/* ============================================================
   Research Hub | 瑞赛赫 — Shared Stylesheet
   Design: Scholarly Clarity — Academic Prestige + Modern Trust
   ============================================================ */

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

:root {
  --primary:       #0C1E45;
  --primary-mid:   #163068;
  --accent:        #B8892A;
  --accent-pale:   #F7F0E2;
  --bg:            #FAFAF8;
  --bg-alt:        #F2F0EB;
  --bg-dark:       #0C1E45;
  --text:          #1A1A1A;
  --text-mid:      #444444;
  --text-muted:    #717171;
  --border:        #E0DDD6;
  --white:         #FFFFFF;
  --success:       #1A6B3C;
  --error:         #B83232;
  --radius:        6px;
  --radius-lg:     12px;
  --shadow-sm:     0 1px 6px rgba(12,30,69,0.07);
  --shadow:        0 4px 20px rgba(12,30,69,0.10);
  --shadow-lg:     0 8px 40px rgba(12,30,69,0.13);
  --transition:    0.22s ease;
  --max-width:     1080px;
  --font:          -apple-system, BlinkMacSystemFont, "PingFang SC",
                   "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans CJK SC",
                   "WenQuanYi Micro Hei", Arial, sans-serif;
}

html { scroll-behavior: smooth; }

body {
  font-family: var(--font);
  font-size: 16px;
  line-height: 1.8;
  color: var(--text);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
}

img { max-width: 100%; display: block; }
a { color: var(--primary); text-decoration: none; transition: color var(--transition); }
a:hover { color: var(--accent); }
ul { list-style: none; }

/* --- Typography Scale --- */
h1, h2, h3, h4 {
  line-height: 1.4;
  font-weight: 700;
  color: var(--primary);
  letter-spacing: -0.01em;
}
h1 { font-size: clamp(1.75rem, 4vw, 2.6rem); }
h2 { font-size: clamp(1.35rem, 3vw, 1.9rem); }
h3 { font-size: clamp(1.1rem, 2vw, 1.35rem); }
h4 { font-size: 1.05rem; font-weight: 600; }
p { margin-bottom: 1rem; color: var(--text-mid); }
p:last-child { margin-bottom: 0; }

/* --- Layout Utilities --- */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
}

.section {
  padding: 72px 0;
}
.section--alt { background: var(--bg-alt); }
.section--dark {
  background: var(--bg-dark);
  color: var(--white);
}
.section--dark h1,
.section--dark h2,
.section--dark h3,
.section--dark h4 { color: var(--white); }
.section--dark p { color: rgba(255,255,255,0.8); }

.section-label {
  display: inline-block;
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 12px;
}

.section-title {
  margin-bottom: 14px;
}
.section-subtitle {
  font-size: 1.05rem;
  color: var(--text-muted);
  margin-bottom: 40px;
  max-width: 640px;
}

/* Gold Rule Divider — visual signature */
.gold-rule {
  width: 48px;
  height: 3px;
  background: var(--accent);
  margin: 20px 0 32px 0;
  border: none;
  border-radius: 2px;
}

/* --- Navigation --- */
.nav {
  position: sticky;
  top: 0;
  z-index: 1000;
  background: var(--white);
  border-bottom: 1px solid var(--border);
  box-shadow: var(--shadow-sm);
}

.nav__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
}

.nav__brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 800;
  font-size: 1rem;
  color: var(--primary);
  white-space: nowrap;
}

.nav__brand-en {
  font-weight: 800;
  font-size: 1rem;
  letter-spacing: 0.04em;
}

.nav__brand-sep {
  width: 1px;
  height: 18px;
  background: var(--border);
}

.nav__brand-cn {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--accent);
}

.nav__links {
  display: flex;
  align-items: center;
  gap: 6px;
}

.nav__links a {
  font-size: 0.82rem;
  font-weight: 500;
  color: var(--text-mid);
  padding: 6px 10px;
  border-radius: var(--radius);
  transition: all var(--transition);
  white-space: nowrap;
}
.nav__links a:hover,
.nav__links a.active {
  color: var(--primary);
  background: var(--accent-pale);
}

.nav__cta {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-shrink: 0;
}

/* Mobile menu - hidden by default on all screen sizes */
.nav__links-mobile { display: none; }

/* Mobile hamburger — CSS only */
.hamburger { display: none; }
.hamburger-check { display: none; }
.hamburger-icon {
  display: none;
  flex-direction: column;
  gap: 5px;
  cursor: pointer;
  padding: 8px;
  border-radius: var(--radius);
}
.hamburger-icon span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--primary);
  border-radius: 2px;
  transition: all var(--transition);
}

