/* ==========================================================================
   絆∞2027 事前登録LP スタイル
   ダーク基調 + HUD風アクセント（mock/index.html の --hud-* 配色を参照）
   外部CDN依存なし・システムフォントスタックのみ使用
   ========================================================================== */

:root {
  --bg-base: #05070a;
  --bg-panel: #0c1017;
  --bg-panel-alt: #10151d;
  --border-soft: rgba(92, 184, 255, 0.18);
  --border-strong: rgba(92, 184, 255, 0.4);

  --hud-blue: #5cb8ff;
  --hud-cyan: #45c8f0;
  --hud-amber: #ffc85c;
  --hud-red: #ff5c5c;
  --hud-green: #7cfc9a;

  --text-primary: #eaf2f8;
  --text-secondary: #9fb1c2;
  --text-muted: #6b7d8e;

  --font-sans: -apple-system, BlinkMacSystemFont, "Hiragino Kaku Gothic ProN",
    "Hiragino Sans", "Yu Gothic", "YuGothic", "Segoe UI", Roboto, sans-serif;

  --max-width: 1080px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

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

img {
  max-width: 100%;
  display: block;
}

a {
  color: var(--hud-blue);
}

.section-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 72px 24px;
}

.section-inner--narrow {
  max-width: 720px;
}

.section-heading {
  font-size: clamp(22px, 4vw, 30px);
  font-weight: 700;
  letter-spacing: 0.02em;
  margin: 0 0 32px;
  text-align: center;
  color: var(--text-primary);
}

.section-lead {
  text-align: center;
  color: var(--text-secondary);
  font-size: 15px;
  margin: 0 0 32px;
}

.legal-note {
  text-align: center;
  color: var(--text-muted);
  font-size: 12px;
  margin-top: 16px;
}

.sp-only {
  display: none;
}

.is-hidden {
  display: none !important;
}

/* ---------- ボタン ---------- */
.btn {
  display: inline-block;
  text-decoration: none;
  font-weight: 700;
  text-align: center;
  border-radius: 4px;
  cursor: pointer;
  transition: transform 0.15s ease, box-shadow 0.15s ease, background 0.15s ease;
}

.btn--primary {
  background: var(--hud-blue);
  color: #06121e;
  border: 1px solid var(--hud-blue);
}

.btn--primary:hover {
  background: #7fc9ff;
  box-shadow: 0 0 18px rgba(92, 184, 255, 0.45);
}

.btn--lg {
  padding: 16px 32px;
  font-size: 16px;
  letter-spacing: 0.04em;
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
  box-shadow: none;
}

/* ---------- ヘッダー ---------- */
.lp-header {
  position: sticky;
  top: 0;
  z-index: 20;
  background: rgba(5, 7, 10, 0.86);
  backdrop-filter: blur(6px);
  border-bottom: 1px solid var(--border-soft);
}

.lp-header__inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 14px 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.lp-logo {
  font-weight: 700;
  letter-spacing: 0.08em;
  font-size: 16px;
  color: var(--text-primary);
}

.lp-logo__infinity {
  color: var(--hud-blue);
}

.lp-header__cta {
  font-size: 13px;
  color: var(--hud-blue);
  border: 1px solid var(--border-strong);
  border-radius: 4px;
  padding: 8px 16px;
  text-decoration: none;
}

.lp-header__cta:hover {
  background: rgba(92, 184, 255, 0.1);
}

/* ---------- ヒーロー ---------- */
.hero {
  position: relative;
  min-height: 82vh;
  display: flex;
  align-items: center;
  overflow: hidden;
  border-bottom: 1px solid var(--border-soft);
}

.hero__bg {
  position: absolute;
  inset: 0;
  background:
    radial-gradient(ellipse at 20% 20%, rgba(92, 184, 255, 0.14), transparent 55%),
    radial-gradient(ellipse at 80% 80%, rgba(255, 92, 92, 0.08), transparent 55%),
    linear-gradient(180deg, #05070a 0%, #070a10 60%, #05070a 100%);
}

.hero__bg::after {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(92, 184, 255, 0.06) 1px, transparent 1px),
    linear-gradient(90deg, rgba(92, 184, 255, 0.06) 1px, transparent 1px);
  background-size: 48px 48px;
  mask-image: radial-gradient(ellipse at 50% 30%, black, transparent 70%);
}

.hero__inner {
  position: relative;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 48px 24px;
  text-align: center;
}

.hero__eyebrow {
  color: var(--hud-cyan);
  font-size: 13px;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  margin: 0 0 20px;
}

.hero__title {
  font-size: clamp(28px, 5vw, 46px);
  font-weight: 800;
  line-height: 1.4;
  margin: 0 0 24px;
  text-shadow: 0 0 24px rgba(92, 184, 255, 0.25);
}

