:root {
    /* Dark Theme (Default) */
    --bg-color: #0f1115;
    --card-bg: #181b21;
    --card-hover: #1f232b;
    --primary: #fbbf24;
    --primary-hover: #fcd34d;
    --text-main: #f3f4f6;
    --text-muted: #9ca3af;
    --border-color: #2d313a;
    --glass-border: rgba(255, 255, 255, 0.08);
    --zebra-stripe: rgba(0, 0, 0, 0.4);
    --line-numbers-bg: #14171c;
    --primary-gradient: linear-gradient(135deg, #fbbf24 0%, #f59e0b 100%);
    --line-numbers-text: #4b5563;
    --block-content-bg: #0d0f12;
    --block-line-numbers-bg: #14171c;
    --block-content-bg-scroll: rgba(0, 0, 0, 0.4);
    --panel-bg: rgba(24, 27, 33, 0.5);
    --panel-header-bg: rgba(24, 27, 33, 0.8);
    --panel-header-text: #9ca3af;
    --drop-overlay-bg: rgba(15, 17, 21, 0.9);
    --highlight-color: #99FF99;
    --highlight-glow: rgba(153, 255, 153, 0.4);
    --badge-bg: rgba(99, 102, 241, 0.1);
    --scrollbar-track: transparent;
    --scrollbar-track-hover: rgba(255, 255, 255, 0.05);
    --scrollbar-thumb: rgba(156, 163, 175, 0.4);
    --scrollbar-thumb-hover: rgba(156, 163, 175, 0.7);
    --lock-color: #4ade80;
    --unlock-color: #fbbf24;
    --toast-text: #000000;

    /* Common */
    --radius-lg: 16px;
    --radius-md: 8px;
    --font-sans: 'Inter', 'Noto Sans KR', 'Malgun Gothic', 'Meiryo', sans-serif;
    --header-height: 80px;
    --line-height: 1.6;
    --actual-line-height: 24px;
    /* Fallback, updated by JS */
    --editor-font-size: 12pt;
    /* Adjustable font size (9pt-15pt) */
}

body.light-theme {
    --bg-color: #f8f9fa;
    --card-bg: #ffffff;
    --card-hover: #f1f3f5;
    --primary: #1B5E20;
    --primary-hover: #2E7D32;
    --primary-gradient: linear-gradient(135deg, #2E7D32 0%, #1B5E20 100%);
    --text-main: #1f2937;
    --text-muted: #6b7280;
    --border-color: #e5e7eb;
    --glass-border: rgba(0, 0, 0, 0.08);
    --zebra-stripe: rgba(0, 0, 0, 0.03);
    --line-numbers-bg: #f1f3f5;
    --line-numbers-text: #9ca3af;
    --block-content-bg: rgba(0, 0, 0, 0.08);
    --block-line-numbers-bg: #f1f3f5;
    --block-content-bg-scroll: #fafafa;
    --drop-overlay-bg: rgba(248, 249, 250, 0.95);
    --panel-bg: rgba(255, 255, 255, 0.8);
    --panel-header-bg: rgba(241, 243, 245, 0.95);
    --panel-header-text: #1f2937;
    --highlight-color: #0f4c81;
    --highlight-glow: rgba(15, 76, 129, 0.2);
    --badge-bg: rgba(27, 94, 32, 0.08);
    --scrollbar-track-hover: rgba(0, 0, 0, 0.05);
    --scrollbar-thumb: rgba(107, 114, 128, 0.4);
    --scrollbar-thumb-hover: rgba(107, 114, 128, 0.7);
    --lock-color: #16a34a;
    --unlock-color: #d97706;
    --toast-text: #ffffff;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    scrollbar-width: thin;
    scrollbar-color: var(--scrollbar-thumb) var(--scrollbar-track);
}

/* Scrollbar Styling - Always visible when content overflows */
::-webkit-scrollbar {
    width: 10px;
    height: 10px;
}

