/* ====================================
   画像・動画圧縮ツール v3.0 - スタイルシート
   FFmpeg.wasm統合版 - 日本人向けシンプル＆信頼性重視デザイン
   ==================================== */

/* ---- CSS Reset & Base ---- */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

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

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Hiragino Kaku Gothic ProN', 'Hiragino Sans', Meiryo, sans-serif;
    line-height: 1.6;
    color: #333333;
    background-color: #f8f9fa;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* ---- Container ---- */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* ---- Header ---- */
.header {
    background: linear-gradient(135deg, #ffffff 0%, #f8f9fa 100%);
    border-bottom: 1px solid #e9ecef;
    padding: 24px 0;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
}

.header-content {
    display: flex;
    align-items: center;
    justify-content: space-between;
    flex-wrap: wrap;
    gap: 16px;
}

.logo-section {
    display: flex;
    align-items: center;
    gap: 16px;
}

.logo-icon {
    color: #3b82f6;
    flex-shrink: 0;
}

.logo-text h1 {
    font-size: 1.75rem;
    font-weight: 700;
    color: #1f2937;
    margin-bottom: 4px;
    letter-spacing: -0.025em;
}

.logo-text p {
    font-size: 0.875rem;
    color: #6b7280;
    font-weight: 500;
}

/* ---- Navigation Menu (日本的なWebサイトスタンダード) ---- */
.main-navigation {
    display: flex;
    align-items: center;
}

.nav-menu {
    display: flex;
    align-items: center;
    gap: 8px;
    list-style: none;
    margin: 0;
    padding: 0;
}

.nav-item {
    display: flex;
    align-items: center;
}

.nav-link {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 10px 16px;
    border-radius: 8px;
    text-decoration: none;
    color: #374151;
    font-weight: 500;
    font-size: 0.875rem;
    border: none;
    background: transparent;
    cursor: pointer;
    transition: all 0.2s ease;
    white-space: nowrap;
}

.nav-link:hover {
    background: linear-gradient(135deg, #f8fafc 0%, #f1f5f9 100%);
    color: #3b82f6;
    border-radius: 8px;
}

.nav-link.help-link:hover {
    background: linear-gradient(135deg, #eff6ff 0%, #dbeafe 100%);
    color: #1d4ed8;
}

.nav-link.tools-link:hover {
    background: linear-gradient(135deg, #fef3c7 0%, #fde68a 100%);
    color: #d97706;
}

.nav-icon {
    flex-shrink: 0;
    color: currentColor;
}

.nav-text {
    font-weight: 500;
    letter-spacing: -0.025em;
}

.version-item {
    margin-left: 8px;
}

.version-badge {
    background: linear-gradient(135deg, #3b82f6 0%, #1d4ed8 100%);
    color: white;
    padding: 6px 12px;
    border-radius: 20px;
    font-size: 0.75rem;
    font-weight: 600;
    letter-spacing: 0.025em;
    box-shadow: 0 2px 8px rgba(59, 130, 246, 0.2);
}

/* ---- Notice Sections ---- */
.privacy-notice {
    background: linear-gradient(135deg, #10b981 0%, #059669 100%);
    color: white;
    padding: 16px 0;
}

.browser-notice {
    background: linear-gradient(135deg, #6366f1 0%, #4f46e5 100%);
    color: white;
    padding: 14px 0;
}

.notice-content {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 12px;
    text-align: center;
    flex-wrap: wrap;
}

.notice-icon {
    flex-shrink: 0;
}

.feature-alert {
    background: linear-gradient(135deg, #f59e0b 0%, #d97706 100%);
    color: white;
    padding: 12px 0;
    animation: alertPulse 3s ease-in-out infinite;
}

.alert-content {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 12px;
    text-align: center;
    flex-wrap: wrap;
}

.alert-icon {
    flex-shrink: 0;
}

@keyframes alertPulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.9; }
}

/* ---- FFmpeg Status Notice (新機能) ---- */
.ffmpeg-notice {
    padding: 14px 0;
    transition: background-color 0.3s ease;
}

.ffmpeg-notice.loading {
    background: linear-gradient(135deg, #f59e0b 0%, #d97706 100%);
    color: white;
}