/* --- Buttons --- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 11px 24px;
  border-radius: var(--radius);
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition);
  border: 2px solid transparent;
  text-align: center;
  white-space: nowrap;
  font-family: var(--font);
}

.btn--primary {
  background: var(--primary);
  color: var(--white);
  border-color: var(--primary);
}
.btn--primary:hover {
  background: var(--primary-mid);
  border-color: var(--primary-mid);
  color: var(--white);
  transform: translateY(-1px);
  box-shadow: var(--shadow);
}

.btn--accent {
  background: var(--accent);
  color: var(--white);
  border-color: var(--accent);
}
.btn--accent:hover {
  background: #9e7520;
  border-color: #9e7520;
  color: var(--white);
  transform: translateY(-1px);
  box-shadow: var(--shadow);
}

.btn--outline {
  background: transparent;
  color: var(--primary);
  border-color: var(--primary);
}
.btn--outline:hover {
  background: var(--primary);
  color: var(--white);
}

.btn--outline-white {
  background: transparent;
  color: var(--white);
  border-color: rgba(255,255,255,0.6);
}
.btn--outline-white:hover {
  background: rgba(255,255,255,0.12);
  color: var(--white);
  border-color: var(--white);
}

.btn--sm {
  padding: 8px 18px;
  font-size: 0.82rem;
}

.btn--lg {
  padding: 14px 32px;
  font-size: 1rem;
}

/* --- Hero --- */
.hero {
  background: var(--bg-dark);
  padding: 80px 0 72px;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: 0; right: 0;
  width: 50%;
  height: 100%;
  background: linear-gradient(135deg, transparent 40%, rgba(184,137,42,0.06) 100%);
  pointer-events: none;
}

.hero::after {
  content: '';
  position: absolute;
  bottom: 0; left: 0;
  width: 100%;
  height: 2px;
  background: linear-gradient(90deg, var(--accent) 0%, transparent 60%);
}

.hero__label {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 0.72rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--accent);
  font-weight: 700;
  margin-bottom: 20px;
}
.hero__label::before {
  content: '';
  display: inline-block;
  width: 24px;
  height: 2px;
  background: var(--accent);
}

.hero h1 {
  color: var(--white);
  max-width: 760px;
  margin-bottom: 20px;
  line-height: 1.35;
}

.hero__en-sub {
  font-size: 0.85rem;
  letter-spacing: 0.1em;
  color: rgba(255,255,255,0.5);
  text-transform: uppercase;
  font-weight: 500;
  margin-bottom: 20px;
  display: block;
}

.hero__desc {
  color: rgba(255,255,255,0.78);
  max-width: 620px;
  font-size: 1.02rem;
  line-height: 1.9;
  margin-bottom: 36px;
}

.hero__ctas {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

/* --- Page Hero (inner pages) --- */
.page-hero {
  background: var(--bg-dark);
  padding: 56px 0 48px;
  position: relative;
}
.page-hero::after {
  content: '';
  position: absolute;
  bottom: 0; left: 0;
  width: 100%;
  height: 2px;
  background: linear-gradient(90deg, var(--accent) 0%, transparent 60%);
}
.page-hero h1 { color: var(--white); margin-bottom: 12px; }
.page-hero p { color: rgba(255,255,255,0.75); max-width: 620px; }
.page-hero__en {
  font-size: 0.82rem;
  letter-spacing: 0.12em;
  color: var(--accent);
  text-transform: uppercase;
  font-weight: 600;
  margin-bottom: 12px;
  display: block;
}

/* --- Cards --- */
.card-grid {
  display: grid;
  gap: 24px;
}
.card-grid--2 { grid-template-columns: repeat(2, 1fr); }
.card-grid--3 { grid-template-columns: repeat(3, 1fr); }
.card-grid--4 { grid-template-columns: repeat(4, 1fr); }

.card {
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 28px;
  transition: all var(--transition);
  position: relative;
}
.card:hover {
  box-shadow: var(--shadow);
  transform: translateY(-2px);
  border-color: rgba(184,137,42,0.3);
}
.card--accent-border {
  border-left: 3px solid var(--accent);
}
.card--flat {
  box-shadow: none;
}
.card--flat:hover { transform: none; }

.card__icon {
  width: 44px;
  height: 44px;
  background: var(--accent-pale);
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 18px;
  font-size: 1.3rem;
}

