/* ─────────────────────────────────────────────────────────────
   shared.css — 早設計 AM DESIGN 全站共用樣式
   ───────────────────────────────────────────────────────────
   這裡是全站設計 token（色票、字體、字級/字距）與共用元件
   （導覽列 nav、按鈕 .btn-cta、區塊標題 .section-header、footer 等）
   的「唯一來源」。三個頁面（index / project / contact）都會 <link> 這支檔。

   ★ 要改色票、字體、共用元件的視覺 → 改這裡，一次全站生效。
   ★ 頁面各自特有的樣式（首頁 hero、作品頁 .p-*、表單 .form-* 等）
     留在各頁 HTML 的 inline <style>，不要搬進來。
   ★ 視覺基準是 index.html，這支檔的內容逐字取自 index.html。

   設計規範文件見 design.md。
   ───────────────────────────────────────────────────────────── */

/* ── Reset & Base ─────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --cream: #f5f0e8;
  --beige: #ebe5d9;
  --dark:  #1a1a18;
  --mid:   #5a5a52;
  --accent:#8b7355;
  --serif: 'Noto Serif TC', 'Georgia', 'Times New Roman', serif;
  --sans:  'Noto Sans TC', 'Arial', 'Helvetica Neue', sans-serif;
  --fs-xs: 0.65rem;
  --fs-sm: 0.78rem;
  --fs-md: 1rem;
  --fs-lg: 1.4rem;
  --fs-xl: 2.5rem;
  --tracking-wide: 0.18em;
  --tracking-wider: 0.28em;
}

html { scroll-behavior: smooth; }

body {
  font-family: var(--serif);
  background: var(--cream);
  color: var(--dark);
  overflow-x: hidden;
}

a { text-decoration: none; color: inherit; }
img { display: block; width: 100%; height: 100%; object-fit: cover; }

/* ── Nav ──────────────────────────────────────── */
nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 100;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 22px 40px;
  transition: background 0.4s;
}
nav.scrolled {
  background: rgba(245, 240, 232, 0.95);
  backdrop-filter: blur(6px);
}

.nav-logo {
  position: relative;
  display: block;
  height: 20px;
}
.nav-logo img {
  height: 100%;
  width: auto;
  display: block;
  transition: opacity 0.4s;
}
.nav-logo .logo-black {
  position: absolute;
  top: 0;
  left: 0;
  opacity: 0;
}
nav.scrolled .nav-logo .logo-white { opacity: 0; }
nav.scrolled .nav-logo .logo-black { opacity: 1; }

.nav-links {
  display: flex;
  gap: 36px;
  list-style: none;
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}
.nav-links a {
  font-family: var(--sans);
  font-size: var(--fs-xs);
  letter-spacing: var(--tracking-wide);
  text-transform: uppercase;
  color: rgba(255,255,255,0.9);
  transition: color 0.3s, opacity 0.3s;
}
.nav-links a:hover { opacity: 0.6; }
nav.scrolled .nav-links a { color: var(--dark); }

.nav-search {
  font-size: 1.1rem;
  color: rgba(255,255,255,0.9);
  cursor: pointer;
  transition: color 0.4s;
}
nav.scrolled .nav-search { color: var(--dark); }

/* Back 連結：全站已改用導覽列（桌機選單／手機漢堡）返回，故隱藏不再顯示 */
.nav-back {
  display: none;
  font-family: var(--sans);
  font-size: var(--fs-xs);
  letter-spacing: var(--tracking-wide);
  text-transform: uppercase;
  color: rgba(255,255,255,0.9);
  transition: color 0.3s, opacity 0.3s;
}
.nav-back:hover { opacity: 0.6; }
nav.scrolled .nav-back { color: var(--dark); }

/* 無封面圖的頁面：導覽列直接維持實色（白字會看不到） */
nav.solid { background: rgba(245, 240, 232, 0.95); backdrop-filter: blur(6px); }
nav.solid .nav-links a, nav.solid .nav-back { color: var(--dark); }
nav.solid .nav-logo .logo-white { opacity: 0; }
nav.solid .nav-logo .logo-black { opacity: 1; }

/* nav 右側容器：Back 連結與漢堡按鈕的共同外框 */
.nav-right { display: flex; align-items: center; gap: 20px; }

/* ── 手機版漢堡選單按鈕（桌機隱藏，600px 以下顯示） ── */
.nav-burger {
  display: none;
  background: none;
  border: none;
  padding: 6px 2px;
  cursor: pointer;
}
.nav-burger span {
  display: block;
  width: 20px;
  height: 1.5px;
  background: rgba(255,255,255,0.9);
  margin: 4.5px 0;
  transition: background 0.3s, transform 0.3s, opacity 0.3s;
}
nav.scrolled .nav-burger span,
nav.solid .nav-burger span,
nav.menu-open .nav-burger span { background: var(--dark); }
/* 開啟時三條線變 X */
nav.menu-open .nav-burger span:nth-child(1) { transform: translateY(6px) rotate(45deg); }
nav.menu-open .nav-burger span:nth-child(2) { opacity: 0; }
nav.menu-open .nav-burger span:nth-child(3) { transform: translateY(-6px) rotate(-45deg); }

