/* ============================================================
   STUDY LEARNING · CISCO IOS LEVEL 1
   Design system: dark industrial, orange accents
   ============================================================ */

:root{
  --bg:#0c0c0b;
  --surface:#111110;
  --surface-2:#131311;
  --border:#1e1e1c;
  --orange:#df7a1e;
  --orange-bg:#1b1008;
  --orange-border:#583210;
  --red:#bf3b2e;
  --red-bg:#1c0a08;
  --green:#6b8e23;
  --green-bg:#0e1408;
  --text:#d4d0c8;
  --text-dim:#7a7670;
  --text-mute:#484844;
  --khaki:#8b7d5b;
  --khaki-bg:#1a1810;
  --mono:'Share Tech Mono','JetBrains Mono',monospace;
  --display:'Barlow Condensed',sans-serif;
  --code:'JetBrains Mono','Share Tech Mono',monospace;
}

*{box-sizing:border-box;margin:0;padding:0}
html,body{height:100%;overflow:hidden}
body{
  background:var(--bg);color:var(--text);
  font-family:var(--display);font-weight:500;
  letter-spacing:0.01em;line-height:1.5;
  -webkit-font-smoothing:antialiased;
}

/* ---------- APP SHELL ---------- */
/* Use dvh on mobile so the dynamic browser chrome (address bar, bottom
   toolbar) does not push the bottom navbar below the visible viewport.
   Fallback to vh for older browsers. */
.app{display:grid;grid-template-rows:auto 1fr auto;height:100vh;height:100dvh;position:relative;z-index:1}

/* ---------- TOP BAR ---------- */
.topbar{
  display:flex;align-items:center;justify-content:space-between;
  padding:14px 24px;background:var(--surface);
  border-bottom:1px solid var(--border);font-family:var(--mono);
}
.brand{display:flex;align-items:center;gap:14px;font-size:11px;letter-spacing:0.18em;text-transform:uppercase;color:var(--text-dim)}
.brand .mark{width:10px;height:10px;background:var(--orange);border-radius:1px;box-shadow:0 0 12px rgba(223,122,30,0.5)}
.brand .sep{color:var(--text-mute)}
.brand b{color:var(--text);font-weight:normal}
.course-tag{
  font-family:var(--mono);font-size:10px;letter-spacing:0.18em;text-transform:uppercase;
  color:var(--orange);padding:4px 10px;border:1px solid var(--orange-border);
  background:var(--orange-bg);border-radius:2px;
}
.progress-meta{font-family:var(--mono);font-size:10px;letter-spacing:0.18em;text-transform:uppercase;color:var(--text-dim)}
.progress-meta b{color:var(--text);font-weight:normal}

.progress-track{height:2px;background:var(--border);position:relative;overflow:hidden}
.progress-fill{
  height:100%;background:var(--orange);width:0%;
  transition:width 0.5s cubic-bezier(0.4,0,0.2,1);
  box-shadow:0 0 8px rgba(223,122,30,0.6);
}

/* ---------- STAGE / SLIDES ---------- */
.stage{position:relative;overflow-y:auto;overflow-x:hidden;padding:48px 32px 32px}
.stage::-webkit-scrollbar{width:8px}
.stage::-webkit-scrollbar-track{background:var(--bg)}
.stage::-webkit-scrollbar-thumb{background:var(--border)}
.stage::-webkit-scrollbar-thumb:hover{background:var(--text-mute)}
.slide{max-width:980px;margin:0 auto;display:none;animation:slideIn 0.45s cubic-bezier(0.2,0.8,0.2,1)}
.slide.active{display:block}
@keyframes slideIn{from{opacity:0;transform:translateY(12px)}to{opacity:1;transform:translateY(0)}}