.ffmpeg-notice.ready {
    background: linear-gradient(135deg, #10b981 0%, #059669 100%);
    color: white;
}

.ffmpeg-notice.error {
    background: linear-gradient(135deg, #ef4444 0%, #dc2626 100%);
    color: white;
}

/* ---- Main Content ---- */
.main-content {
    padding: 40px 0;
}

.main-content section {
    margin-bottom: 40px;
}

/* ---- Upload Section ---- */
.upload-section {
    background: linear-gradient(135deg, #ffffff 0%, #f8f9fa 100%);
    border: 2px dashed #d1d5db;
    border-radius: 12px;
    padding: 48px 32px;
    text-align: center;
    transition: all 0.3s ease;
    cursor: pointer;
    position: relative;
    min-height: 200px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.upload-section:hover {
    border-color: #3b82f6;
    background: linear-gradient(135deg, #ffffff 0%, #f0f9ff 100%);
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(59, 130, 246, 0.1);
}

.upload-section.dragover {
    border-color: #10b981;
    background: linear-gradient(135deg, #ffffff 0%, #f0fdf9 100%);
    transform: scale(1.02);
}

.upload-content {
    width: 100%;
}

.upload-icon {
    color: #6b7280;
    margin-bottom: 16px;
    transition: color 0.3s ease;
}

.upload-section:hover .upload-icon {
    color: #3b82f6;
}

.upload-section.dragover .upload-icon {
    color: #10b981;
}

.upload-section h2 {
    font-size: 1.5rem;
    font-weight: 600;
    color: #1f2937;
    margin-bottom: 8px;
}

.upload-section p {
    color: #6b7280;
    margin-bottom: 16px;
}

.upload-button {
    background: linear-gradient(135deg, #3b82f6 0%, #1d4ed8 100%);
    color: white;
    border: none;
    padding: 8px 16px;
    border-radius: 6px;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s ease;
    text-decoration: underline;
}

.upload-button:hover {
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(59, 130, 246, 0.3);
}

.upload-info {
    margin-top: 16px;
    font-size: 0.875rem;
    color: #6b7280;
}

#fileInput {
    position: absolute;
    width: 100%;
    height: 100%;
    opacity: 0;
    cursor: pointer;
}

/* ---- Controls Section ---- */
.controls-section {
    margin-bottom: 32px;
}

.controls-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 24px;
}

.control-panel {
    background: white;
    border-radius: 12px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.05);
    overflow: hidden;
    transition: box-shadow 0.3s ease;
}

.control-panel:hover {
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.1);
}

.privacy-panel {
    border: 2px solid #f59e0b;
    background: linear-gradient(135deg, #ffffff 0%, #fffbeb 100%);
}

.panel-header {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 20px 24px 16px;
    border-bottom: 1px solid #f3f4f6;
}

.panel-icon {
    color: #3b82f6;
    flex-shrink: 0;
}

.privacy-panel .panel-icon {
    color: #f59e0b;
}

.panel-header h3 {
    font-size: 1.125rem;
    font-weight: 600;
    color: #1f2937;
}

.control-content {
    padding: 20px 24px 24px;
}

/* ---- Slider Controls ---- */
.slider-group {
    margin-bottom: 20px;
}

.slider-label {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 12px;
    font-weight: 500;
    color: #374151;
}

.slider-value {
    font-weight: 600;
    color: #3b82f6;
}

.quality-slider {
    width: 100%;
    height: 6px;
    border-radius: 3px;
    background: #e5e7eb;
    outline: none;
    appearance: none;
    cursor: pointer;
}

.quality-slider::-webkit-slider-thumb {
    appearance: none;
    width: 20px;
    height: 20px;
    border-radius: 50%;
    background: linear-gradient(135deg, #3b82f6 0%, #1d4ed8 100%);
    cursor: pointer;
    border: 2px solid white;
    box-shadow: 0 2px 8px rgba(59, 130, 246, 0.3);
    transition: all 0.2s ease;
}

.quality-slider::-webkit-slider-thumb:hover {
    transform: scale(1.1);
    box-shadow: 0 4px 12px rgba(59, 130, 246, 0.4);
}

