/* FizikRehberi — ortak stil */
:root {
  --bg: #ebe3cf;
  --panel: #f4eee0;
  --ink: #1f1d18;
  --muted: #6e6754;
  --line: #d2c7ac;
  --grid: rgba(70, 55, 25, .07);
  --accent: #1f5c7a;
  --accent-2: #a8432a;
  --ok: #2f7d4f;
  --radius: 6px;
  --sans: "Instrument Sans", system-ui, sans-serif;
  --mono: "JetBrains Mono", ui-monospace, monospace;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #101214; --panel: #16191c; --ink: #e9e7e0; --muted: #8c8a83;
    --line: #2a2e33; --grid: rgba(255, 255, 255, .035);
    --accent: #7db9d8; --accent-2: #e0835f; --ok: #5cc98a; color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --bg: #101214; --panel: #16191c; --ink: #e9e7e0; --muted: #8c8a83;
  --line: #2a2e33; --grid: rgba(255, 255, 255, .035);
  --accent: #7db9d8; --accent-2: #e0835f; --ok: #5cc98a; color-scheme: dark;
}

* { box-sizing: border-box; }
html, body { margin: 0; }
body {
  font-family: var(--sans);
  color: var(--ink);
  background-color: var(--bg);
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}
a { color: inherit; }
.mono { font-family: var(--mono); }
.wrap { max-width: 1120px; margin: 0 auto; padding: 0 16px; }

/* Üst bar */
.bar {
  position: relative; z-index: 10;
}
.bar .wrap { display: flex; align-items: center; gap: 24px; height: 72px; max-width: none; padding: 0 24px; }
.logo { display: flex; align-items: center; gap: 12px; font-size: 25px; text-decoration: none; font-weight: 600; letter-spacing: -.01em; }

.logo em { font-style: normal; color: var(--ink); } /* Labs: açıkta siyah, koyuda beyaz */
.bar nav { display: flex; gap: 20px; margin-left: auto; font-size: 14px; }
.bar .icon-btn, .bar .theme-switch { margin-left: auto; }
.bar nav + .icon-btn, .bar nav + .theme-switch { margin-left: 0; }
.bar nav a { text-decoration: none; color: var(--muted); }
.bar nav a:hover { color: var(--ink); }
.icon-btn {
  display: inline-grid; place-items: center; width: 34px; height: 34px;
  border: 1px solid var(--line); border-radius: var(--radius);
  background: var(--panel); color: var(--ink); cursor: pointer;
}
.icon-btn:hover { border-color: var(--ink); }
.icon-btn svg { width: 16px; height: 16px; }

/* Etiket stili: laboratuvar defteri */
.tag {
  font-family: var(--mono); font-size: 11px; letter-spacing: .08em; text-transform: uppercase;
  color: var(--muted);
}

/* Ana sayfa */
.hero { display: grid; grid-template-columns: 1fr 1.15fr; gap: 48px; align-items: center; padding: 72px 0 56px; }
.hero h1 { font-size: clamp(36px, 5.2vw, 60px); line-height: 1.02; letter-spacing: -.035em; margin: 14px 0 18px; font-weight: 600; }
.hero p { color: var(--muted); font-size: 17px; max-width: 42ch; margin: 0 0 28px; }
.btn[hidden] { display: none; }
.btn {
  display: inline-flex; align-items: center; gap: 8px; padding: 10px 16px;
  border: 1px solid var(--ink); border-radius: var(--radius);
  background: var(--ink); color: var(--bg); text-decoration: none; font-weight: 500; font-size: 14px;
  transition: transform .15s;
}
.btn:hover { transform: translateY(-1px); }
.btn.ghost { background: transparent; color: var(--ink); }
.btns { display: flex; gap: 10px; flex-wrap: wrap; }

.scope { border: 1px solid var(--line); border-radius: var(--radius); background: var(--panel); overflow: hidden; }
.scope-head, .scope-foot {
  display: flex; justify-content: space-between; padding: 8px 12px;
  font-family: var(--mono); font-size: 11px; color: var(--muted);
}
.scope-head { border-bottom: 1px solid var(--line); }
.scope-foot { border-top: 1px solid var(--line); }
.scope canvas { display: block; width: 100%; height: 300px; cursor: crosshair; }
.dot { display: inline-block; width: 7px; height: 7px; border-radius: 50%; background: var(--ok); margin-right: 6px; animation: blink 2s infinite; }
@keyframes blink { 50% { opacity: .3; } }

