:root {
  --bg: #ffffff;
  --surface: #ffffff;
  --text: #102a43;
  --muted: #4f6475;
  --primary: #0068b7;
  --primary-dark: #004b8d;
  --accent: #00a6d6;
  --green: #2e7d32;
  --warning: #b64b00;
  --border: #d8e8f2;
  --border-strong: #b7dbea;
  --shadow: 0 14px 34px rgba(0, 75, 141, 0.10);
  --radius: 18px;
  --max-width: 1120px;
  --map-fixed-width: 400px;
  --font-sans: "Noto Sans JP", -apple-system, BlinkMacSystemFont, "Helvetica Neue", Arial, sans-serif;
}

*,
*::before,
*::after { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  color: var(--text);
  font-family: var(--font-sans);
  line-height: 1.7;
  background: var(--bg);
}

a { color: inherit; }

.container {
  width: min(100% - 32px, var(--max-width));
  margin-inline: auto;
}

.skip-link {
  position: absolute;
  top: -48px;
  left: 16px;
  z-index: 20;
  padding: 10px 14px;
  color: #fff;
  background: var(--primary-dark);
  border-radius: 999px;
}

.skip-link:focus { top: 16px; }

.site-header {
  background: #fff;
  border-top: 8px solid var(--primary);
  border-bottom: 1px solid var(--border);
}

.header-inner { padding: 22px 0; }

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  color: var(--primary-dark);
  font-weight: 900;
  text-decoration: none;
  white-space: nowrap;
}

.brand-mark {
  width: 48px;
  height: auto;
}

.brand-text {
  font-size: clamp(1rem, 2vw, 1.35rem);
  letter-spacing: -0.02em;
}

.breadcrumb {
  padding: 14px 0 10px;
  font-size: 0.92rem;
}

.breadcrumb ol {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  padding: 0;
  margin: 0;
  list-style: none;
}

.breadcrumb li:not(:last-child)::after {
  margin-left: 6px;
  color: var(--muted);
  content: ">";
}

.breadcrumb a {
  color: var(--muted);
  text-decoration: none;
}

.breadcrumb [aria-current="page"] {
  color: var(--primary-dark);
  font-weight: 700;
}

.hero-panel {
  position: relative;
  isolation: isolate;
  overflow: hidden;
  padding: 30px;
  background: linear-gradient(135deg, #ffffff 0%, #f2f9fd 58%, rgba(0, 166, 214, 0.10) 100%);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.hero-panel::before {
  position: absolute;
  inset: 0;
  z-index: -1;
  content: "";
  background-image: url("calendar.png");
  background-repeat: no-repeat;
  background-position: right 28px center;
  background-size: min(46%, 520px) auto;
  opacity: 0.12;
  mix-blend-mode: multiply;
  pointer-events: none;
}

h1, h2, h3 { margin: 0; line-height: 1.7; }

h1 {
  color: var(--primary-dark);
  font-size: clamp(1.8rem, 4vw, 2.7rem);
  letter-spacing: -0.03em;
}

.lead {
  max-width: 740px;
  margin: 12px 0 0;
  color: var(--muted);
  font-size: 1.05rem;
}

.external-link-icon {
  float: right;
  width: 20px;
  height: 20px;
  margin: 2px 0 4px 10px;
}

.notice-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px;
  padding: 20px 0 0;
}

.notice-card {
  padding: 18px;
  background: #fff;
  border: 1px solid var(--border);
  border-left: 8px solid var(--primary);
  border-radius: 16px;
}

.notice-card.important { border-left-color: var(--warning); }


.notice-card h2 {
  color: var(--primary-dark);
  font-size: 1.08rem;
}

.notice-card p:last-child { margin-bottom: 0; color: var(--muted); }

.content-section { padding: 28px 0 0; scroll-margin-top: 18px; }

.section-heading { margin-bottom: 14px; }

.section-heading h2,
.panel h2 {
  color: var(--primary-dark);
  font-size: clamp(1.35rem, 2.5vw, 1.9rem);
}

.section-heading p,
.note { color: var(--muted); }

.panel {
  padding: 24px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.split-panel {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 20px;
  align-items: center;
}

.steps {
  display: grid;
  gap: 10px;
  margin: 18px 0 0;
  padding-left: 1.35rem;
}

.steps li { padding-left: 4px; }

.related-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px;
  margin-top: 16px;
}

.related-link,
.related-note {
  display: block;
  padding: 18px;
  text-decoration: none;
  background: #fff;
  border: 2px solid var(--border-strong);
  border-radius: 16px;
}

.related-link:hover,
.related-link:focus-visible {
  background: #f4fbff;
  border-color: var(--primary);
}

.related-link span,
.related-note span {
  display: block;
  color: var(--primary-dark);
  font-size: 1.05rem;
  font-weight: 900;
}