.quality-slider::-moz-range-thumb {
    width: 20px;
    height: 20px;
    border-radius: 50%;
    background: linear-gradient(135deg, #3b82f6 0%, #1d4ed8 100%);
    cursor: pointer;
    border: 2px solid white;
    box-shadow: 0 2px 8px rgba(59, 130, 246, 0.3);
}

/* ---- Preset Buttons ---- */
.preset-buttons {
    display: flex;
    gap: 8px;
    flex-wrap: wrap;
}

.preset-btn {
    background: linear-gradient(135deg, #f3f4f6 0%, #e5e7eb 100%);
    color: #374151;
    border: 1px solid #d1d5db;
    padding: 8px 16px;
    border-radius: 20px;
    font-size: 0.875rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s ease;
}

.preset-btn:hover {
    background: linear-gradient(135deg, #3b82f6 0%, #1d4ed8 100%);
    color: white;
    border-color: #3b82f6;
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(59, 130, 246, 0.2);
}

/* ---- Video Info (新機能) ---- */
.video-info {
    margin-top: 12px;
    padding: 12px;
    background: #f0f9ff;
    border: 1px solid #e0f2fe;
    border-radius: 6px;
}

.video-info small {
    color: #0c4a6e;
    font-weight: 500;
}

/* ---- Metadata Options ---- */
.metadata-options {
    display: grid;
    gap: 12px;
    margin-bottom: 20px;
}

.metadata-option {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 12px 16px;
    background: white;
    border: 1px solid #e5e7eb;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.2s ease;
}

.metadata-option:hover {
    background: #f9fafb;
    border-color: #d1d5db;
}

.metadata-option input[type="checkbox"] {
    width: 18px;
    height: 18px;
    accent-color: #3b82f6;
    cursor: pointer;
}

.option-text {
    flex: 1;
    font-weight: 500;
    color: #374151;
}

.risk-badge {
    padding: 4px 8px;
    border-radius: 12px;
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.025em;
}

.risk-high {
    background: #fee2e2;
    color: #dc2626;
}

.risk-medium {
    background: #fef3c7;
    color: #d97706;
}

.risk-low {
    background: #d1fae5;
    color: #059669;
}

/* ---- Privacy Score ---- */
.privacy-score {
    background: linear-gradient(135deg, #10b981 0%, #059669 100%);
    color: white;
    text-align: center;
    padding: 20px;
    border-radius: 8px;
}

.score-value {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 4px;
    line-height: 1;
}

.score-label {
    font-size: 0.875rem;
    font-weight: 500;
    opacity: 0.9;
}

/* ---- Action Section ---- */
.action-section {
    margin-bottom: 32px;
}

.action-buttons {
    display: flex;
    gap: 16px;
    justify-content: center;
    flex-wrap: wrap;
}

.action-btn {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 12px 24px;
    border: none;
    border-radius: 8px;
    font-size: 0.875rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s ease;
    text-decoration: none;
    min-width: 160px;
    justify-content: center;
}

.action-btn:hover {
    transform: translateY(-2px);
}

.action-btn.primary {
    background: linear-gradient(135deg, #3b82f6 0%, #1d4ed8 100%);
    color: white;
    box-shadow: 0 4px 12px rgba(59, 130, 246, 0.3);
}

.action-btn.primary:hover {
    box-shadow: 0 8px 25px rgba(59, 130, 246, 0.4);
}

.action-btn.secondary {
    background: linear-gradient(135deg, #f59e0b 0%, #d97706 100%);
    color: white;
    box-shadow: 0 4px 12px rgba(245, 158, 11, 0.3);
}

.action-btn.secondary:hover {
    box-shadow: 0 8px 25px rgba(245, 158, 11, 0.4);
}

.action-btn.success {
    background: linear-gradient(135deg, #10b981 0%, #059669 100%);
    color: white;
    box-shadow: 0 4px 12px rgba(16, 185, 129, 0.3);
}

.action-btn.success:hover {
    box-shadow: 0 8px 25px rgba(16, 185, 129, 0.4);
}

.action-btn.danger {
    background: linear-gradient(135deg, #ef4444 0%, #dc2626 100%);
    color: white;
    box-shadow: 0 4px 12px rgba(239, 68, 68, 0.3);
}

