/* リセットとベーススタイル */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary-color: #ffc107;
    --primary-dark: #ff9800;
    --secondary-color: #666;
    --text-color: #1a1a1a;
    --background-color: #fafafa;
    --card-background: #fff;
    --border-color: #e0e0e0;
    --success-color: #4caf50;
    --error-color: #f44336;
    --warning-color: #ff9800;
    --shadow-light: 0 2px 8px rgba(0, 0, 0, 0.08);
    --shadow-medium: 0 4px 16px rgba(0, 0, 0, 0.12);
    --border-radius: 12px;
    --transition: all 0.2s ease;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background: var(--background-color);
    color: var(--text-color);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* ローディングスクリーン */
.loading-screen {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: var(--background-color);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 9999;
    opacity: 1;
    visibility: visible;
    transition: all 0.3s ease;
}

.loading-screen.hidden {
    opacity: 0;
    visibility: hidden;
}

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

.loading-icon {
    width: 80px;
    height: 80px;
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2.5rem;
    font-weight: bold;
    color: #fff;
    margin: 0 auto 1rem;
    animation: pulse 2s infinite;
}

.loading-text {
    font-size: 1.1rem;
    color: var(--secondary-color);
    font-weight: 500;
}

@keyframes pulse {
    0% { transform: scale(1); }
    50% { transform: scale(1.05); }
    100% { transform: scale(1); }
}

/* アプリケーション全体のコンテナ */
#app {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* ヘッダー */
.app-header {
    background: var(--card-background);
    padding: 1rem 0;
    box-shadow: var(--shadow-light);
    position: sticky;
    top: 0;
    z-index: 100;
}

.header-content {
    max-width: 800px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 1.5rem;
}

.header-left, .header-right {
    width: 60px;
}

.header-center {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.5rem;
}

.app-icon {
    width: 64px;
    height: 64px;
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2rem;
    font-weight: bold;
    color: #fff;
    box-shadow: 0 4px 12px rgba(255, 193, 7, 0.3);
}

.app-title {
    font-size: 1.3rem;
    font-weight: bold;
    color: var(--text-color);
}

.app-subtitle {
    font-size: 0.9rem;
    color: var(--secondary-color);
    margin: 0;
}

.tutorial-button, .menu-button {
    background: none;
    border: none;
    padding: 0.75rem;
    cursor: pointer;
    border-radius: 50%;
    transition: var(--transition);
    position: relative;
}

.tutorial-button:hover, .menu-button:hover {
    background: rgba(255, 193, 7, 0.1);
}

.tutorial-icon, .menu-icon {
    font-size: 1.5rem;
    color: rgba(255, 193, 7, 0.8);
    font-weight: bold;
}

.tutorial-icon {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 24px;
    height: 24px;
    background: var(--primary-color);
    color: #fff;
    border-radius: 50%;
    font-size: 1rem;
}

/* ドロップダウンメニュー */
.dropdown-menu {
    position: absolute;
    top: 100%;
    right: 0;
    background: var(--card-background);
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-medium);
    min-width: 200px;
    opacity: 0;
    visibility: hidden;
    transform: translateY(-10px);
    transition: var(--transition);
    z-index: 1000;
}

.dropdown-menu.show {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.menu-item {
    width: 100%;
    padding: 0.875rem 1rem;
    border: none;
    background: none;
    text-align: left;
    cursor: pointer;
    transition: background-color 0.2s ease;
    display: flex;
    align-items: center;
    gap: 0.75rem;
    font-size: 0.95rem;
    color: var(--text-color);
}

.menu-item:hover {
    background: rgba(255, 193, 7, 0.1);
}

.menu-item:first-child {
    border-radius: var(--border-radius) var(--border-radius) 0 0;
}

.menu-item:last-child {
    border-radius: 0 0 var(--border-radius) var(--border-radius);
}

/* 広告バナー */
.ad-banner {
    max-width: 800px;
    margin: 1rem auto;
    padding: 0 1.5rem;
    text-align: center;
}

.ad-banner-top {
    margin-top: 0;
}

.ad-banner-middle {
    margin: 2rem auto;
}

.ad-banner ins {
    display: block;
    min-height: 90px;
    background: #f5f5f5;
    border-radius: var(--border-radius);
    border: 1px solid var(--border-color);
}

/* メインコンテンツ */
.main-content {
    flex: 1;
    max-width: 800px;
    margin: 0 auto;
    padding: 2rem 1.5rem;
    width: 100%;
}