.related-link small,
.related-note small {
  display: block;
  margin-top: 8px;
  color: var(--muted);
  font-size: 0.92rem;
  line-height: 1.55;
}

.site-footer {
  margin-top: 42px;
  padding: 26px 0;
  color: #fff;
  background: var(--primary-dark);
}

.footer-inner {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  align-items: center;
  justify-content: space-between;
}

.site-footer a { color: #fff; font-weight: 700; }

a:focus-visible {
  outline: 3px solid var(--accent);
  outline-offset: 4px;
  border-radius: 10px;
}

@media (max-width: 980px) {
  .split-panel { grid-template-columns: 1fr; }
}

.cgi-form {
  display: grid;
  grid-template-columns: repeat(2, minmax(140px, 1fr));
  gap: 14px;
  padding: 18px;
  background: #f7fbfe;
  border: 1px solid var(--border);
  border-radius: 16px;
}

.location-field {
  grid-column: 1 / -1;
  margin: 0;
  padding: 0;
  border: 0;
}

.location-field legend {
  margin-bottom: 10px;
  color: var(--primary-dark);
  font-size: clamp(1.15rem, 2vw, 1.45rem);
  font-weight: 900;
}

.radio-prefecture-group {
  display: grid;
  gap: 12px;
}

.radio-prefecture {
  padding: 14px;
  background: #fff;
  border: 1px solid var(--border);
  border-radius: 14px;
}

.radio-prefecture p {
  margin: 0 0 10px;
  color: var(--primary-dark);
  font-weight: 900;
}

.radio-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(130px, 1fr));
  gap: 8px;
}

.niigata-radios {
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
}

.radio-grid label {
  display: flex;
  gap: 8px;
  align-items: center;
  min-height: 44px;
  padding: 9px 10px;
  color: var(--primary-dark);
  font-weight: 800;
  background: #f4f9fd;
  border: 2px solid transparent;
  border-radius: 12px;
  cursor: pointer;
}

.radio-grid input[type="radio"] {
  width: 1.05rem;
  height: 1.05rem;
  accent-color: var(--primary-dark);
}

.radio-grid label:has(input[type="radio"]:checked) {
  background: rgba(46, 125, 50, 0.10);
  border-color: rgba(46, 125, 50, 0.44);
}

.radio-grid label:focus-within {
  outline: 3px solid var(--accent);
  outline-offset: 3px;
}

.form-field {
  display: grid;
  gap: 7px;
}

.form-field span {
  color: var(--primary-dark);
  font-weight: 900;
}

.form-field select {
  width: 100%;
  min-height: 48px;
  padding: 10px 12px;
  color: var(--text);
  font: inherit;
  font-weight: 700;
  background: #fff;
  border: 2px solid var(--border-strong);
  border-radius: 12px;
}

.form-field select:focus-visible {
  outline: 3px solid var(--accent);
  outline-offset: 3px;
}

.form-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  grid-column: 1 / -1;
  align-items: center;
}

.form-actions button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 46px;
  padding: 10px 18px;
  color: #ffffff;
  font: inherit;
  font-weight: 800;
  text-align: center;
  background: var(--primary-dark);
  border: 2px solid transparent;
  border-radius: 13px;
  cursor: pointer;
  box-shadow: 0 8px 18px rgba(0, 75, 141, 0.18);
  transition: border-color 0.18s ease, background-color 0.18s ease, box-shadow 0.18s ease;
}

.form-actions button:hover,
.form-actions button:focus-visible {
  background: var(--primary);
  box-shadow: 0 10px 22px rgba(0, 75, 141, 0.24);
}

.form-note {
  margin-bottom: 0;
}

.form-stack {
  display: grid;
  gap: 14px;
  align-content: start;
  min-width: 0;
  margin-top: 18px;
}

.form-stack .cgi-form {
  width: 100%;
}

.how-to-inline {
  grid-column: 1 / -1;
  padding: 18px;
  background: #fff;
  border: 1px solid var(--border);
  border-radius: 16px;
}

.how-to-inline h2 {
  margin-top: 0;
}

.how-to-inline .steps {
  margin-top: 14px;
}

@media (min-width: 1100px) {
  .calendar-panel {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 24px;
    align-items: start;
  }

  .calendar-panel .clickable-map-panel {
    margin-top: 0;
  }

  .calendar-panel .form-stack {
    min-width: 0;
    margin-top: 0;
  }
}

/* クリッカブルマップ：標準は見やすい固定幅、400px以下は横崩れ防止のため少し縮小します。 */
.clickable-map-panel {
  overflow-wrap: anywhere;
  display: grid;
  grid-template-columns: 1fr;
  gap: 22px;
  align-items: start;
  margin-top: 24px;
  padding: 18px;
  background: linear-gradient(135deg, rgba(0, 75, 141, 0.06), rgba(46, 125, 50, 0.07));
  border: 1px solid var(--border);
  border-radius: 18px;
}