.action-btn.danger:hover {
    box-shadow: 0 8px 25px rgba(239, 68, 68, 0.4);
}

/* ---- File Section ---- */
.file-section {
    margin-bottom: 32px;
}

.file-list {
    background: white;
    border-radius: 12px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.05);
    min-height: 200px;
    overflow: hidden;
}

.empty-state {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 60px 20px;
    color: #9ca3af;
}

.empty-icon {
    margin-bottom: 16px;
}

.empty-state p {
    font-style: italic;
}

/* ---- File Items ---- */
.file-item {
    display: flex;
    align-items: flex-start;
    gap: 16px;
    padding: 24px;
    border-bottom: 1px solid #f3f4f6;
    transition: background-color 0.2s ease;
}

.file-item:last-child {
    border-bottom: none;
}

.file-item:hover {
    background: #f9fafb;
}

.file-icon-container {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 48px;
    height: 48px;
    background: linear-gradient(135deg, #f3f4f6 0%, #e5e7eb 100%);
    border-radius: 8px;
    flex-shrink: 0;
}

.file-icon {
    font-size: 1.5rem;
    color: #6b7280;
}

.file-info {
    flex: 1;
    min-width: 0;
}

.file-name {
    font-weight: 600;
    color: #1f2937;
    margin-bottom: 4px;
    word-break: break-all;
}

.file-details {
    font-size: 0.875rem;
    color: #6b7280;
    margin-bottom: 12px;
}

/* ---- Metadata Info ---- */
.metadata-info {
    background: #f0f9ff;
    border: 1px solid #e0f2fe;
    border-radius: 6px;
    padding: 12px;
    margin: 12px 0;
}

.metadata-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 4px 0;
}

.metadata-label {
    font-weight: 500;
    color: #374151;
    font-size: 0.875rem;
}

.metadata-value {
    font-size: 0.875rem;
    color: #6b7280;
}

.metadata-status {
    display: inline-flex;
    align-items: center;
    padding: 2px 8px;
    border-radius: 12px;
    font-size: 0.75rem;
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.025em;
}

.metadata-status.has-data {
    background: #fee2e2;
    color: #dc2626;
}

.metadata-status.cleaned {
    background: #d1fae5;
    color: #059669;
}

/* ---- Progress Bar ---- */
.file-progress {
    margin: 12px 0;
}

.progress-text {
    font-size: 0.875rem;
    color: #6b7280;
    margin-bottom: 8px;
    text-align: center;
}

.progress-bar {
    width: 100%;
    height: 6px;
    background: #f3f4f6;
    border-radius: 3px;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, #3b82f6 0%, #1d4ed8 100%);
    border-radius: 3px;
    transition: width 0.3s ease;
}

/* ---- File Comparison ---- */
.file-comparison {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
    gap: 16px;
    margin: 16px 0;
    padding: 16px;
    background: #f9fafb;
    border-radius: 8px;
}

.comparison-item {
    text-align: center;
}

.comparison-label {
    font-size: 0.75rem;
    color: #6b7280;
    margin-bottom: 4px;
    text-transform: uppercase;
    letter-spacing: 0.025em;
    font-weight: 500;
}

.comparison-value {
    font-size: 0.875rem;
    font-weight: 600;
    color: #1f2937;
}

.comparison-value.savings {
    color: #059669;
}

/* ---- File Actions ---- */
.file-actions {
    display: flex;
    flex-direction: column;
    gap: 8px;
    flex-shrink: 0;
}

.file-action-btn {
    padding: 6px 12px;
    border: none;
    border-radius: 4px;
    font-size: 0.75rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s ease;
    text-align: center;
    min-width: 80px;
}

.file-action-btn:hover {
    transform: translateY(-1px);
}

.file-action-btn.download {
    background: linear-gradient(135deg, #10b981 0%, #059669 100%);
    color: white;
}

.file-action-btn.metadata {
    background: linear-gradient(135deg, #3b82f6 0%, #1d4ed8 100%);
    color: white;
}

.file-action-btn.remove {
    background: linear-gradient(135deg, #ef4444 0%, #dc2626 100%);
    color: white;
}