.slide-eyebrow{
  font-family:var(--mono);font-size:10px;letter-spacing:0.22em;text-transform:uppercase;
  color:var(--orange);margin-bottom:14px;display:flex;align-items:center;gap:10px;
}
.slide-eyebrow::before{content:'';width:18px;height:1px;background:var(--orange)}
.slide-title{
  font-family:var(--display);font-weight:800;font-size:42px;line-height:1.05;
  letter-spacing:-0.01em;color:var(--text);text-transform:uppercase;margin-bottom:18px;
}
.slide-lede{font-size:18px;line-height:1.55;color:var(--text);max-width:720px;margin-bottom:28px}
.slide-body{font-size:16px;line-height:1.65;color:var(--text)}
.slide-body p{margin-bottom:14px}
.slide-body strong{color:var(--orange);font-weight:700}
.slide-body code{
  font-family:var(--code);font-size:14px;background:var(--orange-bg);
  border:1px solid var(--orange-border);color:var(--orange);
  padding:1px 6px;border-radius:2px;
}

/* ---------- COVER ---------- */
.cover{text-align:left;padding-top:30px}
.cover-stamp{
  display:inline-block;font-family:var(--mono);font-size:10px;letter-spacing:0.25em;
  text-transform:uppercase;color:var(--orange);border:1px solid var(--orange-border);
  background:var(--orange-bg);padding:5px 12px;border-radius:2px;margin-bottom:24px;
}
.cover h1{
  font-family:var(--display);font-weight:800;font-size:68px;line-height:0.95;
  letter-spacing:-0.02em;text-transform:uppercase;margin-bottom:18px;
}
.cover h1 .accent{color:var(--orange)}
.cover-sub{font-size:18px;color:var(--text-dim);max-width:640px;margin-bottom:38px;line-height:1.5}
.cover-meta{
  display:grid;grid-template-columns:repeat(4,1fr);gap:1px;
  background:var(--border);border:1px solid var(--border);
  margin-bottom:38px;max-width:760px;
}
.cover-meta-item{background:var(--surface);padding:14px 18px}
.cover-meta-label{font-family:var(--mono);font-size:9px;letter-spacing:0.22em;text-transform:uppercase;color:var(--text-dim);margin-bottom:4px}
.cover-meta-value{font-family:var(--display);font-weight:700;font-size:18px;color:var(--text);text-transform:uppercase}

/* ---------- TERMINAL ---------- */
.terminal{
  background:#0a0a09;border:1px solid var(--border);border-radius:3px;
  font-family:var(--code);font-size:13.5px;line-height:1.6;
  margin:18px 0 22px;overflow:hidden;
  box-shadow:0 12px 32px rgba(0,0,0,0.6),inset 0 0 0 1px rgba(255,255,255,0.02);
}
.terminal-bar{
  background:var(--surface);border-bottom:1px solid var(--border);
  padding:8px 14px;display:flex;align-items:center;justify-content:space-between;
  font-family:var(--mono);font-size:10px;letter-spacing:0.18em;
  text-transform:uppercase;color:var(--text-dim);
}
.terminal-bar-left{display:flex;gap:8px;align-items:center}
.terminal-dot{width:8px;height:8px;border-radius:50%;background:var(--text-mute)}
.terminal-dot.live{background:var(--orange);box-shadow:0 0 6px rgba(223,122,30,0.7)}
.terminal-screen{
  padding:16px 18px 22px;min-height:160px;max-height:460px;
  overflow-y:auto;color:#d4d0c8;white-space:pre-wrap;word-break:break-word;
}
.terminal-screen::-webkit-scrollbar{width:6px}
.terminal-screen::-webkit-scrollbar-thumb{background:var(--border)}
.term-line{display:block}
.term-prompt{color:var(--orange)}
.term-cmd{color:#e8e4dc}
.term-out{color:var(--text-dim)}
.term-comment{color:var(--khaki);font-style:italic}
.term-warn{color:var(--red)}
.term-ok{color:var(--green)}
.cursor{
  display:inline-block;width:8px;height:14px;background:var(--orange);
  vertical-align:text-bottom;margin-left:1px;animation:blink 1s steps(2) infinite;
}
@keyframes blink{50%{opacity:0}}
.terminal-actions{display:flex;gap:8px;padding:10px 14px;border-top:1px solid var(--border);background:var(--surface)}
.term-btn{
  font-family:var(--mono);font-size:9px;letter-spacing:0.18em;text-transform:uppercase;
  background:transparent;border:1px solid var(--border);color:var(--text-dim);
  padding:6px 12px;border-radius:2px;cursor:pointer;transition:all 0.15s ease;
}
.term-btn:hover{color:var(--orange);border-color:var(--orange-border);background:var(--orange-bg)}

