/* ============================================================
   Linux (RHEL / CentOS) Playground — learning pack styles
   Dark terminal theme · green prompt · Red Hat red accent
   ============================================================ */
:root {
  --bg: #0b0e0c;
  --bg2: #10140f;
  --panel: #141a15;
  --panel2: #1b231b;
  --border: #29342a;
  --text: #d6e2d7;
  --muted: #8ba08d;
  --green: #46d67c;      /* terminal / primary */
  --green2: #1f9e52;
  --red: #ee5a52;        /* Red Hat accent */
  --red2: #c0392b;
  --amber: #ffc453;
  --pink: #ff77b0;
  --purple: #b98cff;
  --blue: #58b0ff;
  --good: #46d67c;
  --bad: #ff6b6b;
  --warn: #ffce5c;
  --code-bg: #06090a;
  --term-bg: #05080a;
  --radius: 13px;
  --mono: 'Cascadia Code', 'JetBrains Mono', 'Consolas', monospace;
}
* { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }
body { background: var(--bg); color: var(--text); font-family: 'Segoe UI', system-ui, -apple-system, sans-serif; line-height: 1.65; font-size: 16px; }
::selection { background: rgba(70,214,124,.28); color: #fff; }

/* nav */
nav.topnav { position: sticky; top: 0; z-index: 100; background: rgba(11,14,12,.94); backdrop-filter: blur(10px); border-bottom: 1px solid var(--border); display: flex; align-items: center; gap: 3px; padding: 10px 18px; overflow-x: auto; white-space: nowrap; }
nav.topnav .brand { font-weight: 800; color: #fff; text-decoration: none; margin-right: 12px; font-size: 15px; flex-shrink: 0; display: flex; align-items: center; gap: 8px; }
nav.topnav .brand .logo { animation: blink 1.3s steps(2,start) infinite; display: inline-block; color: var(--green); }
@keyframes blink { 0%,100% { opacity: 1; } 50% { opacity: .25; } }
nav.topnav a.nl { color: var(--muted); text-decoration: none; font-size: 13px; padding: 5px 9px; border-radius: 8px; flex-shrink: 0; transition: all .16s; }
nav.topnav a.nl:hover { color: #fff; background: var(--panel2); }
nav.topnav a.nl.active { color: #03130a; background: linear-gradient(90deg, var(--green), var(--green2)); font-weight: 700; }
nav.topnav a.nl.visited-page::after { content: ' ✓'; color: var(--good); font-size: 11px; }

/* layout */
.wrap { max-width: 1080px; margin: 0 auto; padding: 32px 24px 90px; }
header.hero { padding: 26px 0 6px; }
.kicker { display: inline-block; font-size: 12px; letter-spacing: 2.5px; text-transform: uppercase; color: var(--green); font-weight: 700; margin-bottom: 10px; }
h1 { font-size: 34px; color: #fff; line-height: 1.18; margin-bottom: 12px; }
h1 .grad { background: linear-gradient(90deg, var(--green), var(--blue)); -webkit-background-clip: text; background-clip: text; color: transparent; }
.lede { color: var(--muted); font-size: 17px; max-width: 820px; }
h2 { font-size: 24px; color: #fff; margin: 46px 0 14px; padding-top: 10px; scroll-margin-top: 78px; }
h2 .num { display: inline-flex; align-items: center; justify-content: center; width: 34px; height: 34px; border-radius: 10px; margin-right: 11px; background: linear-gradient(135deg, var(--green2), #0a6b34); color: #fff; font-size: 16px; vertical-align: -7px; }
h3 { font-size: 18px; color: #e6f4ea; margin: 26px 0 10px; }
p { margin: 10px 0; } p.note-sm { color: var(--muted); font-size: 14px; }
ul, ol { margin: 10px 0 10px 24px; } li { margin: 5px 0; }
strong { color: #fff; } em { color: var(--green); font-style: normal; }
a { color: var(--green); }
hr.sep { border: none; border-top: 1px solid var(--border); margin: 40px 0; }

/* cards */
.card { background: var(--panel); border: 1px solid var(--border); border-radius: var(--radius); padding: 20px 22px; margin: 16px 0; }
.grid2 { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
.grid3 { display: grid; grid-template-columns: repeat(3,1fr); gap: 14px; }
@media (max-width:820px){ .grid2,.grid3 { grid-template-columns: 1fr; } }
.card.hoverable { transition: transform .18s, border-color .18s; }
.card.hoverable:hover { transform: translateY(-3px); border-color: var(--green); }
a.cardlink { text-decoration: none; color: inherit; display: block; }