.card h3 { margin-bottom: 10px; }
.card p { font-size: 0.92rem; }

/* Service cards on home */
.service-list {
  display: grid;
  gap: 16px;
}
.service-item {
  display: flex;
  gap: 20px;
  align-items: flex-start;
  background: var(--white);
  border: 1px solid var(--border);
  border-left: 4px solid var(--accent);
  border-radius: var(--radius);
  padding: 22px 24px;
  transition: box-shadow var(--transition);
}
.service-item:hover { box-shadow: var(--shadow); }

.service-item__num {
  font-size: 0.72rem;
  font-weight: 800;
  letter-spacing: 0.08em;
  color: var(--accent);
  padding-top: 3px;
  white-space: nowrap;
}

.service-item h3 { font-size: 1.05rem; margin-bottom: 6px; }
.service-item p { font-size: 0.9rem; margin: 0; }

/* --- Process Steps --- */
.process-steps {
  display: grid;
  gap: 16px;
}
.process-step {
  display: grid;
  grid-template-columns: 48px 1fr;
  gap: 20px;
  align-items: flex-start;
}
.process-step__num {
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background: var(--primary);
  color: var(--white);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  font-size: 0.95rem;
  flex-shrink: 0;
}
.process-step__content h4 { margin-bottom: 4px; padding-top: 11px; }
.process-step__content p { font-size: 0.9rem; margin: 0; }

/* --- Two column --- */
.two-col {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 40px;
  align-items: start;
}
.two-col--wide { grid-template-columns: 3fr 2fr; }
.two-col--reverse { direction: rtl; }
.two-col--reverse > * { direction: ltr; }

/* --- Integrity Grid (can/cannot) --- */
.integrity-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
}
.integrity-box {
  border-radius: var(--radius-lg);
  padding: 28px;
}
.integrity-box--can {
  background: #EFF8F4;
  border: 1px solid #B5D9C7;
}
.integrity-box--cannot {
  background: #FDF2F2;
  border: 1px solid #E8C0C0;
}
.integrity-box h3 {
  font-size: 1rem;
  margin-bottom: 16px;
  display: flex;
  align-items: center;
  gap: 8px;
}
.integrity-box ul { display: grid; gap: 8px; }
.integrity-box li {
  font-size: 0.9rem;
  color: var(--text-mid);
  display: flex;
  gap: 8px;
  align-items: baseline;
}
.integrity-box li::before { flex-shrink: 0; }
.integrity-box--can li::before { content: '✓'; color: #1A6B3C; font-weight: 700; }
.integrity-box--cannot li::before { content: '✗'; color: #B83232; font-weight: 700; }

/* --- FAQ Accordion (HTML-native, no JS) --- */
.faq-list { display: grid; gap: 8px; }

details.faq-item {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--white);
  overflow: hidden;
  transition: box-shadow var(--transition);
}
details.faq-item[open] {
  box-shadow: var(--shadow-sm);
  border-color: rgba(184,137,42,0.35);
}
details.faq-item summary {
  list-style: none;
  padding: 18px 22px;
  font-weight: 600;
  font-size: 0.95rem;
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
  color: var(--primary);
  user-select: none;
}
details.faq-item summary::-webkit-details-marker { display: none; }
details.faq-item summary::after {
  content: '+';
  font-size: 1.3rem;
  font-weight: 300;
  color: var(--accent);
  flex-shrink: 0;
  transition: transform var(--transition);
  line-height: 1;
}
details.faq-item[open] summary::after { content: '−'; }
.faq-item__body {
  padding: 0 22px 20px;
  font-size: 0.92rem;
  color: var(--text-mid);
  line-height: 1.8;
}

/* --- Contact Form --- */
.form-grid {
  display: grid;
  gap: 20px;
}
.form-group { display: flex; flex-direction: column; gap: 6px; }
.form-group label {
  font-size: 0.88rem;
  font-weight: 600;
  color: var(--primary);
}
.form-group label .req { color: var(--accent); margin-left: 2px; }
.form-control {
  padding: 11px 14px;
  border: 1.5px solid var(--border);
  border-radius: var(--radius);
  font-size: 0.92rem;
  font-family: var(--font);
  color: var(--text);
  background: var(--white);
  transition: border-color var(--transition), box-shadow var(--transition);
  width: 100%;
  -webkit-appearance: none;
}
.form-control:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(12,30,69,0.08);
}
select.form-control { cursor: pointer; }