/* ---------- PANELS ---------- */
.panel{border:1px solid var(--border);border-radius:3px;padding:18px 20px;margin:18px 0;background:var(--surface)}
.panel-label{font-family:var(--mono);font-size:10px;letter-spacing:0.22em;text-transform:uppercase;margin-bottom:10px;display:flex;align-items:center;gap:8px}
.panel-label::before{content:'';width:4px;height:4px;background:currentColor;border-radius:1px}
.panel.field-std{background:var(--khaki-bg);border-color:#3a3520;color:#c4ba9a}
.panel.field-std .panel-label{color:var(--khaki)}
.panel.warn{background:var(--red-bg);border-color:#582a25}
.panel.warn .panel-label{color:var(--red)}
.panel.tip{background:var(--orange-bg);border-color:var(--orange-border)}
.panel.tip .panel-label{color:var(--orange)}
.panel-body{font-size:15px;line-height:1.6}
.panel-body p+p{margin-top:8px}

.two-col{display:grid;grid-template-columns:1fr 1fr;gap:18px;margin:18px 0}
@media (max-width:780px){.two-col{grid-template-columns:1fr}}

/* ---------- CLI MODE TREE ---------- */
.mode-tree{
  font-family:var(--code);font-size:14px;background:#0a0a09;
  border:1px solid var(--border);padding:18px 22px;margin:18px 0;border-radius:3px;
}
.mode-row{display:flex;align-items:center;gap:14px;padding:8px 0;border-bottom:1px dashed var(--border)}
.mode-row:last-child{border-bottom:0}
.mode-prompt{color:var(--orange);min-width:200px;flex-shrink:0}
.mode-name{color:var(--text-dim);font-family:var(--mono);font-size:11px;letter-spacing:0.15em;text-transform:uppercase;min-width:140px}
.mode-desc{color:var(--text);font-family:var(--display);font-size:14px}

/* ---------- DATA TABLES ---------- */
.vtable{width:100%;border-collapse:collapse;margin:14px 0 18px;font-family:var(--code);font-size:13px}
.vtable th{
  text-align:left;font-family:var(--mono);font-size:9px;letter-spacing:0.2em;
  text-transform:uppercase;color:var(--text-dim);padding:8px 10px;
  border-bottom:1px solid var(--border);font-weight:normal;
}
.vtable td{padding:10px;border-bottom:1px solid var(--border);color:var(--text)}
.vtable tr:hover td{background:var(--surface-2)}
.vtable .vid{color:var(--orange)}

/* ---------- STACK VISUAL ---------- */
.stack-vis{margin:24px 0;padding:24px;background:var(--surface);border:1px solid var(--border);border-radius:3px}
.stack-switches{display:flex;flex-direction:column;gap:14px;max-width:560px;margin:0 auto}
.stack-sw{
  background:var(--bg);border:1px solid var(--border);border-radius:3px;padding:14px 18px;
  display:grid;grid-template-columns:auto 1fr auto;gap:18px;align-items:center;position:relative;
}
.stack-sw .sw-num{font-family:var(--display);font-weight:800;font-size:28px;color:var(--orange);line-height:1;min-width:30px}
.stack-sw .sw-meta{font-family:var(--mono);font-size:10px;letter-spacing:0.18em;text-transform:uppercase;color:var(--text-dim)}
.stack-sw .sw-meta b{color:var(--text);font-weight:normal;display:block;margin-top:2px;font-size:13px}
.stack-sw .sw-role{font-family:var(--mono);font-size:9px;letter-spacing:0.2em;text-transform:uppercase;padding:4px 10px;border-radius:2px}
.stack-sw .sw-role.master{background:var(--orange-bg);border:1px solid var(--orange-border);color:var(--orange)}
.stack-sw .sw-role.member{background:var(--surface);border:1px solid var(--border);color:var(--text-dim)}
.stack-sw::after{
  content:'';position:absolute;left:50%;bottom:-14px;transform:translateX(-50%);
  width:2px;height:14px;background:var(--orange);box-shadow:0 0 6px rgba(223,122,30,0.6);
}
.stack-sw:last-child::after{display:none}
.stack-caption{text-align:center;font-family:var(--mono);font-size:10px;letter-spacing:0.2em;text-transform:uppercase;color:var(--text-dim);margin-top:18px}