/* Ders bölümleri */
.course { padding: 40px 0; border-top: 2px solid var(--line); }
.course-head { display: flex; align-items: baseline; justify-content: space-between; gap: 16px; margin-bottom: 20px; flex-wrap: wrap; }
.course-head h2 { font-size: 28px; letter-spacing: -.02em; margin: 4px 0 0; font-weight: 600; }
.course-head .count { font-family: var(--mono); font-size: 13px; color: var(--muted); }

/* Dalga Simülatörü: dersin tamamına ait laboratuvar kartı (haftalardan ayrı, öne çıkan) */
.lab-card { position: relative; display: flex; align-items: center; gap: 24px; min-height: 96px; margin-bottom: 18px; padding: 18px 26px;
  border: 1px solid var(--line); border-radius: var(--radius); background: var(--panel); overflow: hidden; text-decoration: none; color: var(--ink);
  transition: border-color .2s, transform .2s, box-shadow .2s; }
.lab-card::before { content: ""; position: absolute; inset: 0 0 auto 0; height: 3px; background: linear-gradient(90deg, #1a62c9, #16883e, #d1321f); }
@media (prefers-color-scheme: dark) { :root:not([data-theme="light"]) .lab-card::before { background: linear-gradient(90deg, #5aa2ff, #3fd07a, #ff6552); } }
:root[data-theme="dark"] .lab-card::before { background: linear-gradient(90deg, #5aa2ff, #3fd07a, #ff6552); }
@media (hover: hover) { .lab-card:hover { border-color: var(--accent); transform: translateY(-2px); box-shadow: 0 10px 28px rgba(0,0,0,.18); } }
.lab-bg { position: absolute; inset: 0; width: 100%; height: 100%; image-rendering: auto;
  -webkit-mask-image: linear-gradient(90deg, transparent 20%, #000 70%); mask-image: linear-gradient(90deg, transparent 20%, #000 70%); }
.lab-text { position: relative; max-width: 560px; }
.lab-text h3 { margin: 0; font-size: 28px; font-weight: 600; letter-spacing: -.02em; }
.lab-go { position: relative; margin-left: auto; flex: none; padding: 9px 16px; border-radius: 999px; background: var(--ink); color: var(--panel); font-weight: 600; font-size: 14px; }
@media (hover: hover) { .lab-card:hover .lab-go { background: var(--accent); } }
@media (prefers-reduced-motion: reduce) { .lab-card, .lab-card:hover { transform: none; } }
.weeks { border: 1px solid var(--line); border-radius: var(--radius); background: var(--panel); }
.week {
  display: grid; grid-template-columns: 64px minmax(220px, 1fr) minmax(0, 1.5fr); gap: 16px; align-items: center;
  padding: 14px 16px; border-top: 1px solid var(--line);
  opacity: 0; transform: translateY(6px); animation: rise .5s forwards;
}
.week:first-child { border-top: 0; }
@keyframes rise { to { opacity: 1; transform: none; } }
.week .no { font-family: var(--mono); font-size: 13px; color: var(--muted); }
.week .topic { font-size: 15px; }
.sims { display: flex; gap: 6px; flex-wrap: wrap; justify-content: flex-end; }
.chip {
  font-family: var(--mono); font-size: 12px; padding: 4px 10px; border-radius: 999px;
  border: 1px dashed var(--line); color: var(--muted); white-space: nowrap; text-decoration: none;
}
a.chip { border-style: solid; border-color: var(--ink); color: var(--ink); }
a.chip:hover { background: var(--ink); color: var(--panel); }
a.chip::before { content: "▸ "; }
/* Henüz bitmemiş simülasyon: kesikli çerçeve, soluk; yine de tıklanır (iskelet sayfası) */
a.chip.todo { border-style: dashed; border-color: var(--line); color: var(--muted); }
a.chip.todo::before { content: ""; }
a.chip.todo small { font-size: 10.5px; opacity: .8; }
a.chip.todo:hover { background: transparent; color: var(--ink); border-color: var(--muted); }
/* Kategori düğmesi (simülasyon değil, bir simülasyon grubu): köşeli, düz yazı, açılır ok.
   Simülasyonlar yuvarlak, daktilo yazılı haplardır (.chip). */
.cat {
  display: inline-flex; align-items: center; gap: 8px;
  font: 600 13.5px var(--sans); color: var(--ink); cursor: pointer;
  padding: 6px 10px 6px 12px; border-radius: 4px;
  background: var(--bg); border: 1px solid var(--line); border-bottom-width: 2px;
}
.cat::after {
  content: ""; width: 7px; height: 7px; margin-top: -3px;
  border-right: 2px solid currentColor; border-bottom: 2px solid currentColor; transform: rotate(45deg);
  transition: transform .15s;
}
.cat:hover { border-color: var(--ink); }
.cat[aria-expanded="true"] { background: var(--ink); color: var(--panel); border-color: var(--ink); }
.cat[aria-expanded="true"]::after { transform: rotate(-135deg); margin-top: 3px; }
/* içinde hazır simülasyon olmayan kategori: kapalı, "(yakında)" */
.cat:disabled { cursor: default; color: var(--muted); border-style: dashed; border-bottom-width: 1px; }
.cat:disabled:hover { border-color: var(--line); }
.cat:disabled::after { display: none; }
.cat small { font-weight: 400; font-size: .85em; }
/* Açılan kategori: ayrı bir kutu, solunda kategorinin adı */
.week-sub {
  grid-column: 2 / -1; display: flex; flex-wrap: wrap; align-items: center; gap: 6px; justify-content: flex-end;
  background: var(--bg); border: 1px solid var(--line); border-left: 3px solid var(--ink); border-radius: 4px; padding: 8px 10px;
}
.week-sub[hidden] { display: none; }
.sub-label { margin-right: auto; font: 600 12px var(--sans); color: var(--muted); letter-spacing: .02em; }

