/* ==========================================================================
   0. 変数定義 & リセット
   ========================================================================== */
:root {
    /* カラーパレット */
    --color-primary: #4f46e5;       /* メインのインディゴ */
    --color-primary-light: #818cf8; /* ライトインディゴ */
    --color-secondary: #0f172a;     /* ダークスレート（テキスト、背景用） */
    --color-bg-light: #f8fafc;      /* クリーンな背景用グレー */
    --color-border: #e2e8f0;        /* 境界線 */
    --color-text-dark: #0f172a;     /* 主要テキスト */
    --color-text-muted: #64748b;    /* 補助テキスト */
    --color-success: #10b981;       /* 承認・成功用の緑 */
    --color-danger: #ef4444;        /* 否認・警告用の赤 */
    
    /* タイポグラフィ */
    --font-sans: 'Inter', 'Plus Jakarta Sans', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    
    /* アニメーション */
    --transition-smooth: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: var(--font-sans);
    background-color: #ffffff;
    color: var(--color-text-dark);
    line-height: 1.6;
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
}

/* ==========================================================================
   1. 共通ユーティリティ
   ========================================================================== */
.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
}

.text-gradient {
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-light) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.badge {
    display: inline-block;
    padding: 0.25rem 0.75rem;
    background-color: rgba(79, 70, 229, 0.08);
    color: var(--color-primary);
    border-radius: 9999px;
    font-size: 0.85rem;
    font-weight: 600;
    margin-bottom: 1.5rem;
}

/* ボタン */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    font-family: var(--font-sans);
    font-weight: 600;
    border-radius: 8px;
    text-decoration: none;
    transition: var(--transition-smooth);
    cursor: pointer;
}

.btn-sm {
    padding: 0.5rem 1rem;
    font-size: 0.875rem;
}

.btn-lg {
    padding: 0.875rem 2rem;
    font-size: 1rem;
}

.btn-primary {
    background-color: var(--color-primary);
    color: #ffffff;
    border: 1px solid var(--color-primary);
}

.btn-primary:hover {
    background-color: #4338ca;
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(79, 70, 229, 0.2);
}

.btn-secondary {
    background-color: transparent;
    color: var(--color-text-dark);
    border: 1px solid transparent;
}

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

.btn-outline {
    background-color: transparent;
    color: var(--color-primary);
    border: 1px solid var(--color-primary);
}

.btn-outline:hover {
    background-color: rgba(79, 70, 229, 0.05);
    transform: translateY(-2px);
}

.btn-outline-white {
    background-color: transparent;
    color: #ffffff;
    border: 1px solid rgba(255, 255, 255, 0.4);
}

.btn-outline-white:hover {
    background-color: rgba(255, 255, 255, 0.1);
    border-color: #ffffff;
    transform: translateY(-2px);
}

/* ==========================================================================
   2. ヘッダー
   ========================================================================== */
.header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    background-color: rgba(255, 255, 255, 0.85);
    backdrop-filter: blur(8px);
    border-bottom: 1px solid var(--color-border);
    z-index: 1000;
}

.header-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem 2rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.logo {
    text-decoration: none;
}

.logo-text {
    font-family: 'Plus Jakarta Sans', sans-serif;
    font-size: 1.5rem;
    font-weight: 800;
    color: var(--color-secondary);
    letter-spacing: -0.03em;
}

.logo-accent {
    color: var(--color-primary);
}

.nav {
    display: flex;
    gap: 2rem;
}

.nav-link {
    text-decoration: none;
    color: var(--color-text-muted);
    font-size: 0.95rem;
    font-weight: 500;
    transition: var(--transition-smooth);
}

.nav-link:hover {
    color: var(--color-primary);
}

.header-actions {
    display: flex;
    gap: 0.75rem;
}

/* ==========================================================================
   3. ヒーローセクション
   ========================================================================== */
.hero {
    position: relative;
    padding-top: 10rem;
    padding-bottom: 8rem;
    background-color: #ffffff;
    overflow: hidden;
}

.hero-bg-grid {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-image: 
        radial-gradient(var(--color-border) 1px, transparent 1px),
        radial-gradient(var(--color-border) 1px, transparent 1px);
    background-size: 40px 40px;
    background-position: 0 0, 20px 20px;
    opacity: 0.4;
    pointer-events: none;
    z-index: 1;
}