/* ---- Statistics Section ---- */
.stats-section {
    margin-bottom: 40px;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px;
}

.stat-card {
    background: white;
    border-radius: 12px;
    padding: 24px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.05);
    display: flex;
    align-items: center;
    gap: 16px;
    transition: all 0.3s ease;
}

.stat-card:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.1);
}

.stat-card.zip-progress {
    border: 2px solid #6366f1;
    background: linear-gradient(135deg, #ffffff 0%, #f0f4ff 100%);
    animation: zipProgressPulse 2s ease-in-out infinite;
}

@keyframes zipProgressPulse {
    0%, 100% { 
        border-color: #6366f1;
        background: linear-gradient(135deg, #ffffff 0%, #f0f4ff 100%);
    }
    50% { 
        border-color: #4f46e5;
        background: linear-gradient(135deg, #ffffff 0%, #e0e7ff 100%);
    }
}

.stat-icon {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 48px;
    height: 48px;
    background: linear-gradient(135deg, #3b82f6 0%, #1d4ed8 100%);
    border-radius: 8px;
    color: white;
    flex-shrink: 0;
}

.stat-card.zip-progress .stat-icon {
    background: linear-gradient(135deg, #6366f1 0%, #4f46e5 100%);
}

.stat-content {
    flex: 1;
}

.stat-value {
    font-size: 1.75rem;
    font-weight: 700;
    color: #1f2937;
    line-height: 1;
    margin-bottom: 4px;
}

.stat-label {
    font-size: 0.875rem;
    color: #6b7280;
    font-weight: 500;
}

/* ---- Help Section ---- */
.help-section {
    background: white;
    border-radius: 12px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.05);
    overflow: hidden;
}

.help-header {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 24px 32px 20px;
    border-bottom: 1px solid #f3f4f6;
}

.help-icon {
    color: #3b82f6;
    flex-shrink: 0;
}

.help-header h2 {
    font-size: 1.25rem;
    font-weight: 600;
    color: #1f2937;
}

.help-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 24px;
    padding: 32px;
}

.help-item {
    padding: 20px;
    background: #f9fafb;
    border-radius: 8px;
    transition: all 0.2s ease;
}

.help-item:hover {
    background: #f3f4f6;
}

.help-item-header {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 12px;
}

.help-item-header svg {
    color: #3b82f6;
    flex-shrink: 0;
}

.help-item h4 {
    font-size: 1rem;
    font-weight: 600;
    color: #1f2937;
}

.help-item p {
    font-size: 0.875rem;
    color: #6b7280;
    line-height: 1.5;
}

/* ---- Footer ---- */
.footer {
    background: linear-gradient(135deg, #1f2937 0%, #111827 100%);
    color: white;
    padding: 32px 0;
    margin-top: 60px;
}

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

.footer-content p {
    margin-bottom: 8px;
}

.footer-content p:first-child {
    font-weight: 600;
}

.footer-content p:last-child {
    font-size: 0.875rem;
    opacity: 0.8;
}

/* ---- Modal Styles (改善されたデザイン) ---- */
.modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 1000;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 20px;
    box-sizing: border-box;
}

.modal-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.6);
    backdrop-filter: blur(4px);
    cursor: pointer;
}

.modal-content {
    position: relative;
    background: white;
    border-radius: 16px;
    max-width: 800px;
    width: 100%;
    max-height: 90vh;
    overflow-y: auto;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.2);
    animation: modalSlideIn 0.3s ease-out;
}

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

.modal-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 24px 32px;
    border-bottom: 1px solid #f3f4f6;
    background: linear-gradient(135deg, #f8fafc 0%, #f1f5f9 100%);
}

.modal-title-section {
    display: flex;
    align-items: center;
    gap: 12px;
}

.modal-icon {
    color: #3b82f6;
    flex-shrink: 0;
}

.modal-header h2 {
    font-size: 1.5rem;
    font-weight: 700;
    color: #1f2937;
    margin: 0;
}

.modal-close {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    border: none;
    background: transparent;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.2s ease;
    color: #6b7280;
}

.modal-close:hover {
    background: rgba(239, 68, 68, 0.1);
    color: #ef4444;
}