.map-copy h3 {
  margin-bottom: 10px;
  color: var(--primary-dark);
  font-size: clamp(1.15rem, 2vw, 1.45rem);
  font-weight: 900;
}

.map-copy p:last-child {
  margin-bottom: 0;
}

.map-copy .tide-map-wrap {
  margin-top: 14px;
}

.tide-map-wrap {
  position: relative;
  width: var(--map-fixed-width);
  max-width: 100%;
  justify-self: center;
  overflow: hidden;
  background: #fff;
  border: 1px solid var(--border);
  border-radius: 16px;
  box-shadow: 0 10px 24px rgba(0, 75, 141, 0.12);
}

.tide-map-wrap .tide-clickable-map {
display: block;
width: 100%;
height: 410px;
background: #ffffff;
background-color: #ffffff;
}

.map-text-links {
  margin-top: 14px;
  padding-top: 4px;
}

.map-text-links summary {
  color: var(--primary-dark);
  font-weight: 900;
  cursor: pointer;
}

.map-text-links ul {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  padding: 10px 0 0;
  margin: 0;
  list-style: none;
}

.map-text-links a {
  display: inline-flex;
  padding: 7px 10px;
  color: var(--primary-dark);
  font-weight: 800;
  text-decoration: none;
  background: #fff;
  border: 1px solid var(--border);
  border-radius: 999px;
}

.map-text-links a:hover,
.map-text-links a:focus-visible {
  color: #fff;
  background: var(--primary-dark);
}

@media (max-width: 820px) {
  .clickable-map-panel {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 640px) {
  body { font-size: 1.05rem; }
  .brand-text { font-size: clamp(1rem, 4.2vw, 1.15rem); }
  .breadcrumb { font-size: .95rem; }
  h1 { font-size: clamp(1.65rem, 7vw, 2rem); }
  .lead { font-size: 1.05rem; }
  .location-field legend { font-size: 1.25rem; }
  .radio-prefecture p,
  .radio-grid label,
  .form-field span,
  .form-field select,
  .form-actions button { font-size: 1rem; }
  .how-to-inline h2,
  .notice-card h2,
  .related-panel h2 { font-size: 1.3rem; }
  .how-to-inline li,
  .how-to-inline .note,
  .notice-card p,
  .related-link span,
  .related-note span { font-size: 1rem; }
  .related-link small,
  .related-note small,
  .map-copy p,
  .map-text-links summary,
  .map-text-links a,
  .footer-inner { font-size: .95rem; }
.hero-panel::before {
    background-position: right -40px center;
    background-size: 360px auto;
    opacity: 0.08;
  }
  .container { width: min(100% - 24px, var(--max-width)); }
  .header-inner { padding: 18px 0; }
  .brand { gap: 12px; }
  .brand-mark { width: 46px; }
  .hero-panel, .panel { padding: 18px; border-radius: 15px; }
  .notice-grid,
  .related-grid { grid-template-columns: 1fr; }
  .content-section { padding-top: 22px; }
.cgi-form { grid-template-columns: 1fr; }
  .form-actions button { width: 100%; }
.skip-link:focus { top: 10px; }
  .brand-mark { width: 42px; }
  .hero-panel { padding: 18px; }
  .tide-map-wrap { max-width: 100%; }
  .cgi-form { gap: 10px; padding: 14px; }
  .radio-grid label { min-height: 40px; }
  .notice-grid { padding-top: 14px; }
  .site-footer { margin-top: 28px; }
}

@media (max-width: 500px) {
  .clickable-map-panel {
    gap: 14px;
    padding: 12px;
  }

  .map-copy {
    min-width: 0;
  }

  .tide-map-wrap {
    width: 100%;
    max-width: 360px;
    border-radius: 14px;
  }

  .tide-map-wrap .tide-clickable-map {
    height: auto;
    aspect-ratio: 521 / 466.184;
  }

  .map-text-links ul {
    gap: 6px;
  }

  .map-text-links a {
    padding: 6px 8px;
    font-size: 0.88rem;
  }
}

@media (max-width: 400px) {
  .tide-map-wrap {
    max-width: 280px;
  }
}

.map-object-fallback {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 10px 0 0;
  padding: 0;
  list-style: none;
}

.map-object-fallback a {
  display: inline-flex;
  padding: 7px 10px;
  color: var(--primary-dark);
  font-weight: 800;
  text-decoration: none;
  background: #fff;
  border: 1px solid var(--border);
  border-radius: 999px;
}

