@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&family=Fira+Code:wght@400;500&display=swap');

:root {
  --left-w: 250px;
  --right-w: 420px;
  --bg: #0d1117;
  --bg-card: #161b22;
  --bg-hover: #1f2937;
  --border: #30363d;
  --text-1: #f0f6fc;
  --text-2: #8b949e;
  --text-3: #6e7681;
  --html-clr: #f16529;
  --html-dark: #e44d26;
  --css-clr: #4a8fff;
  --css-dark: #264de4;
  --js-clr: #f0db4f;
  --js-dark: #c9b800;
  --react-clr: #61dafb;
  --react-dark: #0ea5e9;
  --tw-clr: #34d399;
  --tw-dark: #059669;
  --radius: 10px;
  --shadow: 0 4px 24px rgba(0,0,0,0.4);
}

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

html { font-size: 16px; }

body {
  font-family: 'Inter', sans-serif;
  background: var(--bg);
  color: var(--text-1);
  height: 100vh;
  overflow: hidden;
}

/* ─── APP GRID ─── */
.app {
  display: grid;
  grid-template-columns: var(--left-w) 1fr 0px;
  grid-template-rows: 100vh;
  height: 100vh;
  transition: grid-template-columns 0.35s cubic-bezier(.4,0,.2,1);
}

.app.right-open {
  grid-template-columns: var(--left-w) 1fr var(--right-w);
}

/* ─── LEFT SIDEBAR ─── */
.left-sidebar {
  background: var(--bg-card);
  border-right: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  overflow: hidden;
  z-index: 10;
}

.sidebar-logo {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 22px 20px 18px;
  border-bottom: 1px solid var(--border);
}

.logo-icon { font-size: 22px; }

.logo-text {
  font-size: 15px;
  font-weight: 700;
  color: var(--text-1);
  letter-spacing: -0.3px;
}

.sidebar-nav {
  padding: 16px 12px;
  flex: 1;
  overflow-y: auto;
}

.nav-label {
  font-size: 10px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 1px;
  color: var(--text-3);
  padding: 0 8px;
  margin-bottom: 8px;
}

.nav-links { list-style: none; display: flex; flex-direction: column; gap: 4px; }

.nav-link {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 12px;
  border-radius: 8px;
  text-decoration: none;
  color: var(--text-2);
  font-size: 14px;
  font-weight: 500;
  transition: all 0.2s;
  position: relative;
}

.nav-link:hover { background: var(--bg-hover); color: var(--text-1); }

.nav-link-icon { font-size: 18px; width: 24px; text-align: center; }

/* Page-specific active states */
.page-html .nav-link.active,
.page-html .nav-link:hover { color: var(--html-clr); }
.page-html .nav-link.active { background: rgba(241,101,41,0.12); }

.page-css .nav-link.active,
.page-css .nav-link:hover { color: var(--css-clr); }
.page-css .nav-link.active { background: rgba(74,143,255,0.12); }

.page-js .nav-link.active,
.page-js .nav-link:hover { color: var(--js-clr); }
.page-js .nav-link.active { background: rgba(240,219,79,0.12); }

.page-react .nav-link.active,
.page-react .nav-link:hover { color: var(--react-clr); }
.page-react .nav-link.active { background: rgba(97,218,251,0.12); }

.page-tw .nav-link.active,
.page-tw .nav-link:hover { color: var(--tw-clr); }
.page-tw .nav-link.active { background: rgba(52,211,153,0.12); }

.sidebar-footer {
  padding: 16px 20px;
  border-top: 1px solid var(--border);
  font-size: 11px;
  color: var(--text-3);
  line-height: 1.5;
}

/* ─── MAIN CONTENT ─── */
.main-content {
  overflow-y: auto;
  padding: 0;
  display: flex;
  flex-direction: column;
}

/* Page Hero */
.page-hero {
  padding: 40px 40px 30px;
  border-bottom: 1px solid var(--border);
  position: relative;
  overflow: hidden;
}