/* 変換セクション */
.converter-section {
    margin-bottom: 3rem;
}

.section-header {
    text-align: center;
    margin-bottom: 2rem;
}

.section-title {
    font-size: 1.6rem;
    font-weight: bold;
    color: var(--text-color);
    margin-bottom: 0.5rem;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.75rem;
}

.section-icon {
    font-size: 1.4rem;
}

.section-description {
    color: var(--secondary-color);
    font-size: 1rem;
    margin: 0;
}

/* 変換カード */
.converter-card {
    background: var(--card-background);
    border-radius: var(--border-radius);
    padding: 2rem;
    box-shadow: var(--shadow-light);
    border: 1px solid var(--border-color);
    transition: var(--transition);
}

.converter-card:hover {
    box-shadow: var(--shadow-medium);
}

/* 入力グループ */
.input-group {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
    margin-bottom: 2rem;
}

.input-wrapper, .select-wrapper {
    position: relative;
}

.input-label {
    position: absolute;
    top: -0.5rem;
    left: 0.75rem;
    background: var(--card-background);
    padding: 0 0.5rem;
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--primary-color);
    z-index: 10;
}

.converter-input, .unit-select {
    width: 100%;
    padding: 1rem;
    border: 2px solid var(--border-color);
    border-radius: var(--border-radius);
    font-size: 1rem;
    transition: var(--transition);
    background: var(--background-color);
}

.converter-input:focus, .unit-select:focus {
    outline: none;
    border-color: var(--primary-color);
    background: var(--card-background);
    box-shadow: 0 0 0 3px rgba(255, 193, 7, 0.1);
}

.unit-select {
    cursor: pointer;
}

/* 結果セクション */
.result-section {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-bottom: 1rem;
}

.result-display {
    flex: 1;
    padding: 1.25rem;
    background: linear-gradient(135deg, #fff9c4, #fff3e0);
    border: 2px solid var(--primary-color);
    border-radius: var(--border-radius);
    font-size: 1.2rem;
    font-weight: 600;
    color: #e65100;
    min-height: 3.5rem;
    display: flex;
    align-items: center;
    transition: var(--transition);
}

.result-display.empty {
    color: var(--secondary-color);
    font-weight: normal;
    border-color: var(--border-color);
    background: #f5f5f5;
}

.result-placeholder {
    opacity: 0.7;
}

.copy-button {
    padding: 1rem 1.5rem;
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    color: #fff;
    border: none;
    border-radius: var(--border-radius);
    cursor: pointer;
    font-size: 0.95rem;
    font-weight: 600;
    transition: var(--transition);
    display: flex;
    align-items: center;
    gap: 0.5rem;
    min-width: 110px;
    justify-content: center;
}

.copy-button:hover:not(:disabled) {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(255, 193, 7, 0.3);
}

.copy-button:active:not(:disabled) {
    transform: translateY(0);
}

.copy-button:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none;
}

.copy-icon {
    font-size: 1rem;
}

/* 例文セクション */
.example-section {
    text-align: center;
    padding-top: 1rem;
    border-top: 1px solid var(--border-color);
}

.example-text {
    font-size: 0.9rem;
    color: var(--secondary-color);
    font-style: italic;
    margin: 0;
}

/* 使用例セクション */
.examples-section {
    margin: 3rem 0;
    text-align: center;
}

.examples-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1.5rem;
    margin-top: 2rem;
}

.example-card {
    background: var(--card-background);
    padding: 1.5rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-light);
    border: 1px solid var(--border-color);
    transition: var(--transition);
}

.example-card:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-medium);
}

.example-icon {
    font-size: 2rem;
    margin-bottom: 1rem;
}

.example-title {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--text-color);
    margin-bottom: 0.5rem;
}

.example-desc {
    font-size: 0.9rem;
    color: var(--secondary-color);
    margin: 0;
}

/* フッター */
.app-footer {
    background: var(--card-background);
    border-top: 1px solid var(--border-color);
    margin-top: 4rem;
    padding: 3rem 0 1.5rem;
    position: relative;
    z-index: 1;
    width: 100%;
    clear: both;
}

.footer-content {
    max-width: 800px;
    margin: 0 auto;
    padding: 0 1.5rem;
    display: grid;
    grid-template-columns: 1fr 2fr;
    gap: 3rem;
}

.footer-section {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.footer-logo {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-bottom: 0.5rem;
}

.footer-icon {
    width: 40px;
    height: 40px;
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.2rem;
    font-weight: bold;
    color: #fff;
}

.footer-title {
    font-size: 1.2rem;
    font-weight: bold;
    color: var(--text-color);
}

