:root {
    --bg-body: #dadada;       --bg-paper: #fbfbfb;      
    --text-primary: #111827;  --text-secondary: #4b5563;
    --border-color: #cbd5e1;  --accent-color: #3b82f6;  
    --hover-bg: rgba(0, 0, 0, 0.05);
    --success-color: #10b981; --warning-color: #f59e0b; --danger-color: #ef4444;
    --dropdown-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
    --h-heading: #2563eb;     --h-bold: #dc2626;        --h-italic: #059669;
    --h-code: #d97706;        --h-list: #8b5cf6;        --h-quote: #64748b;
    --h-link: #0891b2;        --h-math: #c026d3;
    --h-html: #0d9488;        --h-css-sel: #ea580c;     --h-css-prop: #2563eb;
    --h-css-val: #059669;      --h-comment: #94a3b8;     --h-math-cmd: #86198f;
    --selection-bg: rgba(59, 130, 246, 0.28);
}

@media (prefers-color-scheme: dark) {
    :root {
        --bg-body: #0f172a;       --bg-paper: #1c1f24;      
        --text-primary: #f8fafc;  --text-secondary: #94a3b8;
        --border-color: #334155;
        --hover-bg: rgba(255, 255, 255, 0.08);
        --dropdown-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.3);
        --h-heading: #60a5fa;     --h-bold: #f87171;        --h-italic: #34d399;
        --h-code: #fbbf24;        --h-list: #a78bfa;        --h-quote: #94a3b8;
        --h-link: #22d3ee;        --h-math: #e879f9;
        --h-html: #2dd4bf;        --h-css-sel: #fb923c;     --h-css-prop: #60a5fa;
        --h-css-val: #34d399;      --h-comment: #64748b;     --h-math-cmd: #f5d0fe;
        --selection-bg: rgba(96, 165, 250, 0.38);
    }
}

* { box-sizing: border-box; }
body {
    font-family: system-ui, -apple-system, sans-serif;
    margin: 0; background-color: var(--bg-body); color: var(--text-primary);
    display: flex; flex-direction: column; height: 100dvh; overflow: hidden;
    transition: background-color 0.3s, color 0.3s;
}

header {
    height: auto; min-height: 50px; background: var(--bg-paper); border-bottom: 1px solid var(--border-color);
    display: flex; align-items: center; padding: 0 16px; justify-content: space-between;
    z-index: 100; flex-shrink: 0;
    padding-top: env(safe-area-inset-top);
    padding-left: max(16px, env(safe-area-inset-left));
    padding-right: max(16px, env(safe-area-inset-right));
}

.logo-group { display: flex; align-items: center; gap: 10px; height: 100%; }
.logo { display: flex; align-items: center; justify-content: center; width: 32px; height: 32px; }
.logo svg { width: 100%; height: 100%; fill: currentColor; display: block; }

.controls { display: flex; align-items: center; gap: 12px; }
button.icon-btn { background: transparent; border: none; color: var(--text-secondary); width: 36px; height: 36px; border-radius: 8px; cursor: pointer; display: flex; align-items: center; justify-content: center; transition: all 0.2s ease; }
button.icon-btn:hover { background-color: var(--hover-bg); color: var(--text-primary); }

.url-stats { display: flex; align-items: center; gap: 8px; cursor: pointer; padding: 6px 10px; border-radius: 20px; transition: background 0.2s; }
.url-stats:hover { background: var(--hover-bg); }
.url-stats span { font-family: 'Roboto Mono', monospace; font-size: 12px; color: var(--text-primary); display: none; white-space: nowrap; }
.url-stats.active span { display: inline-block; }
.dot { width: 12px; height: 12px; border-radius: 50%; background-color: var(--success-color); box-shadow: 0 0 4px rgba(0,0,0,0.1); flex-shrink: 0; }

.dropdown { position: relative; }
.container { display: flex; flex: 1; overflow: hidden; }
.panel { flex: 1; display: none; flex-direction: column; height: 100%; overflow: hidden; background: var(--bg-paper); position: relative; }
.panel.active { display: flex; }
#editorPanel { border-right: 1px solid var(--border-color); }