footer { padding: 32px 0 48px; border-top: 2px solid var(--line); color: var(--muted); font-size: 13px; }

@media (max-width: 820px) {
  .hero { grid-template-columns: 1fr; padding-top: 40px; gap: 28px; }
  .bar nav { display: none; }
  .bar .icon-btn, .bar .theme-switch { margin-left: auto; }
  .week { grid-template-columns: 44px minmax(0, 1fr); }
  .sims { grid-column: 2; justify-content: flex-start; }
  .week-sub { grid-column: 1 / -1; justify-content: flex-start; }
  .sub-label { flex-basis: 100%; }
  .lab-card { padding: 16px 18px; }
  .lab-text h3 { font-size: 22px; }
}
@media (prefers-reduced-motion: reduce) {
  .week { animation: none; opacity: 1; transform: none; }
}

/* ---------- Simülasyon sayfası: ekrana tam sığar, sayfa kaymaz ---------- */
.sim-page main.wrap { display: flex; flex-direction: column; height: calc(100vh - 72px); height: calc(100dvh - 72px); }
.sim-title { display: flex; align-items: flex-end; justify-content: space-between; gap: 12px; padding: 12px 0 10px; flex-wrap: wrap; }
.sim-title h1 { margin: 2px 0 0; font-size: 26px; letter-spacing: -.02em; font-weight: 600; line-height: 1.15; }
.sim-formula { font-size: 17px; }
.sim-formula .eq { overflow: visible; }
.sim-layout { flex: 1; min-height: 0; display: grid; grid-template-columns: minmax(0, 1fr) 360px; gap: 14px; padding-bottom: 14px; }

.stage { position: relative; min-height: 0; border: 1px solid var(--line); border-radius: var(--radius); background: var(--panel); overflow: hidden; }
.stage canvas { position: absolute; inset: 0; display: block; width: 100%; height: 100%; }
.stage-hint { position: absolute; left: 12px; bottom: 10px; font-size: 13px; color: var(--muted); pointer-events: none; }