.footer-description {
    font-size: 0.9rem;
    color: var(--secondary-color);
    line-height: 1.6;
    margin: 0;
}

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

.footer-column-title {
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-color);
    margin-bottom: 0.75rem;
}

.footer-link-list {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.footer-link-list a {
    color: var(--secondary-color);
    text-decoration: none;
    font-size: 0.9rem;
    transition: var(--transition);
}

.footer-link-list a:hover {
    color: var(--primary-color);
}

.footer-bottom {
    max-width: 800px;
    margin: 0 auto;
    padding: 2rem 1.5rem 0;
    border-top: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.footer-copyright {
    font-size: 0.8rem;
    color: var(--secondary-color);
    margin: 0;
}

.footer-social {
    display: flex;
    gap: 1rem;
}

.footer-social a {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
    border-radius: 50%;
    background: var(--background-color);
    color: var(--secondary-color);
    text-decoration: none;
    transition: var(--transition);
}

.footer-social a:hover {
    background: var(--primary-color);
    color: #fff;
}

.social-icon {
    font-size: 1.2rem;
}

/* オンボーディングモーダル */
.onboarding-overlay {
    background: rgba(0, 0, 0, 0.8);
}

.onboarding-content {
    max-width: 600px;
    width: 100%;
    max-height: 90vh;
    padding: 0;
    overflow: hidden;
}

.onboarding-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1.5rem;
    border-bottom: 1px solid var(--border-color);
}

.skip-button {
    background: none;
    border: none;
    color: var(--secondary-color);
    font-size: 0.95rem;
    font-weight: 500;
    cursor: pointer;
    padding: 0.5rem;
    border-radius: 6px;
    transition: var(--transition);
}

.skip-button:hover {
    background: var(--background-color);
    color: var(--text-color);
}

.progress-container {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.progress-bar {
    width: 120px;
    height: 4px;
    background: var(--border-color);
    border-radius: 2px;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--primary-color), var(--primary-dark));
    width: 25%;
    transition: width 0.3s ease;
}

.progress-text {
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--secondary-color);
    min-width: 40px;
}

.onboarding-body {
    padding: 2rem;
    min-height: 400px;
    position: relative;
    overflow-y: auto;
    max-height: 500px;
}

.onboarding-step {
    display: none;
    text-align: center;
    animation: fadeIn 0.3s ease;
}

.onboarding-step.active {
    display: block;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

.step-icon {
    font-size: 4rem;
    margin-bottom: 1.5rem;
    display: inline-block;
}

.welcome-icon {
    width: 80px;
    height: 80px;
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2.5rem;
    font-weight: bold;
    color: #fff;
    margin: 0 auto 1.5rem;
}

.step-title {
    font-size: 1.8rem;
    font-weight: bold;
    color: var(--text-color);
    margin-bottom: 1rem;
}

.step-description {
    font-size: 1.1rem;
    color: var(--secondary-color);
    line-height: 1.6;
    margin-bottom: 2rem;
}

.step-illustration {
    margin: 2rem 0;
}

.demo-conversion {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 1rem;
    padding: 1.5rem;
    background: var(--background-color);
    border-radius: var(--border-radius);
    font-size: 1.2rem;
    font-weight: 600;
}

.demo-input {
    color: var(--primary-color);
}

.demo-unit {
    color: var(--text-color);
}

.demo-arrow {
    color: var(--secondary-color);
    font-size: 1.5rem;
}

.demo-result {
    color: var(--primary-dark);
}

.demo-ui {
    background: var(--card-background);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    padding: 1.5rem;
    box-shadow: var(--shadow-light);
}

.demo-input-group {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
    margin-bottom: 1rem;
}

.demo-field {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.demo-field label {
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--primary-color);
}

.demo-field input, .demo-field select {
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    font-size: 0.9rem;
}

.demo-result-display {
    padding: 1rem;
    background: linear-gradient(135deg, #fff9c4, #fff3e0);
    border: 2px solid var(--primary-color);
    border-radius: 6px;
    font-size: 1.1rem;
    font-weight: 600;
    color: #e65100;
    text-align: center;
}

.step-points {
    text-align: left;
    max-width: 400px;
    margin: 0 auto;
}

.point {
    padding: 0.5rem 0;
    font-size: 1rem;
    color: var(--text-color);
}

.demo-reverse {
    background: var(--background-color);
    padding: 2rem;
    border-radius: var(--border-radius);
}

.demo-input-example {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 1rem;
    font-size: 1.2rem;
    font-weight: 600;
}

