:root {
    --bg-app: #F5F5F7;
    --bg-sidebar: #FFFFFF;
    --bg-card: #FFFFFF;
    --bg-input: #FAFAFA;
    --bg-input-hover: #F2F2F7;
    --bg-size-label: #F5F5F7;
    --primary: #007AFF;
    --primary-hover: #0062CC;
    --destructive: #FF3B30;
    --text: #1D1D1F;
    --text-secondary: #86868B;
    --border: #E5E5EA;
    --bg-tab-track: #E5E5EA;
    --bg-tab-indicator: #FFFFFF;
    --bg-upload-filled: #FFFFFF;
    --shadow-card: 0 2px 8px rgba(0, 0, 0, 0.04);
    --shadow-modal: 0 20px 40px rgba(0, 0, 0, 0.2);
    --radius-md: 10px;
    --radius-sm: 6px;
    --focus-ring: 0 0 0 3px rgba(0, 122, 255, 0.3);
}

/* Dark Mode Overrides */
[data-theme="dark"] {
    --bg-app: #000000;
    --bg-sidebar: #1C1C1E;
    --bg-card: #1C1C1E;
    --bg-input: #2C2C2E;
    --bg-input-hover: #3A3A3C;
    --bg-size-label: #2C2C2E;
    --primary: #0A84FF;
    --primary-hover: #0077CC;
    --text: #F5F5F7;
    --text-secondary: #8E8E93;
    --border: #38383A;
    --bg-tab-track: #2C2C2E;
    --bg-tab-indicator: #636366;
    --bg-upload-filled: #3A3A3C;
    --shadow-card: 0 2px 8px rgba(0, 0, 0, 0.5);
    --shadow-modal: 0 20px 40px rgba(0, 0, 0, 0.6);
}

/* Automatic System Preference */
@media (prefers-color-scheme: dark) {
    :root:not([data-theme="light"]) {
        --bg-app: #000000;
        --bg-sidebar: #1C1C1E;
        --bg-card: #1C1C1E;
        --bg-input: #2C2C2E;
        --bg-input-hover: #3A3A3C;
        --bg-size-label: #2C2C2E;
        --primary: #0A84FF;
        --primary-hover: #0077CC;
        --text: #F5F5F7;
        --text-secondary: #8E8E93;
        --border: #38383A;
        --bg-tab-track: #2C2C2E;
        --bg-tab-indicator: #636366;
        --bg-upload-filled: #3A3A3C;
        --shadow-card: 0 2px 8px rgba(0, 0, 0, 0.5);
        --shadow-modal: 0 20px 40px rgba(0, 0, 0, 0.6);
    }
}

body {
    font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
    background-color: var(--bg-app);
    color: var(--text);
    display: flex;
    flex-direction: row;
    height: 100vh;
    margin: 0;
    overflow: hidden;
    -webkit-font-smoothing: antialiased;
    user-select: none;
    -webkit-user-select: none;
}

/* --- Sidebar --- */
.sidebar {
    background: var(--bg-sidebar);
    width: 380px;
    min-width: 380px;
    height: 100%;
    border-right: 1px solid var(--border);
    display: flex;
    flex-direction: column;
    padding: 32px;
    box-sizing: border-box;
    overflow-y: auto;
    z-index: 10;
}

.sidebar-header-row {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 24px;
}

.header-actions {
    display: flex;
    align-items: center;
    gap: 4px;
}

.header-text h1 {
    margin: 0 0 6px 0;
    font-size: 20px;
    font-weight: 700;
    color: var(--text);
}

.header-text p {
    color: var(--text-secondary);
    font-size: 13px;
    line-height: 1.4;
    margin: 0;
}

/* Unified Icon Buttons */
.icon-btn {
    background: none;
    border: none;
    cursor: pointer;
    color: var(--text-secondary);
    width: 32px;
    height: 32px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.2s;
}

