/* ============================================================
   Shared styles for the Astronomical Calculations Curriculum
   ============================================================ */
:root{
  --bg-0:#04070f; --bg-1:#070c18; --bg-2:#0b1222; --bg-3:#0f1830;
  --line:#1a2744; --line-2:#243458;
  --cyan:#22d3ee; --cyan-dim:rgba(34,211,238,0.6); --cyan-glow:rgba(34,211,238,0.18);
  --pink:#f472b6; --gold:#fbbf24; --violet:#a78bfa; --green:#4ade80;
  --txt:#e2e8f0; --txt-dim:#94a3b8; --txt-faint:#64748b;

  /* ===== type system (hybrid) =====
     display → للعناوين الكبرى فقط (العربي Marhey / الإنجليزي Crimson Pro)
     body    → لكل المتن والواجهة (العربي IBM Plex Sans Arabic / الإنجليزي Space Grotesk)
     mono    → للأرقام والأكواد والليبل التقنية (JetBrains Mono) */
  --font-display: 'Almarai', 'Crimson Pro', 'IBM Plex Sans Arabic', 'Space Grotesk', sans-serif;
  --font-body:    'IBM Plex Sans Arabic', 'Space Grotesk', system-ui, sans-serif;
  --font-mono:    'JetBrains Mono', ui-monospace, monospace;
}
html[dir="ltr"]{
  --font-display: 'Crimson Pro', 'Almarai', 'Space Grotesk', serif;
  --font-body:    'Space Grotesk', 'IBM Plex Sans Arabic', system-ui, sans-serif;
}
*{ box-sizing:border-box; }
html,body,#root{ height:100%; margin:0; }
body{
  background:
    radial-gradient(ellipse at 20% -10%, rgba(34,211,238,0.06), transparent 55%),
    radial-gradient(ellipse at 100% 100%, rgba(244,114,182,0.04), transparent 45%),
    var(--bg-0);
  color: var(--txt);
  font-family: var(--font-body);
  font-feature-settings: "ss01","ss02";
  overflow:hidden;
}
button, input, select{ font-family: inherit; color: inherit; }

/* ===== shell: sidebar + main ===== */
.shell{ height:100%; display:grid; grid-template-columns: 320px 1fr;
        min-height:0; overflow:hidden; }
.shell > aside{
  background: linear-gradient(180deg, var(--bg-1), var(--bg-0));
  border-inline-end:1px solid var(--line);
  display:flex; flex-direction:column; min-height:0;
}
.shell > main{ min-height:0; overflow:hidden; display:flex; flex-direction:column; }

/* ===== sidebar brand ===== */
.sb-brand{
  padding: 18px 18px 14px;
  border-bottom:1px solid var(--line);
  display:flex; align-items:center; gap:12px;
}
.sb-brand-mark{
  width:42px; height:42px; border-radius:10px;
  background: rgba(34,211,238,0.06);
  border:1px solid var(--line-2);
  display:flex; align-items:center; justify-content:center;
  box-shadow: 0 0 30px var(--cyan-glow) inset;
  flex-shrink:0;
}
.sb-brand-title{ font-family: var(--font-display);
                 font-size:16px; font-weight:800; letter-spacing:0; line-height:1.2; }
html[dir="ltr"] .sb-brand-title{ font-size:18px; font-weight:600; letter-spacing:-0.01em; }
.sb-brand-sub{ font-size:10.5px; color:var(--txt-dim);
               font-family:'JetBrains Mono',monospace; margin-top:3px;
               letter-spacing:0.04em; }

/* ===== sidebar: back arrow (lesson pages) ===== */
.sb-back{
  display:flex; align-items:center; justify-content:center;
  width:36px; height:36px;
  margin: 12px 18px 0;
  background: var(--bg-2); border:1px solid var(--line-2);
  border-radius:8px; color: var(--txt-dim);
  font-size:18px; text-decoration:none;
  transition: all .15s;
}
.sb-back:hover{
  color: var(--cyan); border-color: var(--cyan-dim);
  background: rgba(34,211,238,0.06);
}