.checkbox-group { display: grid; gap: 10px; }
.checkbox-item {
  display: flex;
  align-items: center;
  gap: 10px;
  cursor: pointer;
  font-size: 0.9rem;
  color: var(--text-mid);
}
.checkbox-item input[type="checkbox"] {
  width: 17px;
  height: 17px;
  accent-color: var(--primary);
  cursor: pointer;
  flex-shrink: 0;
}

/* Form feedback messages */
#form-success, #form-error {
  display: none;
  padding: 20px 24px;
  border-radius: var(--radius-lg);
  margin-top: 20px;
}
#form-success {
  background: #EFF8F4;
  border: 1px solid #B5D9C7;
  color: var(--success);
}
#form-error {
  background: #FDF2F2;
  border: 1px solid #E8C0C0;
  color: var(--error);
}
#form-success h3, #form-error h3 {
  font-size: 1rem;
  margin-bottom: 8px;
  color: inherit;
}
#form-success p, #form-error p {
  font-size: 0.9rem;
  margin-bottom: 6px;
  color: inherit;
}
#form-success strong, #form-error strong { font-weight: 700; }

.wechat-fallback {
  background: var(--accent-pale);
  border: 1px solid rgba(184,137,42,0.3);
  border-radius: var(--radius-lg);
  padding: 20px 24px;
  margin-top: 24px;
}
.wechat-fallback h4 {
  font-size: 0.95rem;
  color: var(--primary);
  margin-bottom: 8px;
}
.wechat-fallback p {
  font-size: 0.88rem;
  color: var(--text-mid);
  margin-bottom: 6px;
}
.wechat-id {
  font-size: 1.05rem;
  font-weight: 800;
  color: var(--accent);
  letter-spacing: 0.05em;
}

/* --- Checklist / Feature List --- */
.check-list { display: grid; gap: 10px; }
.check-list li {
  display: flex;
  gap: 10px;
  align-items: baseline;
  font-size: 0.92rem;
  color: var(--text-mid);
}
.check-list li::before {
  content: '→';
  color: var(--accent);
  font-weight: 700;
  flex-shrink: 0;
}

/* Highlight box */
.highlight-box {
  background: var(--accent-pale);
  border-left: 4px solid var(--accent);
  border-radius: 0 var(--radius) var(--radius) 0;
  padding: 20px 24px;
  margin: 24px 0;
}
.highlight-box p { font-size: 0.92rem; color: var(--text-mid); margin: 0; }

/* Notice box */
.notice-box {
  background: #EFF8F4;
  border-left: 4px solid #1A6B3C;
  border-radius: 0 var(--radius) var(--radius) 0;
  padding: 18px 22px;
}
.notice-box p { font-size: 0.9rem; color: #1A6B3C; margin: 0; }

/* --- CTA Banner --- */
.cta-banner {
  background: var(--primary);
  padding: 60px 0;
  text-align: center;
  position: relative;
  overflow: hidden;
}
.cta-banner::before {
  content: '';
  position: absolute;
  top: 0; left: 0;
  width: 100%;
  height: 2px;
  background: linear-gradient(90deg, transparent, var(--accent), transparent);
}
.cta-banner h2 { color: var(--white); margin-bottom: 14px; }
.cta-banner p { color: rgba(255,255,255,0.75); margin-bottom: 28px; max-width: 540px; margin-left: auto; margin-right: auto; }
.cta-banner .btn-group { display: flex; justify-content: center; flex-wrap: wrap; gap: 12px; }

/* --- Stat / Info Bar --- */
.info-bar {
  display: grid;
  gap: 0;
}
.info-bar--4 { grid-template-columns: repeat(4, 1fr); }
.info-bar__item {
  padding: 28px 24px;
  border-right: 1px solid var(--border);
  text-align: center;
}
.info-bar__item:last-child { border-right: none; }
.info-bar__item h3 {
  font-size: 1.5rem;
  color: var(--accent);
  margin-bottom: 4px;
}
.info-bar__item p { font-size: 0.82rem; color: var(--text-muted); margin: 0; }

/* --- Resource / Download card --- */
.resource-card {
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 32px;
  display: flex;
  gap: 28px;
  align-items: flex-start;
  box-shadow: var(--shadow-sm);
}
.resource-card__icon {
  width: 56px;
  height: 56px;
  background: var(--accent-pale);
  border-radius: var(--radius-lg);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.6rem;
  flex-shrink: 0;
}
.resource-card__body { flex: 1; }
.resource-card__body h3 { margin-bottom: 8px; }
.resource-card__body p { font-size: 0.92rem; margin-bottom: 16px; }
.resource-card__meta {
  display: flex;
  gap: 16px;
  margin-bottom: 16px;
  flex-wrap: wrap;
}
.resource-card__tag {
  font-size: 0.75rem;
  font-weight: 600;
  background: var(--accent-pale);
  color: var(--accent);
  border-radius: 100px;
  padding: 3px 10px;
}