.icon-btn:hover {
    background-color: rgba(0, 0, 0, 0.05);
    color: var(--text);
}

[data-theme="dark"] .icon-btn:hover {
    background-color: rgba(255, 255, 255, 0.1);
}

.icon-btn svg {
    width: 18px;
    height: 18px;
}

.icon-btn.destructive:hover {
    color: var(--destructive);
    background-color: rgba(255, 59, 48, 0.1);
}

.divider-vertical {
    width: 1px;
    height: 16px;
    background-color: var(--border);
    margin: 0 4px;
}

/* --- Tabs --- */
.tabs {
    background: var(--bg-tab-track);
    padding: 2px;
    border-radius: 999px;
    display: flex;
    position: relative;
    margin-bottom: 24px;
    user-select: none;
    height: 28px;
    flex-shrink: 0;
}

.tab-btn {
    flex: 1;
    border: none;
    background: transparent;
    color: var(--text);
    font-size: 13px;
    font-weight: 500;
    cursor: pointer;
    position: relative;
    z-index: 2;
    transition: color 0.2s ease;
}

.tab-btn.active {
    font-weight: 600;
}

.tab-indicator {
    position: absolute;
    top: 2px;
    bottom: 2px;
    left: 2px;
    width: calc(33.33% - 2px);
    background: var(--bg-tab-indicator);
    border-radius: 999px;
    box-shadow: 0 3px 8px rgba(0, 0, 0, 0.12), 0 3px 1px rgba(0, 0, 0, 0.04);
    transition: transform 0.25s cubic-bezier(0.2, 0.8, 0.2, 1);
    z-index: 1;
}

/* --- Drop Zones --- */
.view-wrapper {
    position: relative;
    flex-grow: 1;
}

.view-section {
    display: none;
    animation: fadeIn 0.2s ease;
}

.view-section.active {
    display: block;
}

@keyframes fadeIn {
    from {
        opacity: 0;
    }

    to {
        opacity: 1;
    }
}

.grid-2 {
    display: grid;
    grid-template-columns: 1fr;
    gap: 16px;
}

.grid-6 {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 12px;
}

.upload-box {
    background-color: var(--bg-input);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    height: 72px;
    position: relative;
    display: flex;
    flex-direction: row;
    align-items: center;
    justify-content: flex-start;
    padding: 0 16px;
    cursor: pointer;
    overflow: hidden;
    transition: all 0.2s ease;
}

.upload-box:hover {
    background-color: var(--bg-input-hover);
    border-color: var(--text-secondary);
}

/* Drag & Drop Highlight */
.upload-box.drag-over {
    background-color: #EBF8FF;
    border-color: var(--primary);
    box-shadow: 0 0 0 2px rgba(0, 122, 255, 0.2);
}

.upload-box.has-file {
    background-color: var(--bg-upload-filled);
    border-color: var(--primary);
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.05);
}

.upload-box input {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    opacity: 0;
    cursor: pointer;
    z-index: 10;
}

/* Single Source Box Override */
#box-single {
    height: 160px;
    flex-direction: column;
    justify-content: center;
    text-align: center;
}

.ai-trigger-btn {
    position: absolute;
    bottom: 12px;
    right: 12px;
    width: 32px;
    height: 32px;
    border-radius: 50%;
    background: var(--bg-app);
    border: 1px solid var(--border);
    color: var(--primary);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.2s;
    z-index: 20;
}

.ai-trigger-btn:hover {
    transform: scale(1.1);
    background: var(--bg-card);
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
}

.ai-trigger-btn svg {
    width: 16px;
    height: 16px;
}

#box-single .thumb-preview {
    width: 64px;
    height: 64px;
    margin: 0 0 16px 0;
}

/* Thumbnails */
.thumb-preview {
    width: 36px;
    height: 36px;
    background-color: var(--border);
    border-radius: 6px;
    margin-right: 12px;
    background-size: cover;
    background-position: center;
    flex-shrink: 0;
    border: 1px solid rgba(0, 0, 0, 0.05);
    transition: background-image 0.2s ease;
}

