:root{
  --bg:#0b0e13;
  --bg-elevated:#12161d;
  --bg-card:#0f1319;
  --text:#e8ecf1;
  --text-muted:#9aa4b2;
  --text-faint:#6b7583;
  --accent-up:#e8b23a;
  --accent-down:#e0685d;
  --accent-signal:#4f9de0;
  --border:#1e2530;
  --border-hover:#2c3543;
  --radius:6px;
}

*{box-sizing:border-box;}
html{scroll-behavior:smooth;}
body{
  margin:0;background:var(--bg);color:var(--text);
  font-family:'IBM Plex Sans', sans-serif;font-size:16px;line-height:1.6;
  -webkit-font-smoothing:antialiased;
}
a{color:inherit;text-decoration:none;}
.wrap{max-width:1120px;margin:0 auto;padding:0 28px;}
.mono{font-family:'IBM Plex Mono',monospace;}

/* Header / Nav ------------------------------------------------------- */
header.site{border-bottom:1px solid var(--border);position:sticky;top:0;background:rgba(11,14,19,0.92);backdrop-filter:blur(8px);z-index:50;}
.nav-inner{display:flex;align-items:center;justify-content:space-between;padding:24px 42px;max-width:1120px;margin:0 auto;}
.brand{display:flex;align-items:center;gap:15px;}
.brand-mark{width:45px;height:45px;object-fit:contain;display:block;}
.brand-text{display:flex;flex-direction:column;line-height:1.2;}
.brand-text strong{font-family:'Space Grotesk',sans-serif;font-size:27px;letter-spacing:0.01em;}
.brand-text span{font-size:10px;color:var(--text-muted);font-family:'IBM Plex Mono',monospace;}
nav.main{display:flex;align-items:center;gap:6px;}
nav.main a{font-size:17px;padding:12px 21px;border-radius:var(--radius);color:var(--text-muted);transition:color .15s, background .15s;}
nav.main a:hover{color:var(--text);background:var(--bg-elevated);}
nav.main a.active{color:var(--accent-up);}
.nav-user{color:var(--text-muted);font-family:'IBM Plex Mono',monospace;font-size:17px;margin-right:8px;}

/* Hero ----------------------------------------------------------------- */
.hero{padding:64px 0 40px;}
.hero-grid{display:grid;grid-template-columns:1.1fr 0.9fr;gap:48px;align-items:center;}
.eyebrow{font-family:'IBM Plex Mono',monospace;font-size:14px;text-transform:uppercase;letter-spacing:.08em;color:var(--accent-up);margin-bottom:14px;}
.hero-title{font-family:'Space Grotesk',sans-serif;font-size:clamp(38px,5vw,55px);line-height:1.15;margin:0 0 20px;letter-spacing:-0.01em;}
.grad{background:linear-gradient(90deg,var(--accent-up),var(--accent-signal));-webkit-background-clip:text;background-clip:text;color:transparent;}
.hero-lead{color:var(--text-muted);font-size:21px;line-height:1.6;max-width:62ch;margin:0 0 26px;}
.hero-cta{display:flex;gap:12px;flex-wrap:wrap;}
.btn{display:inline-block;padding:13px 22px;border-radius:var(--radius);font-size:17px;font-weight:500;transition:opacity .15s, background .15s;}
.btn-primary{background:var(--accent-up);color:#1a1305;}
.btn-primary:hover{opacity:.88;}
.btn-ghost{border:1px solid var(--border-hover);color:var(--text);}
.btn-ghost:hover{background:var(--bg-elevated);}

/* Sections / cards ------------------------------------------------------ */
.section{padding:48px 0;}
.section-head{max-width:70ch;margin-bottom:30px;}
.section-head h2{font-family:'Space Grotesk',sans-serif;font-size:30px;margin:0 0 12px;}
.section-head p{color:var(--text-muted);font-size:18px;line-height:1.6;margin:0;}