/* --- Breadcrumb --- */
.breadcrumb {
  display: flex;
  gap: 8px;
  align-items: center;
  font-size: 0.8rem;
  color: rgba(255,255,255,0.5);
  margin-bottom: 16px;
}
.breadcrumb a { color: rgba(255,255,255,0.6); }
.breadcrumb a:hover { color: var(--accent); }
.breadcrumb span { color: rgba(255,255,255,0.35); }

/* --- Footer --- */
.footer {
  background: #080F1E;
  color: rgba(255,255,255,0.6);
  padding: 52px 0 32px;
}
.footer__grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 40px;
  margin-bottom: 40px;
}
.footer__brand { margin-bottom: 14px; }
.footer__brand-name {
  font-size: 1rem;
  font-weight: 800;
  color: var(--white);
  display: flex;
  align-items: center;
  gap: 10px;
}
.footer__brand-sep {
  width: 1px;
  height: 16px;
  background: rgba(255,255,255,0.2);
}
.footer__brand-cn { font-size: 0.88rem; color: var(--accent); font-weight: 600; }
.footer__tagline { font-size: 0.85rem; line-height: 1.7; margin-top: 10px; }

.footer__col h4 {
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: rgba(255,255,255,0.4);
  margin-bottom: 14px;
  color: var(--white);
}
.footer__col ul { display: grid; gap: 8px; }
.footer__col li a {
  font-size: 0.85rem;
  color: rgba(255,255,255,0.55);
  transition: color var(--transition);
}
.footer__col li a:hover { color: var(--accent); }

.footer__bottom {
  border-top: 1px solid rgba(255,255,255,0.08);
  padding-top: 24px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px;
  font-size: 0.8rem;
}
.footer__integrity {
  font-size: 0.78rem;
  color: rgba(255,255,255,0.35);
  max-width: 500px;
}
.footer__integrity a {
  color: rgba(255,255,255,0.45);
  text-decoration: underline;
  text-underline-offset: 2px;
}

/* --- English page styles --- */
.en-page { font-family: "Georgia", "Times New Roman", serif; }
.en-page h1, .en-page h2, .en-page h3 { font-family: var(--font); }

/* --- Tags / Badges --- */
.tag {
  display: inline-flex;
  align-items: center;
  font-size: 0.75rem;
  font-weight: 600;
  border-radius: 100px;
  padding: 3px 10px;
}
.tag--blue { background: #E8EFFC; color: #1B40A0; }
.tag--green { background: #EAF5EE; color: #1A6B3C; }
.tag--gold { background: var(--accent-pale); color: #7A5E1A; }

/* --- Responsive --- */
@media (max-width: 900px) {
  .nav__links { display: none; }
  .hamburger-icon { display: flex; }

  .hamburger-check:checked ~ .nav__links-mobile {
    display: flex;
    flex-direction: column;
    position: fixed;
    top: 64px;
    left: 0;
    right: 0;
    background: var(--white);
    padding: 20px 24px;
    border-bottom: 1px solid var(--border);
    gap: 8px;
    box-shadow: var(--shadow);
    z-index: 999;
  }
  .nav__links-mobile { display: none; }
  .nav__links-mobile a {
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--text-mid);
    padding: 10px 12px;
    border-radius: var(--radius);
    display: block;
  }

  .two-col,
  .two-col--wide,
  .integrity-grid { grid-template-columns: 1fr; }

  .card-grid--2,
  .card-grid--3,
  .card-grid--4 { grid-template-columns: 1fr; }

  .info-bar--4 { grid-template-columns: 1fr 1fr; }

  .footer__grid { grid-template-columns: 1fr 1fr; }

  .hero { padding: 56px 0 48px; }

  .resource-card { flex-direction: column; }
}

@media (max-width: 600px) {
  .section { padding: 52px 0; }
  .info-bar--4 { grid-template-columns: 1fr; }
  .info-bar__item { border-right: none; border-bottom: 1px solid var(--border); }
  .info-bar__item:last-child { border-bottom: none; }
  .footer__grid { grid-template-columns: 1fr; }
  .hero__ctas { flex-direction: column; }
  .cta-banner .btn-group { flex-direction: column; align-items: center; }
  .nav__cta .btn { display: none; }
  .two-col--reverse { direction: ltr; }
}