::-webkit-scrollbar-track {
    background: var(--scrollbar-track-hover);
    /* Always show track background for visibility */
}

::-webkit-scrollbar-thumb {
    background: var(--scrollbar-thumb);
    border-radius: 10px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--scrollbar-thumb-hover);
}

body {
    background-color: var(--bg-color);
    color: var(--text-main);
    font-family: var(--font-sans);
    line-height: var(--line-height);
    height: 100vh;
    overflow: hidden;
}

.app-container {
    width: 100%;
    height: 100%;
    display: flex;
    flex-direction: column;
    padding: 0 1.5rem 1.5rem 1.5rem;
    min-width: 1200px;
}

/* Header */
header {
    height: var(--header-height);
    display: flex;
    align-items: center;
    flex-shrink: 0;
}

h1 {
    font-size: 1.75rem;
    font-weight: 800;
}

.gradient-text {
    background: var(--primary-gradient);
    background-clip: text;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.version-tag {
    display: inline-block;
    font-size: 0.7rem;
    font-weight: normal;
    color: var(--bg-color);
    background: var(--primary);
    padding: 1px 4px;
    border-radius: 4px;
    margin-left: 8px;
    vertical-align: middle;
    line-height: 1.2;
    transform: translateY(2px);
    opacity: 0.9;
}

/* Theme Toggle Button */
.theme-toggle {
    margin-left: auto;
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: 0.5rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.3s ease;
    color: var(--text-muted);
}

.theme-toggle:hover {
    background: var(--card-hover);
    border-color: var(--primary);
    color: var(--primary);
}

.theme-toggle svg {
    width: 20px;
    height: 20px;
    transition: transform 0.3s ease;
}

.theme-toggle .sun-icon {
    display: none;
}

.theme-toggle .moon-icon {
    display: block;
}

body.light-theme .theme-toggle .sun-icon {
    display: block;
}

body.light-theme .theme-toggle .moon-icon {
    display: none;
}

.theme-toggle:hover svg {
    transform: rotate(15deg);
}

/* Text Size Control */
.text-size-control {
    display: flex;
    align-items: center;
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: 2px;
}

.text-size-control .btn-icon {
    border: none;
    background: transparent;
    padding: 0.4rem 0.6rem;
    color: var(--text-muted);
}

.text-size-control .btn-icon:hover {
    color: var(--primary);
    background: var(--card-hover);
}

/* Split View Layout */
.split-view {
    display: flex;
    gap: 1.5rem;
    flex: 1;
    min-height: 0;
}

.panel {
    flex: 1;
    background: var(--panel-bg);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    display: flex;
    flex-direction: column;
    flex-direction: column;
    transition: all 0.5s cubic-bezier(0.4, 0, 0.2, 1);
    min-width: 0;
}

.input-panel {
    overflow: hidden;
    /* Fix corner clipping for input panel specifically */
}

.panel-header {
    padding: 1rem 1.5rem;
    min-height: 64px;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: var(--panel-header-bg);
    flex-shrink: 0;
    border-top-left-radius: var(--radius-lg);
    border-top-right-radius: var(--radius-lg);
    position: relative;
}

.filename-display {
    position: absolute;
    left: 50%;
    top: 50%;
    transform: translate(-50%, -50%);
    font-size: 0.85rem;
    font-weight: 500;
    color: var(--text-muted);
    max-width: 40%;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    transition: all 0.2s ease;
}

.panel-header h2 {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--text-color);
}

.btn-text {
    display: flex;
    align-items: center;
    gap: 6px;
    background: transparent;
    border: none;
    color: var(--text-color);
    font-size: 0.85rem;
    font-weight: 500;
    padding: 6px 12px;
    border-radius: 6px;
    cursor: pointer;
    transition: all 0.2s;
}

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

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

.btn-outline:hover {
    border-color: var(--primary-color);
    color: var(--primary-color);
}

/* Result Panel */
.result-panel {
    position: relative;
    overflow: visible;
    background: var(--bg-color);
}

