/* Bố cục: thanh chuyên mục dính trên cùng, lưới thẻ bài viết, trang bài một cột hẹp dễ đọc.
   Màu lấy từ bàn làm việc điện tử: nền xám nguội như mặt bàn, màu nhấn đồng của mối hàn. */
:root {
  --bg: #f3f4f7;
  --surface: #ffffff;
  --surface-2: #eceef2;
  --fg: #15181e;
  --muted: #59616e;
  --line: #dcdfe6;
  --accent: #a94b06;
  --accent-soft: #fbeade;
  --code-bg: #1b1f27;
  --code-fg: #e7ebf1;
  --warn-bg: #fdf3e2;
  --warn-fg: #7a4b05;
  --c-esp32: #0c6b63;
  --c-esp8266: #6b3fa0;
  --c-arduino: #14558f;
  --c-raspberry-pi: #a8184c;
  --c-micropython: #2f6a1f;
  --display: "Bitter", Georgia, serif;
  --body: "Be Vietnam Pro", system-ui, -apple-system, "Segoe UI", sans-serif;
  --mono: "JetBrains Mono", ui-monospace, "Cascadia Mono", Consolas, monospace;
  --wrap: 1120px;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #101319;
    --surface: #171b23;
    --surface-2: #1f2430;
    --fg: #e6e9ef;
    --muted: #98a1b0;
    --line: #28303c;
    --accent: #f0a35e;
    --accent-soft: #2e2318;
    --code-bg: #0b0e13;
    --code-fg: #e7ebf1;
    --warn-bg: #2b2213;
    --warn-fg: #e7bd74;
    --c-esp32: #4fc0b4;
    --c-esp8266: #b394e8;
    --c-arduino: #6fb1ee;
    --c-raspberry-pi: #f286aa;
    --c-micropython: #8fd073;
    color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --bg: #101319; --surface: #171b23; --surface-2: #1f2430; --fg: #e6e9ef;
  --muted: #98a1b0; --line: #28303c; --accent: #f0a35e; --accent-soft: #2e2318;
  --code-bg: #0b0e13; --code-fg: #e7ebf1; --warn-bg: #2b2213; --warn-fg: #e7bd74;
  --c-esp32: #4fc0b4; --c-esp8266: #b394e8; --c-arduino: #6fb1ee;
  --c-raspberry-pi: #f286aa; --c-micropython: #8fd073;
  color-scheme: dark;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 110px; }
body {
  margin: 0; background: var(--bg); color: var(--fg);
  font-family: var(--body); font-size: 16px; line-height: 1.65;
  -webkit-text-size-adjust: 100%;
}
img { max-width: 100%; height: auto; }
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }
h1, h2, h3 { font-family: var(--display); font-weight: 700; line-height: 1.2; text-wrap: balance; margin: 0; }
:focus-visible { outline: 2px solid var(--accent); outline-offset: 3px; border-radius: 3px; }
.sr-only { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; }
.skip { position: absolute; left: -9999px; }
.skip:focus { left: 8px; top: 8px; z-index: 50; background: var(--accent); color: #fff; padding: 8px 14px; border-radius: 4px; }
[hidden] { display: none !important; }

.band-inner, .top-inner, .cat-inner, .foot-inner, .foot-bottom, .hero-inner, .post-inner {
  max-width: var(--wrap); margin: 0 auto;
  padding-left: max(20px, env(safe-area-inset-left, 0px));
  padding-right: max(20px, env(safe-area-inset-right, 0px));
}

/* ----- Đầu trang ----- */
.top { background: var(--surface); border-bottom: 1px solid var(--line); }
.top-inner { display: flex; flex-wrap: wrap; gap: 16px; align-items: center; justify-content: space-between; padding-block: 16px; }
.logo { display: flex; align-items: center; gap: 12px; color: var(--fg); }
.logo:hover { text-decoration: none; }
.logo-mark {
  font-family: var(--mono); font-weight: 600; font-size: 1.05rem;
  background: var(--accent); color: #fff; padding: 7px 10px; border-radius: 6px;
}
:root[data-theme="dark"] .logo-mark, :root:not([data-theme="light"]) .logo-mark { color: #1a1206; }
@media (prefers-color-scheme: light) { :root:not([data-theme="dark"]) .logo-mark { color: #fff; } }
.logo-text { display: flex; flex-direction: column; line-height: 1.25; }
.logo-text b { font-family: var(--display); font-size: 1.3rem; letter-spacing: -0.01em; }
.logo-text small { color: var(--muted); font-size: 0.8rem; }
.top-nav { display: flex; gap: 22px; font-size: 0.93rem; }
.top-nav a { color: var(--muted); }
.top-nav a[aria-current="page"] { color: var(--fg); }

