/* Modern NCE UI — Apple-inspired, minimal, adaptive */
:root {
  --bg: #0a0a0c;
  --surface: #0f1014;
  --card: #14161b;
  --text: #e7e7ea;
  --muted: #a1a1a7;
  --border: rgba(255,255,255,0.08);
  --shadow: 0 10px 30px rgba(0,0,0,0.4);
  --accent: #0a84ff; /* iOS Blue */
  --accent-2: #7c4dff; /* purple */
  --radius: 14px;
  --control-h: 34px; /* unified control height */
  --content-max: 780px; /* unified content width */
}

/* Fallback for browsers that don't support color-mix() */
@supports not (color: color-mix(in srgb, red, blue)) {
  .last-seen{ background: var(--accent); }
  .lesson-item:hover{ border-color: var(--accent); }
  .segmented.tabs{ background: rgba(10, 10, 12, 0.7); }
  .fav-btn:hover{ background: rgba(10, 132, 255, 0.1); }
  .fav-btn.active:hover{ background: rgba(10, 132, 255, 0.15); }
}

@media (prefers-color-scheme: light) {
  :root { --bg:#f5f5f7; --surface:#f8f8fa; --card:#ffffff; --text:#1d1d1f; --muted:#6e6e73; --border:rgba(0,0,0,0.08); --shadow:0 12px 30px rgba(0,0,0,0.08);} 
}

*{box-sizing:border-box}
html,body{height:100%}
/* Ensure hidden elements don't display (robust across browsers) */
[hidden]{display:none !important}
body{
  margin:0;
  font-family:-apple-system,BlinkMacSystemFont,"SF Pro Text","SF Pro Display","Helvetica Neue",Arial,"Microsoft YaHei",sans-serif;
  color:var(--text);
  background: linear-gradient(180deg,
               color-mix(in srgb, var(--bg) 98%, var(--accent) 2%),
               color-mix(in srgb, var(--bg) 98%, var(--accent-2) 2%)) fixed;
}

/* Subtle animated ambient layer with smooth fade-in */
body::before{
  content:""; position:fixed; inset:0; pointer-events:none; z-index:-1;
  background: radial-gradient(900px 600px at 15% 5%, color-mix(in srgb, var(--accent) 10%, transparent), transparent 60%),
              radial-gradient(900px 600px at 85% 0%, color-mix(in srgb, var(--accent-2) 8%, transparent), transparent 60%);
  opacity:0; animation: bgFade .9s ease-out forwards;
}

@keyframes bgFade { from { opacity:0 } to { opacity:.8 } }

@media (prefers-reduced-motion: reduce){
  body::before{ animation: none; opacity:.6 }
}

.container{max-width:1200px;margin:0 auto;padding:0 24px}

/* Header / Hero - Modern Apple style */
.hero{padding:60px 0 24px;text-align:center;position:relative}
.hero .brand{
  font-size:11px;
  color:var(--muted);
  letter-spacing:.1em;
  text-transform:uppercase;
  margin-bottom:12px;
  font-weight:600;
  opacity:0.8;
}
.hero h1{
  font-size:52px;
  line-height:1.1;
  letter-spacing:-.03em;
  margin:0 0 12px;
  font-weight:700;
  background: linear-gradient(135deg, color-mix(in srgb, var(--text) 90%, var(--accent) 10%), color-mix(in srgb, var(--accent-2) 60%, var(--text) 40%));
  -webkit-background-clip:text;
  background-clip:text;
  color:transparent;
}
.hero p{color:var(--muted);margin:0;font-size:16px;font-weight:500}
.hero .subtitle{
  margin-top:8px;
  margin-bottom:16px;
  font-size:15px;
  color:var(--muted);
  letter-spacing:0.03em;
  font-weight:500;
  opacity:0.9;
}
/* badges removed per design feedback */

/* Back/Speed buttons inline with player — unify control height with audio */
.back-inline{display:inline-flex;align-items:center;gap:6px;height:var(--control-h);padding:0 12px;border-radius:999px;border:1px solid var(--border);background:var(--surface);box-shadow:var(--shadow);color:inherit;flex:0 0 auto;}
.back-inline svg{width:14px;height:14px}
.back-inline[aria-pressed="true"]{background:color-mix(in srgb, var(--accent) 20%, var(--surface));color:var(--accent)}
/* Compact, icon-only button variant */
.back-inline.icon-only{padding:0 10px}
.back-inline.icon-only svg{width:16px;height:16px;fill:none;stroke:currentColor;stroke-width:1.6}

