/* --- 基本設定 --- */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
  scroll-padding-top: 80px;
  /* スティッキーヘッダーの高さを考慮 */
}

body {
  font-family: var(--font-family-base);
  line-height: 1.7;
  color: var(--color-text-dark);
  background-color: var(--color-secondary);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* --- CSS変数定義 (:root) --- */
:root {
  /* 色 (design_concept, wireframe準拠) */
  --color-primary: #002a5c;
  /* ネイビー: ベース、信頼性 */
  --color-secondary: #ffffff;
  /* ホワイト: 背景 */
  --color-accent: #00aeef;
  /* ブライトブルー: CTA、アクセント */
  --color-bg-light: #f5f7fa;
  /* ライトグレー: セクション背景 */
  --color-text-dark: #333333;
  /* ダークグレー: 基本テキスト */
  --color-text-light: #ffffff;
  /* ホワイト: 暗い背景上のテキスト */
  --color-border: #e0e0e0;
  /* 罫線色 */

  /* タイポグラフィ (design_concept, wireframe準拠) */
  --font-family-base: "Noto Sans JP", sans-serif;
  --font-weight-regular: 400;
  --font-weight-medium: 500;
  --font-weight-bold: 700;
  --font-weight-black: 900;

  /* レイアウト・スペーシング */
  --container-width: 1100px;
  --section-padding-y: 80px;
  --header-height: 80px;
}

/* --- 汎用クラス --- */
.container {
  max-width: var(--container-width);
  margin-left: auto;
  margin-right: auto;
  padding-left: 24px;
  padding-right: 24px;
}

.bg-dark {
  background-color: var(--color-primary);
  color: var(--color-text-light);
}

.bg-light {
  background-color: var(--color-bg-light);
}

.text-center {
  text-align: center;
}
.text-left {
  text-align: left;
}
.text-center p,
.text-center h2 {
  margin-left: auto;
  margin-right: auto;
}

.sp-only {
  display: none;
}

/* --- 見出し・テキストスタイル --- */
h1,
h2,
h3 {
  font-family: var(--font-family-base);
  line-height: 1.4;
}

.section-title {
  font-size: 2.25rem;
  font-weight: var(--font-weight-bold);
  text-align: center;
  margin-bottom: 48px;
}

p {
  margin-bottom: 16px;
  max-width: 70ch;
}

p.lead {
  font-size: 1.125rem;
  line-height: 1.8;
  margin-bottom: 32px;
}

/* --- 画像基本スタイル --- */
img {
  max-width: 100%;
  height: auto;
  display: block;
  vertical-align: middle;
}

/* --- ボタン --- */
.cta-button {
  display: inline-block;
  font-family: var(--font-family-base);
  font-weight: var(--font-weight-bold);
  text-decoration: none;
  border-radius: 8px;
  padding: 12px 24px;
  transition: opacity 0.3s ease;
  background-color: var(--color-primary);
  color: var(--color-text-light);
  border: 2px solid transparent;
}

.cta-button.accent {
  background-color: var(--color-accent);
  color: var(--color-text-light);
}

.cta-button.large {
  font-size: 1.125rem;
  padding: 16px 48px;
}

.cta-button:hover {
  opacity: 0.8;
}

/* --- ヘッダー --- */
.sticky-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background-color: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.05);
  height: var(--header-height);
}

.header-container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  height: 100%;
}

.logo p {
  font-weight: var(--font-weight-bold);
  color: var(--color-primary);
  text-decoration: none;
  font-size: 1.1rem;
  margin-bottom: 0;
}

.hamburger-menu {
  display: none;
}

/* --- ヒーローセクション (#hero) --- */
.hero-section {
  position: relative;
  display: flex;
  align-items: center;
  min-height: calc(100vh - var(--header-height));
  color: var(--color-text-light);
  padding: 80px 0;
}

.hero-background {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-image: url("img/seikei_main.jpg");
  background-size: cover;
  background-position: center;
  z-index: -2;
}

.hero-overlay {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: var(--color-primary);
  opacity: 0.4;
  z-index: -1;
}