.demo-amount {
    color: var(--text-color);
}

.demo-converted {
    color: var(--primary-color);
}

.step-note {
    font-size: 0.95rem;
    color: var(--secondary-color);
    font-style: italic;
    margin-top: 1rem;
}

.features-grid {
    display: grid;
    gap: 1rem;
    margin: 1.5rem 0;
    text-align: left;
}

.feature-item {
    display: flex;
    align-items: flex-start;
    gap: 1rem;
    padding: 1rem;
    background: var(--background-color);
    border-radius: var(--border-radius);
}

.feature-icon {
    font-size: 1.5rem;
    min-width: 40px;
}

.feature-content h4 {
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-color);
    margin-bottom: 0.25rem;
}

.feature-content p {
    font-size: 0.9rem;
    color: var(--secondary-color);
    margin: 0;
    line-height: 1.4;
}

.step-final {
    margin-top: 2rem;
    text-align: center;
}

.step-final h3 {
    font-size: 1.4rem;
    font-weight: bold;
    color: var(--primary-color);
    margin-bottom: 0.5rem;
}

.step-final p {
    font-size: 1rem;
    color: var(--secondary-color);
    margin: 0;
}

.onboarding-navigation {
    display: flex;
    gap: 1rem;
    padding: 1.5rem;
    border-top: 1px solid var(--border-color);
    background: var(--background-color);
}

.nav-button {
    flex: 1;
    padding: 1rem;
    border: none;
    border-radius: var(--border-radius);
    cursor: pointer;
    font-size: 0.95rem;
    font-weight: 600;
    transition: var(--transition);
}

.prev-button {
    background: var(--card-background);
    color: var(--secondary-color);
    border: 1px solid var(--border-color);
}

.prev-button:hover:not(:disabled) {
    background: var(--background-color);
    color: var(--text-color);
}

.prev-button:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.next-button, .start-button {
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    color: #fff;
}

.next-button:hover, .start-button:hover {
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(255, 193, 7, 0.3);
}

/* モーダル共通スタイル */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.5);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s ease;
    padding: 1rem;
}

.modal-overlay.show {
    opacity: 1;
    visibility: visible;
}

.modal-content {
    background: var(--card-background);
    border-radius: var(--border-radius);
    max-width: 600px;
    width: 100%;
    max-height: 80vh;
    overflow: hidden;
    transform: scale(0.9);
    transition: transform 0.3s ease;
}

.modal-overlay.show .modal-content {
    transform: scale(1);
}

.modal-header {
    padding: 1.5rem;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.modal-title {
    font-size: 1.3rem;
    font-weight: bold;
    color: var(--text-color);
}

.close-button {
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    padding: 0.25rem;
    color: var(--secondary-color);
    transition: color 0.2s ease;
}

.close-button:hover {
    color: var(--text-color);
}

.modal-body {
    padding: 1.5rem;
    max-height: 60vh;
    overflow-y: auto;
}

/* 履歴モーダル */
.history-actions {
    margin-bottom: 1rem;
    text-align: right;
}

.clear-history-button {
    padding: 0.5rem 1rem;
    background: var(--error-color);
    color: #fff;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    font-size: 0.9rem;
    transition: background-color 0.2s ease;
}

.clear-history-button:hover {
    background: #d32f2f;
}

.history-list {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.history-item {
    padding: 1rem;
    background: var(--background-color);
    border-radius: var(--border-radius);
    border: 1px solid var(--border-color);
}

.history-item-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 0.5rem;
}

.conversion-type {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.8rem;
    color: var(--secondary-color);
    font-weight: 600;
}

.history-time {
    font-size: 0.8rem;
    color: var(--secondary-color);
}

.history-conversion {
    font-size: 0.95rem;
    color: var(--text-color);
    font-weight: 500;
}

.empty-state {
    text-align: center;
    color: var(--secondary-color);
    padding: 2rem;
}

/* 設定モーダル */
.settings-group {
    margin-bottom: 2rem;
}

.settings-title {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--text-color);
    margin-bottom: 1rem;
}

.radio-group {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.radio-option {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    cursor: pointer;
    padding: 0.75rem;
    border-radius: 6px;
    transition: background-color 0.2s ease;
}

.radio-option:hover {
    background: var(--background-color);
}

.radio-option input[type="radio"] {
    margin: 0;
    accent-color: var(--primary-color);
}

.radio-label {
    font-size: 0.9rem;
    color: var(--text-color);
}

/* ヘルプモーダル */
.help-content {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.help-section h4 {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--text-color);
    margin-bottom: 0.5rem;
}