.panel {
  min-height: 0; overflow-y: auto; display: flex; flex-direction: column; gap: 12px;
  border: 1px solid var(--line); border-radius: var(--radius); background: var(--panel); padding: 14px; font-size: 15px;
}
.panel > * { flex-shrink: 0; } /* taşarsa öğeler ezilmesin (overflow:hidden olan .seg 2 px'e iniyordu) */
.panel .tag { font-size: 11.5px; }
.panel .btn { font-size: 14px; padding: 8px 12px; }
.opt-row { display: grid; grid-template-columns: 62px 1fr; align-items: center; gap: 10px; }
.checks { display: flex; flex-wrap: wrap; gap: 6px 18px; }

.ctrl label { display: flex; justify-content: space-between; font-size: 14.5px; margin-bottom: 4px; }
.ctrl output { font-family: var(--mono); }
input[type=range] { width: 100%; accent-color: var(--accent); }
input[type=checkbox] { accent-color: var(--accent); width: 16px; height: 16px; margin: 0; }
.check { display: flex; align-items: center; gap: 7px; font-size: 14.5px; cursor: pointer; }
.seg { display: grid; grid-auto-flow: column; grid-auto-columns: 1fr; border: 1px solid var(--line); border-radius: var(--radius); overflow: hidden; }
.seg button { font: inherit; font-size: 13.5px; padding: 7px 6px; border: 0; background: transparent; color: var(--muted); cursor: pointer; white-space: nowrap; }
.seg button + button { border-left: 1px solid var(--line); }
.seg button[aria-pressed="true"] { background: var(--ink); color: var(--panel); }

.vtable { width: 100%; border-collapse: collapse; font-family: var(--mono); font-size: 14px; }
.vtable th, .vtable td { text-align: right; padding: 4px; border-bottom: 1px solid var(--line); font-weight: 400; }
.vtable th { color: var(--muted); font-family: var(--sans); }
.vtable td:first-child, .vtable th:first-child { text-align: left; }

.readouts { display: grid; grid-template-columns: 1fr 1fr; gap: 8px; }
.readout { border: 1px solid var(--line); border-radius: var(--radius); padding: 8px 10px; }
.readout b { display: block; font-family: var(--mono); font-size: 20px; font-weight: 500; }
.row { display: flex; gap: 8px; }
.row .btn { flex: 1; justify-content: center; }
.row .seg.speed { flex: none; }
.row .seg.speed button { padding: 7px 10px; }
.row .btn.icon { flex: none; padding: 6px 9px; }
.btn.icon svg { width: 18px; height: 18px; display: block; }
.note { margin: 0; font-size: 13.5px; color: var(--muted); border-left: 2px solid var(--line); padding-left: 10px; }

/* Formüller: her satır tek parça; KaTeX biraz büyük, sonuç kalın */
.calc { border-top: 1px solid var(--line); padding-top: 8px; font-size: 15px; line-height: 1.75; }
.calc .katex { font-size: 1.12em; }
.eq { white-space: nowrap; overflow: hidden; }
.rules { border-top: 1px solid var(--line); padding-top: 8px; }
.rules-list { border-top: 0; padding-top: 2px; font-size: 14px; line-height: 1.7; }
.rules-list b { font-weight: 600; }
.rules-list i { color: var(--muted); }
.c1 { color: var(--accent); }
.c2 { color: var(--accent-2); }

/* Sol sütunda üst üste iki alan (ör. şerit + tablo) */
.stack { display: flex; flex-direction: column; gap: 14px; min-height: 0; }
.stack > .stage { flex: 1; }
.card { border: 1px solid var(--line); border-radius: var(--radius); background: var(--panel); padding: 10px 14px; }
.num-input {
  width: 100%; font: 500 22px var(--mono); color: var(--ink); background: var(--bg);
  border: 1px solid var(--line); border-radius: var(--radius); padding: 6px 10px;
}
.num-input:focus { outline: 2px solid var(--accent); outline-offset: -1px; }
.seg.pfx button { padding: 7px 0; font-family: var(--mono); font-size: 14px; }
.seg.pfx.from button[aria-pressed="true"] { background: var(--accent); color: var(--panel); }
.seg.pfx.to button[aria-pressed="true"] { background: var(--accent-2); color: var(--panel); }
select.unit { font: 500 15px var(--mono); color: var(--ink); background: var(--bg); border: 1px solid var(--line); border-radius: var(--radius); padding: 6px 8px; }

/* Tam ekran: çizim + panel birlikte */
.sim-layout:fullscreen { background: var(--bg); padding: 14px; height: 100vh; }