.hero-content {
  text-align: left;
}

.hero-content h1 {
  font-size: 3.5rem;
  font-weight: var(--font-weight-black);
  margin-bottom: 24px;
}

.scroll-indicator {
  position: absolute;
  bottom: 30px;
  left: 50%;
  transform: translateX(-50%);
  width: 40px;
  height: 40px;
}

.scroll-indicator img {
  width: 100%;
  height: 100%;
  object-fit: contain;
}

/* --- 課題共感セクション (#problem) --- */
.problem-section {
  padding: var(--section-padding-y) 0;
}

.problem-cards {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 32px;
}

.card {
  border: 1px solid var(--color-border);
  border-radius: 8px;
  padding: 32px;
  padding-top: 16px;
  background-color: var(--color-secondary);
}

.card-icon {
  width: 60px;
  height: 60px;
  margin: auto;
  margin-bottom: 24px;
  object-fit: cover;
  aspect-ratio: 1 / 1;
}

.card h3 {
  font-size: 1.25rem;
  font-weight: var(--font-weight-bold);
  margin-bottom: 16px;
}

.card ul {
  list-style: none;
  padding-left: 0;
}

.card li {
  position: relative;
  padding-left: 20px;
}

.card li::before {
  content: "✓";
  position: absolute;
  left: 0;
  color: var(--color-accent);
  font-weight: bold;
}

/* --- ソリューション提示セクション (#solution-declaration) --- */
.solution-declaration-section {
  padding: var(--section-padding-y) 0;
}

.declaration-title {
  font-size: 2.5rem;
  font-weight: var(--font-weight-bold);
  margin-bottom: 24px;
}

/* --- 技術的優位性セクション (#usp-technology) --- */
.usp-technology-section {
  padding: var(--section-padding-y) 0;
}

.interactive-diagram {
  max-width: 800px;
  width: 100%;
  height: auto;
  aspect-ratio: 16 / 9;
  object-fit: cover;
  margin: 48px auto;
}

.tech-points {
  display: flex;
  justify-content: center;
  gap: 32px;
  list-style: none;
  padding-left: 0;
  margin-top: 32px;
}

.tech-points li {
  border: 1px solid rgba(255, 255, 255, 0.5);
  padding: 8px 16px;
  border-radius: 30px;
}

/* --- 対応範囲の広さセクション (#usp-onestop) --- */
.usp-onestop-section {
  padding: var(--section-padding-y) 0;
}

.step-flow {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 16px;
  margin-top: 48px;
  position: relative;
}

.step-item {
  background-color: var(--color-bg-light);
  padding: 12px 24px;
  border-radius: 8px;
  font-weight: var(--font-weight-medium);
}

.benefit-copy {
  margin-top: 48px;
}

/* --- 信頼の裏付けセクション (#reasons) --- */
.reasons-section {
  padding: var(--section-padding-y) 0;
}

.reasons-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 32px;
}

.reason-card h3 {
  font-size: 1.25rem;
  margin-bottom: 8px;
}

.reason-photo {
  width: 100%;
  height: 200px;
  margin-bottom: 24px;
  object-fit: cover;
  aspect-ratio: 4 / 3;
}

/* --- 導入の流れセクション (#flow) --- */
.flow-section {
  padding: var(--section-padding-y) 0;
}

.flow-list {
  list-style: none;
  max-width: 800px;
  margin: 0 auto;
  border-left: 2px solid var(--color-accent);
}

.flow-list li {
  position: relative;
  padding-left: 40px;
  padding-bottom: 48px;
}

.flow-list li::before {
  content: "";
  position: absolute;
  left: -9px;
  top: 5px;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background-color: var(--color-accent);
  border: 2px solid var(--color-secondary);
}

.flow-list li:last-child {
  padding-bottom: 0;
}

.flow-list h3 {
  font-size: 1.5rem;
}

/* --- FAQセクション (#faq) --- */
.faq-section {
  padding: var(--section-padding-y) 0;
}