.hero-container {
    position: relative;
    z-index: 2;
    display: grid;
    grid-template-columns: 1.2fr 0.8fr;
    gap: 4rem;
    align-items: center;
}

.hero-title {
    font-family: 'Plus Jakarta Sans', sans-serif;
    font-size: 3.25rem;
    font-weight: 800;
    line-height: 1.2;
    color: var(--color-secondary);
    margin-bottom: 1.5rem;
    letter-spacing: -0.02em;
}

.hero-lead {
    font-size: 1.125rem;
    color: var(--color-text-muted);
    margin-bottom: 2.5rem;
    max-width: 580px;
}

.hero-buttons {
    display: flex;
    gap: 1rem;
}

/* 網の目のビジュアル */
.mesh-network {
    width: 100%;
    max-width: 400px;
    margin: 0 auto;
}

.mesh-svg {
    width: 100%;
    height: auto;
    filter: drop-shadow(0 10px 20px rgba(79, 70, 229, 0.15));
}

.node {
    stroke: #ffffff;
    stroke-width: 3px;
    transition: var(--transition-smooth);
}

.node-buy {
    fill: var(--color-primary);
}

.node-sell {
    fill: var(--color-primary-light);
}

.node:hover {
    transform: scale(1.1);
    cursor: pointer;
}

.node-text {
    font-family: var(--font-sans);
    font-size: 10px;
    font-weight: 800;
    fill: #ffffff;
    pointer-events: none;
}

/* ==========================================================================
   4. コンセプトセクション
   ========================================================================== */
.concept-section {
    padding: 8rem 0;
    background-color: var(--color-bg-light);
    border-top: 1px solid var(--color-border);
    border-bottom: 1px solid var(--color-border);
}

.section-header {
    text-align: center;
    max-width: 700px;
    margin: 0 auto 5rem auto;
}

.section-tag {
    font-family: 'Plus Jakarta Sans', sans-serif;
    font-size: 0.875rem;
    font-weight: 700;
    color: var(--color-primary);
    text-transform: uppercase;
    letter-spacing: 0.1em;
    display: block;
    margin-bottom: 0.75rem;
}

.section-header h2 {
    font-family: 'Plus Jakarta Sans', sans-serif;
    font-size: 2.25rem;
    font-weight: 800;
    color: var(--color-secondary);
    margin-bottom: 1rem;
    letter-spacing: -0.01em;
}

.section-header p {
    color: var(--color-text-muted);
    font-size: 1.05rem;
}

.concept-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 2rem;
}

.concept-card {
    background-color: #ffffff;
    padding: 3rem 2rem;
    border-radius: 12px;
    border: 1px solid var(--color-border);
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.05);
    transition: var(--transition-smooth);
}

.concept-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.05), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    border-color: var(--color-primary-light);
}

.concept-icon {
    width: 48px;
    height: 48px;
    color: var(--color-primary);
    margin-bottom: 1.5rem;
}

.concept-card h3 {
    font-size: 1.25rem;
    font-weight: 700;
    margin-bottom: 1rem;
}

.concept-card p {
    color: var(--color-text-muted);
    font-size: 0.95rem;
    line-height: 1.6;
}

/* ==========================================================================
   5. 特徴・仕様セクション
   ========================================================================== */
.features-section {
    padding: 8rem 0;
    background-color: #ffffff;
}

.features-list {
    display: flex;
    flex-direction: column;
    gap: 8rem;
    margin-top: 4rem;
}

.feature-item {
    display: grid;
    grid-template-columns: 1.1fr 0.9fr;
    gap: 5rem;
    align-items: center;
}

.feature-item.reverse {
    grid-template-columns: 0.9fr 1.1fr;
}

.feature-item.reverse .feature-content {
    grid-column: 2;
}

.feature-item.reverse .feature-preview {
    grid-column: 1;
    grid-row: 1;
}

.feature-content h3 {
    font-family: 'Plus Jakarta Sans', sans-serif;
    font-size: 1.75rem;
    font-weight: 700;
    margin-bottom: 1rem;
}

.feature-content p {
    color: var(--color-text-muted);
    font-size: 1.05rem;
    margin-bottom: 2rem;
}