/* Telefon / dar tablet (dikey): çizim üstte ve kaydırırken yerinde kalır, panel altında sayfayla kayar */
@media (max-width: 820px) {
  .sim-page main.wrap { height: auto; }
  .sim-layout { grid-template-columns: minmax(0, 1fr); }
  .stage { position: sticky; top: 0; z-index: 3; height: min(58vh, 520px); height: min(58svh, 520px); }
  .stack > .stage { flex: none; }
  .stack > .card { overflow-x: auto; }
  /* İçeriği HTML olan (kartlı) sahneler: yapışkan değil, içerik kadar uzar */
  .stage.board, .stage.board2 { position: relative; height: auto; overflow: visible; }
  .stage.board2 .cvwrap { height: 300px; flex: none; }
  .stage.board2 .bottom { columns: 1; }
  .stage.board .ref { overflow-x: auto; }
  .panel { overflow: visible; min-width: 0; }
  .row { flex-wrap: wrap; }
  .sim-title h1 { font-size: 21px; }
  .sim-formula { max-width: 100%; overflow-x: auto; font-size: 14px; }
}
/* Telefon yatay: kısa ekran; üst bar incelir, çizim ve panel yan yana, sayfa kaymaz */
@media (max-height: 520px) and (orientation: landscape) and (min-width: 560px) {
  .bar .wrap { height: 44px; }
  .logo { font-size: 18px; gap: 8px; }
  .logo .mark { width: 32px; height: 32px; }
  .theme-switch { transform: scale(.8); }
  .sim-page main.wrap { height: calc(100vh - 44px); height: calc(100dvh - 44px); }
  .sim-title { padding: 2px 0 6px; }
  .sim-title .tag, .sim-formula { display: none; }
  .sim-title h1 { font-size: 17px; }
  .sim-layout { grid-template-columns: minmax(0, 1fr) 290px; gap: 8px; padding-bottom: 8px; }
  .stage { position: relative; height: auto; }
  .stack { overflow-y: auto; }                       /* çizim görünür alanı doldurur, altındaki kart kayarak görülür */
  .stack > .stage { flex: none; height: calc(100dvh - 44px - 46px); }
  .panel { overflow-y: auto; padding: 8px 10px; gap: 8px; font-size: 14px; }
}
/* Dikey telefonda "yan çevir" önerisi (kapatılabilir) */
.rotate-hint { display: none; }
.rotate-hint svg { flex: none; width: 20px; height: 20px; color: var(--accent); }
.rotate-hint button { margin-left: auto; flex: none; border: 0; background: none; color: var(--muted); font-size: 20px; line-height: 1; padding: 2px 6px; cursor: pointer; }
@media (max-width: 600px) and (orientation: portrait) {
  .sim-page .rotate-hint.to-landscape { display: flex; align-items: center; gap: 10px; margin: 0 0 10px; padding: 8px 10px 8px 12px;
    border: 1px solid var(--line); border-radius: var(--radius); background: var(--panel); font-size: 13.5px; color: var(--muted); }
}

/* Üst bar ikonu (şeffaf zemin): açık temada siyah çerçeveli, koyu temada beyaz çerçeveli */
.logo .mark { width: 58px; height: 58px; }
.logo .mark.dark { display: none; }
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) .logo .mark.light { display: none; }
  :root:not([data-theme="light"]) .logo .mark.dark { display: inline; }
}
:root[data-theme="dark"] .logo .mark.light { display: none; }
:root[data-theme="dark"] .logo .mark.dark { display: inline; }

/* Sol alt: GitHub (+ ana sayfada e-posta) */

/* Giriş animasyonu (ana sayfa): zemin, logo görselinin kendi zeminiyle aynı renk */
.intro { position: fixed; inset: 0; z-index: 100; display: grid; place-items: center; background: #fff; cursor: pointer; transition: opacity .6s ease; }
.intro.dark { background: #0a0b0d; }
.intro[hidden] { display: none; }
.intro img {
  width: min(720px, 86vw); height: auto; opacity: 0; transform: scale(.96); transition: opacity .6s ease, transform 2s ease;
  /* görselin kenarları zemine yumuşakça erir: dikdörtgen çerçeve ve JPEG ton farkı görünmez */
  -webkit-mask-image: linear-gradient(to right, transparent, #000 13%, #000 87%, transparent),
                      linear-gradient(to bottom, transparent, #000 8%, #000 92%, transparent);
  -webkit-mask-composite: source-in;
  mask-image: linear-gradient(to right, transparent, #000 13%, #000 87%, transparent),
              linear-gradient(to bottom, transparent, #000 8%, #000 92%, transparent);
  mask-composite: intersect;
}
.intro.in img { opacity: 1; transform: scale(1); }
.intro.out { opacity: 0; pointer-events: none; }