.cat-bar { position: sticky; top: 0; z-index: 20; background: var(--surface-2); border-bottom: 1px solid var(--line); }
.cat-inner { display: flex; gap: 6px; overflow-x: auto; padding-block: 8px; scrollbar-width: thin; }
.cat-inner a {
  font-family: var(--mono); font-size: 0.82rem; letter-spacing: 0.01em;
  color: var(--muted); padding: 6px 12px; border-radius: 999px; white-space: nowrap;
}
.cat-inner a:hover { background: var(--surface); color: var(--fg); text-decoration: none; }
.cat-inner a[aria-current="page"] { background: var(--accent); color: #fff; }
@media (prefers-color-scheme: dark) { :root:not([data-theme="light"]) .cat-inner a[aria-current="page"] { color: #1a1206; } }
:root[data-theme="dark"] .cat-inner a[aria-current="page"] { color: #1a1206; }

/* ----- Hero ----- */
.hero { background: var(--surface); border-bottom: 1px solid var(--line); }
.hero-inner { display: grid; grid-template-columns: 1.6fr 1fr; gap: 40px; padding-block: 48px 52px; align-items: start; }
.eyebrow { font-family: var(--body); font-size: 0.75rem; letter-spacing: 0.08em; text-transform: uppercase; color: var(--accent); }
.hero-text h1 { font-size: clamp(1.9rem, 4vw, 2.7rem); margin: 10px 0 14px; letter-spacing: -0.015em; }
.hero-text p { margin: 0 0 22px; color: var(--muted); font-size: 1.05rem; max-width: 52ch; }
.btn {
  display: inline-block; background: var(--accent); color: #fff;
  padding: 11px 22px; border-radius: 6px; font-weight: 500; font-size: 0.95rem;
}
.btn:hover { text-decoration: none; filter: brightness(1.08); }
@media (prefers-color-scheme: dark) { :root:not([data-theme="light"]) .btn { color: #1a1206; } }
:root[data-theme="dark"] .btn { color: #1a1206; }
.hero-side { background: var(--bg); border: 1px solid var(--line); border-radius: 10px; padding: 22px; }
.hero-side > b { font-family: var(--display); font-size: 1.05rem; display: block; margin-bottom: 12px; }
.starter { list-style: none; margin: 0; padding: 0; display: flex; flex-direction: column; }
.starter li { border-top: 1px solid var(--line); }
.starter li:first-child { border-top: 0; }
.starter a { display: flex; flex-direction: column; gap: 2px; padding: 11px 0; color: var(--fg); font-size: 0.93rem; line-height: 1.4; }
.starter a:hover { color: var(--accent); text-decoration: none; }
.starter span { font-family: var(--mono); font-size: 0.7rem; color: var(--muted); letter-spacing: 0.04em; text-transform: uppercase; }

/* ----- Dải nội dung ----- */
.band { border-bottom: 1px solid var(--line); }
.band-inner { padding-block: 44px; }
.band-head { display: flex; flex-wrap: wrap; gap: 14px; align-items: flex-end; justify-content: space-between; margin-bottom: 22px; }
.band-head h2 { font-size: 1.5rem; }
.band-head h2 a { color: var(--fg); }
.band-head p { margin: 6px 0 0; color: var(--muted); font-size: 0.93rem; max-width: 60ch; }
.more { font-family: var(--body); font-size: 0.82rem; white-space: nowrap; }

.page-head { background: var(--surface); border-bottom: 1px solid var(--line); }
.page-head .band-inner { padding-block: 40px; }
.page-head h1 { font-size: clamp(1.8rem, 4vw, 2.4rem); margin: 8px 0 10px; }
.page-head p { margin: 0; color: var(--muted); max-width: 60ch; }

.grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); gap: 18px; }
.card { background: var(--surface); border: 1px solid var(--line); border-radius: 10px; border-top: 3px solid var(--line); transition: border-top-color .15s, transform .15s; }
.card:hover { border-top-color: var(--accent); }
.card-link { display: flex; flex-direction: column; gap: 9px; padding: 18px; height: 100%; color: var(--fg); min-width: 0; }
.card-link:hover { text-decoration: none; }
.card-link:hover h3 { color: var(--accent); }
.card-top { display: flex; flex-wrap: wrap; align-items: center; gap: 10px; }
.chip { font-family: var(--mono); font-size: 0.68rem; letter-spacing: 0.06em; text-transform: uppercase; font-weight: 600; padding: 3px 9px; border-radius: 4px; border: 1px solid currentColor; }
.chip-esp32 { color: var(--c-esp32); }
.chip-esp8266 { color: var(--c-esp8266); }
.chip-arduino { color: var(--c-arduino); }
.chip-raspberry-pi { color: var(--c-raspberry-pi); }
.chip-micropython { color: var(--c-micropython); }
.lvl { font-size: 0.75rem; color: var(--muted); }
.card h3 { font-size: 1.12rem; }
.card p { margin: 0; color: var(--muted); font-size: 0.9rem; flex: 1; }
.card-meta { display: flex; flex-wrap: wrap; gap: 14px; font-family: var(--body); font-size: 0.72rem; color: var(--muted); font-variant-numeric: tabular-nums; }

.searchbar { display: flex; flex-wrap: wrap; gap: 12px; align-items: center; margin-bottom: 20px; }
.searchbar input {
  flex: 1; min-width: 200px; font: inherit; font-size: 0.95rem;
  padding: 11px 14px; border-radius: 8px; border: 1px solid var(--line);
  background: var(--surface); color: var(--fg);
}
.count { font-family: var(--body); font-size: 0.8rem; color: var(--muted); }
.empty { color: var(--muted); padding: 10px 0; }

.note-band { border-bottom: 0; }
.note { padding-block: 36px; }
.note h2 { font-size: 1.2rem; margin-bottom: 8px; }
.note p { margin: 0; color: var(--muted); max-width: 70ch; }

/* ----- Bài viết ----- */
.post-inner { padding-block: 32px 56px; max-width: 820px; }
.crumb { font-family: var(--body); font-size: 0.78rem; color: var(--muted); margin-bottom: 22px; display: flex; gap: 8px; flex-wrap: wrap; }
.post-head { display: flex; flex-direction: column; gap: 12px; padding-bottom: 24px; border-bottom: 1px solid var(--line); }
.post-head h1 { font-size: clamp(1.75rem, 4.5vw, 2.5rem); letter-spacing: -0.015em; }
.lede { margin: 0; color: var(--muted); font-size: 1.08rem; max-width: 60ch; }

.toc { background: var(--surface); border: 1px solid var(--line); border-left: 3px solid var(--accent); border-radius: 8px; padding: 16px 20px; margin: 26px 0; }
.toc b { font-family: var(--body); font-size: 0.75rem; letter-spacing: 0.06em; text-transform: uppercase; color: var(--muted); }
.toc ol { margin: 8px 0 0; padding-left: 20px; font-size: 0.93rem; }
.toc li { margin: 3px 0; }

.content { font-size: 1.04rem; line-height: 1.78; }
.content h2 { font-size: 1.45rem; margin: 2em 0 .6em; padding-top: .3em; }
.content h3 { font-size: 1.12rem; margin: 1.8em 0 .5em; font-family: var(--body); font-weight: 600; color: var(--accent); }
.content p { margin: 0 0 1.1em; max-width: 68ch; }
.content ul, .content ol { max-width: 68ch; padding-left: 1.3em; margin: 0 0 1.1em; }
.content li { margin-bottom: .35em; }
.content code { font-family: var(--mono); font-size: 0.87em; background: var(--surface-2); padding: 2px 6px; border-radius: 4px; word-break: break-word; }
.content pre { background: var(--code-bg); color: var(--code-fg); padding: 14px 16px; border-radius: 8px; overflow-x: auto; }
.content pre code { background: none; padding: 0; font-size: 0.85rem; color: inherit; }
.hint { font-size: 0.88rem; color: var(--muted); }
.warn { font-size: 0.92rem; background: var(--warn-bg); color: var(--warn-fg); border-radius: 8px; padding: 12px 16px; max-width: 68ch; }