.hero__sub {
  color: var(--text-secondary);
  font-size: 16px;
  margin: 0 auto 12px;
  max-width: 560px;
}

.hero__note {
  color: var(--text-muted);
  font-size: 12px;
  margin: 0 0 32px;
}

/* ---------- 課題提起/共感 ---------- */
.empathy {
  background: var(--bg-panel);
  border-bottom: 1px solid var(--border-soft);
}

.empathy__heading {
  text-align: center;
  font-size: clamp(20px, 3.4vw, 26px);
  font-weight: 700;
  margin: 0 0 28px;
}

.empathy__body {
  text-align: center;
  color: var(--text-secondary);
  font-size: 15px;
  margin: 0 0 24px;
}

.empathy__closer {
  text-align: center;
  color: var(--hud-blue);
  font-weight: 700;
  font-size: 16px;
}

/* ---------- 特徴セクション ---------- */
.features {
  border-bottom: 1px solid var(--border-soft);
}

.features__grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 20px;
  margin-bottom: 40px;
}

.feature-card {
  background: var(--bg-panel);
  border: 1px solid var(--border-soft);
  border-radius: 6px;
  padding: 24px;
  position: relative;
}

.feature-card__num {
  display: inline-block;
  font-size: 12px;
  color: var(--hud-blue);
  letter-spacing: 0.1em;
  border: 1px solid var(--border-strong);
  border-radius: 3px;
  padding: 2px 8px;
  margin-bottom: 12px;
}

.feature-card__title {
  font-size: 17px;
  margin: 0 0 10px;
  color: var(--text-primary);
}

.feature-card__body {
  color: var(--text-secondary);
  font-size: 14px;
  margin: 0;
}

.feature-card__note {
  color: var(--text-muted);
  font-size: 11px;
  margin: 10px 0 0;
}

.highlight-block {
  background: linear-gradient(135deg, rgba(92, 184, 255, 0.1), rgba(124, 252, 154, 0.05));
  border: 1px solid var(--border-strong);
  border-radius: 6px;
  padding: 28px;
  text-align: center;
}

.highlight-block__lead {
  font-size: 18px;
  font-weight: 700;
  color: var(--hud-green);
  margin: 0 0 12px;
}

.highlight-block__body {
  color: var(--text-secondary);
  font-size: 14px;
  margin: 0;
  max-width: 560px;
  margin-inline: auto;
}

/* ---------- ゲームプレイ紹介 ---------- */
.gameplay {
  background: var(--bg-panel);
  border-bottom: 1px solid var(--border-soft);
}

.screenshot-frame {
  position: relative;
  max-width: 720px;
  margin: 0 auto;
  aspect-ratio: 16 / 9;
  background: #060a0f;
  border: 1px solid var(--border-strong);
  border-radius: 6px;
  overflow: hidden;
}

.screenshot-frame__placeholder {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 8px;
  background:
    repeating-linear-gradient(45deg, rgba(92, 184, 255, 0.05) 0 2px, transparent 2px 14px);
}

.screenshot-frame__placeholder-label {
  color: var(--hud-blue);
  font-size: 14px;
  letter-spacing: 0.15em;
  font-weight: 700;
}

.screenshot-frame__placeholder-sub {
  color: var(--text-muted);
  font-size: 12px;
  text-align: center;
  padding: 0 24px;
}

.hud-deco {
  position: absolute;
  width: 24px;
  height: 24px;
  border-color: var(--hud-cyan);
  opacity: 0.6;
}

.hud-deco--tl { top: 12px; left: 12px; border-top: 2px solid; border-left: 2px solid; }
.hud-deco--tr { top: 12px; right: 12px; border-top: 2px solid; border-right: 2px solid; }
.hud-deco--bl { bottom: 12px; left: 12px; border-bottom: 2px solid; border-left: 2px solid; }
.hud-deco--br { bottom: 12px; right: 12px; border-bottom: 2px solid; border-right: 2px solid; }

/* ---------- 機体紹介 ---------- */
.mech-type-list {
  list-style: none;
  margin: 0 0 8px;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 14px;
}

.mech-type-list__item {
  background: var(--bg-panel);
  border: 1px solid var(--border-soft);
  border-radius: 6px;
  padding: 18px 14px;
  text-align: center;
}

.mech-type-list__item p {
  color: var(--text-secondary);
  font-size: 12.5px;
  margin: 0;
}

.mech-type-list__badge {
  display: inline-block;
  color: var(--hud-amber);
  font-weight: 700;
  font-size: 13px;
  margin-bottom: 10px;
}

/* ---------- 事前登録セクション ---------- */
.pre-register {
  background: var(--bg-panel);
  border-bottom: 1px solid var(--border-soft);
}

.benefit-list {
  display: flex;
  flex-direction: column;
  gap: 14px;
  margin-bottom: 8px;
}

