/* =========================================================
   THIẾT KẾ: Bưu thiếp du học (Study-abroad postcard)
   Màu:
     --paper   giấy kem ấm - nền chính
     --ink     mực đen ấm  - chữ chính
     --ink-70  mực nhạt    - chữ phụ
     --line    viền mảnh
     --airmail xanh airmail - link, nhấn
     --stamp   đỏ tem thư   - dùng tiết chế (dấu, nhãn nhỏ)
   Font:
     --font-display  Fraunces  (tiêu đề)
     --font-body     Inter     (nội dung)
     --font-mono     IBM Plex Mono (ngày tháng, nhãn, điều hướng)
   ========================================================= */

:root {
  --paper: #f6f1e7;
  --paper-2: #efe7d6;
  --ink: #2b2620;
  --ink-70: #6b6255;
  --line: #ded2b8;
  --airmail: #3e5c76;
  --stamp: #a63a3a;

  --font-display: "Fraunces", serif;
  --font-body: "Inter", sans-serif;
  --font-mono: "IBM Plex Mono", monospace;

  --max-width: 780px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 17px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  * { animation: none !important; transition: none !important; }
}

/* --- Viền phong bì hàng không (airmail) --- */
.airmail-border {
  height: 6px;
  width: 100%;
  background: repeating-linear-gradient(
    45deg,
    var(--airmail) 0 14px,
    var(--paper) 14px 22px,
    var(--stamp) 22px 36px,
    var(--paper) 36px 44px
  );
}

a { color: var(--airmail); text-decoration: none; }
a:hover { text-decoration: underline; }
a:focus-visible, button:focus-visible {
  outline: 2px solid var(--airmail);
  outline-offset: 3px;
}

img { max-width: 100%; display: block; }

/* --- Header / điều hướng --- */
.site-header {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 28px 24px 20px;
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 28px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  text-decoration: none;
  margin-right: auto; /* đẩy menu + tìm kiếm dồn hẳn sang phải */
}
.brand-mark {
  width: 34px;
  height: 34px;
  display: block;
}
.brand-name {
  font-family: var(--font-mono);
  font-size: 15px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--ink);
  white-space: nowrap;
}
.brand:hover .brand-name { color: var(--stamp); }

.logo {
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  border: 1px solid var(--ink);
  border-radius: 50%;
  width: 46px;
  height: 46px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--ink);
  text-decoration: none;
  flex-shrink: 0;
}
.logo:hover { text-decoration: none; background: var(--paper-2); }

nav.main-nav {
  display: flex;
  gap: 22px;
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}
nav.main-nav a { color: var(--ink-70); white-space: nowrap; }
nav.main-nav a.active,
nav.main-nav a:hover { color: var(--stamp); text-decoration: none; }

/* --- Nút mở menu (chỉ hiện trên di động) --- */
.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  gap: 5px;
  width: 42px;
  height: 42px;
  border: 1px solid var(--ink);
  border-radius: 6px;
  background: transparent;
  cursor: pointer;
  padding: 0;
  flex-shrink: 0;
}
.nav-toggle span {
  display: block;
  width: 18px;
  height: 2px;
  background: var(--ink);
  transition: transform 0.2s ease, opacity 0.2s ease;
}
.nav-toggle[aria-expanded="true"] span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] span:nth-child(2) { opacity: 0; }
.nav-toggle[aria-expanded="true"] span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* --- Bố cục di động: menu thu gọn dạng xổ xuống --- */
@media (max-width: 680px) {
  .site-header { padding: 20px 20px 16px; gap: 14px; }

  .nav-toggle { display: flex; }

  nav.main-nav {
    display: none;
    order: 3;
    width: 100%;
    flex-direction: column;
    gap: 0;
    margin-top: 6px;
    border-top: 1px solid var(--line);
  }
  nav.main-nav.open { display: flex; }
  nav.main-nav a {
    padding: 15px 4px;
    font-size: 14px;
    border-bottom: 1px solid var(--line);
  }
  nav.main-nav a:last-child { border-bottom: none; }