.editor-container { position: relative; flex: 1; overflow: hidden; }
#editor {
    width: 100%; height: 100%; padding: 24px; padding-bottom: calc(24px + env(safe-area-inset-bottom));
    font-family: 'Roboto Mono', monospace !important;
    font-size: 15px; line-height: 1.6; border: none; outline: none; resize: none;
    background: transparent !important; color: transparent !important; caret-color: var(--text-primary);
    white-space: pre-wrap; word-wrap: break-word; z-index: 2; position: relative;
    scrollbar-gutter: stable; overflow-y: auto; overflow-x: hidden; tab-size: 4;
}
#editor-highlighting {
    position: absolute; top: 0; left: 0; width: 100%; height: 100%; padding: 24px; padding-bottom: calc(24px + env(safe-area-inset-bottom));
    font-family: 'Roboto Mono', monospace !important; font-size: 15px; line-height: 1.6;
    overflow-y: hidden; pointer-events: none; white-space: pre-wrap; word-wrap: break-word;
    color: var(--text-primary); z-index: 1; scrollbar-gutter: stable; tab-size: 4;
}
.h-heading { color: var(--h-heading); font-weight: bold; }
.h-bold { color: var(--h-bold); font-weight: bold; }
.h-italic { color: var(--h-italic); font-style: italic; }
.h-bold-italic { color: var(--h-bold); font-weight: bold; font-style: italic; }
.h-strikethrough { text-decoration: line-through; opacity: 0.6; }
.h-code { color: var(--h-code); background-color: rgba(217, 119, 6, 0.1); }
.h-list { color: var(--h-list); font-weight: bold; }
/* 疊層高亮類別不得含任何影響版面的屬性（border/padding/margin 會使文字與游標錯位）；
   quote 左緣色帶以背景漸層繪製：零版面影響、行內換行時每視覺行都會出現 */
.h-quote { color: var(--h-quote); font-style: italic; background: linear-gradient(90deg, var(--border-color) 0 2px, transparent 2px); }
.h-link-text { color: var(--h-link); text-decoration: underline; }
.h-math { color: var(--h-math); font-weight: 500; }
.h-html { color: var(--h-html); }
.h-css-sel { color: var(--h-css-sel); }
.h-css-prop { color: var(--h-css-prop); }
.h-css-val { color: var(--h-css-val); }
.h-comment { color: var(--h-comment); font-style: italic; }
.h-string { color: var(--h-code); }
.h-math-cmd { color: var(--h-math-cmd); }

#preview-container { flex: 1; overflow-y: auto; padding: 32px 48px; padding-bottom: calc(32px + env(safe-area-inset-bottom)); }
.markdown-body { background: transparent !important; color: var(--text-primary) !important; line-height: 1.8; }
.katex-display { background: transparent !important; color: inherit; padding: 10px 0; }

.dropdown-menu { position: absolute; top: 100%; right: 0; background-color: var(--bg-paper); border: 1px solid var(--border-color); border-radius: 12px; box-shadow: var(--dropdown-shadow); min-width: 180px; display: none; flex-direction: column; padding: 8px; z-index: 1000; }
.dropdown-menu.show { display: flex; }
.dropdown-item { display: flex; align-items: center; gap: 12px; padding: 10px 12px; border: none; background: transparent; color: var(--text-primary); cursor: pointer; font-size: 14px; border-radius: 6px; width: 100%; text-align: left; }
.dropdown-item:hover { background-color: var(--hover-bg); }

/* 通知卡片：與 dropdown 同一的設計語言（paper + 邊框 + 陰影 + 12px 圓角），
   淡入並上浮；避讓 home indicator；尊重 reduced-motion */
#toast { position: fixed; bottom: calc(32px + env(safe-area-inset-bottom)); left: 50%; transform: translate(-50%, 8px); background: var(--bg-paper); color: var(--text-primary); border: 1px solid var(--border-color); box-shadow: var(--dropdown-shadow); padding: 12px 24px; border-radius: 12px; font-size: 14px; opacity: 0; transition: opacity 0.3s, transform 0.3s; z-index: 2000; pointer-events: none; }
#toast.show { opacity: 1; transform: translate(-50%, 0); }
@media (prefers-reduced-motion: reduce) { #toast { transition: none; } }

:root { scrollbar-width: thin; scrollbar-color: var(--border-color) transparent; }

/* 選取反白：半透明主題色調，語法色彩可透過選取範圍顯現（編輯器文字為透明色） */
::selection { background: var(--selection-bg); }

/* 拖放匯入懸停提示 */
body.drag-over .container { outline: 2px dashed var(--accent-color); outline-offset: -6px; }

/* 列印/匯出 PDF：只印預覽區（預覽在 shadow 內，其文字顏色由 localSheet 的 print 覆寫處理）；
   面板背景清為透明——「列印背景圖形」開啟時內容區域仍維持純白（--bg-paper 的 #fbfbfb 會印成淡灰） */
@media print {
    header, #editorPanel, #toast { display: none !important; }
    body { height: auto !important; overflow: visible !important; background: #fff !important; }
    .container { display: block !important; overflow: visible !important; }
    .panel { background: transparent !important; }
    #previewPanel { display: flex !important; }
    #preview-container { padding: 0 !important; overflow: visible !important; }
}

::-webkit-scrollbar { width: 10px; height: 10px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--border-color); border: 2px solid transparent; border-radius: 10px; background-clip: content-box; }
::-webkit-scrollbar-thumb:hover { background: var(--text-secondary); }
::-webkit-scrollbar-corner { background: transparent; }

@media (max-width: 768px) { #preview-container { padding: 24px; padding-bottom: calc(24px + env(safe-area-inset-bottom)); } .url-stats span { font-size: 11px; } }