/* Segmented control */
.segmented{display:inline-flex;gap:6px;background:color-mix(in srgb, var(--bg) 70%, transparent);border:1px solid var(--border);border-radius:999px;padding:4px;margin-top:14px;backdrop-filter:saturate(120%) blur(10px)}
.segmented .seg{appearance:none;border:0;background:transparent;color:var(--text);font-size:12px;padding:8px 12px;border-radius:999px;cursor:pointer;text-decoration:none;transition:background .15s ease, color .15s ease; white-space:nowrap}
.segmented .seg.active{background:color-mix(in srgb, var(--accent) 20%, var(--card));box-shadow:var(--shadow)}
/* tiny segmented for minimal toolbar switches */
.segmented.tiny{padding:2px;gap:2px}
.segmented.tiny .seg{font-size:11px;padding:6px 8px}

/* Smaller top tabs for book switch - Apple style */
.segmented.tabs{
  padding:6px;
  gap:4px;
  margin-top:20px;
  display:inline-flex;
  background:color-mix(in srgb, var(--bg) 70%, transparent);
  border-radius:16px;
  border:1px solid var(--border);
  backdrop-filter:saturate(120%) blur(10px);
}
.seg-wrap{max-width:var(--content-max); margin:0 auto; display:flex; justify-content:center}
.segmented.tabs .seg{
  font-size:13px;
  font-weight:600;
  padding:10px 20px;
  border-radius:12px;
  transition:all .2s cubic-bezier(0.25, 0.46, 0.45, 0.94);
  letter-spacing:0.3px;
}
.segmented.tabs .seg:hover{
  background:color-mix(in srgb, var(--surface) 80%, transparent);
  transform:scale(1.02);
}
.segmented.tabs .seg.active{
  background:var(--surface);
  color:var(--accent);
  box-shadow:0 4px 12px rgba(0,0,0,0.1);
}

@media (max-width: 768px){
  .hero{padding:40px 0 20px}
  .hero h1{font-size:42px}
  .hero .subtitle{font-size:14px}
  .segmented.tabs{
    gap:2px;
    padding:4px;
    margin-top:16px;
  }
  .segmented.tabs .seg{
    font-size:12px;
    padding:8px 16px;
  }
  .lessons-grid{grid-template-columns:1fr;gap:6px}
  .lesson-item{padding:16px}
  .lesson-title{font-size:16px}
}

/* Book cards grid */
.grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(260px,1fr));gap:18px;padding:26px 0 64px}
.card{position:relative;border:1px solid var(--border);background:var(--surface);border-radius:var(--radius);box-shadow:var(--shadow);overflow:hidden;transition:transform .2s ease, box-shadow .2s ease}
.card:hover{transform:translateY(-4px)}
.card img{width:100%;height:160px;object-fit:cover;display:block;opacity:.9}
.card .body{padding:14px 14px 16px}
.card .title{font-weight:700;margin:6px 0 4px}
.card .sub{font-size:12px;color:var(--muted)}


/* Last seen section - integrated into lessons */
.last-seen-section{margin-bottom:12px}

/* Lessons container */
.lessons{padding:10px 0 40px; max-width:var(--content-max); margin:0 auto}

/* Lessons grid - Apple-inspired design */
.lessons-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(320px,1fr));gap:8px}
.lesson-item{
  background:var(--surface);
  border-radius:16px;
  border:1px solid var(--border);
  padding:20px;
  text-decoration:none;
  color:inherit;
  transition:all .2s cubic-bezier(0.25, 0.46, 0.45, 0.94);
  position:relative;
  overflow:hidden;
  display:flex;
  align-items:center;
  justify-content:space-between;
}
.lesson-item:hover{
  transform:scale(1.02);
  box-shadow:0 8px 25px rgba(0,0,0,0.12);
  border-color:color-mix(in srgb, var(--accent) 20%, var(--border));
}
.lesson-item:active{
  transform:scale(1.01);
}
.lesson-content{display:flex;flex-direction:column;justify-content:center;flex:1;min-width:0;height:100%}
.lesson-num{
  font-size:11px;
  font-weight:600;
  color:var(--accent);
  letter-spacing:0.5px;
  text-transform:uppercase;
  margin-bottom:4px;
}
.lesson-title{
  font-size:17px;
  font-weight:600;
  line-height:1.3;
  color:var(--text);
}

/* Favorite button on lesson item - Apple style */
.fav-btn{
  flex:0 0 auto;
  width:32px;
  height:32px;
  display:inline-flex;
  align-items:center;
  justify-content:center;
  background:transparent;
  color:var(--muted);
  opacity:0;
  transition:all .2s cubic-bezier(0.25, 0.46, 0.45, 0.94);
  cursor:pointer;
  padding:0;
  margin:0;
  border:none;
  outline:none;
  border-radius:8px;
}
.lesson-item:hover .fav-btn{opacity:0.5}
.fav-btn:hover{
  opacity:1;
  color:var(--accent);
  background:color-mix(in srgb, var(--accent) 10%, transparent);
  transform:scale(1.1);
}
.fav-btn.active{
  opacity:1;
  color:var(--accent);
}
.fav-btn.active:hover{
  background:color-mix(in srgb, var(--accent) 15%, transparent);
}
.fav-btn svg{width:18px;height:18px;fill:currentColor}