/* badges / callouts */
.badge { display: inline-block; padding: 2px 10px; border-radius: 20px; font-size: 12px; font-weight: 700; letter-spacing: .3px; }
.badge.green { background: rgba(70,214,124,.14); color: var(--green); border: 1px solid rgba(70,214,124,.4); }
.badge.red { background: rgba(238,90,82,.14); color: var(--red); border: 1px solid rgba(238,90,82,.42); }
.badge.blue { background: rgba(88,176,255,.14); color: var(--blue); border: 1px solid rgba(88,176,255,.4); }
.badge.amber { background: rgba(255,196,83,.14); color: var(--amber); border: 1px solid rgba(255,196,83,.4); }
.badge.pink { background: rgba(255,119,176,.14); color: var(--pink); border: 1px solid rgba(255,119,176,.4); }
.badge.purple { background: rgba(185,140,255,.14); color: var(--purple); border: 1px solid rgba(185,140,255,.4); }
.callout { border-radius: var(--radius); padding: 15px 18px 15px 52px; margin: 18px 0; position: relative; border: 1px solid; }
.callout::before { position: absolute; left: 16px; top: 13px; font-size: 20px; }
.callout.info { background: rgba(88,176,255,.08); border-color: rgba(88,176,255,.35); } .callout.info::before { content: 'ℹ️'; }
.callout.tip { background: rgba(70,214,124,.07); border-color: rgba(70,214,124,.32); } .callout.tip::before { content: '💡'; }
.callout.warn { background: rgba(255,206,92,.07); border-color: rgba(255,206,92,.35); } .callout.warn::before { content: '⚠️'; }
.callout.danger { background: rgba(238,90,82,.08); border-color: rgba(238,90,82,.4); } .callout.danger::before { content: '🚨'; }
.callout.play { background: rgba(70,214,124,.07); border-color: rgba(70,214,124,.32); } .callout.play::before { content: '🎮'; }
.callout .ct { font-weight: 700; color: #fff; display: block; margin-bottom: 3px; }

/* code blocks */
.code { background: var(--code-bg); border: 1px solid var(--border); border-radius: var(--radius); margin: 16px 0; overflow: hidden; }
.code .code-head { display: flex; justify-content: space-between; align-items: center; padding: 8px 14px; background: var(--panel2); border-bottom: 1px solid var(--border); font-size: 12.5px; color: var(--muted); font-family: var(--mono); }
.code .copybtn { background: transparent; color: var(--muted); border: 1px solid var(--border); border-radius: 6px; padding: 3px 12px; font-size: 12px; cursor: pointer; transition: all .15s; font-family: inherit; }
.code .copybtn:hover { color: #fff; border-color: var(--green); } .code .copybtn.copied { color: var(--good); border-color: var(--good); }
.code pre { padding: 14px 16px; overflow-x: auto; font-family: var(--mono); font-size: 13.5px; line-height: 1.55; color: #cbe0d0; }
.code pre .cmd { color: var(--green); font-weight: 700; }
.code pre .opt { color: var(--blue); }
.code pre .str { color: var(--amber); }
.code pre .cmt { color: #5a6f5c; font-style: italic; }
.code pre .path { color: var(--pink); }
.code pre .prompt { color: var(--red); }