.help-section p {
    font-size: 0.9rem;
    color: var(--secondary-color);
    line-height: 1.5;
    margin-bottom: 0.5rem;
}

.help-example {
    font-family: monospace;
    background: var(--background-color);
    padding: 0.5rem;
    border-radius: 4px;
    border-left: 3px solid var(--primary-color);
    font-size: 0.85rem;
}

.help-shortcuts {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.help-shortcuts li {
    display: flex;
    align-items: center;
    gap: 1rem;
    font-size: 0.9rem;
    color: var(--secondary-color);
}

kbd {
    background: var(--background-color);
    border: 1px solid var(--border-color);
    border-radius: 4px;
    padding: 0.25rem 0.5rem;
    font-size: 0.8rem;
    font-family: monospace;
    color: var(--text-color);
}

/* アバウトモーダル */
.about-content {
    display: flex;
    flex-direction: column;
    gap: 2rem;
    text-align: center;
}

.about-header .about-icon {
    width: 80px;
    height: 80px;
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2.5rem;
    font-weight: bold;
    color: #fff;
    margin: 0 auto 1rem;
}

.about-header h2 {
    font-size: 2rem;
    font-weight: bold;
    color: var(--text-color);
    margin-bottom: 0.5rem;
}

.version {
    font-size: 0.9rem;
    color: var(--secondary-color);
    font-weight: 500;
}

.about-description p {
    font-size: 1rem;
    color: var(--secondary-color);
    line-height: 1.6;
    text-align: left;
}

.about-features, .about-company {
    text-align: left;
}

.about-features h4, .about-company h4 {
    font-size: 1.2rem;
    font-weight: 600;
    color: var(--text-color);
    margin-bottom: 1rem;
}

.about-features ul {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.about-features li {
    position: relative;
    padding-left: 1.5rem;
    color: var(--secondary-color);
    font-size: 0.95rem;
}

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

.about-company p {
    margin-bottom: 1rem;
}

.company-links {
    display: flex;
    gap: 1rem;
    justify-content: flex-start;
}

.company-links a {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 500;
    transition: color 0.2s ease;
}

.company-links a:hover {
    color: var(--primary-dark);
    text-decoration: underline;
}

/* アラート */
.alert-overlay {
    position: fixed;
    top: 2rem;
    right: 2rem;
    z-index: 2000;
    opacity: 0;
    visibility: hidden;
    transform: translateX(100px);
    transition: all 0.3s ease;
}

.alert-overlay.show {
    opacity: 1;
    visibility: visible;
    transform: translateX(0);
}

.alert-content {
    background: var(--success-color);
    color: #fff;
    padding: 1rem 1.5rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-medium);
    display: flex;
    align-items: center;
    gap: 0.75rem;
    font-size: 0.95rem;
    font-weight: 500;
}

.alert-icon {
    font-size: 1.2rem;
}

/* レスポンシブデザイン */
@media (max-width: 768px) {
    .main-content {
        padding: 1.5rem 1rem;
    }
    
    .converter-card {
        padding: 1.5rem;
    }
    
    .input-group {
        grid-template-columns: 1fr;
        gap: 1rem;
    }
    
    .result-section {
        flex-direction: column;
        gap: 1rem;
    }
    
    .copy-button {
        width: 100%;
    }
    
    .examples-grid {
        grid-template-columns: 1fr;
    }
    
    .footer-content {
        grid-template-columns: 1fr;
        gap: 2rem;
        text-align: center;
    }
    
    .footer-links {
        grid-template-columns: 1fr;
        gap: 1.5rem;
    }
    
    .footer-bottom {
        flex-direction: column;
        gap: 1rem;
        text-align: center;
    }
    
    .modal-overlay {
        padding: 0.5rem;
    }
    
    .modal-body {
        max-height: 70vh;
    }
    
    .onboarding-body {
        padding: 1.5rem;
    }
    
    .demo-input-group {
        grid-template-columns: 1fr;
    }
    
    .alert-overlay {
        top: 1rem;
        right: 1rem;
        left: 1rem;
    }
}

@media (max-width: 480px) {
    .header-content {
        padding: 0 1rem;
    }
    
    .app-icon {
        width: 56px;
        height: 56px;
        font-size: 1.8rem;
    }
    
    .app-title {
        font-size: 1.2rem;
    }
    
    .section-title {
        font-size: 1.4rem;
    }
    
    .converter-input,
    .unit-select {
        padding: 0.875rem;
        font-size: 0.95rem;
    }
    
    .step-title {
        font-size: 1.5rem;
    }
    
    .onboarding-navigation {
        flex-direction: column;
    }
}