.page-hero::before {
  content: '';
  position: absolute;
  inset: 0;
  opacity: 0.05;
  pointer-events: none;
}

.page-html .page-hero::before { background: radial-gradient(ellipse at 20% 50%, var(--html-clr), transparent 60%); }
.page-css .page-hero::before { background: radial-gradient(ellipse at 20% 50%, var(--css-clr), transparent 60%); }
.page-js .page-hero::before { background: radial-gradient(ellipse at 20% 50%, var(--js-clr), transparent 60%); }
.page-react .page-hero::before { background: radial-gradient(ellipse at 20% 50%, var(--react-clr), transparent 60%); }
.page-tw .page-hero::before { background: radial-gradient(ellipse at 20% 50%, var(--tw-clr), transparent 60%); }

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 4px 12px;
  border-radius: 100px;
  font-size: 12px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  margin-bottom: 14px;
}

.page-html .hero-badge { background: rgba(241,101,41,0.15); color: var(--html-clr); border: 1px solid rgba(241,101,41,0.3); }
.page-css .hero-badge { background: rgba(74,143,255,0.15); color: var(--css-clr); border: 1px solid rgba(74,143,255,0.3); }
.page-js .hero-badge { background: rgba(240,219,79,0.15); color: var(--js-clr); border: 1px solid rgba(240,219,79,0.3); }
.page-react .hero-badge { background: rgba(97,218,251,0.15); color: var(--react-clr); border: 1px solid rgba(97,218,251,0.3); }
.page-tw .hero-badge { background: rgba(52,211,153,0.15); color: var(--tw-clr); border: 1px solid rgba(52,211,153,0.3); }

.hero-title {
  font-size: 36px;
  font-weight: 800;
  letter-spacing: -1px;
  margin-bottom: 10px;
  line-height: 1.1;
}

.page-html .hero-title { color: var(--html-clr); }
.page-css .hero-title { color: var(--css-clr); }
.page-js .hero-title { color: var(--js-clr); }
.page-react .hero-title { color: var(--react-clr); }
.page-tw .hero-title { color: var(--tw-clr); }

.hero-sub {
  font-size: 15px;
  color: var(--text-2);
  max-width: 500px;
  line-height: 1.6;
}

.hero-stats {
  display: flex;
  gap: 24px;
  margin-top: 20px;
}

.stat {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.stat-num {
  font-size: 22px;
  font-weight: 700;
  color: var(--text-1);
}

.stat-label { font-size: 11px; color: var(--text-3); text-transform: uppercase; letter-spacing: 0.5px; }

/* Topics Section */
.topics-section { padding: 30px 40px; flex: 1; }

.topics-heading {
  font-size: 14px;
  font-weight: 600;
  color: var(--text-3);
  text-transform: uppercase;
  letter-spacing: 0.8px;
  margin-bottom: 18px;
}

.topics-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: 12px;
}

.topic-btn {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px 18px;
  cursor: pointer;
  display: flex;
  align-items: flex-start;
  gap: 12px;
  text-align: left;
  transition: all 0.2s;
  color: var(--text-1);
  position: relative;
  overflow: hidden;
}

.topic-btn::before {
  content: '';
  position: absolute;
  left: 0; top: 0; bottom: 0;
  width: 3px;
  border-radius: 3px 0 0 3px;
  opacity: 0;
  transition: opacity 0.2s;
}

.page-html .topic-btn::before { background: var(--html-clr); }
.page-css .topic-btn::before { background: var(--css-clr); }
.page-js .topic-btn::before { background: var(--js-clr); }
.page-react .topic-btn::before { background: var(--react-clr); }
.page-tw .topic-btn::before { background: var(--tw-clr); }

.topic-btn:hover {
  border-color: transparent;
  transform: translateY(-2px);
  box-shadow: var(--shadow);
}