/* ── CTA Button ────────────────────────────────── */
.btn-cta {
  display: inline-block;
  margin-top: 36px;
  font-family: var(--sans);
  font-size: 0.72rem;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: #fff;
  background: transparent;
  border: 1px solid rgba(255,255,255,0.6);
  padding: 15px 34px;
  cursor: pointer;
  transition: background 0.35s, color 0.35s;
}
.btn-cta:hover { background: #fff; color: var(--dark); }

.btn-cta.dark {
  color: var(--dark);
  border-color: var(--dark);
}
.btn-cta.dark:hover { background: var(--dark); color: #fff; }

/* ── Tab Button（首頁流程頁籤、作品分類篩選共用）── */
.btn-tab {
  font-family: var(--sans);
  font-size: 0.72rem;
  letter-spacing: 0.18em;
  padding: 12px 28px;
  background: transparent;
  border: 1px solid rgba(26,26,24,0.25);
  color: var(--mid);
  cursor: pointer;
  transition: background 0.3s, color 0.3s, border-color 0.3s;
}
.btn-tab:hover { color: var(--dark); border-color: var(--dark); }
.btn-tab.active {
  background: var(--dark);
  color: #fff;
  border-color: var(--dark);
}

/* ── Section Header ────────────────────────────── */
.section-header {
  text-align: center;
  padding: 80px 40px 50px;
}

.section-header .eyebrow {
  font-family: var(--sans);
  font-size: var(--fs-xs);
  letter-spacing: var(--tracking-wider);
  text-transform: uppercase;
  color: var(--mid);
  margin-bottom: 18px;
}

.section-header h2 {
  font-family: var(--serif);
  font-size: 1.7rem;
  font-weight: 400;
  letter-spacing: 0.06em;
}

/* ── Link (underline) ──────────────────────────── */
.link-underline {
  display: inline-block;
  font-family: var(--sans);
  font-size: 0.62rem;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--dark);
  border-bottom: 1px solid var(--dark);
  padding-bottom: 2px;
  transition: opacity 0.3s;
}
.link-underline:hover { opacity: 0.5; }

/* ── Footer ───────────────────────────────────── */
footer {
  background: var(--dark);
  color: rgba(255,255,255,0.7);
  padding: 70px 60px 40px;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr;
  gap: 40px;
  margin-bottom: 60px;
}

.footer-brand h3 {
  font-family: var(--serif);
  font-size: var(--fs-sm);
  letter-spacing: var(--tracking-wider);
  text-transform: uppercase;
  color: #fff;
  margin-bottom: 20px;
}

.footer-brand p {
  font-family: var(--sans);
  font-size: 0.9rem;
  line-height: 1.9;
  max-width: 300px;
}

.footer-brand .mail {
  display: inline-block;
  margin-top: 22px;
  font-family: var(--sans);
  font-size: 0.8rem;
  color: rgba(255,255,255,0.85);
  letter-spacing: 0.05em;
  transition: color 0.3s;
}
.footer-brand .mail:hover { color: #fff; }

.footer-col h4 {
  font-family: var(--sans);
  font-size: 0.6rem;
  letter-spacing: 0.25em;
  text-transform: uppercase;
  color: rgba(255,255,255,0.45);
  margin-bottom: 20px;
}

.footer-col ul { list-style: none; }

.footer-col ul li { margin-bottom: 12px; }

.footer-col ul li a {
  font-family: var(--sans);
  font-size: 0.78rem;
  color: rgba(255,255,255,0.65);
  transition: color 0.3s;
}
.footer-col ul li a:hover { color: #fff; }

.footer-bottom {
  border-top: 1px solid rgba(255,255,255,0.1);
  padding-top: 30px;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.footer-bottom p {
  font-family: var(--sans);
  font-size: 0.65rem;
  color: rgba(255,255,255,0.35);
  letter-spacing: 0.1em;
}

/* ── Animations ────────────────────────────────── */
.fade-in {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.8s ease, transform 0.8s ease;
}
.fade-in.visible {
  opacity: 1;
  transform: none;
}

/* ── Responsive (nav + footer 共用部分) ─────────── */
@media (max-width: 900px) {
  .footer-grid { grid-template-columns: 1fr 1fr; }
  nav { padding: 18px 24px; }
  .nav-links { gap: 20px; }
}

@media (max-width: 600px) {
  /* 手機版：顯示漢堡按鈕，選單收進導覽列下方的面板 */
  .nav-burger { display: block; }
  nav.menu-open {
    background: rgba(245, 240, 232, 0.97);
    backdrop-filter: blur(6px);
  }
  nav.menu-open .nav-logo .logo-white { opacity: 0; }
  nav.menu-open .nav-logo .logo-black { opacity: 1; }
  .nav-links {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    transform: none;
    flex-direction: column;
    gap: 0;
    background: rgba(245, 240, 232, 0.97);
    backdrop-filter: blur(6px);
    border-top: 1px solid rgba(26,26,24,0.08);
    padding: 8px 0 12px;
  }
  nav.menu-open .nav-links { display: flex; }
  .nav-links a {
    display: block;
    padding: 14px 28px;
    color: var(--dark);
  }
  .footer-grid { grid-template-columns: 1fr; }
  footer { padding: 60px 24px 30px; }
  .footer-brand p { max-width: none; }
}