/* ===== sidebar meta (lang switcher) ===== */
.sb-meta{ padding: 10px 18px; border-bottom:1px solid var(--line);
          display:flex; align-items:center; justify-content:space-between;
          gap:10px; }
.sb-meta-label{ font-size:10px; color:var(--txt-faint);
                font-family:'JetBrains Mono',monospace;
                text-transform:uppercase; letter-spacing:0.18em; }
.seg{ display:flex; background:var(--bg-2); border:1px solid var(--line-2);
      border-radius:6px; overflow:hidden; }
.seg button{ background:transparent; border:none; color:var(--txt-dim);
             padding:5px 12px; cursor:pointer; font-size:11px;
             font-family:'JetBrains Mono',monospace; letter-spacing:0.03em; }
.seg button.on{ background:var(--cyan); color:#000; font-weight:600; }

/* ===== lesson list ===== */
.sb-list{ flex:1; overflow-y:auto; padding: 8px 10px 20px; }
.sb-group-label{
  font-size:10px; letter-spacing:0.2em; text-transform:uppercase;
  color:var(--cyan); font-family:'JetBrains Mono',monospace;
  padding: 14px 10px 6px;
}
.sb-item{
  display:flex; align-items:center; gap:10px;
  padding: 10px 10px; margin: 2px 0;
  border-radius:7px; cursor:pointer; text-decoration:none;
  color:var(--txt-dim); transition: background .12s, color .12s;
  border: 1px solid transparent;
}
.sb-item:hover{ background: rgba(34,211,238,0.04); color:var(--txt); }
.sb-item.active{
  background: rgba(34,211,238,0.08);
  border-color: var(--cyan-dim);
  color:var(--txt);
}
.sb-item.active .sb-num{ background:var(--cyan); color:#000; }
.sb-item.missing .sb-num{ background: rgba(167,139,250,0.15);
                          color: var(--violet); border: 1px dashed var(--violet); }
.sb-item.missing.active .sb-num{ background: var(--violet); color:#000; border:none; }
.sb-num{
  width:28px; height:28px; border-radius:7px;
  background: var(--bg-2); color: var(--txt-dim);
  font-family:'JetBrains Mono',monospace;
  font-size:11px; font-weight:600;
  display:flex; align-items:center; justify-content:center;
  flex-shrink:0; letter-spacing:0; transition: background .12s;
}
.sb-text{ min-width:0; flex:1; }
.sb-title{ font-size:13px; line-height:1.35; }
.sb-sub{ font-size:10.5px; color:var(--txt-faint);
         font-family:'JetBrains Mono',monospace;
         margin-top:2px; white-space:nowrap; overflow:hidden; text-overflow:ellipsis; }

/* ===== main: header ===== */
.lesson-head{
  flex-shrink:0; padding: 20px 28px 16px;
  border-bottom:1px solid var(--line);
  background: linear-gradient(to bottom, rgba(15,24,48,0.55), transparent);
  display:flex; align-items:flex-start; justify-content:space-between; gap:20px;
}
.lh-left{ min-width:0; flex:1; }
.lh-tag{
  display:inline-flex; gap:8px; align-items:center;
  font-size:10.5px; color:var(--cyan);
  font-family:'JetBrains Mono',monospace;
  letter-spacing:0.2em; text-transform:uppercase;
  background: rgba(34,211,238,0.06);
  border:1px solid var(--line-2);
  padding:4px 10px; border-radius:20px; margin-bottom:10px;
}
.lh-tag.missing{ color: var(--violet);
                 background: rgba(167,139,250,0.06);
                 border-color: rgba(167,139,250,0.3); }
.lh-title{ font-family: var(--font-display);
           font-size:28px; font-weight:800; letter-spacing:0;
           line-height:1.2; margin:0; }
html[dir="ltr"] .lh-title{ font-size:32px; font-weight:600; letter-spacing:-0.015em; }
.lh-goal{ font-size:13px; color:var(--txt-dim); line-height:1.6;
          margin-top:8px; max-width:80ch; }