.topic-btn:hover::before { opacity: 1; }

.page-html .topic-btn:hover { background: rgba(241,101,41,0.08); }
.page-css .topic-btn:hover { background: rgba(74,143,255,0.08); }
.page-js .topic-btn:hover { background: rgba(240,219,79,0.08); }
.page-react .topic-btn:hover { background: rgba(97,218,251,0.08); }
.page-tw .topic-btn:hover { background: rgba(52,211,153,0.08); }

.topic-btn.active::before { opacity: 1; }
.page-html .topic-btn.active { background: rgba(241,101,41,0.12); border-color: rgba(241,101,41,0.3); }
.page-css .topic-btn.active { background: rgba(74,143,255,0.12); border-color: rgba(74,143,255,0.3); }
.page-js .topic-btn.active { background: rgba(240,219,79,0.12); border-color: rgba(240,219,79,0.3); }
.page-react .topic-btn.active { background: rgba(97,218,251,0.12); border-color: rgba(97,218,251,0.3); }
.page-tw .topic-btn.active { background: rgba(52,211,153,0.12); border-color: rgba(52,211,153,0.3); }

.topic-btn-icon { font-size: 22px; flex-shrink: 0; margin-top: 1px; }

.topic-btn-text { flex: 1; }

.topic-btn-title { font-size: 13px; font-weight: 600; line-height: 1.3; margin-bottom: 4px; }

.topic-btn-num {
  font-size: 11px;
  color: var(--text-3);
}

/* ─── RIGHT SIDEBAR ─── */
.right-sidebar {
  background: var(--bg-card);
  border-left: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  overflow: hidden;
  position: relative;
}

.right-empty {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  height: 100%;
  gap: 12px;
  color: var(--text-3);
  padding: 40px;
  text-align: center;
}

.right-empty-icon { font-size: 48px; opacity: 0.4; }
.right-empty-title { font-size: 15px; font-weight: 600; color: var(--text-2); }
.right-empty-sub { font-size: 13px; line-height: 1.5; }

.right-content {
  display: flex;
  flex-direction: column;
  height: 100%;
  overflow: hidden;
}

/* Topic Header in Right Sidebar */
.topic-hdr {
  padding: 20px 20px 16px;
  border-bottom: 1px solid var(--border);
  flex-shrink: 0;
}

.topic-hdr-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  margin-bottom: 12px;
}

.topic-hdr-icon { font-size: 28px; }

.topic-hdr-close {
  background: none;
  border: 1px solid var(--border);
  color: var(--text-2);
  width: 30px;
  height: 30px;
  border-radius: 6px;
  cursor: pointer;
  font-size: 14px;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.2s;
  flex-shrink: 0;
}

.topic-hdr-close:hover { background: var(--bg-hover); color: var(--text-1); }

.topic-hdr-title {
  font-size: 18px;
  font-weight: 700;
  line-height: 1.3;
  margin-bottom: 4px;
}

.topic-hdr-num { font-size: 12px; color: var(--text-3); }

/* Voice Button */
.voice-btn {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 14px;
  border-radius: 8px;
  border: none;
  cursor: pointer;
  font-size: 13px;
  font-weight: 600;
  font-family: 'Inter', sans-serif;
  transition: all 0.2s;
  margin-top: 4px;
  width: 100%;
  justify-content: center;
}

.page-html .voice-btn { background: rgba(241,101,41,0.15); color: var(--html-clr); }
.page-html .voice-btn:hover { background: rgba(241,101,41,0.25); }
.page-html .voice-btn.playing { background: var(--html-clr); color: #fff; }

.page-css .voice-btn { background: rgba(74,143,255,0.15); color: var(--css-clr); }
.page-css .voice-btn:hover { background: rgba(74,143,255,0.25); }
.page-css .voice-btn.playing { background: var(--css-clr); color: #fff; }

.page-js .voice-btn { background: rgba(240,219,79,0.15); color: var(--js-clr); }
.page-js .voice-btn:hover { background: rgba(240,219,79,0.25); }
.page-js .voice-btn.playing { background: var(--js-dark); color: #fff; }