.module-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(260px,1fr));gap:16px;}
.module-card{display:block;padding:22px;border:1px solid var(--border);border-radius:10px;background:var(--bg-card);transition:border-color .15s, transform .15s;position:relative;}
.module-card:not(.pending):hover{border-color:var(--accent-up);transform:translateY(-2px);}
.module-card.pending{opacity:.55;}
.module-card .idx{font-family:'IBM Plex Mono',monospace;font-size:14px;color:var(--accent-up);}
.module-card h4{font-family:'Space Grotesk',sans-serif;font-size:20px;margin:10px 0 8px;}
.module-card p{color:var(--text-muted);font-size:16px;line-height:1.55;margin:0;}
.module-card .badge{display:inline-block;margin-top:10px;font-size:13px;font-family:'IBM Plex Mono',monospace;color:var(--text-faint);border:1px solid var(--border);border-radius:4px;padding:2px 8px;}

/* Terminal -------------------------------------------------------------- */
.terminal{border:1px solid var(--border);border-radius:8px;overflow:hidden;margin:22px 0;background:#0a0d12;}
.terminal-bar{display:flex;align-items:center;gap:7px;padding:10px 14px;background:var(--bg-elevated);border-bottom:1px solid var(--border);}
.terminal-bar .dot{width:10px;height:10px;border-radius:50%;background:var(--border-hover);}
.terminal-bar .label{margin-left:8px;font-family:'IBM Plex Mono',monospace;font-size:13.5px;color:var(--text-faint);}
.terminal pre{margin:0;padding:16px 18px;font-family:'IBM Plex Mono',monospace;font-size:15.5px;line-height:1.65;overflow-x:auto;color:var(--text);}
.terminal pre .p{color:var(--accent-up);}
.terminal pre .c{color:var(--text-faint);}

/* Lesson layout ----------------------------------------------------------- */
.crumb{padding:20px 28px 0;font-size:14.5px;color:var(--text-faint);font-family:'IBM Plex Mono',monospace;}
.crumb a{color:var(--text-muted);}
.crumb a:hover{color:var(--accent-up);}
.crumb .sep{margin:0 8px;}

.lesson-head{padding:28px 0 8px;border-bottom:1px solid var(--border);margin-bottom:34px;}
.lesson-head h1{font-family:'Space Grotesk',sans-serif;font-size:clamp(30px,4vw,42px);margin:8px 0 16px;}
.lesson-head .lead{color:var(--text-muted);font-size:19px;line-height:1.6;max-width:70ch;margin:0 0 20px;}

.lesson-body{max-width:74ch;margin:0 auto 40px;}
.lesson-body h2{font-family:'Space Grotesk',sans-serif;font-size:25px;margin:44px 0 16px;}
.lesson-body p{font-size:18px;line-height:1.75;color:#c4cdd8;margin:0 0 18px;}
.lesson-body code{font-family:'IBM Plex Mono',monospace;font-size:0.9em;background:var(--bg-elevated);padding:2px 6px;border-radius:4px;color:var(--accent-up);}

.callout{border-left:3px solid var(--accent-signal);background:var(--bg-elevated);border-radius:0 8px 8px 0;padding:18px 22px;margin:24px 0;}
.callout .eyebrow{margin-bottom:8px;color:var(--accent-signal);}
.callout p{margin:0;font-size:17px;color:var(--text-muted);}

.table-wrap{overflow-x:auto;margin:20px 0;}
table.data{width:100%;border-collapse:collapse;font-size:16.5px;}
table.data th{text-align:left;padding:10px 14px;border-bottom:2px solid var(--border-hover);color:var(--text-faint);font-weight:600;font-size:14.5px;text-transform:uppercase;letter-spacing:.03em;}
table.data td{padding:11px 14px;border-bottom:1px solid var(--border);color:#c4cdd8;}

.locked-notice{max-width:60ch;margin:80px auto;text-align:center;padding:40px;border:1px solid var(--border);border-radius:12px;background:var(--bg-card);}
.locked-notice svg{width:48px;height:48px;margin-bottom:18px;}
.locked-notice h1{font-family:'Space Grotesk',sans-serif;font-size:24px;margin:0 0 12px;}
.locked-notice p{color:var(--text-muted);font-size:17px;line-height:1.6;margin:0 0 22px;}