.feature-bullets {
    list-style: none;
}

.feature-bullets li {
    position: relative;
    padding-left: 1.75rem;
    margin-bottom: 1rem;
    font-size: 0.95rem;
    color: var(--color-text-dark);
}

.feature-bullets li::before {
    content: "✓";
    position: absolute;
    left: 0;
    top: -2px;
    color: var(--color-primary);
    font-weight: bold;
    font-size: 1.1rem;
}

/* UIモックアップ表現（CSSのみ） */
.ui-mockup {
    background-color: #ffffff;
    border: 1px solid var(--color-border);
    border-radius: 12px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.05);
    overflow: hidden;
}

.mockup-header {
    background-color: var(--color-bg-light);
    padding: 0.75rem 1rem;
    border-bottom: 1px solid var(--color-border);
    display: flex;
    gap: 0.5rem;
}

.mockup-dot {
    width: 8px;
    height: 8px;
    background-color: #cbd5e1;
    border-radius: 50%;
}

.mockup-body {
    padding: 1.5rem;
}

.mockup-title {
    font-weight: 700;
    font-size: 0.9rem;
    margin-bottom: 1rem;
    color: var(--color-text-dark);
}

.mockup-form-group {
    background-color: var(--color-bg-light);
    padding: 1rem;
    border-radius: 6px;
    margin-bottom: 1.5rem;
}

.mockup-form-group label {
    display: block;
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--color-text-muted);
    margin-bottom: 0.5rem;
}

.mockup-checkbox {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.85rem;
    font-weight: 500;
    margin-bottom: 0.5rem;
}

.mockup-checkbox .checked {
    width: 12px;
    height: 12px;
    background-color: var(--color-primary);
    border-radius: 2px;
    display: inline-block;
}

.mockup-flow {
    display: flex;
    align-items: center;
    justify-content: space-between;
    font-size: 0.75rem;
    font-weight: 600;
}

.mockup-flow .step {
    padding: 0.25rem 0.5rem;
    background-color: var(--color-bg-light);
    border-radius: 4px;
    color: var(--color-text-muted);
}

.mockup-flow .step.active {
    background-color: var(--color-primary);
    color: #ffffff;
}

.mockup-flow .arrow {
    color: #cbd5e1;
}

/* トグルボックス（招待機能のプレビュー用） */
.status-toggle-box {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 1rem;
    background-color: var(--color-bg-light);
    border-radius: 6px;
    margin-bottom: 1rem;
}

.status-toggle-box .label {
    font-size: 0.85rem;
    font-weight: 500;
}

.status-badge {
    font-size: 0.75rem;
    padding: 0.25rem 0.75rem;
    border-radius: 9999px;
    font-weight: 600;
}

.status-badge.active {
    background-color: rgba(16, 185, 129, 0.1);
    color: var(--color-success);
}

.mockup-hint {
    font-size: 0.7rem;
    color: var(--color-text-muted);
    line-height: 1.4;
}

/* ==========================================================================
   6. CTAセクション
   ========================================================================== */
.cta-section {
    padding: 8rem 0;
    background-color: var(--color-secondary);
    color: #ffffff;
    text-align: center;
    position: relative;
    overflow: hidden;
}

.cta-container {
    position: relative;
    z-index: 2;
    max-width: 800px;
}

.cta-section h2 {
    font-family: 'Plus Jakarta Sans', sans-serif;
    font-size: 2.75rem;
    font-weight: 800;
    margin-bottom: 1.5rem;
    letter-spacing: -0.01em;
}

.cta-section p {
    color: #94a3b8;
    font-size: 1.15rem;
    margin-bottom: 3rem;
}

.cta-buttons {
    display: flex;
    justify-content: center;
    gap: 1.5rem;
}

/* ==========================================================================
   7. フッター
   ========================================================================== */
.footer {
    background-color: #ffffff;
    border-top: 1px solid var(--color-border);
    padding: 4rem 0 3rem 0;
}

.footer-container {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 2rem;
}

.footer-brand {
    text-align: center;
}

.footer-brand p {
    color: var(--color-text-muted);
    font-size: 0.9rem;
    margin-top: 0.5rem;
}

.footer-bottom {
    border-top: 1px solid var(--color-border);
    width: 100%;
    padding-top: 2rem;
    text-align: center;
}