.lh-nav{ display:flex; gap:8px; flex-shrink:0; }
.lh-nav a{
  display:inline-flex; align-items:center; gap:6px;
  padding: 8px 14px; border-radius:7px;
  background: var(--bg-2); border:1px solid var(--line-2);
  color: var(--txt-dim); font-family:'JetBrains Mono',monospace;
  font-size:11px; text-decoration:none;
  transition: all .15s;
}
.lh-nav a:hover{ color: var(--cyan); border-color: var(--cyan-dim);
                 background: rgba(34,211,238,0.06); }

/* ===== main body (2-column: stage | side) ===== */
.lesson-body{ flex:1; min-height:0; display:grid;
              grid-template-columns: 1fr 380px; overflow:hidden; }
.stage-col{ min-height:0; overflow:hidden; position:relative;
            background:
              radial-gradient(ellipse at center, #05090f 0%, #020307 100%); }
.stage-col::before{
  content:""; position:absolute; inset:0;
  background-image:
    linear-gradient(rgba(34,211,238,0.03) 1px, transparent 1px),
    linear-gradient(90deg, rgba(34,211,238,0.03) 1px, transparent 1px);
  background-size: 40px 40px;
  mask-image: radial-gradient(ellipse at center, black 30%, transparent 82%);
  pointer-events:none;
}
.side-col{
  min-height:0; overflow-y:auto;
  border-inline-start:1px solid var(--line);
  background: linear-gradient(180deg, var(--bg-1), var(--bg-0));
  padding: 20px;
}

/* ===== reusable cards ===== */
.card{
  background: var(--bg-2);
  border:1px solid var(--line);
  border-radius:10px; padding: 14px 16px;
  margin-bottom: 14px;
}
.card-title{
  font-size:10.5px; letter-spacing:0.2em; text-transform:uppercase;
  font-family:'JetBrains Mono',monospace;
  color:var(--cyan); margin-bottom:10px; font-weight:600;
  display:flex; align-items:center; gap:8px;
}
.card-title .swatch{ width:10px; height:10px; border-radius:50%; }
.card.pink .card-title{ color:var(--pink); }
.card.gold .card-title{ color:var(--gold); }
.card.violet .card-title{ color:var(--violet); }
.card.green .card-title{ color:var(--green); }
.card.pink{ border-inline-start:3px solid var(--pink); }
.card.cyan{ border-inline-start:3px solid var(--cyan); }
.card.gold{ border-inline-start:3px solid var(--gold); }
.card.violet{ border-inline-start:3px solid var(--violet); }
.card.green{ border-inline-start:3px solid var(--green); }

.kv{ display:flex; justify-content:space-between; gap:12px;
     padding: 6px 0; font-size:12.5px;
     border-bottom:1px dashed rgba(148,163,184,0.08); }
.kv:last-child{ border:none; }
.kv .k{ color:var(--txt-dim); }
.kv .v{ color:var(--txt); font-family:'JetBrains Mono',monospace;
        direction:ltr; text-align:end; }
.kv.hi{ background:rgba(34,211,238,0.06); margin: 4px -16px;
        padding: 7px 16px; border-radius:5px; border:none; }
.kv.hi .v{ color:var(--cyan); font-weight:600; }

/* ===== formula boxes ===== */
.fx{
  background: linear-gradient(135deg, rgba(34,211,238,0.04), rgba(244,114,182,0.02));
  border:1px solid var(--line);
  border-radius:10px; padding: 14px;
  margin-bottom: 14px;
}
.fx-label{ font-size:10px; letter-spacing:0.2em; text-transform:uppercase;
           color:var(--cyan); font-family:'JetBrains Mono',monospace;
           margin-bottom:8px; }
.fx-line{ font-family:'JetBrains Mono',monospace; font-size:13px;
          color:var(--txt); padding:5px 0;
          direction:ltr; text-align:start; line-height:1.5; }
.fx-hint{ font-size:11px; color:var(--txt-faint);
          font-family:'JetBrains Mono',monospace; margin-top:6px;
          direction:ltr; line-height:1.6; }