/* Kısa ekranlar (ör. 1280×720 projektör): panel aralıkları sıkışır */
@media (max-height: 760px) {
  .panel { gap: 8px; padding: 10px 14px; }
  .ctrl label { margin-bottom: 1px; }
  .calc, .rules { padding-top: 6px; }
}

/* Logo yazısı: Ma mavi, Le yeşil, Ti kırmızı (küp ikonunun renkleri); Labs --ink */
.wm .l1 { color: #1a62c9; }
.wm .l2 { color: #16883e; }
.wm .l3 { color: #d1321f; }
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) .wm .l1 { color: #5aa2ff; }
  :root:not([data-theme="light"]) .wm .l2 { color: #3fd07a; }
  :root:not([data-theme="light"]) .wm .l3 { color: #ff6552; }
}
:root[data-theme="dark"] .wm .l1 { color: #5aa2ff; }
:root[data-theme="dark"] .wm .l2 { color: #3fd07a; }
:root[data-theme="dark"] .wm .l3 { color: #ff6552; }

/* Tema anahtarı: açıkta güneş (sarı) solda, koyuda ay (beyaz-mavi) sağda */
.theme-switch {
  position: relative; flex: none; width: 66px; height: 36px; padding: 0; cursor: pointer;
  border-radius: 999px; border: 2px solid var(--muted); background: #f6c945; transition: background .25s, border-color .25s;
}
.theme-switch:hover { border-color: var(--ink); }
.theme-switch:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
.theme-switch .knob {
  position: absolute; top: 2px; left: 2px; width: 28px; height: 28px; border-radius: 50%;
  display: grid; place-items: center; background: #fff7d6; box-shadow: 0 1px 3px rgba(0, 0, 0, .25);
  transition: transform .28s cubic-bezier(.4, .2, .2, 1.2), background .25s;
}
.theme-switch svg { width: 19px; height: 19px; grid-area: 1 / 1; transition: opacity .2s, transform .28s; }
.theme-switch .sun { color: #f2a900; }
.theme-switch .moon { color: #cfe2ff; opacity: 0; transform: rotate(-60deg) scale(.6); }
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) .theme-switch { background: #8ec2ff; border-color: #F20707; }
  :root:not([data-theme="light"]) .theme-switch .knob { transform: translateX(30px); background: #22324a; }
  :root:not([data-theme="light"]) .theme-switch .sun { opacity: 0; transform: rotate(60deg) scale(.6); }
  :root:not([data-theme="light"]) .theme-switch .moon { opacity: 1; transform: none; }
}
:root[data-theme="dark"] .theme-switch { background: #8ec2ff; border-color: #F20707; }
:root[data-theme="dark"] .theme-switch .knob { transform: translateX(30px); background: #22324a; }
:root[data-theme="dark"] .theme-switch .sun { opacity: 0; transform: rotate(60deg) scale(.6); }
:root[data-theme="dark"] .theme-switch .moon { opacity: 1; transform: none; }
@media (prefers-reduced-motion: reduce) { .theme-switch .knob, .theme-switch svg { transition: none; } }



/* Geniş ekranda (sol boşluk ≥ ~350 px) büyük logo: küp üstte, yazı altta; bardan aşağı sol boşluğa taşar.
   Bar yüksekliği değişmez, simülasyon alanı küçülmez. */
@media (min-width: 1840px) {
  /* sol boşluğun ortasına */
  .bar .logo { position: absolute; top: 18px; left: calc((100vw - 1120px) / 4); transform: translateX(-50%); flex-direction: column; gap: 4px; font-size: 40px; letter-spacing: -.02em; }
  .bar .logo .mark { width: 190px; height: 190px; }
}