.page-react .voice-btn { background: rgba(97,218,251,0.15); color: var(--react-clr); }
.page-react .voice-btn:hover { background: rgba(97,218,251,0.25); }
.page-react .voice-btn.playing { background: var(--react-dark); color: #fff; }

.page-tw .voice-btn { background: rgba(52,211,153,0.15); color: var(--tw-clr); }
.page-tw .voice-btn:hover { background: rgba(52,211,153,0.25); }
.page-tw .voice-btn.playing { background: var(--tw-dark); color: #fff; }

.voice-pulse {
  width: 8px; height: 8px;
  border-radius: 50%;
  background: currentColor;
  animation: pulse 0.8s ease-in-out infinite;
  display: none;
}

.voice-btn.playing .voice-pulse { display: block; }
.voice-btn.playing .voice-static { display: none; }

@keyframes pulse {
  0%, 100% { transform: scale(1); opacity: 1; }
  50% { transform: scale(1.4); opacity: 0.6; }
}

/* Voice Selector */
.voice-settings {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-top: 10px;
  padding-top: 10px;
  border-top: 1px solid var(--border);
}

.voice-settings-label {
  font-size: 11px;
  font-weight: 600;
  color: var(--text-3);
  white-space: nowrap;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.voice-select {
  flex: 1;
  background: var(--bg);
  border: 1px solid var(--border);
  color: var(--text-2);
  border-radius: 7px;
  padding: 6px 28px 6px 10px;
  font-size: 12px;
  font-family: 'Inter', sans-serif;
  cursor: pointer;
  outline: none;
  appearance: none;
  -webkit-appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 24 24' fill='none' stroke='%236e7681' stroke-width='2.5'%3E%3Cpolyline points='6 9 12 15 18 9'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 8px center;
  min-width: 0;
  transition: border-color 0.2s, color 0.2s;
  max-width: 100%;
  overflow: hidden;
  text-overflow: ellipsis;
}

.voice-select:hover { border-color: var(--text-3); color: var(--text-1); }

.page-html .voice-select:focus { border-color: var(--html-clr); box-shadow: 0 0 0 2px rgba(241,101,41,0.15); }
.page-css .voice-select:focus  { border-color: var(--css-clr);  box-shadow: 0 0 0 2px rgba(74,143,255,0.15); }
.page-js .voice-select:focus   { border-color: var(--js-clr);   box-shadow: 0 0 0 2px rgba(240,219,79,0.15); }
.page-react .voice-select:focus { border-color: var(--react-clr); box-shadow: 0 0 0 2px rgba(97,218,251,0.15); }
.page-tw .voice-select:focus    { border-color: var(--tw-clr);   box-shadow: 0 0 0 2px rgba(52,211,153,0.15); }

.voice-select option {
  background: #1e293b;
  color: var(--text-1);
  padding: 4px;
}

/* Topic Body */
.topic-body {
  flex: 1;
  overflow-y: auto;
  padding: 20px;
  scrollbar-width: thin;
  scrollbar-color: var(--border) transparent;
}

.topic-body::-webkit-scrollbar { width: 5px; }
.topic-body::-webkit-scrollbar-track { background: transparent; }
.topic-body::-webkit-scrollbar-thumb { background: var(--border); border-radius: 10px; }

/* Content Styles inside topic-body */
.topic-body h3 {
  font-size: 15px;
  font-weight: 700;
  margin: 20px 0 10px;
  padding-bottom: 6px;
  border-bottom: 1px solid var(--border);
}

.page-html .topic-body h3 { color: var(--html-clr); border-color: rgba(241,101,41,0.2); }
.page-css .topic-body h3 { color: var(--css-clr); border-color: rgba(74,143,255,0.2); }
.page-js .topic-body h3 { color: var(--js-clr); border-color: rgba(240,219,79,0.2); }
.page-react .topic-body h3 { color: var(--react-clr); border-color: rgba(97,218,251,0.2); }
.page-tw .topic-body h3 { color: var(--tw-clr); border-color: rgba(52,211,153,0.2); }