.footer-bottom p {
    font-size: 0.85rem;
    color: var(--color-text-muted);
}

/* ==========================================================================
   8. レスポンシブ対応 (メディアクエリ)
   ========================================================================== */
@media (max-width: 992px) {
    .hero-container {
        grid-template-columns: 1fr;
        text-align: center;
        gap: 3rem;
    }
    .hero-title {
        font-size: 2.5rem;
    }
    .hero-lead {
        margin-left: auto;
        margin-right: auto;
    }
    .hero-buttons {
        justify-content: center;
    }
    .mesh-network {
        max-width: 320px;
    }
    .concept-grid {
        grid-template-columns: 1fr;
    }
    .feature-item, .feature-item.reverse {
        grid-template-columns: 1fr;
        gap: 3rem;
    }
    .feature-item.reverse .feature-content {
        grid-column: auto;
    }
    .feature-item.reverse .feature-preview {
        grid-column: auto;
        grid-row: auto;
    }
}

@media (max-width: 768px) {
    .header-container {
        flex-direction: column;
        gap: 1rem;
    }
    .nav {
        gap: 1rem;
    }
    .cta-buttons {
        flex-direction: column;
        align-items: center;
        gap: 1rem;
    }
    .cta-buttons .btn {
        width: 100%;
        max-width: 300px;
    }
}

/* ==========================================================================
   9. フォーム・アカウント登録画面用スタイル
   ========================================================================== */
.register-section {
    padding-top: 10rem;
    padding-bottom: 8rem;
    background-color: var(--color-bg-light);
    min-height: 100vh;
    display: flex;
    align-items: center;
}

.form-wrapper {
    background-color: #ffffff;
    border: 1px solid var(--color-border);
    border-radius: 16px;
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.05);
    padding: 3rem;
    max-width: 800px;
    width: 100%;
    margin: 0 auto;
}

.form-title {
    font-family: 'Plus Jakarta Sans', sans-serif;
    font-size: 2rem;
    font-weight: 800;
    text-align: center;
    margin-bottom: 2.5rem;
    color: var(--color-secondary);
}

/* ステップインジケータ */
.step-bar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    position: relative;
    max-width: 500px;
    margin: 0 auto 3.5rem auto;
}

.step-bar::before {
    content: "";
    position: absolute;
    top: 20px;
    left: 0;
    right: 0;
    height: 3px;
    background-color: var(--color-border);
    z-index: 1;
}

.step-bar-progress {
    position: absolute;
    top: 20px;
    left: 0;
    height: 3px;
    background-color: var(--color-primary);
    z-index: 1;
    transition: var(--transition-smooth);
}

/* 各ステップの幅比率 */
.step-bar.step-1 .step-bar-progress { width: 0%; }
.step-bar.step-2 .step-bar-progress { width: 50%; }
.step-bar.step-3 .step-bar-progress { width: 100%; }

.step-node {
    position: relative;
    z-index: 2;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.5rem;
}

.step-circle {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    background-color: #ffffff;
    border: 3px solid var(--color-border);
    color: var(--color-text-muted);
    font-weight: 700;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.95rem;
    transition: var(--transition-smooth);
}

.step-node.active .step-circle {
    border-color: var(--color-primary);
    background-color: var(--color-primary);
    color: #ffffff;
    box-shadow: 0 4px 10px rgba(79, 70, 229, 0.2);
}

.step-node.completed .step-circle {
    border-color: var(--color-primary);
    background-color: #ffffff;
    color: var(--color-primary);
}

.step-label {
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--color-text-muted);
    transition: var(--transition-smooth);
}

.step-node.active .step-label {
    color: var(--color-primary);
}

.step-node.completed .step-label {
    color: var(--color-text-dark);
}

/* フォームグループ */
.form-group {
    margin-bottom: 2rem;
}

.form-label {
    display: block;
    font-weight: 700;
    font-size: 0.95rem;
    margin-bottom: 0.75rem;
    color: var(--color-text-dark);
}

.form-required {
    display: inline-block;
    padding: 0.15rem 0.4rem;
    background-color: var(--color-danger);
    color: #ffffff;
    font-size: 0.75rem;
    font-weight: 700;
    border-radius: 4px;
    margin-left: 0.5rem;
    vertical-align: middle;
}