/* terminal */
.terminal { background: var(--term-bg); border: 1px solid var(--border); border-radius: var(--radius); margin: 20px 0; overflow: hidden; box-shadow: 0 6px 30px rgba(0,0,0,.4); }
.terminal .term-bar { display: flex; align-items: center; gap: 8px; padding: 8px 13px; background: linear-gradient(180deg,#1c241c,#141a14); border-bottom: 1px solid var(--border); }
.terminal .term-bar .tdot { width: 12px; height: 12px; border-radius: 50%; } .terminal .term-bar .tdot.r { background:#ff5f57; } .terminal .term-bar .tdot.y { background:#febc2e; } .terminal .term-bar .tdot.g { background:#28c840; }
.terminal .term-bar .ttitle { margin-left: 8px; font-family: var(--mono); font-size: 12.5px; color: var(--muted); }
.terminal .term-goal { padding: 11px 15px; background: rgba(88,176,255,.06); border-bottom: 1px solid var(--border); font-size: 14px; color: var(--text); }
.terminal .term-goal b { color: #fff; }
.terminal .term-body { padding: 12px 15px; font-family: var(--mono); font-size: 13.5px; line-height: 1.55; min-height: 60px; max-height: 420px; overflow-y: auto; white-space: pre-wrap; word-break: break-word; }
.terminal .term-line { color: #cbe0d0; }
.terminal .term-echo { color: #eaf5ec; }
.terminal .term-echo .p { color: var(--green); font-weight: 700; }
.terminal .term-echo .cwd { color: var(--blue); }
.terminal .term-err { color: var(--bad); }
.terminal .term-ok { color: var(--good); }
.terminal .term-inputrow { display: flex; align-items: center; gap: 8px; padding: 9px 15px; border-top: 1px solid var(--border); background: rgba(255,255,255,.015); }
.terminal .term-prompt { font-family: var(--mono); font-size: 13.5px; white-space: nowrap; }
.terminal .term-prompt .p { color: var(--green); font-weight: 700; } .terminal .term-prompt .cwd { color: var(--blue); }
.terminal .term-in { flex: 1; background: transparent; border: none; outline: none; color: #eaf5ec; font-family: var(--mono); font-size: 13.5px; caret-color: var(--green); }
.terminal .term-actions { display: flex; gap: 8px; padding: 9px 15px; border-top: 1px solid var(--border); background: var(--panel2); flex-wrap: wrap; align-items: center; }
.terminal .t-btn { background: var(--panel); color: var(--text); border: 1px solid var(--border); padding: 7px 15px; border-radius: 8px; font-weight: 700; font-size: 13px; cursor: pointer; font-family: inherit; }
.terminal .t-btn.check { border-color: var(--green); color: var(--green); } .terminal .t-btn.check:hover { background: rgba(70,214,124,.1); }
.terminal .t-btn.reset:hover { border-color: var(--amber); color: var(--amber); }
.terminal .t-hint { font-size: 12px; color: var(--muted); margin-left: auto; }
.terminal .term-verdict { padding: 0 15px 12px; font-family: var(--mono); font-size: 13px; }
.terminal .term-verdict .ok { color: var(--good); } .terminal .term-verdict .no { color: var(--bad); }

/* permission calculator */
.permcalc { background: var(--panel); border: 1px solid var(--border); border-radius: var(--radius); margin: 20px 0; overflow: hidden; }
.permcalc .pc-head { padding: 10px 15px; background: linear-gradient(90deg, rgba(70,214,124,.13), transparent); border-bottom: 1px solid var(--border); font-weight: 700; color: #fff; font-size: 14px; }
.permcalc .pc-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 0; }
@media (max-width:640px){ .permcalc .pc-grid { grid-template-columns: 1fr; } }
.permcalc .pc-col { padding: 14px 16px; border-right: 1px solid var(--border); }
.permcalc .pc-col:last-child { border-right: none; }
.permcalc .pc-col h4 { font-size: 13px; text-transform: uppercase; letter-spacing: 1px; color: var(--green); margin-bottom: 10px; }
.permcalc label.pc-bit { display: flex; align-items: center; gap: 9px; padding: 6px 0; cursor: pointer; font-family: var(--mono); font-size: 14px; }
.permcalc label.pc-bit input { accent-color: var(--green); width: 16px; height: 16px; }
.permcalc .pc-out { display: flex; flex-wrap: wrap; align-items: center; gap: 18px; padding: 15px 16px; background: var(--term-bg); border-top: 1px solid var(--border); }
.permcalc .pc-octal { font-family: var(--mono); font-size: 34px; font-weight: 800; color: var(--green); letter-spacing: 4px; }
.permcalc .pc-sym { font-family: var(--mono); font-size: 20px; color: var(--amber); letter-spacing: 2px; }
.permcalc .pc-cmd { font-family: var(--mono); font-size: 14px; color: var(--muted); margin-left: auto; }
.permcalc .pc-cmd b { color: var(--pink); }

/* reference tables */
table.tbl { width: 100%; border-collapse: collapse; margin: 16px 0; font-size: 14.5px; background: var(--panel); border-radius: var(--radius); overflow: hidden; }
table.tbl th { background: var(--panel2); color: #fff; text-align: left; padding: 10px 14px; font-size: 13px; border-bottom: 2px solid var(--border); }
table.tbl td { padding: 9px 14px; border-bottom: 1px solid var(--border); vertical-align: top; }
table.tbl tr:last-child td { border-bottom: none; }
table.tbl code, p code, li code, td code { background: rgba(70,214,124,.12); color: #a9ecc3; padding: 1px 6px; border-radius: 5px; font-family: var(--mono); font-size: .88em; }

/* accordions / quizzes / diagrams */
details.acc { background: var(--panel); border: 1px solid var(--border); border-radius: var(--radius); margin: 12px 0; overflow: hidden; }
details.acc summary { cursor: pointer; padding: 15px 20px; font-weight: 700; color: #fff; list-style: none; display: flex; align-items: center; gap: 10px; }
details.acc summary::-webkit-details-marker { display: none; }
details.acc summary::before { content: '▸'; color: var(--green); transition: transform .2s; }
details.acc[open] summary::before { transform: rotate(90deg); }
details.acc summary:hover { background: var(--panel2); }
details.acc .acc-body { padding: 4px 22px 18px; border-top: 1px solid var(--border); }