.faq-list {
  max-width: 800px;
  margin: 0 auto;
}

.faq-item {
  border-bottom: 1px solid var(--color-border);
}

.faq-item summary {
  font-size: 1.125rem;
  font-weight: var(--font-weight-bold);
  padding: 24px 0;
  cursor: pointer;
  list-style: none;
  position: relative;
  padding-right: 30px;
}

.faq-item summary::-webkit-details-marker {
  display: none;
}

.faq-item summary::after {
  content: "+";
  position: absolute;
  right: 0;
  font-size: 1.5rem;
  color: var(--color-accent);
}

.faq-item[open] summary::after {
  content: "-";
}

.faq-answer {
  padding-bottom: 24px;
}

/* --- クロージングCTAセクション (#cta) --- */
.cta-section {
  padding: var(--section-padding-y) 0;
}

.cta-title {
  font-size: 2.5rem;
  font-weight: var(--font-weight-bold);
}

.cta-actions {
  margin-top: 48px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 24px;
}

.cta-phone {
  display: flex;
  flex-direction: column;
  align-items: center;
}

.phone-label {
  font-size: 0.9rem;
}

.phone-number {
  font-size: 1.75rem;
  font-weight: var(--font-weight-bold);
  color: var(--color-text-light);
  text-decoration: none;
}

.phone-reception {
  font-size: 0.9rem;
  opacity: 0.8;
}

/* --- フッター --- */
.site-footer {
  background-color: #222;
  color: #ccc;
  padding: 48px 0;
  font-size: 0.9rem;
}

.footer-info .company-name {
  font-weight: var(--font-weight-bold);
  font-size: 1rem;
}

.footer-nav {
  margin: 16px 0;
}

.footer-nav a {
  color: #ccc;
  text-decoration: none;
  margin: 0 12px;
}

.footer-nav a:hover {
  text-decoration: underline;
}

.copyright {
  font-size: 0.8rem;
  opacity: 0.7;
  margin-top: 16px;
  margin-bottom: 0;
}

/* --- レスポンシブ対応 --- */
@media (max-width: 768px) {
  html {
    font-size: 15px;
    scroll-padding-top: 60px;
  }

  :root {
    --section-padding-y: 60px;
    --header-height: 60px;
  }

  .sp-only {
    display: block;
  }

  .section-title {
    font-size: 1.8rem;
    margin-bottom: 32px;
  }

  /* ヘッダー */
  .header-nav .cta-button {
    display: none;
  }

  /* モバイルではCTAを非表示 */
  .hamburger-menu {
    display: block;
    background: none;
    border: none;
    cursor: pointer;
    width: 30px;
    height: 20px;
    position: relative;
  }

  .hamburger-menu span {
    display: block;
    width: 100%;
    height: 2px;
    background-color: var(--color-primary);
    position: absolute;
    left: 0;
    transition: all 0.3s;
  }

  .hamburger-menu span:nth-child(1) {
    top: 0;
  }

  .hamburger-menu span:nth-child(2) {
    top: 50%;
    transform: translateY(-50%);
  }

  .hamburger-menu span:nth-child(3) {
    bottom: 0;
  }

  /* ヒーロー */
  .hero-section {
    min-height: 80vh;
  }

  .hero-content {
    text-align: center;
  }

  .hero-content h1 {
    font-size: 2.5rem;
  }

  .hero-content p.lead {
    font-size: 1rem;
  }

  .hero-content .cta-button.large {
    padding: 12px 24px;
    font-size: 1rem;
  }

  /* 各セクションのグリッドレイアウトを1カラムに */
  .problem-cards,
  .reasons-grid {
    grid-template-columns: 1fr;
    gap: 24px;
  }

  .tech-points {
    flex-direction: column;
    align-items: center;
  }

  .flow-list {
    padding-left: 20px;
  }

  .flow-list li {
    padding-left: 20px;
  }

  .declaration-title {
    font-size: 1.8rem;
  }
  .cta-title {
    font-size: 1.8rem;
  }
}
.pt-0 {
  padding-top: 0;
}