/* Layout Toggle Button */
.layout-toggle {
    position: absolute;
    left: 0;
    top: 50%;
    transform: translate(-50%, -50%);

    z-index: 10;
    background: var(--primary);
    color: black;
    border: none;
    width: 16px;
    height: 36px;
    border-radius: 4px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: -2px 0 8px rgba(0, 0, 0, 0.2);
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    opacity: 1;
}

body.light-theme .layout-toggle {
    color: white;
}

.layout-toggle:hover {
    background: var(--primary-hover);
    transform: translate(-50%, -50%) scale(1.1);
}

.layout-toggle svg {
    transition: transform 0.3s;
}

/* Expanded State */
.split-view.expanded .input-panel {
    flex: 0;
    min-width: 0;
    padding: 0;
    border: none;
    opacity: 0;
    margin-right: -1.5rem;
    pointer-events: none;
}

.split-view.expanded .result-panel {
    flex: 1;
}

.split-view.expanded .layout-toggle {
    left: 0;
    transform: translate(-50%, -50%);
    border-radius: 4px;
}

.split-view.expanded .layout-toggle:hover {
    transform: translate(-50%, -50%) scale(1.1);
}

.split-view.expanded .layout-toggle svg {
    transform: rotate(180deg);
}

/* Input Controls */
.input-control-group {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.divider {
    width: 1px;
    height: 18px;
    background-color: var(--border-color);
    margin: 0 0.25rem;
}

.input-control-group label {
    font-size: 0.875rem;
    color: var(--text-muted);
}

.input-control-group input {
    background: var(--bg-color);
    border: 1px solid var(--border-color);
    color: var(--text-main);
    padding: 0.4rem 0.75rem;
    border-radius: var(--radius-md);
    width: 80px;
    font-size: 0.9rem;
    outline: none;
    text-align: center;
}

.input-control-group input:focus {
    border-color: var(--primary);
}

.drop-zone.full-height {
    flex: 1;
    position: relative;
    background: transparent;
    border: none;
    display: flex;
    flex-direction: column;
    min-height: 0;
    border-bottom-left-radius: var(--radius-lg);
    border-bottom-right-radius: var(--radius-lg);
}

/* Editor Wrapper & Line Numbers */
.editor-wrapper {
    flex: 1;
    display: flex;
    position: relative;
    overflow: hidden;
    min-height: 0;
}

.line-numbers {
    width: 60px;
    flex-shrink: 0;
    background: var(--line-numbers-bg);
    border-right: 1px solid var(--border-color);
    color: var(--line-numbers-text);
    font-family: monospace;
    font-size: var(--editor-font-size);
    text-align: right;
    /* Padding synced with line-height for zebra alignment */
    padding: var(--actual-line-height, 24px) 0.5rem;
    line-height: var(--actual-line-height);
    user-select: none;
    overflow: hidden;
    white-space: pre;
    cursor: pointer;
}

textarea {
    flex: 1;
    height: 100%;
    background: transparent;
    border: none;
    color: var(--text-main);
    font-family: monospace;
    font-size: var(--editor-font-size);
    /* Padding synced with line-height for zebra alignment */
    padding: var(--actual-line-height, 1.5rem);
    resize: none;
    resize: none;
    outline: none;
    line-height: var(--actual-line-height);
    overflow-y: auto;
    white-space: pre;

    /* Padding synced with line-height for zebra alignment */
    padding: var(--actual-line-height, 24px);
    resize: none;
    resize: none;
    outline: none;
    line-height: var(--actual-line-height);
    overflow-y: auto;
    white-space: pre;

    /* Zebra Striping - uses robust background-size for perfect alignment */
    background-image: linear-gradient(to bottom,
            transparent 50%,
            var(--zebra-stripe) 50%);
    background-size: 100% calc(var(--actual-line-height) * 2);
    /* Start stripe pattern at the same offset as the first text line */
    background-position-y: var(--actual-line-height, 24px);
    background-attachment: local;
}