/* ===== control row ===== */
.ctl-row{ margin-bottom:12px; }
.ctl-row label{
  display:flex; justify-content:space-between; gap:8px;
  font-size:10px; letter-spacing:0.1em; text-transform:uppercase;
  color:var(--txt-faint); margin-bottom:6px;
  font-family:'JetBrains Mono',monospace;
}
.ctl-row label .val{ color:var(--cyan); direction:ltr; letter-spacing:0; }
.ctl-row input[type="range"]{ width:100%; -webkit-appearance:none; appearance:none;
  background:transparent; height:22px; margin:0; }
.ctl-row input[type="range"]::-webkit-slider-runnable-track{
  height:4px; background: linear-gradient(90deg, var(--cyan-glow), var(--line-2));
  border-radius:2px; }
.ctl-row input[type="range"]::-webkit-slider-thumb{
  -webkit-appearance:none; appearance:none; width:14px; height:14px; border-radius:50%;
  background:var(--cyan); margin-top:-5px;
  box-shadow: 0 0 0 3px rgba(34,211,238,0.2); cursor:grab; }
.ctl-row input[type="range"]::-moz-range-track{
  height:4px; background:var(--line-2); border-radius:2px; }
.ctl-row input[type="range"]::-moz-range-thumb{
  width:14px; height:14px; border-radius:50%; background:var(--cyan); border:none;
  box-shadow: 0 0 0 3px rgba(34,211,238,0.2); cursor:grab; }
.ctl-row input[type="number"], .ctl-row select{
  width:100%; background:var(--bg-2); color:var(--txt);
  border:1px solid var(--line-2); border-radius:6px;
  padding:7px 9px; font-size:12.5px; font-family:'JetBrains Mono',monospace;
}
.ctl-row input[type="number"]:focus, .ctl-row select:focus{
  outline:none; border-color:var(--cyan); box-shadow:0 0 0 3px var(--cyan-glow); }

/* ===== chips / hint ===== */
.hint{
  font-size:12px; color:var(--txt-dim); line-height:1.6;
  background: rgba(34,211,238,0.04);
  border: 1px solid var(--line);
  border-radius:7px; padding:10px 12px;
}
.hint strong{ color:var(--txt); }

/* ===== step cards (derivations) ===== */
.step{ background:var(--bg-2); border:1px solid var(--line);
       border-radius:10px; margin-bottom:12px; overflow:hidden; }
.step-head{ display:flex; align-items:center; gap:10px;
            padding:10px 14px; background:rgba(34,211,238,0.04);
            border-bottom:1px solid var(--line); }
.step-num{ width:24px; height:24px; border-radius:50%;
           background:var(--cyan); color:#000; font-weight:700; font-size:12px;
           display:flex; align-items:center; justify-content:center;
           font-family:'JetBrains Mono',monospace; flex-shrink:0; }
.step-title{ font-size:13px; font-weight:500; }
.step-body{ padding:10px 14px; }

/* ===== lesson link (prev/next) ===== */
.lesson-nav-bottom{
  display:grid; grid-template-columns:1fr 1fr; gap:10px;
  margin-top:18px;
}
.lesson-nav-bottom a{
  display:flex; flex-direction:column; gap:3px;
  padding:12px 14px; border-radius:8px;
  background: var(--bg-2); border:1px solid var(--line);
  color: var(--txt-dim); text-decoration:none;
  transition: all .15s;
}
.lesson-nav-bottom a:hover{ border-color: var(--cyan-dim);
                            background: rgba(34,211,238,0.04);
                            color: var(--txt); }
.lesson-nav-bottom .nav-dir{ font-size:10px; color:var(--txt-faint);
                             font-family:'JetBrains Mono',monospace;
                             letter-spacing:0.2em; text-transform:uppercase; }
.lesson-nav-bottom .nav-t{ font-size:13px; color:var(--txt); line-height:1.35; }