/* ---------- KNOWLEDGE CHECK ---------- */
.kc-wrap{background:var(--surface);border:1px solid var(--border);border-radius:3px;padding:24px 28px;margin:18px 0}
.kc-stamp{
  display:inline-block;font-family:var(--mono);font-size:10px;letter-spacing:0.22em;
  text-transform:uppercase;color:var(--orange);border:1px solid var(--orange-border);
  background:var(--orange-bg);padding:4px 10px;border-radius:2px;margin-bottom:16px;
}
.kc-q{font-family:var(--display);font-weight:700;font-size:22px;line-height:1.3;color:var(--text);margin-bottom:18px}
.kc-options{display:flex;flex-direction:column;gap:8px;margin-bottom:18px}
.kc-opt{
  background:var(--bg);border:1px solid var(--border);border-radius:2px;
  padding:14px 18px;cursor:pointer;transition:all 0.15s ease;
  display:flex;align-items:center;gap:14px;text-align:left;
  font-family:var(--display);font-size:15px;color:var(--text);font-weight:500;width:100%;
}
.kc-opt:hover{border-color:var(--orange-border);background:var(--surface-2)}
.kc-opt .kc-letter{
  font-family:var(--mono);font-size:11px;letter-spacing:0.15em;color:var(--text-dim);
  width:24px;flex-shrink:0;border-right:1px solid var(--border);padding-right:14px;
}
.kc-opt.correct{border-color:#3a5a1c;background:var(--green-bg);color:#a6c068}
.kc-opt.correct .kc-letter{color:#a6c068;border-color:#3a5a1c}
.kc-opt.wrong{border-color:#582a25;background:var(--red-bg);color:#d68a82}
.kc-opt.wrong .kc-letter{color:#d68a82;border-color:#582a25}
.kc-opt[disabled]{cursor:default;pointer-events:none}
.kc-feedback{display:none;padding:14px 16px;border-radius:2px;font-size:14px;line-height:1.55;margin-top:10px}
.kc-feedback.shown{display:block}
.kc-feedback.right{background:var(--green-bg);border:1px solid #3a5a1c;color:#a6c068}
.kc-feedback.miss{background:var(--red-bg);border:1px solid #582a25;color:#d68a82}
.kc-feedback b{font-family:var(--mono);font-size:10px;letter-spacing:0.2em;text-transform:uppercase;display:block;margin-bottom:4px}

/* ---------- CHAPTER DIVIDER ---------- */
.chapter{text-align:center;padding:40px 20px}
.chapter-num{font-family:var(--mono);font-size:14px;letter-spacing:0.4em;color:var(--orange);margin-bottom:16px}
.chapter-title{font-family:var(--display);font-weight:800;font-size:54px;line-height:1;letter-spacing:-0.01em;text-transform:uppercase;margin-bottom:14px}
.chapter-sub{font-size:16px;color:var(--text-dim);max-width:520px;margin:0 auto}
.chapter-rule{width:60px;height:2px;background:var(--orange);margin:24px auto;box-shadow:0 0 8px rgba(223,122,30,0.5)}

/* ---------- COMPLETION CERTIFICATE ---------- */
.cert{text-align:center;padding:40px 20px;border:2px solid var(--orange-border);background:var(--orange-bg);border-radius:3px;margin:20px 0;position:relative}
.cert::before,.cert::after{content:'';position:absolute;width:30px;height:30px;border:2px solid var(--orange)}
.cert::before{top:8px;left:8px;border-right:0;border-bottom:0}
.cert::after{bottom:8px;right:8px;border-left:0;border-top:0}
.cert-stamp{font-family:var(--mono);font-size:11px;letter-spacing:0.3em;color:var(--orange);margin-bottom:16px}
.cert h2{font-family:var(--display);font-weight:800;font-size:46px;line-height:1;letter-spacing:-0.01em;text-transform:uppercase;margin-bottom:16px}
.cert-score{font-family:var(--mono);font-size:32px;color:var(--orange);margin:24px 0 12px}
.cert-desc{color:var(--text);max-width:520px;margin:0 auto}