/* Safari-specific fix for textarea zebra stripes */
@supports (-webkit-touch-callout: none) {
    textarea {
        background-attachment: scroll;
    }
}

.drop-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    color: var(--primary);
    background: var(--drop-overlay-bg);
    z-index: 20;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.2s ease;
}

.drop-zone.drag-active .drop-overlay {
    opacity: 1;
}

/* Results Panel */
.blocks-list {
    flex: 1;
    overflow-y: auto;
    padding: 1.5rem;
    border-bottom-left-radius: var(--radius-lg);
    border-bottom-right-radius: var(--radius-lg);
    display: flex;
    flex-direction: column;
    gap: 1rem;
    contain: content;
    /* Performance optimization */
}

.empty-state {
    color: var(--text-muted);
    text-align: center;
    margin-top: 30%;
    font-style: italic;
    opacity: 0.6;
}

.badge {
    background: var(--badge-bg);
    color: var(--primary-hover);
    padding: 0.25rem 0.6rem;
    border-radius: 999px;
    font-size: 0.8rem;
    font-weight: 600;
}

#input-line-count,
#result-count {
    min-width: 100px;
    text-align: center;
    display: inline-block;
}

.block-card {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: 0.5rem;
    transition: all 0.2s ease;
    contain: content;
    /* Performance optimization */
}

.block-card.highlighted {
    border-color: color-mix(in srgb, var(--highlight-color), transparent 20%) !important;
    box-shadow: 0 0 8px var(--highlight-glow);
}



.block-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 0.5rem;
    font-size: 0.875rem;
    color: var(--text-muted);
}

.block-body {
    background: var(--block-content-bg);
    border-radius: 4px;
    font-family: monospace;
    font-size: 0.85rem;
    color: var(--text-muted);
    max-height: 190px;
    overflow-x: auto;
    overflow-y: hidden;
    margin-bottom: 0;
    border: 1px solid transparent;
    cursor: pointer;
    transition: background-color 0.2s;
    overscroll-behavior-x: contain;
}

.block-flex-wrapper {
    display: flex;
    min-height: 100%;
    width: max-content;
    min-width: 100%;
}

/* Safari-specific fix for zebra stripes */
@supports (-webkit-touch-callout: none) {
    .block-content {
        background-attachment: scroll;
    }

    textarea {
        background-attachment: scroll !important;
    }
}

/* Restore highlight effect on click */
.block-body.highlight-active {
    background: var(--block-content-bg-scroll);
    border-color: transparent;
    box-shadow: 0 0 0 2px var(--card-bg), 0 0 0 3px color-mix(in srgb, var(--primary), transparent 20%);
    overflow: auto;
    /* Enable all scrolling on click */
}

.block-body.highlight-active .block-content {
    color: #ffffff;
}

body.light-theme .block-body.highlight-active .block-content {
    color: #000000;
}

.block-line-numbers {
    flex-shrink: 0;
    min-width: 40px;
    padding: 0.5rem 0.6rem;
    text-align: right;
    line-height: var(--actual-line-height);
    font-size: var(--editor-font-size);
    font-family: monospace;
    cursor: pointer;
    border-right: 1px solid var(--border-color);
    background: var(--block-line-numbers-bg);
    color: var(--line-numbers-text);
    white-space: pre;
    user-select: none;
    position: sticky;
    left: 0;
    z-index: 10;
    /* Higher z-index to prevent text overlap during horizontal scroll */
}

.block-content {
    flex: 1;
    padding: 0.5rem;
    white-space: pre;
    line-height: var(--actual-line-height);
    font-size: var(--editor-font-size);
    /* No wrap to match line numbers */
    color: var(--text-muted);
    background: transparent;
    position: relative;
    z-index: 1;
    /* Lower z-index to prevent overlap */

    /* Zebra Striping - Applied only to content area */
    background-image: linear-gradient(to bottom,
            transparent 50%,
            var(--zebra-stripe) 50%);
    background-position-y: 0.5rem;
    background-size: 100% calc(var(--actual-line-height) * 2);
    background-repeat: repeat;
    background-attachment: local;
}