.quiz { background: linear-gradient(160deg, var(--panel), var(--bg2)); border: 1px solid var(--border); border-radius: var(--radius); padding: 22px 24px; margin: 24px 0; }
.quiz .q-head { display: flex; align-items: center; gap: 10px; margin-bottom: 6px; } .quiz .q-head .q-ico { font-size: 22px; } .quiz .q-head h3 { margin: 0; }
.quiz .q-item { margin: 18px 0; padding-top: 14px; border-top: 1px dashed var(--border); }
.quiz .q-text { font-weight: 700; color: #fff; margin-bottom: 10px; }
.quiz label.q-opt { display: flex; gap: 10px; align-items: flex-start; padding: 9px 13px; margin: 6px 0; border-radius: 9px; cursor: pointer; border: 1px solid var(--border); background: var(--bg2); transition: border-color .15s; font-size: 15px; }
.quiz label.q-opt:hover { border-color: var(--green); } .quiz label.q-opt input { margin-top: 4px; accent-color: var(--green); }
.quiz label.q-opt.correct { border-color: var(--good); background: rgba(70,214,124,.1); }
.quiz label.q-opt.wrong { border-color: var(--bad); background: rgba(255,107,107,.08); }
.quiz .q-expl { display: none; margin-top: 10px; padding: 12px 14px; border-left: 3px solid var(--green); background: rgba(70,214,124,.06); border-radius: 0 9px 9px 0; font-size: 14.5px; color: var(--muted); }
.quiz .q-expl.show { display: block; animation: fadeIn .3s ease; }
.quiz .q-check { margin-top: 16px; background: var(--green2); color: #fff; border: none; padding: 10px 26px; border-radius: 9px; font-weight: 700; font-size: 15px; cursor: pointer; }
.quiz .q-check:hover { filter: brightness(1.12); }
.quiz .q-score { margin-top: 12px; font-weight: 800; font-size: 16px; } .quiz .q-score.pass { color: var(--good); } .quiz .q-score.fail { color: var(--warn); }
@keyframes fadeIn { from { opacity: 0; transform: translateY(6px); } to { opacity: 1; transform: none; } }

.diagram { background: radial-gradient(ellipse at 50% 0%, #0f1a12 0%, var(--bg2) 70%); border: 1px solid var(--border); border-radius: var(--radius); padding: 14px; margin: 20px 0; overflow: hidden; }
.diagram svg { width: 100%; height: auto; display: block; }
.diagram .dg-controls { display: flex; gap: 10px; margin: 4px 6px 8px; align-items: center; }
.diagram .replaybtn { background: var(--panel2); color: var(--text); border: 1px solid var(--border); border-radius: 8px; padding: 6px 16px; font-size: 13px; font-weight: 700; cursor: pointer; }
.diagram .replaybtn:hover { border-color: var(--green); color: #fff; } .diagram .dg-cap { font-size: 13px; color: var(--muted); }
svg text { font-family: 'Segoe UI', system-ui, sans-serif; } svg .mono { font-family: var(--mono); }

/* checklist, page nav, misc */
.checklist { list-style: none; margin-left: 4px; } .checklist li { padding-left: 30px; position: relative; }
.checklist li::before { content: '✅'; position: absolute; left: 0; }
.checklist.todo li::before { content: '☐'; color: var(--green); font-size: 19px; top: -2px; }
.kbd { font-family: var(--mono); background: var(--panel2); border: 1px solid var(--border); border-bottom-width: 3px; border-radius: 6px; padding: 1px 7px; font-size: .85em; }
.progressbar { height: 9px; background: var(--panel2); border-radius: 6px; overflow: hidden; margin: 8px 0 4px; }
.progressbar > div { height: 100%; background: linear-gradient(90deg, var(--green), var(--blue)); border-radius: 6px; transition: width .5s ease; }
.pagenav { display: flex; justify-content: space-between; margin-top: 60px; gap: 14px; }
.pagenav a { flex: 1; text-decoration: none; border: 1px solid var(--border); border-radius: var(--radius); padding: 14px 18px; color: var(--text); background: var(--panel); transition: border-color .15s, transform .15s; }
.pagenav a:hover { border-color: var(--green); transform: translateY(-2px); }
.pagenav a .pn-dir { font-size: 12px; color: var(--muted); display: block; } .pagenav a .pn-t { font-weight: 700; color: #fff; }
.pagenav a.next { text-align: right; }
.center { text-align: center; } .mt0 { margin-top: 0; }