/* Bước Chân Xanh 2026 — token màu và bố cục theo DESIGN.md (TEC-60) */
:root {
  --green: #1E7A34;
  --green-dark: #145A26;
  --green-light: #E6F4EA;
  --green-lime: #7BC950;
  --bg: #FFFFFF;
  --bg-soft: #F6F8F5;
  --text: #1A2E1F;
  --text-muted: #5A6B5E;
  --border: #D8E4D9;
  --error: #C0392B;
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: "Be Vietnam Pro", system-ui, -apple-system, "Segoe UI", sans-serif;
  font-size: 16px;
  color: var(--text);
  background: var(--bg);
}
a { color: var(--green); }

/* S0 — Header cố định */
.header {
  position: sticky;
  top: 0;
  z-index: 10;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 12px 20px;
  background: var(--bg);
  border-bottom: 1px solid var(--border);
}
.logo { font-weight: 800; font-size: 18px; color: var(--green-dark); text-decoration: none; }
.logo span { color: var(--green); }

/* Nút bấm: viên thuốc, cao tối thiểu 48px */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 48px;
  min-width: 44px;
  padding: 0 24px;
  border-radius: 999px;
  font-weight: 700;
  font-size: 16px;
  text-decoration: none;
  cursor: pointer;
  transition: background-color .15s ease, transform .15s ease;
}
.btn-primary { background: var(--green); color: #fff; border: 2px solid var(--green); }
.btn-primary:hover { background: var(--green-dark); border-color: var(--green-dark); }
.btn-outline { background: var(--bg); color: var(--green-dark); border: 2px solid var(--green); }
.btn-outline:hover { background: var(--green-light); }
.btn:focus-visible, a:focus-visible { outline: 3px solid var(--green-lime); outline-offset: 2px; }

/* Khung trang: một cột, tối đa 1120px ở giữa */
.container { max-width: 1120px; margin: 0 auto; padding: 0 20px; }
.section { padding: 64px 0; }
.section + .section { border-top: 1px solid var(--border); }
.section-title { font-size: 24px; font-weight: 800; color: var(--green-dark); margin: 0 0 8px; }
.section-sub { color: var(--text-muted); margin: 0 0 32px; }

/* S1 — Hero */
.hero { padding: 64px 0; }
.hero-eyebrow {
  display: inline-block;
  margin: 0 0 16px;
  padding: 6px 14px;
  border-radius: 999px;
  background: var(--green-light);
  color: var(--green-dark);
  font-size: 14px;
  font-weight: 700;
}
.hero-title { font-size: 32px; font-weight: 800; line-height: 1.15; color: var(--green-dark); margin: 0 0 16px; }
.hero-text { color: var(--text-muted); line-height: 1.6; margin: 0 0 24px; max-width: 560px; }
.hero-art {
  margin: 32px 0;
  padding: 32px 16px;
  border-radius: 16px;
  background: var(--green-light);
  text-align: center;
  font-size: 40px;
  letter-spacing: 8px;
}
.hero-art span { display: block; margin-top: 12px; font-size: 14px; letter-spacing: 0; color: var(--text-muted); }
.hero-note { color: var(--text-muted); font-size: 14px; margin: 16px 0 0; }

/* S3 — Thời gian & địa điểm: 2 thẻ */
.info-grid { display: grid; gap: 16px; }
.info-card {
  padding: 24px;
  border: 1px solid var(--border);
  border-radius: 16px;
  background: var(--bg-soft);
}
.info-card .icon { font-size: 28px; }
.info-card h3 { margin: 8px 0; font-size: 20px; color: var(--green-dark); }
.info-card p { margin: 0; line-height: 1.6; }
.placeholder { color: var(--text-muted); font-style: italic; }

/* S4 — Cự ly & phí: 3 thẻ */
.distances { background: var(--green-light); }
.distances .section { border-top: none; }
.distance-grid { display: grid; gap: 16px; }
.distance-card {
  padding: 28px 24px;
  border: 1px solid var(--border);
  border-radius: 16px;
  background: var(--bg);
  text-align: center;
  transition: transform .15s ease;
}
.distance-card:hover { transform: translateY(-2px); }
.distance-card.featured { border: 2px solid var(--green-dark); position: relative; }
.badge {
  position: absolute;
  top: -12px;
  left: 50%;
  transform: translateX(-50%);
  padding: 4px 12px;
  border-radius: 999px;
  background: var(--green);
  color: #fff;
  font-size: 13px;
  font-weight: 700;
  white-space: nowrap;
}
.distance-name { font-size: 32px; font-weight: 800; color: var(--green-dark); margin: 8px 0; }
.distance-desc { color: var(--text-muted); line-height: 1.6; margin: 0 0 16px; }
.distance-fee { font-size: 18px; font-weight: 700; margin: 0 0 20px; }
.benefits-note { text-align: center; color: var(--text-muted); margin: 24px 0 0; }

/* Khối giữ chỗ cho các task sau (TEC-62/TEC-63) */
.coming-soon {
  padding: 48px 24px;
  text-align: center;
  color: var(--text-muted);
  border: 1px dashed var(--border);
  border-radius: 16px;
}

