/* Ringkasan Buku — style.css
   Mobile-first, tanpa dependensi. Tema lewat [data-tema]. */

:root {
  --lebar-toc: 288px;
  --lebar-baca: 74ch;
  --radius: 14px;
  --radius-kecil: 9px;
  --jarak: 16px;
  --transisi: 180ms ease;
  --font: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", sans-serif;
}

[data-tema="terang"] {
  --bg: #f6f7f9;
  --bg-naik: #ffffff;
  --bg-lembut: #eef0f4;
  --teks: #16181d;
  --teks-lembut: #5a6070;
  --teks-samar: #858b9b;
  --garis: #e2e5ec;
  --garis-kuat: #cdd2dd;
  --aksen: #2f6bff;
  --aksen-lembut: #eaf0ff;
  --bayang: 0 1px 2px rgba(20, 24, 35, .06), 0 8px 24px rgba(20, 24, 35, .05);
}

[data-tema="gelap"] {
  --bg: #0f1115;
  --bg-naik: #171a21;
  --bg-lembut: #1e222b;
  --teks: #e8eaf0;
  --teks-lembut: #a7adbd;
  --teks-samar: #7d8393;
  --garis: #262b35;
  --garis-kuat: #333a47;
  --aksen: #7aa2ff;
  --aksen-lembut: #1c2740;
  --bayang: 0 1px 2px rgba(0, 0, 0, .4), 0 10px 30px rgba(0, 0, 0, .35);
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  font-family: var(--font);
  font-size: 16.5px;
  line-height: 1.68;
  color: var(--teks);
  background: var(--bg);
  overflow-wrap: break-word;
}

h1, h2, h3, h4 { line-height: 1.28; margin: 0 0 .5em; font-weight: 650; letter-spacing: -.01em; }
p { margin: 0 0 .85em; }
a { color: var(--aksen); }
:focus-visible { outline: 2px solid var(--aksen); outline-offset: 2px; border-radius: 4px; }

.sr {
  position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px;
  overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; border: 0;
}

.lompat {
  position: absolute; left: -999px; top: 0; z-index: 50;
  background: var(--bg-naik); color: var(--teks); padding: 10px 14px; border-radius: 0 0 var(--radius-kecil) 0;
}
.lompat:focus { left: 0; }

/* ---------- Progres membaca ---------- */
.progres {
  position: fixed; inset: 0 0 auto 0; height: 3px; z-index: 40;
  background: transparent; pointer-events: none;
}
.progres span {
  display: block; height: 100%; width: 0;
  background: var(--aksen); transition: width 120ms linear;
}

/* ---------- App bar ---------- */
.appbar {
  position: sticky; top: 0; z-index: 30;
  display: flex; align-items: center; gap: 8px;
  padding: 10px 12px;
  background: color-mix(in srgb, var(--bg-naik) 88%, transparent);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--garis);
}
.merek { font-size: 1.02rem; margin: 0; flex: 1; }
.aksi { display: flex; gap: 4px; }

.ikon {
  width: 44px; height: 44px; flex: none;
  display: inline-flex; align-items: center; justify-content: center;
  font-size: 1.05rem; line-height: 1;
  color: var(--teks-lembut); background: transparent;
  border: 1px solid transparent; border-radius: 10px; cursor: pointer;
  transition: background var(--transisi), color var(--transisi);
}
.ikon:hover { background: var(--bg-lembut); color: var(--teks); }
.ikon[aria-expanded="true"] { background: var(--aksen-lembut); color: var(--aksen); }

/* ---------- Baris cari ---------- */
.caribar {
  position: sticky; top: 65px; z-index: 29;
  display: flex; align-items: center; gap: 10px;
  padding: 8px 12px; background: var(--bg-naik); border-bottom: 1px solid var(--garis);
}
.caribar input {
  flex: 1; min-width: 0; font: inherit; color: var(--teks);
  background: var(--bg-lembut); border: 1px solid var(--garis-kuat);
  border-radius: 999px; padding: 10px 14px;
}
.caribar input::-webkit-search-cancel-button { cursor: pointer; }
.info-cari { font-size: .8rem; color: var(--teks-samar); white-space: nowrap; }