/* ===== objective banner ===== */
.objective{
  background: linear-gradient(135deg, rgba(34,211,238,0.07), rgba(244,114,182,0.04));
  border:1px solid var(--line-2);
  border-radius:10px; padding: 12px 14px;
  margin-bottom:14px;
  display:flex; gap:12px; align-items:flex-start;
}
.objective-icon{
  width:28px; height:28px; border-radius:7px;
  background:rgba(34,211,238,0.1); color:var(--cyan);
  display:flex; align-items:center; justify-content:center;
  font-size:14px; flex-shrink:0;
}
.objective-text{ font-size:12.5px; color:var(--txt); line-height:1.6; }
.objective-text strong{ color:var(--cyan); }

/* ===== scrollbars ===== */
::-webkit-scrollbar{ width:9px; height:9px; }
::-webkit-scrollbar-track{ background:transparent; }
::-webkit-scrollbar-thumb{ background:var(--line-2); border-radius:10px; }
::-webkit-scrollbar-thumb:hover{ background:var(--cyan-dim); }

html[dir="rtl"] .ctl-row input[type="number"]{ direction:ltr; text-align:end; }

/* ===== badge for "missing" lessons ===== */
.missing-badge{
  display:inline-block; font-size:9.5px;
  background: rgba(167,139,250,0.12); color: var(--violet);
  border: 1px solid rgba(167,139,250,0.3);
  padding: 2px 8px; border-radius: 20px; margin-inline-start: 8px;
  font-family:'JetBrains Mono',monospace; letter-spacing:0.08em;
  vertical-align: middle;
}

/* ===== empty / placeholder state for lessons-to-come ===== */
.placeholder{
  height:100%; display:flex; flex-direction:column;
  align-items:center; justify-content:center; gap:14px;
  color: var(--txt-dim);
  padding: 40px;
  text-align:center;
}
.placeholder-icon{
  width:72px; height:72px; border-radius:18px;
  background: rgba(167,139,250,0.08);
  border: 1px dashed rgba(167,139,250,0.4);
  display:flex; align-items:center; justify-content:center;
  color: var(--violet); font-size:28px;
}
.placeholder h2{ font-family: var(--font-display);
                 font-size:22px; font-weight:800; letter-spacing:0;
                 margin:0; color:var(--txt); }
html[dir="ltr"] .placeholder h2{ font-weight:600; letter-spacing:-0.01em; }
.placeholder p{ font-size:13px; max-width:50ch; line-height:1.7; margin:0; }

/* ===== stage overlay / legend ===== */
.stage-legend{
  position:absolute; top:16px; inset-inline-start:16px;
  display:flex; gap:8px; flex-wrap:wrap; pointer-events:none; z-index:5;
}
.stage-legend .chip{
  display:inline-flex; align-items:center; gap:7px;
  font-size:10.5px; color:var(--txt-dim);
  font-family:'JetBrains Mono',monospace;
  background: rgba(4,7,15,0.7);
  padding: 4px 9px; border-radius:20px;
  border:1px solid var(--line);
  backdrop-filter: blur(6px);
}
.stage-legend .chip .dot{ width:8px; height:8px; border-radius:50%; }
.stage-tag{
  position:absolute; bottom:14px; inset-inline-end:16px;
  font-size:10.5px; color:var(--txt-faint);
  font-family:'JetBrains Mono',monospace;
  background: rgba(4,7,15,0.7);
  padding: 4px 10px; border-radius:20px;
  border:1px solid var(--line);
  backdrop-filter: blur(6px);
  pointer-events:none;
}