  .search-dates { flex-wrap: wrap; row-gap: 6px; }
  .search-dates input[type="date"] { max-width: 46%; }

  .filter-chip { padding: 8px 14px; }
}

main {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 40px 24px 100px;
}

h1, h2, h3 {
  font-family: var(--font-display);
  font-weight: 600;
  line-height: 1.15;
  margin: 0 0 0.4em;
}

h1 { font-size: clamp(2.2rem, 5vw, 3.4rem); }
h2 { font-size: clamp(1.5rem, 3vw, 2rem); margin-top: 2.2em; }

p { margin: 0 0 1.1em; }

.eyebrow {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--stamp);
  display: inline-block;
  margin-bottom: 14px;
}

/* --- Con dấu bưu điện (postmark) - dấu ấn riêng của trang --- */
.postmark {
  --size: 108px;
  width: var(--size);
  height: var(--size);
  border: 2px solid var(--ink);
  border-radius: 50%;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  font-family: var(--font-mono);
  color: var(--ink);
  flex-shrink: 0;
  position: relative;
  transform: rotate(-6deg);
}
.postmark::before,
.postmark::after {
  content: "";
  position: absolute;
  left: 6px; right: 6px;
  border-top: 1px solid var(--ink);
}
.postmark::before { top: 26px; }
.postmark::after { bottom: 26px; }
.postmark .pm-date { font-size: 11px; letter-spacing: 0.06em; margin-top: 2px; }
.postmark .pm-place {
  font-size: 9.5px;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  padding: 0 8px;
  margin-top: 2px;
}

/* --- Hero (trang chủ) --- */
.hero {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 32px;
  flex-wrap: wrap;
  border-bottom: 1px solid var(--line);
  padding-bottom: 40px;
  margin-bottom: 40px;
}
.hero-text { max-width: 520px; }
.hero-text .lead { font-size: 1.15rem; color: var(--ink-70); }

/* --- Danh sách bài blog: thẻ kiểu bưu thiếp --- */
.post-list { display: flex; flex-direction: column; gap: 0; }

.post-card {
  display: grid;
  grid-template-columns: 108px 1fr;
  gap: 20px;
  align-items: start;
  padding: 26px 0;
  border-bottom: 1px solid var(--line);
}
.post-card:first-child { padding-top: 0; }

.post-card h3 { margin-bottom: 6px; }
.post-card h3 a { color: var(--ink); }
.post-card .excerpt { color: var(--ink-70); margin-bottom: 6px; }
.post-card .tags {
  font-family: var(--font-mono);
  font-size: 11.5px;
  color: var(--airmail);
  letter-spacing: 0.04em;
}

@media (max-width: 560px) {
  .post-card { grid-template-columns: 72px 1fr; }
  .postmark { --size: 72px; }
  .postmark .pm-date { font-size: 9px; }
  .postmark .pm-place { font-size: 8px; }
}

/* --- Bài viết đơn --- */
.post-header { border-bottom: 1px solid var(--line); padding-bottom: 28px; margin-bottom: 28px; }
.post-meta { display: flex; align-items: center; gap: 16px; margin-top: 14px; }
.post-meta .postmark { --size: 64px; transform: rotate(-4deg); }
.post-meta .postmark .pm-date { font-size: 8.5px; }
.post-meta .postmark .pm-place { font-size: 7.5px; }
.post-body :is(h2, h3) { margin-top: 1.6em; }
.back-link { display: inline-block; margin-top: 40px; font-family: var(--font-mono); font-size: 13px; }