.form-control {
    width: 100%;
    padding: 0.875rem 1.25rem;
    border: 1px solid var(--color-border);
    border-radius: 8px;
    font-family: var(--font-sans);
    font-size: 1rem;
    color: var(--color-text-dark);
    transition: var(--transition-smooth);
    background-color: #ffffff;
}

.form-control:focus {
    outline: none;
    border-color: var(--color-primary-light);
    box-shadow: 0 0 0 4px rgba(79, 70, 229, 0.1);
}

.form-control::placeholder {
    color: #94a3b8;
}

.form-select {
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' fill='none' viewBox='0 0 24 24' stroke='%2364748b'%3E%3Cpath stroke-linecap='round' stroke-linejoin='round' stroke-width='2' d='M19 9l-7 7-7-7'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 1.25rem center;
    background-size: 1.25rem;
    padding-right: 3rem;
}

.form-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1.5rem;
}

@media (max-width: 768px) {
    .form-row {
        grid-template-columns: 1fr;
        gap: 0;
    }
}

/* チェックボックスとラジオボタンのカスタムデザイン */
.form-check-group {
    display: flex;
    gap: 1.5rem;
    margin-top: 0.5rem;
}

.form-check-label {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    cursor: pointer;
    font-weight: 500;
    font-size: 0.95rem;
}

.form-check-input {
    width: 1.2rem;
    height: 1.2rem;
    border: 2px solid var(--color-border);
    border-radius: 4px;
    accent-color: var(--color-primary);
    cursor: pointer;
}

.form-check-input[type="radio"] {
    border-radius: 50%;
}

.form-hint {
    font-size: 0.85rem;
    color: var(--color-text-muted);
    margin-top: 0.5rem;
}

/* 利用規約同意用エリア */
.terms-box {
    background-color: var(--color-bg-light);
    border: 1px solid var(--color-border);
    border-radius: 8px;
    padding: 1.5rem;
    height: 150px;
    overflow-y: scroll;
    font-size: 0.85rem;
    color: var(--color-text-muted);
    margin-bottom: 1.5rem;
}

/* 確認画面表示テーブル */
.confirm-table {
    width: 100%;
    border-collapse: collapse;
    margin-bottom: 3rem;
}

.confirm-table th,
.confirm-table td {
    padding: 1.25rem 1.5rem;
    border-bottom: 1px solid var(--color-border);
    text-align: left;
    font-size: 0.95rem;
}

.confirm-table th {
    width: 30%;
    color: var(--color-text-muted);
    font-weight: 600;
}

.confirm-table td {
    width: 70%;
    color: var(--color-text-dark);
    font-weight: 500;
}

@media (max-width: 576px) {
    .confirm-table th,
    .confirm-table td {
        display: block;
        width: 100%;
        padding: 0.75rem 0.5rem;
    }
    .confirm-table th {
        border-bottom: none;
        padding-bottom: 0.25rem;
    }
}

/* ボタン配置 */
.form-buttons {
    display: flex;
    justify-content: center;
    gap: 1.5rem;
    margin-top: 3rem;
}

.form-buttons .btn {
    min-width: 180px;
}

@media (max-width: 576px) {
    .form-buttons {
        flex-direction: column;
        align-items: stretch;
    }
    .form-buttons .btn {
        width: 100%;
    }
}

/* 完了画面 */
.complete-content {
    text-align: center;
    padding: 2rem 0;
}

.complete-icon {
    width: 80px;
    height: 80px;
    background-color: rgba(16, 185, 129, 0.1);
    color: var(--color-success);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 2rem auto;
}

.complete-icon svg {
    width: 40px;
    height: 40px;
}

.complete-title {
    font-size: 1.75rem;
    font-weight: 800;
    margin-bottom: 1.5rem;
    color: var(--color-secondary);
}

.complete-text {
    color: var(--color-text-muted);
    margin-bottom: 3rem;
    line-height: 1.8;
}

/* エラーメッセージ */
.error-text {
    color: var(--color-danger);
    font-size: 0.85rem;
    font-weight: 600;
    margin-top: 0.5rem;
    display: none;
}

.form-control.is-invalid {
    border-color: var(--color-danger);
    box-shadow: 0 0 0 4px rgba(239, 68, 68, 0.1);
}