.box-content {
    display: flex;
    flex-direction: column;
    pointer-events: none;
}

.label {
    font-weight: 600;
    font-size: 13px;
    color: var(--text);
}

.sub-label {
    font-size: 11px;
    color: var(--text-secondary);
    margin-top: 2px;
}

/* --- Footer --- */
.sidebar-footer {
    margin-top: 20px;
    padding-top: 20px;
    border-top: 1px solid var(--border);
}

button.action-btn {
    background-color: var(--primary);
    color: white;
    border: none;
    height: 40px;
    border-radius: 999px;
    font-weight: 600;
    font-size: 14px;
    cursor: pointer;
    width: 100%;
    transition: all 0.2s ease;
    box-shadow: 0 1px 2px rgba(0, 0, 0, 0.1);
}

button.action-btn:disabled {
    background-color: #E5E5EA;
    color: #8E8E93;
    cursor: default;
    box-shadow: none;
}

button.action-btn:hover:not(:disabled) {
    background-color: var(--primary-hover);
}

button.action-btn:active:not(:disabled) {
    transform: scale(0.98);
}

/* --- Main Preview Area --- */
.preview-area {
    flex-grow: 1;
    background-color: var(--bg-app);
    padding: 40px;
    overflow-y: auto;
    display: flex;
    flex-direction: column;
    align-items: center;
    scroll-snap-type: y proximity;
}

.preview-header {
    width: 100%;
    max-width: 800px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 30px;
}

.preview-header h2 {
    font-size: 18px;
    font-weight: 600;
    margin: 0;
    color: var(--text);
}

.preview-header span {
    font-size: 12px;
    color: var(--text-secondary);
}

.preview-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
    gap: 24px;
    width: 100%;
    max-width: 800px;
}

.preview-card {
    background: var(--bg-card);
    border-radius: 12px;
    padding: 20px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: space-between;
    box-shadow: var(--shadow-card);
    border: 1px solid rgba(0, 0, 0, 0.02);
    aspect-ratio: 1;
    position: relative;
}

.icon-container {
    flex-grow: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 100%;
}

.icon-container img {
    image-rendering: -webkit-optimize-contrast;
    filter: drop-shadow(0 4px 6px rgba(0, 0, 0, 0.15));
    transition: transform 0.2s;
}

/* Empty State Dashed Box */
.empty-placeholder {
    width: 48px;
    height: 48px;
    border: 2px dashed var(--border);
    border-radius: 8px;
}

.size-label {
    margin-top: 12px;
    font-size: 11px;
    color: var(--text-secondary);
    font-weight: 600;
    background: var(--bg-size-label);
    padding: 4px 8px;
    border-radius: 4px;
}

.input-group {
    display: flex;
    flex-direction: column;
    gap: 6px;
}

.input-group label {
    font-size: 12px;
    font-weight: 600;
    color: var(--text);
}

.text-input {
    background: var(--bg-input);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    padding: 10px;
    color: var(--text);
    font-family: inherit;
    font-size: 13px;
    outline: none;
    transition: border-color 0.2s;
}

.text-input:focus {
    border-color: var(--primary);
    box-shadow: var(--focus-ring);
}

.text-input.area {
    min-height: 80px;
    resize: vertical;
}

.text-input.select {
    appearance: none;
    background-image: url("data:image/svg+xml;charset=US-ASCII,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20width%3D%22292.4%22%20height%3D%22292.4%22%3E%3Cpath%20fill%3D%22%23007AFF%22%20d%3D%22M287%2069.4a17.6%2017.6%200%200%200-13-5.4H18.4c-5%200-9.3%201.8-12.9%205.4A17.6%2017.6%200%200%200%200%2082.2c0%205%201.8%209.3%205.4%2012.9l128%20127.9c3.6%203.6%207.8%205.4%2012.8%205.4s9.2-1.8%2012.8-5.4L287%2095c3.5-3.5%205.4-7.8%205.4-12.8%200-5-1.9-9.2-5.5-12.8z%22%2F%3E%3C%2Fsvg%3E");
    background-repeat: no-repeat;
    background-position: right 10px top 50%;
    background-size: 10px auto;
    padding-right: 30px;
}