/* ---------- Tata letak ---------- */
.tata { display: block; }
#utama { padding: var(--jarak) 12px 40px; }

/* ---------- Daftar isi ---------- */
.toc {
  position: fixed; inset: 0 auto 0 0; z-index: 35;
  width: min(86vw, var(--lebar-toc));
  display: flex; flex-direction: column;
  background: var(--bg-naik); border-right: 1px solid var(--garis);
  transform: translateX(-102%);
  transition: transform var(--transisi);
}
.toc.terbuka { transform: none; }
.toc-head {
  display: flex; align-items: center; justify-content: space-between;
  gap: 8px; padding: 10px 10px 6px; border-bottom: 1px solid var(--garis);
}
.toc-head h2 { font-size: .78rem; text-transform: uppercase; letter-spacing: .09em; color: var(--teks-samar); margin: 0; }
.toc-nav { flex: 1; overflow-y: auto; padding: 10px 8px 40px; overscroll-behavior: contain; }
.toc-bab { margin-bottom: 6px; }
.toc-bab > a {
  display: block; padding: 10px; border-radius: var(--radius-kecil);
  font-size: .92rem; font-weight: 600; color: var(--teks); text-decoration: none;
}
.toc-bab > a:hover { background: var(--bg-lembut); }
.toc-bab.aktif > a { background: var(--aksen-lembut); color: var(--aksen); }
.toc-sub { list-style: none; margin: 2px 0 4px; padding: 0 0 0 10px; border-left: 1px solid var(--garis); }
.toc-sub a {
  display: block; padding: 8px 9px; font-size: .84rem; line-height: 1.4;
  color: var(--teks-lembut); text-decoration: none; border-radius: 7px;
}
.toc-sub a:hover { background: var(--bg-lembut); color: var(--teks); }
.toc-sub a.aktif { color: var(--aksen); }

.backdrop { position: fixed; inset: 0; z-index: 34; background: rgba(10, 12, 18, .5); }

/* ---------- Keadaan memuat & galat ---------- */
.keadaan { max-width: 520px; margin: 12vh auto; text-align: center; }
.keadaan h2 { font-size: 1.25rem; }
.pimpin { color: var(--teks-lembut); }
.pemutar {
  width: 30px; height: 30px; margin: 0 auto 14px;
  border: 3px solid var(--garis-kuat); border-top-color: var(--aksen);
  border-radius: 50%; animation: putar .9s linear infinite;
}
@keyframes putar { to { transform: rotate(360deg); } }
@media (prefers-reduced-motion: reduce) {
  .pemutar { animation-duration: 2.4s; }
  html { scroll-behavior: auto; }
  * { transition-duration: 1ms !important; }
}

/* ---------- Tombol ---------- */
.tombol {
  display: inline-flex; align-items: center; justify-content: center; gap: 6px;
  font: inherit; font-size: .92rem; font-weight: 600;
  padding: 10px 16px; border-radius: 999px; cursor: pointer;
  color: var(--teks); background: var(--bg-naik); border: 1px solid var(--garis-kuat);
  transition: background var(--transisi), border-color var(--transisi), opacity var(--transisi);
}
.tombol:hover { background: var(--bg-lembut); }
.tombol.utama { background: var(--aksen); border-color: var(--aksen); color: #fff; }
.tombol.utama:hover { filter: brightness(1.06); }
.tombol.kecil { padding: 10px 15px; font-size: .84rem; min-height: 44px; }
.tombol[disabled] { opacity: .5; cursor: not-allowed; }

/* ---------- Kepala buku ---------- */
.buku-head { max-width: var(--lebar-baca); margin: 8px auto 22px; }
.buku-head h1 { font-size: 1.6rem; }
.penulis { color: var(--teks-lembut); font-size: .95rem; margin-bottom: .6em; }
.desk { color: var(--teks-lembut); font-size: .96rem; }
.label { font-size: .72rem; text-transform: uppercase; letter-spacing: .09em; color: var(--teks-samar); margin-bottom: .4em; }
.statistik { font-size: .8rem; color: var(--teks-samar); margin-top: 10px; }