.modal-body {
    padding: 32px;
}

.help-section-modal {
    margin-bottom: 32px;
}

.help-section-modal:last-child {
    margin-bottom: 0;
}

.section-header {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 20px;
}

.section-icon {
    font-size: 1.5rem;
    flex-shrink: 0;
}

.section-header h3 {
    font-size: 1.25rem;
    font-weight: 600;
    color: #1f2937;
    margin: 0;
}

/* ---- Step List (使い方ガイド) ---- */
.step-list {
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.step-item {
    display: flex;
    gap: 16px;
    padding: 20px;
    background: linear-gradient(135deg, #f8fafc 0%, #f1f5f9 100%);
    border-radius: 12px;
    border: 1px solid #e2e8f0;
    transition: all 0.2s ease;
}

.step-item:hover {
    background: linear-gradient(135deg, #eff6ff 0%, #dbeafe 100%);
    border-color: #bfdbfe;
    transform: translateY(-1px);
}

.step-number {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 32px;
    height: 32px;
    background: linear-gradient(135deg, #3b82f6 0%, #1d4ed8 100%);
    color: white;
    border-radius: 50%;
    font-weight: 700;
    font-size: 0.875rem;
    flex-shrink: 0;
}

.step-content {
    flex: 1;
}

.step-content h4 {
    font-size: 1rem;
    font-weight: 600;
    color: #1f2937;
    margin: 0 0 8px 0;
}

.step-content p {
    font-size: 0.875rem;
    color: #6b7280;
    line-height: 1.5;
    margin: 0;
}

/* ---- Security Features (安全性について) ---- */
.security-features {
    display: grid;
    gap: 16px;
}

.security-item {
    display: flex;
    gap: 16px;
    padding: 20px;
    background: linear-gradient(135deg, #f0fdf4 0%, #dcfce7 100%);
    border-radius: 12px;
    border: 1px solid #bbf7d0;
    transition: all 0.2s ease;
}

.security-item:hover {
    background: linear-gradient(135deg, #ecfdf5 0%, #d1fae5 100%);
    border-color: #86efac;
    transform: translateY(-1px);
}

.security-icon {
    font-size: 1.5rem;
    flex-shrink: 0;
}

.security-content {
    flex: 1;
}

.security-content h4 {
    font-size: 1rem;
    font-weight: 600;
    color: #1f2937;
    margin: 0 0 8px 0;
}

.security-content p {
    font-size: 0.875rem;
    color: #6b7280;
    line-height: 1.5;
    margin: 0;
}

/* ---- Developer Section ---- */
.developer-section {
    background: linear-gradient(135deg, #fefce8 0%, #fef3c7 100%);
    border: 1px solid #fde68a;
    border-radius: 12px;
    padding: 24px;
}

.developer-comment {
    margin-top: 16px;
}

.comment-content {
    font-size: 0.95rem;
    line-height: 1.6;
    color: #374151;
}

.comment-content p {
    margin-bottom: 16px;
}

.comment-content p:last-child {
    margin-bottom: 0;
}

.signature {
    margin-top: 20px;
    padding-top: 16px;
    border-top: 1px solid #fbbf24;
}

.signature p {
    font-style: italic;
    color: #92400e;
    font-weight: 500;
    margin: 0;
}

.modal-footer {
    display: flex;
    justify-content: center;
    padding: 24px 32px;
    border-top: 1px solid #f3f4f6;
    background: #f9fafb;
}

.btn-primary {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 12px 32px;
    background: linear-gradient(135deg, #3b82f6 0%, #1d4ed8 100%);
    color: white;
    border: none;
    border-radius: 8px;
    font-weight: 600;
    font-size: 0.875rem;
    cursor: pointer;
    transition: all 0.2s ease;
    box-shadow: 0 4px 12px rgba(59, 130, 246, 0.3);
}

.btn-primary:hover {
    background: linear-gradient(135deg, #1d4ed8 0%, #1e40af 100%);
    transform: translateY(-1px);
    box-shadow: 0 8px 25px rgba(59, 130, 246, 0.4);
}