/* Lesson page */
.toolbar{position:sticky;top:0;z-index:10;background:transparent;padding:6px 0 4px;border-bottom:none}
.toolbar .row{display:flex;align-items:center;justify-content:flex-end;gap:10px}
.toolbar .info{display:flex;align-items:center;gap:10px}
.toolbar .title{font-weight:700}
.toolbar .sub{font-size:12px;color:var(--muted)}
.controls{display:flex;align-items:center;gap:8px}
.btn{appearance:none;border:1px solid var(--border);background:color-mix(in srgb, var(--card) 90%, transparent);backdrop-filter:saturate(120%) blur(10px);color:inherit;border-radius:10px;padding:6px 10px;cursor:pointer}
.btn:hover{transform:translateY(-1px)}

.sentences{padding:12px 0 22px; max-width:var(--content-max); margin:0 auto}
.sentence{border:1px solid var(--border);background:var(--surface);border-radius:var(--radius);box-shadow:var(--shadow);padding:12px 14px;margin:10px 0;cursor:pointer;transition:transform .12s ease}
.sentence:hover{transform:translateY(-2px)}
.sentence.active{border-left:4px solid var(--accent);background:color-mix(in srgb, var(--accent) 10%, var(--card))}
.en{font-weight:700;font-size:18px}
.cn{font-size:13px;color:var(--muted);margin-top:4px}
.lang-en .cn{display:none}
.lang-cn .en{display:none}

/* Auto Continue Card */
.auto-continue-card{display:inline-flex; gap:4px; background:color-mix(in srgb, var(--bg) 70%, transparent); border:1px solid var(--border); border-radius:999px; padding:4px; backdrop-filter:saturate(120%) blur(10px); animation:fadeIn 0.2s ease-out; height:var(--control-h); align-items:center;}
.auto-continue-option{display:flex; align-items:center; gap:0; border-radius:999px; transition:all 0.15s ease;}
.auto-continue-option input[type="radio"]{appearance:none; position:absolute; opacity:0;}
.auto-continue-option label{display:block; padding:6px 10px; font-size:12px; color:var(--text); cursor:pointer; border-radius:999px; transition:all 0.15s ease; margin:0; white-space:nowrap;}
.auto-continue-option input[type="radio"]:checked + label{background:color-mix(in srgb, var(--accent) 20%, var(--card)); color:var(--accent); box-shadow:var(--shadow);}
.auto-continue-option:hover label{background:color-mix(in srgb, var(--surface) 80%, transparent);}

@keyframes fadeIn{from{opacity:0; transform:scale(0.95);} to{opacity:1; transform:scale(1);}}
@keyframes slideDown{from{opacity:0; transform:translate(-50%, -20px);} to{opacity:1; transform:translate(-50%, 0);}}
@keyframes slideUp{from{opacity:1; transform:translate(-50%, 0);} to{opacity:0; transform:translate(-50%, -20px);}}

/* Responsive auto continue */
@media (max-width: 768px){
  .auto-continue-card{gap:2px; padding:3px;}
  .auto-continue-option label{padding:5px 8px; font-size:11px;}
}

/* Audio */
.player{display:flex; align-items:center; gap:8px; margin:6px auto 10px; padding:0; background:transparent; border:none; box-shadow:none; min-height:var(--control-h); max-width:var(--content-max); width:100%;}
.player audio{display:block; flex:1; width:100%; max-width:var(--content-max); height:var(--control-h); accent-color: var(--accent); background: transparent;}

/* Lesson bottom navigation */
.lesson-nav{display:flex; justify-content:space-between; gap:10px; padding:6px 0 16px; max-width:var(--content-max); margin:0 auto}
.btn-nav{display:inline-flex; align-items:center; justify-content:center; padding:8px 14px; min-width:96px;
  border-radius:999px; border:1px solid var(--border); background:var(--surface); color:inherit; text-decoration:none; box-shadow:var(--shadow);
  transition:transform .15s ease, box-shadow .15s ease}
.btn-nav:hover{transform:translateY(-2px); box-shadow:var(--shadow)}

/* Footer - Modern Apple style */
footer{
  padding:32px 0;
  color:var(--muted);
  text-align:center;
  margin-top:40px;
  border-top:1px solid var(--border);
}
footer p{
  margin:6px 0;
  text-align:center;
  font-size:14px;
  font-weight:500;
}
.repo{margin-bottom:8px}
.gh-link{
  display:inline-flex;
  align-items:center;
  gap:6px;
  color:var(--muted);
  text-decoration:none;
  transition:all .2s ease;
  padding:8px 12px;
  border-radius:8px;
}
.gh-link:hover{
  color:var(--text);
  background:color-mix(in srgb, var(--surface) 50%, transparent);
}
.byline a, .thanks a{
  color:var(--muted);
  text-decoration:none;
  transition:color .2s ease;
}
.byline a:hover, .thanks a:hover{
  color:var(--accent);
}