/* --- Form liên hệ --- */
form { display: flex; flex-direction: column; gap: 18px; max-width: 480px; }
label {
  font-family: var(--font-mono);
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--ink-70);
}
input, textarea {
  font-family: var(--font-body);
  font-size: 16px;
  padding: 12px 14px;
  border: 1px solid var(--line);
  border-radius: 4px;
  background: #fff;
  color: var(--ink);
}
input:focus, textarea:focus { border-color: var(--airmail); outline: none; }
button.submit {
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  background: var(--ink);
  color: var(--paper);
  border: none;
  padding: 14px 22px;
  border-radius: 4px;
  cursor: pointer;
  width: fit-content;
}
button.submit:hover { background: var(--airmail); }

.contact-list { list-style: none; padding: 0; margin: 28px 0 0; display: flex; flex-direction: column; gap: 10px; }
.contact-list li { font-family: var(--font-mono); font-size: 14px; }

/* --- Footer --- */
footer {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 30px 24px 60px;
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--ink-70);
  border-top: 1px solid var(--line);
}
/* --- Nút tìm kiếm (nhỏ gọn, tinh tế) --- */


/* --- Lớp phủ + hộp thoại tìm kiếm --- */
.search-overlay {
  position: fixed;
  inset: 0;
  background: rgba(43, 38, 32, 0.35);
  display: none;
  align-items: flex-start;
  justify-content: center;
  padding: 10vh 20px 20px;
  z-index: 100;
}
.search-overlay.open { display: flex; }

.search-panel {
  background: var(--paper);
  width: 100%;
  max-width: 560px;
  max-height: 74vh;
  border-radius: 10px;
  box-shadow: 0 20px 50px rgba(43, 38, 32, 0.3);
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

.search-input-row {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 14px 18px;
  border-bottom: 1px solid var(--line);
  flex-shrink: 0;
}
.search-input-row svg { width: 17px; height: 17px; color: var(--ink-70); flex-shrink: 0; }
#search-input {
  flex: 1;
  border: none;
  background: transparent;
  font-family: var(--font-body);
  font-size: 16px;
  color: var(--ink);
  padding: 0;
}
#search-input:focus { outline: none; }
.search-close {
  border: none;
  background: transparent;
  color: var(--ink-70);
  font-family: var(--font-mono);
  font-size: 11px;
  cursor: pointer;
  padding: 4px 8px;
  border: 1px solid var(--line);
  border-radius: 4px;
}
.search-close:hover { color: var(--ink); border-color: var(--ink); }

.search-filters {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  padding: 12px 18px;
  border-bottom: 1px solid var(--line);
  flex-shrink: 0;
}
.filter-chip {
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.03em;
  padding: 5px 11px;
  border: 1px solid var(--line);
  border-radius: 20px;
  background: transparent;
  color: var(--ink-70);
  cursor: pointer;
}
.filter-chip:hover { border-color: var(--ink-70); }
.filter-chip.active {
  background: var(--ink);
  border-color: var(--ink);
  color: var(--paper);
}

.search-dates {
  display: flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-mono);
  font-size: 11.5px;
  color: var(--ink-70);
}
.search-dates input[type="date"] {
  font-family: var(--font-mono);
  font-size: 11.5px;
  border: 1px solid var(--line);
  border-radius: 4px;
  padding: 4px 6px;
  background: #fff;
  color: var(--ink);
}

.search-results {
  overflow-y: auto;
  padding: 6px 18px 18px;
}
.search-results .post-card { padding: 16px 0; }
.search-results .postmark { --size: 56px; }
.search-results .postmark .pm-date { font-size: 8px; }
.search-results .postmark .pm-place { font-size: 7px; }

.search-empty {
  padding: 30px 18px;
  text-align: center;
  color: var(--ink-70);
  font-size: 14px;
}

.logo { color: var(--ink); }
.logo:hover { color: var(--stamp); }

.search-page {
  margin-top: 30px;
  border-top: 1px solid var(--line);
}
.search-page .search-input-row {
  padding: 18px 0;
  border-bottom: 1px solid var(--line);
}
.search-page .search-filters {
  padding: 14px 0;
  border-bottom: 1px solid var(--line);
}
.search-page .search-results {
  padding: 10px 0 0;
}