/* Admin panel ------------------------------------------------------------------ */
.admin-shell{padding:50px 0 80px;max-width:900px;}
.admin-login-card{max-width:380px;margin:60px auto;padding:36px;border:1px solid var(--border);border-radius:12px;background:var(--bg-card);}
.admin-login-card h1{font-family:'Space Grotesk',sans-serif;font-size:24.5px;margin:0 0 22px;}
.admin-login-card input[type="password"],
.admin-login-card input[type="text"]{
  width:100%;padding:10px 12px;margin-bottom:14px;border-radius:4px;box-sizing:border-box;
  border:1px solid var(--border);background:var(--bg-card);color:var(--text);
  font-family:'IBM Plex Mono',monospace;font-size:18px;
}
.admin-login-card input[type="password"]:focus,
.admin-login-card input[type="text"]:focus{outline:none;border-color:var(--accent-signal);}
.admin-login-card button{width:100%;padding:12px;border-radius:var(--radius);background:var(--accent-up);color:#1a1305;font-weight:500;font-size:17px;cursor:pointer;}
.admin-login-card .error{color:#f0a3a3;font-size:15px;margin:0 0 14px;}
.admin-topbar{display:flex;justify-content:space-between;align-items:center;margin-bottom:28px;}
.admin-topbar h1{font-family:'Space Grotesk',sans-serif;font-size:26px;margin:0;}
.admin-group{margin-bottom:36px;}
.admin-group h2{font-family:'Space Grotesk',sans-serif;font-size:19px;margin:0 0 14px;color:var(--text-muted);}
.admin-row{display:flex;justify-content:space-between;align-items:center;padding:14px 16px;border:1px solid var(--border);border-radius:8px;margin-bottom:8px;background:var(--bg-card);}
.admin-row.is-locked{border-color:rgba(224,104,93,0.4);}
.admin-row .title{font-weight:500;}
.admin-row .right{display:flex;align-items:center;gap:10px;}
.status-badge{font-size:13px;font-family:'IBM Plex Mono',monospace;padding:3px 10px;border-radius:20px;}
.status-badge.open{background:rgba(232,178,58,0.15);color:var(--accent-up);}
.status-badge.locked{background:rgba(224,104,93,0.15);color:var(--accent-down);}
.admin-row button, .status-badge[type="submit"]{padding:7px 14px;border-radius:var(--radius);border:1px solid var(--border-hover);background:var(--bg-elevated);color:var(--text);font-size:14.5px;cursor:pointer;}

/* Assessment-Center ------------------------------------------------------------- */
.assessment-form{max-width:74ch;margin:0 auto;}
.assessment-q{border:1px solid var(--border);border-radius:10px;padding:20px 22px;margin-bottom:16px;background:var(--bg-card);}
.assessment-q-num{font-family:'IBM Plex Mono',monospace;font-size:13px;color:var(--accent-signal);margin-bottom:8px;}
.assessment-q-text{font-size:18px;font-weight:500;color:var(--text);margin-bottom:14px;}
.assessment-q-options{display:flex;flex-direction:column;gap:8px;}
.assessment-option{display:flex;align-items:flex-start;gap:10px;padding:10px 14px;border:1px solid var(--border-hover);border-radius:var(--radius);background:var(--bg-elevated);cursor:pointer;font-size:16px;}
.assessment-option:hover{border-color:var(--accent-up);}
.assessment-option input{margin-top:4px;}
.assessment-review{display:flex;gap:14px;padding:16px 18px;border-radius:8px;margin-bottom:10px;border:1px solid var(--border);}
.assessment-review.is-correct{border-left:3px solid var(--accent-up);}
.assessment-review.is-wrong{border-left:3px solid var(--accent-down);}
.assessment-review-icon{font-size:18px;flex-shrink:0;}
.is-correct .assessment-review-icon{color:var(--accent-up);}
.is-wrong .assessment-review-icon{color:var(--accent-down);}
.assessment-review-q{font-size:16.5px;color:var(--text);}
.assessment-review-info{font-size:14.5px;color:var(--text-faint);margin-top:4px;}

/* Footer ------------------------------------------------------------------------- */
footer{border-top:1px solid var(--border);padding:28px 0;margin-top:20px;}
footer .wrap{display:flex;justify-content:space-between;flex-wrap:wrap;gap:10px;font-size:14px;color:var(--text-faint);}

@media (max-width:760px){
  .hero-grid{grid-template-columns:1fr;}
  nav.main{display:none;}
}