.topic-body h3:first-child { margin-top: 0; }

.topic-body p {
  font-size: 13.5px;
  line-height: 1.75;
  color: var(--text-2);
  margin-bottom: 12px;
}

.topic-body ul, .topic-body ol {
  padding-left: 20px;
  margin-bottom: 14px;
}

.topic-body li {
  font-size: 13.5px;
  color: var(--text-2);
  line-height: 1.7;
  margin-bottom: 4px;
}

.topic-body strong { color: var(--text-1); font-weight: 600; }

.topic-body code {
  font-family: 'Fira Code', monospace;
  font-size: 12px;
  background: rgba(255,255,255,0.06);
  padding: 2px 6px;
  border-radius: 4px;
  color: var(--text-1);
}

.topic-body pre {
  background: #0a0d12;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 16px;
  overflow-x: auto;
  margin: 14px 0;
  position: relative;
}

.topic-body pre code {
  background: none;
  padding: 0;
  font-size: 12.5px;
  line-height: 1.7;
  color: #e6edf3;
}

.code-lang {
  position: absolute;
  top: 8px;
  right: 10px;
  font-size: 10px;
  color: var(--text-3);
  font-family: 'Fira Code', monospace;
  text-transform: uppercase;
}

.info-box {
  background: rgba(255,255,255,0.04);
  border-left: 3px solid;
  border-radius: 0 8px 8px 0;
  padding: 12px 14px;
  margin: 14px 0;
  font-size: 13px;
  line-height: 1.65;
  color: var(--text-2);
}

.page-html .info-box { border-color: var(--html-clr); background: rgba(241,101,41,0.06); }
.page-css .info-box { border-color: var(--css-clr); background: rgba(74,143,255,0.06); }
.page-js .info-box { border-color: var(--js-clr); background: rgba(240,219,79,0.06); }
.page-react .info-box { border-color: var(--react-clr); background: rgba(97,218,251,0.06); }
.page-tw .info-box { border-color: var(--tw-clr); background: rgba(52,211,153,0.06); }

.tag-list {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin: 10px 0 14px;
}

.tag {
  padding: 3px 10px;
  border-radius: 100px;
  font-size: 11px;
  font-weight: 600;
  font-family: 'Fira Code', monospace;
}

.page-html .tag { background: rgba(241,101,41,0.12); color: var(--html-clr); border: 1px solid rgba(241,101,41,0.25); }
.page-css .tag { background: rgba(74,143,255,0.12); color: var(--css-clr); border: 1px solid rgba(74,143,255,0.25); }
.page-js .tag { background: rgba(240,219,79,0.12); color: var(--js-clr); border: 1px solid rgba(240,219,79,0.25); }
.page-react .tag { background: rgba(97,218,251,0.12); color: var(--react-clr); border: 1px solid rgba(97,218,251,0.25); }
.page-tw .tag { background: rgba(52,211,153,0.12); color: var(--tw-clr); border: 1px solid rgba(52,211,153,0.25); }

/* Scrollbar for main content */
.main-content::-webkit-scrollbar { width: 5px; }
.main-content::-webkit-scrollbar-track { background: transparent; }
.main-content::-webkit-scrollbar-thumb { background: var(--border); border-radius: 10px; }
.main-content { scrollbar-width: thin; scrollbar-color: var(--border) transparent; }

/* Responsive */
@media (max-width: 1000px) {
  :root { --right-w: 360px; }
}

@media (max-width: 768px) {
  .app { grid-template-columns: 0px 1fr 0px; }
  .left-sidebar { position: fixed; left: -250px; top: 0; height: 100vh; transition: left 0.3s; z-index: 100; }
  .left-sidebar.open { left: 0; }
}