/* Sections on index (e.g., recents) */
.section{ padding:6px 0 8px }
.section-title{ font-size:12px; color:var(--muted); letter-spacing:.02em; margin:4px 2px 8px; }

/* Last seen card - 融入整体设计 */
.last-seen{
  background:var(--surface);
  border-radius:16px;
  border:1px solid var(--border);
  border-left:4px solid var(--accent);
  padding:20px;
  text-decoration:none;
  color:inherit;
  transition:all .2s cubic-bezier(0.25, 0.46, 0.45, 0.94);
  position:relative;
  display:flex;
  align-items:center;
  justify-content:space-between;
  margin-bottom:8px;
}
.last-seen:hover{
  transform:scale(1.02);
  box-shadow:0 8px 25px rgba(0,0,0,0.12);
  border-color:color-mix(in srgb, var(--accent) 30%, var(--border));
  border-left-color:var(--accent);
}
.last-seen:active{
  transform:scale(1.01);
}
.last-seen .lesson-content::before{
  content:'继续学习';
  position:absolute;
  top:-6px;
  left:0;
  font-size:10px;
  font-weight:600;
  color:var(--accent);
  background:var(--surface);
  padding:0 6px;
  border-radius:4px;
  letter-spacing:0.5px;
  text-transform:uppercase;
}

/* Links */
a{color:inherit}
a{text-decoration:none}

/* GitHub icon link */
.gh-link svg{width:18px;height:18px;fill:currentColor;opacity:.8;vertical-align:middle;transition:opacity .2s ease, transform .2s ease}
.gh-link:hover svg{opacity:1;transform:translateY(-1px)}

/* Smooth theme transitions for surfaces */
body, .card, .lesson-item, .sentence{ transition: background-color .35s ease, color .35s ease, box-shadow .35s ease, border-color .35s ease; }

/* Settings Panel (Apple-like modal sheet) */
.settings-overlay{position:fixed; inset:0; background:color-mix(in srgb, var(--bg) 30%, rgba(0,0,0,0.35)); backdrop-filter:saturate(130%) blur(12px); -webkit-backdrop-filter:saturate(130%) blur(12px); z-index:900;}
.settings-panel{position:fixed; left:50%; top:50%; transform:translate(-50%,-52%) scale(.98); width:min(92vw, 520px); max-height:min(86vh, 680px); overflow:auto; background:var(--surface); border:1px solid var(--border); border-radius:16px; box-shadow:var(--shadow); z-index:901; padding:12px 14px; display:flex; flex-direction:column; gap:10px; opacity:0;}
.settings-overlay, .settings-panel{transition:opacity .22s ease, transform .22s ease}
.settings-overlay{opacity:0}
.settings-overlay.show{opacity:1}
.settings-panel.show{opacity:1; transform:translate(-50%,-50%) scale(1)}
.settings-header{display:flex; align-items:center; justify-content:space-between; padding:4px 6px 2px 6px; border-bottom:1px solid color-mix(in srgb, var(--border) 70%, transparent);}
.settings-header h2{font-size:16px; font-weight:600; margin:6px 0;}
.icon-btn{display:inline-flex; align-items:center; justify-content:center; width:28px; height:28px; border-radius:8px; border:1px solid var(--border); background:var(--surface); color:inherit; box-shadow:var(--shadow); cursor:pointer}
.icon-btn:hover{background:color-mix(in srgb, var(--surface) 80%, transparent)}
.settings-body{display:flex; flex-direction:column; gap:10px; padding:4px}
.settings-group{display:flex; align-items:flex-start; justify-content:space-between; gap:12px; padding:12px; border:1px solid var(--border); border-radius:12px; background:color-mix(in srgb, var(--bg) 70%, transparent)}
.settings-left{display:flex; flex-direction:column; gap:4px; min-width:0;}
.settings-label{font-size:13px; color:var(--text); font-weight:600}
.settings-desc{font-size:12px; color:var(--muted); line-height:1.5}
.settings-control{display:flex; align-items:center; gap:8px}
.settings-footer{display:flex; justify-content:space-between; padding:6px}
.settings-control #modeToggle{display:none}

/* Make inline controls adapt nicely inside panel */
.settings-panel .back-inline{height:28px; padding:0 10px}
.settings-panel .auto-continue-card{height:auto; padding:6px}
.settings-panel .auto-continue-option label{padding:6px 10px}

/* Hide overflow-prone inline controls on small screens (defensive) */
@media (max-width: 560px){
  .player .back-inline:not(#backLink):not(#settingsBtn){display:none}
}