.block-actions {
    display: flex;
    gap: 0.5rem;
    justify-content: flex-end;
    align-items: center;
}

.btn-icon {
    position: relative;
    cursor: pointer;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    padding: 0.25rem;
    background: var(--card-bg);
    color: var(--text-muted);
    display: flex;
    transition: all 0.2s;
}

.btn-icon:not(:disabled):hover {
    background: var(--card-hover);
    color: var(--text-main);
    border-color: var(--text-muted);
}

.btn-icon:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    filter: grayscale(1);
    background: var(--card-bg);
}

.notification-badge {
    position: absolute;
    top: -6px;
    right: -6px;
    background-color: #ef4444;
    color: white;
    font-size: 0.65rem;
    font-weight: 700;
    min-width: 16px;
    height: 16px;
    border-radius: 999px;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 0 4px;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
    animation: popIn 0.2s cubic-bezier(0.175, 0.885, 0.32, 1.275);
    pointer-events: none;
}

@keyframes popIn {
    from {
        transform: scale(0);
    }

    to {
        transform: scale(1);
    }
}

.icon-sm {
    width: 18px;
    height: 18px;
}

/* Toast */
.toast {
    position: fixed;
    bottom: 2rem;
    left: 50%;
    transform: translateX(-50%);
    background: var(--primary);
    color: var(--toast-text);
    padding: 0.75rem 1.5rem;
    border-radius: 999px;
    font-weight: 500;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
    animation: fadeIn 0.3s cubic-bezier(0.16, 1, 0.3, 1);
    z-index: 100;
}

.toast.hidden {
    display: none;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translate(-50%, 1rem);
    }

    to {
        opacity: 1;
        transform: translate(-50%, 0);
    }
}

/* Swapped State */
.split-view.swapped {
    flex-direction: row-reverse;
}

/* Fix shadow and positioning for layout toggle in swapped state */
.split-view.swapped .layout-toggle {
    left: auto;
    right: 0;
    transform: translate(50%, -50%);
    box-shadow: 2px 0 8px rgba(0, 0, 0, 0.2);
}

.split-view.swapped .layout-toggle:hover {
    transform: translate(50%, -50%) scale(1.1);
}

/* Icon rotation for swapped state */
.split-view.swapped .layout-toggle svg {
    transform: rotate(180deg);
}

/* Expanded State logic when Swapped */
.split-view.swapped.expanded .layout-toggle svg {
    transform: rotate(0deg);
}

/* Fix margin collapse for input panel when swapped and expanded */
.split-view.swapped.expanded .input-panel {
    margin-right: 0;
    margin-left: -1.5rem;
}

.split-view.swapped.expanded .layout-toggle {
    left: auto;
    right: 0;
    transform: translate(50%, -50%);
}

.split-view.swapped.expanded .layout-toggle:hover {
    transform: translate(50%, -50%) scale(1.1);
}

/* Read-only Textarea Style */
textarea[readonly] {
    cursor: not-allowed;
    opacity: 1;
    color: #9ca3af;
    background-color: rgba(0, 0, 0, 0.3);
    /* Darker for dark theme */
}

body.light-theme textarea[readonly] {
    background-color: rgba(0, 0, 0, 0.05);
    color: #4b5563;
    /* Lighter for light theme */
}

textarea[readonly]::placeholder {
    color: transparent;
}

/* Lock Button Active/Inactive Visuals */
#lock-toggle-btn svg {
    transition: transform 0.2s;
}

#lock-toggle-btn.unlocked {
    color: var(--unlock-color);
    border-color: var(--unlock-color);
}

#lock-toggle-btn.locked {
    color: var(--lock-color);
    border-color: var(--lock-color);
}

/* Reduced width for layout toggle as requested */
#layout-toggle-btn {
    width: 12px !important;
    /* Force reduction */
    padding: 0;
    justify-content: center;
}