/* S2 — Đồng hồ đếm ngược (TEC-62): 4 ô, nền xanh đậm, chữ trắng */
.countdown-section {
  background: var(--green-dark);
  color: #fff;
  padding: 64px 0;
  text-align: center;
}
.countdown-title { font-size: 24px; font-weight: 800; margin: 0 0 24px; }
.countdown-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 12px;
  max-width: 640px;
  margin: 0 auto;
}
.countdown-box {
  padding: 16px 8px;
  border-radius: 16px;
  background: rgba(255, 255, 255, 0.12);
}
.countdown-number { display: block; font-size: 32px; font-weight: 800; }
.countdown-label { display: block; font-size: 14px; margin-top: 4px; }
.countdown-status { margin: 20px 0 0; font-size: 16px; line-height: 1.6; }
.countdown-status:empty { display: none; }

/* S7 — Form đăng ký (TEC-62) */
#register-form { max-width: 560px; }
.form-field { margin: 0 0 24px; border: none; padding: 0; }
.form-field label, .form-field legend {
  display: block;
  font-weight: 700;
  color: var(--green-dark);
  margin-bottom: 8px;
}
.form-field input[type="text"], .form-field select {
  width: 100%;
  min-height: 48px;
  padding: 0 16px;
  border: 2px solid var(--border);
  border-radius: 12px;
  font: inherit;
  color: var(--text);
  background: var(--bg);
}
.form-field input[type="text"]:focus, .form-field select:focus {
  outline: 3px solid var(--green-lime);
  outline-offset: 2px;
  border-color: var(--green);
}
.distance-options { display: grid; gap: 12px; }
.distance-option {
  display: flex;
  align-items: center;
  gap: 12px;
  min-height: 48px;
  padding: 0 16px;
  border: 2px solid var(--border);
  border-radius: 12px;
  font-weight: 600;
  cursor: pointer;
}
.distance-option:has(input:checked) {
  border-color: var(--green);
  background: var(--green-light);
}
.form-error { color: var(--error); margin: 8px 0 0; min-height: 1.2em; }
.form-error:empty { display: none; }
.form-success {
  margin: 24px 0 0;
  padding: 16px;
  border-radius: 12px;
  background: var(--green-light);
  color: var(--green-dark);
  font-weight: 700;
  line-height: 1.6;
}
.form-success[hidden] { display: none; }

/* S5 — Lộ trình (TEC-63): 3 thẻ theo cự ly */
.route-grid { display: grid; gap: 16px; }
.route-card {
  padding: 24px;
  border: 1px solid var(--border);
  border-left: 6px solid var(--green);
  border-radius: 16px;
  background: var(--bg-soft);
}
.route-card p { margin: 0; line-height: 1.6; }
.route-name { font-size: 24px; font-weight: 800; color: var(--green-dark); margin: 0 0 8px; }

/* S6 — Giải thưởng (TEC-63): nền xen kẽ xanh nhạt, lưới thẻ */
.prizes { background: var(--green-light); }
.prizes .section { border-top: none; }
.prize-grid { display: grid; gap: 16px; }
.prize-card {
  padding: 28px 24px;
  border: 1px solid var(--border);
  border-radius: 16px;
  background: var(--bg);
  text-align: center;
  transition: transform .15s ease;
}
.prize-card:hover { transform: translateY(-2px); }
.prize-icon { font-size: 32px; }
.prize-name { font-size: 24px; font-weight: 800; color: var(--green-dark); margin: 8px 0; }
.prize-card p { margin: 0; line-height: 1.6; }

/* S8 — Nhà tài trợ (TEC-63): lưới logo, khung giữ chỗ khi chưa có logo thật */
.sponsor-grid { display: grid; gap: 16px; }
.sponsor-placeholder {
  padding: 48px 24px;
  text-align: center;
  border: 1px dashed var(--border);
  border-radius: 16px;
}
.sponsor-placeholder p { margin: 0; line-height: 1.6; }

/* S9 — Footer */
.footer { background: var(--green-dark); color: #fff; padding: 48px 0; }
.footer a { color: #fff; }
.footer p { margin: 8px 0; line-height: 1.6; }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .btn, .distance-card, .prize-card { transition: none; }
}

/* Tablet: 640–1024px */
@media (min-width: 640px) {
  .hero-title { font-size: 44px; }
  .section-title { font-size: 28px; }
  .info-grid { grid-template-columns: 1fr 1fr; }
  .distance-grid { grid-template-columns: 1fr 1fr 1fr; }
  .route-grid { grid-template-columns: 1fr 1fr 1fr; }
  .prize-grid { grid-template-columns: 1fr 1fr; }
  .sponsor-grid { grid-template-columns: 1fr 1fr; }
}

/* Desktop: > 1024px */
@media (min-width: 1024px) {
  .section { padding: 96px 0; }
  .hero-title { font-size: 56px; }
  .section-title { font-size: 32px; }
  .hero-inner { display: grid; grid-template-columns: 1.2fr 1fr; gap: 48px; align-items: center; }
  .hero-art { margin: 0; padding: 64px 24px; font-size: 56px; }
  .prize-grid { grid-template-columns: 1fr 1fr 1fr; }
  .sponsor-grid { grid-template-columns: repeat(4, 1fr); }
}