.ai-result {
    margin-top: 16px;
    display: flex;
    flex-direction: column;
    gap: 12px;
    align-items: center;
}

.ai-result img {
    width: 128px;
    height: 128px;
    border-radius: 12px;
    box-shadow: var(--shadow-card);
    background: var(--bg-card);
}

.ai-config-row {
    display: flex;
    gap: 12px;
    margin-bottom: 12px;
}

.privacy-note {
    display: flex;
    align-items: center;
    gap: 8px;
    background: var(--bg-input);
    padding: 8px 12px;
    border-radius: var(--radius-sm);
    margin-bottom: 16px;
}

.privacy-note svg {
    width: 14px;
    height: 14px;
    color: var(--text-secondary);
}

.privacy-note span {
    font-size: 11px;
    color: var(--text-secondary);
    line-height: 1.3;
}

.checkbox-row {
    display: flex;
    align-items: center;
    gap: 8px;
    margin-top: 8px;
}

.checkbox-row label {
    font-size: 13px;
    color: var(--text);
    cursor: pointer;
}

.action-btn.secondary {
    background-color: var(--bg-input);
    color: var(--text);
    border: 1px solid var(--border);
}

.mt-large {
    margin-top: 24px;
}

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

/* --- Modal --- */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: rgba(0, 0, 0, 0.4);
    backdrop-filter: blur(4px);
    z-index: 1000;
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.2s ease;
}

.modal-overlay.open {
    opacity: 1;
    pointer-events: auto;
}

.modal-content {
    background: var(--bg-card);
    width: 90%;
    max-width: 680px;
    border-radius: 16px;
    padding: 32px;
    box-shadow: var(--shadow-modal);
    transform: scale(0.95);
    transition: transform 0.2s cubic-bezier(0.2, 0.8, 0.2, 1);
    border: 1px solid var(--border);
}

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

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 16px;
}

.modal-header h3 {
    margin: 0;
    font-size: 20px;
    color: var(--text);
}

.close-modal-btn {
    background: none;
    border: none;
    font-size: 24px;
    color: var(--text-secondary);
    cursor: pointer;
    padding: 0;
    line-height: 1;
}

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

.modal-body .modal-intro {
    color: var(--text-secondary);
    font-size: 15px;
    line-height: 1.5;
    margin-top: 0;
    margin-bottom: 24px;
}

/* Guide Grid */
.guide-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 20px;
    margin-bottom: 24px;
}

@media (max-width: 600px) {
    .guide-grid {
        grid-template-columns: 1fr 1fr;
    }
}

.guide-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
}

.guide-visual {
    width: 56px;
    height: 56px;
    background-color: var(--bg-input);
    border-radius: 14px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 12px;
    color: var(--primary);
    transition: background-color 0.2s;
}

.guide-visual svg {
    width: 28px;
    height: 28px;
}

.guide-item h4 {
    margin: 0 0 6px 0;
    font-size: 14px;
    font-weight: 600;
    color: var(--text);
}

.guide-item p {
    margin: 0;
    font-size: 12px;
    color: var(--text-secondary);
    line-height: 1.4;
}

.preview-footer {
    margin-top: 60px;
    padding-bottom: 20px;
    text-align: center;
    width: 100%;
    scroll-snap-align: end;
}
.preview-footer p {
    margin: 4px 0;
    font-size: 12px;
    color: var(--text-secondary);
}
.preview-footer .footer-brand {
    font-weight: 600;
    color: var(--text);
}