.tw { overflow-x: auto; margin: 0 0 1.2em; border: 1px solid var(--line); border-radius: 8px; }
table { width: 100%; border-collapse: collapse; font-size: 0.93rem; background: var(--surface); }
th, td { text-align: left; padding: 10px 14px; border-bottom: 1px solid var(--line); }
th { font-family: var(--body); font-size: 0.75rem; letter-spacing: 0.05em; text-transform: uppercase; color: var(--muted); background: var(--surface-2); }
tr:last-child td { border-bottom: 0; }
td:nth-child(2), td:nth-child(3) { font-variant-numeric: tabular-nums; }

.code { margin: 0 0 1.4em; border-radius: 8px; overflow: hidden; border: 1px solid var(--line); }
.code figcaption { display: flex; align-items: center; justify-content: space-between; gap: 12px; background: var(--surface-2); padding: 8px 14px; }
.fname { font-family: var(--mono); font-size: 0.78rem; color: var(--muted); }
.copy { font: inherit; font-family: var(--body); font-size: 0.74rem; cursor: pointer; background: var(--surface); color: var(--fg); border: 1px solid var(--line); border-radius: 5px; padding: 5px 11px; }
.copy:hover { border-color: var(--accent); color: var(--accent); }
.code pre { margin: 0; border-radius: 0; }

.faq { list-style: none; padding: 0; margin: 0 0 1.4em; }
.faq li { display: flex; flex-direction: column; gap: 3px; padding: 14px 0; border-top: 1px solid var(--line); max-width: 68ch; }
.faq li:last-child { border-bottom: 1px solid var(--line); }
.faq b { font-weight: 600; }
.faq span { color: var(--muted); font-size: 0.95rem; }

.pn { display: flex; flex-wrap: wrap; gap: 16px; justify-content: space-between; margin-top: 36px; padding-top: 22px; border-top: 1px solid var(--line); }
.pn a { display: flex; flex-direction: column; gap: 2px; max-width: 48%; min-width: 0; color: var(--accent); }
.pn a.r { text-align: right; margin-left: auto; }
.pn small { font-family: var(--body); font-size: 0.72rem; color: var(--muted); text-transform: uppercase; letter-spacing: 0.05em; }
.pn span { font-family: var(--display); font-weight: 600; font-size: 0.98rem; line-height: 1.35; }

/* ----- Trang tĩnh ----- */
.prose { max-width: 720px; }
.prose h2 { font-size: 1.35rem; margin: 1.8em 0 .5em; }
.prose p, .prose ul { max-width: 65ch; }
.facts { display: grid; grid-template-columns: max-content 1fr; gap: 8px 22px; margin: 18px 0; font-size: 0.95rem; }
.facts dt { color: var(--muted); font-family: var(--body); font-size: 0.82rem; }
.facts dd { margin: 0; }

/* ----- Chân trang ----- */
.site-foot { background: var(--surface); border-top: 1px solid var(--line); }
.foot-inner { display: grid; grid-template-columns: 2fr 1fr 1fr; gap: 32px; padding-block: 40px 28px; }
.foot-inner b { font-family: var(--display); font-size: 1rem; display: block; margin-bottom: 8px; }
.foot-inner p { margin: 0; color: var(--muted); font-size: 0.9rem; max-width: 40ch; }
.foot-inner ul { list-style: none; margin: 0; padding: 0; display: flex; flex-direction: column; gap: 6px; font-size: 0.9rem; }
.foot-inner ul a { color: var(--muted); }
.foot-inner ul a:hover { color: var(--accent); }
.foot-bottom { display: flex; flex-wrap: wrap; gap: 10px; justify-content: space-between; padding-block: 16px 28px; border-top: 1px solid var(--line); font-size: 0.82rem; color: var(--muted); }

@media (max-width: 860px) {
  .hero-inner { grid-template-columns: 1fr; gap: 28px; padding-block: 34px 38px; }
  .foot-inner { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 560px) {
  .band-inner { padding-block: 32px; }
  .grid { grid-template-columns: 1fr; }
  .foot-inner { grid-template-columns: 1fr; gap: 24px; }
  .pn a, .pn a.r { max-width: 100%; text-align: left; margin-left: 0; }
  .logo-text small { display: none; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  * { transition: none !important; }
}