@media (min-width: 981px) {
  .site-header { border-top-width: 6px; }
  .header-inner { padding: 10px 0; }
  .brand-mark { width: 42px; }
  .breadcrumb { padding: 8px 0 6px; font-size: 0.86rem; }
  .hero-panel { padding: 18px 20px; border-radius: 14px; }
  .hero-panel::before { background-size: min(34%, 380px) auto; opacity: 0.08; }
  h1 { font-size: clamp(1.55rem, 3vw, 2.25rem); }
  .lead { margin-top: 6px; font-size: 0.96rem; line-height: 1.55; }
  .content-section { padding-top: 16px; }
  .panel { padding: 16px; border-radius: 14px; }
  .calendar-panel { grid-template-columns: minmax(320px, 0.9fr) minmax(420px, 1.1fr); gap: 14px; }
  .clickable-map-panel { gap: 10px; margin-top: 0; padding: 12px; border-radius: 14px; }
  .map-copy h3 { margin-bottom: 4px; font-size: 1.08rem; }
  .map-copy p { margin: 0 0 8px; font-size: 0.92rem; line-height: 1.5; }
  .tide-map-wrap { max-width: 330px; border-radius: 12px; }
  .tide-map-wrap .tide-clickable-map { height: 335px; }
  .map-text-links { margin-top: 8px; }
  .map-text-links ul { gap: 6px; padding-top: 8px; }
  .map-text-links a { padding: 5px 8px; font-size: 0.84rem; }
  .form-stack { gap: 10px; margin-top: 0; }
  .cgi-form { grid-template-columns: minmax(0, 1fr) 112px 112px; gap: 10px; padding: 12px; border-radius: 14px; }
  .location-field legend { margin-bottom: 6px; font-size: 1.08rem; }
  .radio-prefecture-group { grid-template-columns: 1.45fr 0.75fr 0.9fr; gap: 8px; }
  .radio-prefecture { padding: 10px; border-radius: 12px; }
  .radio-prefecture p { margin-bottom: 6px; font-size: 0.92rem; }
  .radio-grid { gap: 6px; grid-template-columns: repeat(auto-fit, minmax(86px, 1fr)); }
  .niigata-radios { grid-template-columns: repeat(3, minmax(82px, 1fr)); }
  .radio-grid label { min-height: 34px; padding: 6px 8px; font-size: 0.88rem; border-radius: 10px; }
  .radio-grid input[type="radio"] { width: 0.95rem; height: 0.95rem; }
  .form-field { gap: 4px; }
  .form-field span { font-size: 0.9rem; }
  .form-field select { min-height: 38px; padding: 6px 9px; border-radius: 10px; }
  .form-actions { gap: 8px; }
  .form-actions button { min-height: 38px; padding: 7px 14px; border-radius: 11px; }
  .how-to-inline { padding: 10px 12px; border-radius: 12px; }
  .how-to-inline h2 { font-size: 1.05rem; }
  .how-to-inline .steps { margin-top: 8px; gap: 4px; }
  .how-to-inline li, .how-to-inline .note { font-size: 0.9rem; line-height: 1.45; }
  .notice-grid { gap: 10px; padding-top: 14px; }
  .notice-card { padding: 12px; border-left-width: 6px; border-radius: 12px; }
  .notice-card h2 { font-size: 1rem; }
  .notice-card p { margin-top: 6px; font-size: 0.9rem; line-height: 1.5; }
  .related-grid { gap: 10px; margin-top: 10px; }
  .related-link, .related-note { padding: 12px; border-radius: 12px; }
  .site-footer { margin-top: 26px; padding: 16px 0; }
}

@media (min-width: 641px) and (max-width: 1099px) {
  .calendar-panel { grid-template-columns: 1fr; gap: 14px; }
  .radio-prefecture-group { grid-template-columns: 1fr; }
  .tide-map-wrap { max-width: 400px; }
}

@media (min-width: 901px) {
  .cgi-form .radio-prefecture-group {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 8px;
  }

  .cgi-form .radio-prefecture-group .radio-prefecture:nth-child(1) {
    grid-column: 1 / -1;
  }

  .cgi-form .radio-prefecture-group .radio-prefecture:nth-child(2),
  .cgi-form .radio-prefecture-group .radio-prefecture:nth-child(3) {
    grid-column: auto;
  }

  .cgi-form .radio-prefecture-group .radio-prefecture:nth-child(1) .niigata-radios {
    grid-template-columns: repeat(3, minmax(92px, 1fr));
  }

  .cgi-form .radio-prefecture-group .radio-prefecture:nth-child(2) .radio-grid,
  .cgi-form .radio-prefecture-group .radio-prefecture:nth-child(3) .radio-grid {
    grid-template-columns: repeat(auto-fit, minmax(84px, 1fr));
  }
}