.lanjut {
  display: flex; flex-wrap: wrap; align-items: center; gap: 10px;
  max-width: var(--lebar-baca); margin: 0 auto 20px; padding: 12px 14px;
  background: var(--aksen-lembut); border-radius: var(--radius);
  font-size: .88rem; color: var(--teks);
}

/* ---------- Bab & sub-bab ---------- */
#konten { max-width: var(--lebar-baca); margin: 0 auto; }

.bab { margin-bottom: 42px; scroll-margin-top: 84px; }
.bab-head { padding-bottom: 12px; margin-bottom: 18px; border-bottom: 2px solid var(--garis); }
.bab-no { font-size: .74rem; text-transform: uppercase; letter-spacing: .1em; color: var(--aksen); font-weight: 700; margin-bottom: .3em; }
.bab-judul { font-size: 1.35rem; margin: 0; }
.bab-asli { font-size: .84rem; color: var(--teks-samar); font-style: italic; margin: .35em 0 0; }

.blok { margin-bottom: 22px; }
.blok-judul {
  font-size: .74rem; text-transform: uppercase; letter-spacing: .09em;
  color: var(--teks-samar); margin: 0 0 .6em; font-weight: 700;
}

.subbab {
  padding: 16px; margin-bottom: 16px;
  background: var(--bg-naik); border: 1px solid var(--garis); border-radius: var(--radius);
  box-shadow: var(--bayang); scroll-margin-top: 84px;
}
.subbab-head { display: flex; align-items: baseline; gap: 8px; margin-bottom: 10px; }
.subbab-no {
  font-size: .78rem; font-weight: 700; color: var(--aksen);
  background: var(--aksen-lembut); padding: 2px 8px; border-radius: 999px; flex: none;
}
.subbab-judul { font-size: 1.06rem; margin: 0; }
.subbab-asli { font-size: .8rem; color: var(--teks-samar); font-style: italic; margin: -.4em 0 .8em; }

.konsep { list-style: none; margin: 0; padding: 0; }
.konsep li { padding: 9px 0; border-top: 1px solid var(--garis); }
.konsep li:first-child { border-top: 0; }
.konsep b { display: block; font-size: .93rem; }
.konsep span { font-size: .9rem; color: var(--teks-lembut); }

.contoh { margin: 0; padding-left: 20px; }
.contoh li { font-size: .92rem; color: var(--teks-lembut); margin-bottom: .35em; }

.antar { display: flex; gap: 10px; max-width: var(--lebar-baca); margin: 28px auto 0; }
.antar .tombol { flex: 1; }
.kaki { max-width: var(--lebar-baca); margin: 30px auto 0; padding-top: 16px; border-top: 1px solid var(--garis); }
.kaki p { font-size: .8rem; color: var(--teks-samar); }

.tersembunyi { display: none !important; }

/* ---------- Tablet & desktop ---------- */
@media (min-width: 700px) {
  body { font-size: 17px; }
  .buku-head h1 { font-size: 1.95rem; }
  .bab-judul { font-size: 1.55rem; }
  .subbab { padding: 20px 22px; }
  #utama { padding: 20px 22px 60px; }
  .antar { justify-content: space-between; }
  .antar .tombol { flex: 0 1 auto; }
  .tombol.kecil { min-height: 0; padding: 8px 14px; }
}

@media (min-width: 1000px) {
  .tata { display: grid; grid-template-columns: var(--lebar-toc) minmax(0, 1fr); }
  .toc { position: sticky; top: 65px; height: calc(100vh - 65px); transform: none; width: auto; }
  #btn-toc, #btn-toc-tutup, .backdrop { display: none; }
  .caribar { top: 65px; padding-left: 22px; }
  #utama { padding: 26px 34px 70px; }
  .merek { font-size: 1.06rem; }
}