.benefit-list__item {
  display: flex;
  align-items: flex-start;
  gap: 14px;
  background: var(--bg-panel-alt);
  border: 1px solid var(--border-soft);
  border-radius: 6px;
  padding: 16px 18px;
}

.benefit-list__badge {
  flex: none;
  font-size: 11px;
  color: var(--hud-blue);
  border: 1px solid var(--border-strong);
  border-radius: 3px;
  padding: 4px 8px;
  white-space: nowrap;
}

.benefit-list__item p {
  margin: 0;
  color: var(--text-secondary);
  font-size: 13.5px;
}

.placeholder-value {
  color: var(--hud-amber);
  border-bottom: 1px dashed var(--hud-amber);
  padding: 0 2px;
}

/* ---------- フォーム ---------- */
.register-form {
  margin-top: 36px;
  background: var(--bg-base);
  border: 1px solid var(--border-strong);
  border-radius: 8px;
  padding: 28px;
}

.register-form__row {
  margin-bottom: 18px;
}

.register-form__label {
  display: block;
  font-size: 13px;
  color: var(--text-secondary);
  margin-bottom: 8px;
}

.register-form__input {
  width: 100%;
  padding: 12px 14px;
  background: var(--bg-panel);
  border: 1px solid var(--border-soft);
  border-radius: 4px;
  color: var(--text-primary);
  font-size: 15px;
}

.register-form__input:focus {
  outline: none;
  border-color: var(--hud-blue);
  box-shadow: 0 0 0 3px rgba(92, 184, 255, 0.18);
}

.register-form__input:invalid:not(:placeholder-shown) {
  border-color: var(--hud-red);
}

.register-form__error {
  color: var(--hud-red);
  font-size: 12px;
  margin: 8px 0 0;
}

.register-form__checks {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin-bottom: 24px;
}

.register-form__check {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  font-size: 12.5px;
  color: var(--text-secondary);
  cursor: pointer;
}

.register-form__check input {
  margin-top: 3px;
  accent-color: var(--hud-blue);
}

.inline-link {
  color: var(--hud-blue);
  text-decoration: underline;
}

.register-form__submit {
  width: 100%;
}

.register-form__result {
  margin: 16px 0 0;
  text-align: center;
  font-size: 13px;
  color: var(--hud-green);
}

.register-form__result.is-error {
  color: var(--hud-red);
}

/* ---------- ロードマップ ---------- */
.roadmap {
  border-bottom: 1px solid var(--border-soft);
}

/* ---------- FAQ ---------- */
.faq {
  background: var(--bg-panel);
  border-bottom: 1px solid var(--border-soft);
}

.faq-list {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.faq-item {
  background: var(--bg-panel-alt);
  border: 1px solid var(--border-soft);
  border-radius: 6px;
  padding: 4px 18px;
}

.faq-item__q {
  cursor: pointer;
  padding: 14px 0;
  font-size: 14.5px;
  font-weight: 600;
  color: var(--text-primary);
  list-style: none;
}

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

.faq-item__q::before {
  content: "+";
  color: var(--hud-blue);
  display: inline-block;
  width: 20px;
  font-weight: 700;
}

.faq-item[open] .faq-item__q::before {
  content: "\2212";
}

.faq-item__a {
  color: var(--text-secondary);
  font-size: 13.5px;
  margin: 0 0 16px 20px;
}

/* ---------- フッターCTA ---------- */
.footer-cta {
  text-align: center;
  border-bottom: 1px solid var(--border-soft);
}

.footer-cta__heading {
  font-size: clamp(22px, 4vw, 28px);
  font-weight: 700;
  margin: 0 0 28px;
}

.footer-cta__sns {
  margin-top: 24px;
  color: var(--text-muted);
  font-size: 13px;
}

/* ---------- フッター ---------- */
.lp-footer {
  padding: 32px 0 48px;
}

.lp-footer__copyright {
  text-align: center;
  color: var(--text-muted);
  font-size: 12px;
  margin: 0 0 12px;
}

.lp-footer__legal {
  text-align: center;
  color: var(--text-muted);
  font-size: 11px;
  margin: 0 0 12px;
  line-height: 1.6;
}

.lp-footer__links {
  text-align: center;
  font-size: 12px;
  margin: 0;
}

/* ==========================================================================
   レスポンシブ（モバイル1カラム）
   ========================================================================== */
@media (max-width: 768px) {
  .sp-only {
    display: inline;
  }

  .section-inner {
    padding: 56px 20px;
  }

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

  .mech-type-list {
    grid-template-columns: repeat(2, 1fr);
  }

  .hero {
    min-height: 92vh;
  }

  .register-form {
    padding: 20px;
  }
}

@media (max-width: 420px) {
  .mech-type-list {
    grid-template-columns: 1fr 1fr;
  }
}