/* ---------- NAVIGATION ---------- */
.navbar{display:flex;align-items:center;justify-content:space-between;padding:14px 24px;padding-bottom:calc(14px + env(safe-area-inset-bottom,0px));background:var(--surface);border-top:1px solid var(--border);gap:14px}
.nav-info{font-family:var(--mono);font-size:10px;letter-spacing:0.18em;text-transform:uppercase;color:var(--text-dim);flex:1;text-align:center}
.nav-info b{color:var(--text);font-weight:normal}
.nav-btn{
  font-family:var(--mono);font-size:11px;letter-spacing:0.2em;text-transform:uppercase;
  background:transparent;border:1px solid var(--border);color:var(--text);
  padding:10px 22px;border-radius:2px;cursor:pointer;transition:all 0.18s ease;
}
.nav-btn:hover:not([disabled]){border-color:var(--orange-border);color:var(--orange);background:var(--orange-bg)}
.nav-btn[disabled]{opacity:0.3;cursor:not-allowed}
.nav-btn.primary{border-color:var(--orange-border);color:var(--orange);background:var(--orange-bg)}
.nav-btn.primary:hover:not([disabled]){background:var(--orange);color:var(--bg);box-shadow:0 0 14px rgba(223,122,30,0.4)}

/* ---------- FIELD LIST ---------- */
ul.fieldlist{list-style:none;padding:0;margin:14px 0}
ul.fieldlist li{padding:10px 14px 10px 28px;border-left:2px solid var(--orange);background:var(--surface);margin-bottom:6px;font-size:15px;position:relative}
ul.fieldlist li::before{content:'»';position:absolute;left:10px;color:var(--orange);font-family:var(--mono)}

/* ---------- TROUBLESHOOTING FLOW ---------- */
.tshoot-flow{margin:18px 0;border-left:2px solid var(--orange);padding-left:18px}
.tshoot-step{margin-bottom:18px;padding-bottom:14px;border-bottom:1px dashed var(--border)}
.tshoot-step:last-child{border-bottom:0}
.tshoot-step .step-num{font-family:var(--mono);font-size:10px;letter-spacing:0.22em;color:var(--orange);text-transform:uppercase;margin-bottom:6px;display:block}
.tshoot-step .step-q{font-family:var(--display);font-weight:700;font-size:18px;color:var(--text);margin-bottom:6px}
.tshoot-step .step-cmd{font-family:var(--code);font-size:13px;color:var(--orange);background:var(--orange-bg);border:1px solid var(--orange-border);padding:6px 10px;border-radius:2px;display:inline-block;margin:6px 0}
.tshoot-step .step-desc{font-size:14px;color:var(--text-dim);line-height:1.55}

/* ---------- AMBIENT GRID ---------- */
.bg-grid{
  position:fixed;inset:0;pointer-events:none;z-index:0;
  background-image:linear-gradient(rgba(223,122,30,0.025) 1px,transparent 1px),linear-gradient(90deg,rgba(223,122,30,0.025) 1px,transparent 1px);
  background-size:48px 48px;
}

/* ---------- RESPONSIVE ---------- */
@media (max-width:680px){
  .stage{padding:24px 16px}
  .cover h1{font-size:42px}
  .slide-title{font-size:30px}
  .chapter-title{font-size:36px}
  .cert h2{font-size:32px}
  .cover-meta{grid-template-columns:repeat(2,1fr)}
  .topbar{padding:10px 14px;flex-wrap:wrap;gap:8px}
  .navbar{padding:10px 14px}
  .nav-btn{padding:8px 14px;font-size:10px}
  .terminal{font-size:12px}
  .mode-row{flex-direction:column;align-items:flex-start;gap:4px}
  .mode-prompt,.mode-name{min-width:0}
}