/* Dokunmatik ekran: kaydırıcı ve düğmeler parmakla rahat tutulsun */
@media (pointer: coarse) {
  input[type=range] { height: 28px; }
  .seg button { padding-top: 9px; padding-bottom: 9px; }
}

/* Çok dar telefon (≈320 px): üst bar sığsın */
@media (max-width: 360px) {
  .bar .wrap { padding: 0 12px; gap: 10px; }
  .logo { font-size: 20px; gap: 8px; }
  .logo .mark { width: 44px; height: 44px; }
  .theme-switch { transform: scale(.85); transform-origin: right center; }
}
/* Kısa geniş ekran (ör. yakınlaştırılmış projeksiyon): üst üste iki alanlı sayfada çizim ezilmesin, alttaki kart kayarak görülür */
@media (max-height: 700px) and (min-width: 821px) {
  .stack { overflow-y: auto; }
  .stack > .stage { flex: none; height: max(300px, calc(100dvh - 170px)); }
}

.sr-only { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; }
/* "Dikey çevirin" önerisi (dikeyde daha iyi duran sayfalar): yatay telefonda, sim-layout'un üstünde ince şerit */
@media (max-height: 520px) and (orientation: landscape) and (min-width: 560px) {
  .sim-page .rotate-hint.to-portrait { display: flex; align-items: center; gap: 8px; margin: 0 0 6px; padding: 4px 8px 4px 10px;
    border: 1px solid var(--line); border-radius: var(--radius); background: var(--panel); font-size: 12.5px; color: var(--muted); }
}

/* Açık tema şimdilik kapalı (core.js: ACIK_TEMA): tema anahtarı gizli */
[data-theme-toggle] { display: none !important; }

/* Quatressence ana sayfasına dönüş */
.bar .home-link { margin-left: auto; font-size: 14px; color: var(--muted); text-decoration: none; white-space: nowrap; }
.bar .home-link:hover { color: var(--ink); }
.bar nav + .home-link { margin-left: 20px; }
@media (max-width: 820px) { .bar nav + .home-link { margin-left: auto; } .bar .home-link { font-size: 13px; } }

/* Ana sayfa: ders seçimi (her ders kendi sayfasında) */
.course-pick { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 20px; padding: 64px 0 80px; }
.pick {
  position: relative; display: flex; flex-direction: column; gap: 6px; min-height: 170px; padding: 26px 26px 22px; overflow: hidden;
  background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius); text-decoration: none;
}
.pick::before { content: ""; position: absolute; inset: 0 0 auto; height: 4px; background: linear-gradient(90deg, #5aa2ff, #3fd07a, #ff6552); }
.pick h2 { margin: 0; font-size: 32px; font-weight: 600; letter-spacing: -.02em; }
.pick-go { margin-top: auto; align-self: flex-end; font-size: 14px; color: var(--muted); }
@media (hover: hover) { .pick:hover { border-color: var(--ink); } .pick:hover .pick-go { color: var(--ink); } }
.course-head h1 { font-size: 28px; letter-spacing: -.02em; margin: 4px 0 0; font-weight: 600; }
@media (max-width: 820px) { .course-pick { grid-template-columns: 1fr; padding: 28px 0 48px; gap: 14px; } .pick { min-height: 130px; } .pick h2 { font-size: 26px; } }

/* Geri dön düğmeleri: görünür hap düğme */
.bar nav a, .bar .home-link, .back {
  display: inline-flex; align-items: center; padding: 7px 14px; border: 1px solid var(--line); border-radius: 999px;
  background: var(--panel); color: var(--ink); font-size: 14px; font-weight: 500; line-height: 1.2; text-decoration: none; white-space: nowrap;
}
.bar nav a:hover, .bar .home-link:hover, .back:hover { border-color: var(--ink); color: var(--ink); }
.bar nav + .home-link { margin-left: 10px; }
.back { margin-bottom: 14px; }
@media (max-width: 820px) {
  .bar nav { display: flex; margin-left: auto; }
  .bar nav + .home-link { display: none; }   /* telefonda yalnız bağlamdaki geri düğmesi */
  .bar nav a, .bar .home-link, .back { padding: 5px 10px; font-size: 12.5px; }
  .bar nav { margin-right: 4px; }
}