 0.35);
  margin-bottom: 12px;
}

#wbCanvas {
  display: block;
  width: 100%;
  height: 100%;
  touch-action: none;
  cursor: crosshair;
  background: #FFFFFF;
}

/* ---- Action buttons ---- */
.wb-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 24px;
}

.wb-btn {
  background: var(--bg-card);
  border: 1px solid var(--border);
  color: var(--text-primary);
  padding: 9px 18px;
  border-radius: 9999px;
  font-family: var(--font);
  font-size: 13px;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.12s, border-color 0.12s, color 0.12s, transform 0.12s;
}

.wb-btn:hover {
  background: var(--bg-hover);
  border-color: var(--green);
}

.wb-btn:active {
  transform: scale(0.97);
}

.wb-btn:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}

.wb-btn--primary {
  background: var(--green);
  border-color: var(--green);
  color: #000000;
}

.wb-btn--primary:hover {
  background: var(--green-hover);
  border-color: var(--green-hover);
  color: #000000;
}

.wb-btn--danger:hover {
  border-color: var(--red);
  color: var(--red);
}

/* ---- Mobile ad ---- */
.ad-slot--mobile {
  display: none;
  margin-bottom: 24px;
}

/* ---- Info & FAQ sections ---- */
.info-section {
  margin-bottom: 40px;
}

.info-section h2,
.faq-section h2,
.cross-links h2 {
  font-size: 22px;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 8px;
}

.info-section h3 {
  font-size: 17px;
  font-weight: 600;
  color: var(--text-primary);
  margin: 20px 0 8px;
}

.info-section p,
.faq-item p {
  font-size: 15px;
  color: var(--text-secondary);
  line-height: 1.75;
  margin-bottom: 12px;
}

.faq-section {
  margin-bottom: 40px;
}

.faq-item {
  border-top: 1px solid var(--border);
  padding: 20px 0;
}

.faq-item h3 {
  font-size: 16px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 10px;
}

/* ---- Cross-links ---- */
.cross-links {
  padding: 32px 0;
  border-top: 1px solid var(--border);
  margin-bottom: 24px;
}

.cross-links-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
  margin-top: 16px;
}

.service-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 16px;
  display: flex;
  flex-direction: column;
  gap: 6px;
  text-decoration: none;
  transition: background 0.15s, border-color 0.15s, transform 0.15s;
}

.service-card:hover {
  background: var(--bg-hover);
  border-color: var(--green);
  transform: scale(1.02);
}

.service-icon {
  font-size: 24px;
}

.service-name {
  font-size: 14px;
  font-weight: 600;
  color: var(--text-primary);
}

.service-desc {
  font-size: 12px;
  color: var(--text-secondary);
}

/* ---- Ad slots ---- */
.ad-slot {
  display: flex;
  justify-content: center;
  align-items: center;
  background: var(--bg-card);
  border-radius: 4px;
  overflow: hidden;
}

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

.ad-slot--sticky {
  position: sticky;
  top: 88px;
}

/* ---- Footer ---- */
.footer {
  background: var(--bg);
  border-top: 1px solid var(--border);
  padding: 32px 24px;
  text-align: center;
}

.footer-links {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 8px 24px;
  margin-bottom: 12px;
}

.footer-links a {
  color: var(--text-secondary);
  font-size: 14px;
  text-decoration: none;
  transition: color 0.15s;
}

.footer-links a:hover {
  color: var(--text-primary);
}

.footer-copyright {
  font-size: 13px;
  color: var(--text-muted);
}

/* ---- Responsive ---- */

/* 1100px: collapse right sidebar */
@media (max-width: 1100px) {
  .layout-3col {
    grid-template-columns: 180px 1fr;
  }
  .sidebar-right {
    display: none;
  }
  .ad-slot--mobile {
    display: flex;
  }
}

/* 1024px: also collapse left sidebar (per spec) */
@media (max-width: 1024px) {
  .layout-3col {
    grid-template-columns: 1fr;
    padding: 20px 16px;
    gap: 16px;
  }
  .sidebar-left {
    display: none;
  }
  .ad-slot--mobile {
    display: flex;
  }
}

/* 768px */
@media (max-width: 768px) {
  .page-header h1 {
    font-size: 28px;
  }
  .cross-links-grid {
    grid-template-columns: 1fr 1fr;
  }
  .header-nav {
    display: none;
  }
  .wb-toolbar {
    gap: 10px;
    padding: 8px;
  }
  .wb-tool-group + .wb-tool-group {
    border-left: none;
    padding-left: 0;
    border-top: 1px solid var(--border);
    padding-top: 8px;
    width: 100%;
  }
  .wb-props {
    justify-content: flex-start;
  }
  .wb-prop--slider {
    min-width: 140px;
  }
}

@media (max-width: 480px) {
  .cross-links-grid {
    grid-template-columns: 1fr;
  }
  .wb-tool-btn {
    width: 36px;
    height: 36px;
  }
  .wb-btn {
    flex: 1 1 calc(33.333% - 6px);
    padding: 9px 10px;
    font-size: 12px;
  }
}