/* ---- Responsive Design ---- */
@media (max-width: 768px) {
    .container {
        padding: 0 16px;
    }
    
    .header-content {
        flex-direction: column;
        text-align: center;
        gap: 16px;
    }
    
    .logo-section {
        justify-content: center;
    }
    
    .main-navigation {
        width: 100%;
        justify-content: center;
    }
    
    .nav-menu {
        flex-wrap: wrap;
        justify-content: center;
        gap: 8px;
    }
    
    .nav-link {
        padding: 8px 12px;
        font-size: 0.8rem;
    }
    
    .modal-content {
        margin: 10px;
        max-height: 95vh;
    }
    
    .modal-header {
        padding: 20px 24px;
    }
    
    .modal-header h2 {
        font-size: 1.25rem;
    }
    
    .modal-body {
        padding: 24px;
    }
    
    .step-item {
        flex-direction: column;
        gap: 12px;
        padding: 16px;
    }
    
    .step-number {
        align-self: flex-start;
    }
    
    .security-item {
        flex-direction: column;
        gap: 12px;
        padding: 16px;
    }
    
    .security-icon {
        align-self: flex-start;
    }
    
    .modal-footer {
        padding: 20px 24px;
    }
    
    .btn-primary {
        width: 100%;
        justify-content: center;
    }
    
    .main-content {
        padding: 24px 0;
    }
    
    .upload-section {
        padding: 32px 20px;
    }
    
    .controls-grid {
        grid-template-columns: 1fr;
    }
    
    .action-buttons {
        flex-direction: column;
        align-items: stretch;
    }
    
    .action-btn {
        width: 100%;
    }
    
    .file-comparison {
        grid-template-columns: 1fr 1fr;
    }
    
    .help-grid {
        grid-template-columns: 1fr;
        padding: 20px;
    }
    
    .stats-grid {
        grid-template-columns: 1fr;
    }
    
    .file-actions {
        flex-direction: row;
        flex-wrap: wrap;
    }
    
    .notice-content,
    .alert-content {
        flex-direction: column;
        gap: 8px;
    }
}

@media (max-width: 480px) {
    .logo-text h1 {
        font-size: 1.5rem;
    }
    
    .upload-section h2 {
        font-size: 1.25rem;
    }
    
    .file-item {
        flex-direction: column;
        align-items: flex-start;
    }
    
    .file-actions {
        width: 100%;
        flex-direction: row;
        justify-content: flex-start;
    }
}

/* ---- Accessibility ---- */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

/* ---- Print Styles ---- */
@media print {
    .header,
    .privacy-notice,
    .feature-alert,
    .browser-notice,
    .ffmpeg-notice,
    .action-section,
    .footer {
        display: none;
    }
    
    .main-content {
        padding: 0;
    }
    
    .file-list,
    .help-section {
        box-shadow: none;
        border: 1px solid #e5e7eb;
    }
}

/* ---- Update Highlights (v3.1 新機能) ---- */
.update-highlights {
    margin-bottom: 20px;
}

.highlight-item {
    display: flex;
    align-items: flex-start;
    gap: 16px;
    padding: 16px;
    background: linear-gradient(135deg, #f0f9ff 0%, #e0f2fe 100%);
    border: 1px solid #bae6fd;
    border-radius: 8px;
    margin-bottom: 12px;
    transition: all 0.2s ease;
}

.highlight-item:hover {
    background: linear-gradient(135deg, #e0f2fe 0%, #bae6fd 100%);
    transform: translateY(-1px);
}

.highlight-icon {
    font-size: 1.5rem;
    flex-shrink: 0;
    width: 32px;
    text-align: center;
}

.highlight-content {
    flex: 1;
}

.highlight-content h4 {
    font-size: 1rem;
    font-weight: 600;
    color: #0c4a6e;
    margin-bottom: 4px;
}

.highlight-content p {
    font-size: 0.875rem;
    color: #0369a1;
    line-height: 1.5;
    margin: 0;
}

/* ---- Responsive for Highlights ---- */
@media (max-width: 768px) {
    .highlight-item {
        flex-direction: column;
        text-align: center;
    }
    
    .highlight-icon {
        align-self: center;
        margin-bottom: 8px;
    }
}