/* ============================================================
   MD Preview - Style Sheet
   ============================================================ */

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

html {
    font-size: 16px;
    -webkit-text-size-adjust: 100%;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial,
        sans-serif, "Apple Color Emoji", "Segoe UI Emoji";
    background-color: #0d1117;
    color: #c9d1d9;
    height: 100vh;
    overflow: hidden;
    display: flex;
    flex-direction: column;
}

/* ----- CSS Custom Properties ----- */
:root {
    --header-height: 56px;
    --tabs-height: 0px;
    --color-bg-primary: #0d1117;
    --color-bg-header: #161b22;
    --color-bg-editor: #1a1f26;
    --color-bg-preview: #ffffff;
    --color-border: #30363d;
    --color-text-primary: #c9d1d9;
    --color-text-header: #f0f6fc;
    --color-accent: #58a6ff;
    --color-btn-bg: #21262d;
    --color-btn-hover: #30363d;
    --color-btn-text: #c9d1d9;
    --color-success: #3fb950;
    --color-danger: #f85149;
}

/* ============================================================
   Header
   ============================================================ */
.header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    min-height: var(--header-height);
    padding: 10px 16px;
    background-color: var(--color-bg-header);
    border-bottom: 1px solid var(--color-border);
    flex-shrink: 0;
    z-index: 10;
    gap: 12px;
}

.header__title {
    font-size: 1.125rem;
    font-weight: 700;
    color: var(--color-text-header);
    letter-spacing: 0.02em;
    white-space: nowrap;
    flex-shrink: 0;
}

.header__actions {
    display: flex;
    align-items: center;
    gap: 8px;
    flex-wrap: wrap;
    justify-content: flex-end;
}

/* ----- File name input ----- */
.filename-input {
    height: 32px;
    min-width: 160px;
    padding: 0 10px;
    font-size: 0.8125rem;
    font-family: inherit;
    color: var(--color-btn-text);
    background-color: var(--color-btn-bg);
    border: 1px solid var(--color-border);
    border-radius: 6px;
    outline: none;
}

.filename-input::placeholder {
    color: #8b949e;
}

.filename-input:focus {
    border-color: var(--color-accent);
    box-shadow: 0 0 0 2px rgba(88, 166, 255, 0.15);
}

/* ----- Buttons ----- */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    height: 32px;
    padding: 0 14px;
    font-size: 0.8125rem;
    font-weight: 500;
    font-family: inherit;
    color: var(--color-btn-text);
    background-color: var(--color-btn-bg);
    border: 1px solid var(--color-border);
    border-radius: 6px;
    cursor: pointer;
    transition: background-color 0.15s ease, border-color 0.15s ease, color 0.15s ease;
    white-space: nowrap;
    user-select: none;
    line-height: 1;
}

.btn:hover {
    background-color: var(--color-btn-hover);
    border-color: #8b949e;
}

.btn:focus-visible {
    outline: 2px solid var(--color-accent);
    outline-offset: 2px;
}

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

.btn--success {
    color: var(--color-success);
    border-color: var(--color-success);
}

.btn--danger {
    color: var(--color-danger);
    border-color: var(--color-danger);
}

/* ============================================================
   Tabs (Mobile Only)
   ============================================================ */
.tabs {
    display: none;
    flex-shrink: 0;
    height: 40px;
    background-color: var(--color-bg-header);
    border-bottom: 1px solid var(--color-border);
}

.tabs__tab {
    flex: 1;
    height: 100%;
    font-size: 0.875rem;
    font-weight: 500;
    font-family: inherit;
    color: #8b949e;
    background: none;
    border: none;
    border-bottom: 2px solid transparent;
    cursor: pointer;
    transition: color 0.15s ease, border-color 0.15s ease;
}

.tabs__tab:hover {
    color: var(--color-text-primary);
}

.tabs__tab--active {
    color: var(--color-accent);
    border-bottom-color: var(--color-accent);
}

.tabs__tab:focus-visible {
    outline: 2px solid var(--color-accent);
    outline-offset: -2px;
}

/* ============================================================
   Main Content Area
   ============================================================ */
.main {
    display: flex;
    flex: 1;
    overflow: hidden;
    height: calc(100vh - var(--header-height) - var(--tabs-height));
}

/* ----- Panes ----- */
.pane {
    width: 50%;
    height: 100%;
    overflow: hidden;
}

.pane--editor {
    border-right: 1px solid var(--color-border);
    position: relative;
}

/* ----- Editor ----- */
.editor {
    display: block;
    width: 100%;
    height: 100%;
    padding: 20px;
    font-family: "SF Mono", "Fira Code", "Fira Mono", "Roboto Mono",
        "Cascadia Code", Menlo, Monaco, Consolas, "Courier New", monospace;
    font-size: 0.875rem;
    line-height: 1.7;
    color: #e6edf3;
    background-color: var(--color-bg-editor);
    border: none;
    outline: none;
    resize: none;
    tab-size: 4;
    -moz-tab-size: 4;
    overflow-y: auto;
}

.editor::selection {
    background-color: rgba(88, 166, 255, 0.3);
}

/* ----- Preview ----- */
.pane--preview {
    overflow-y: auto;
    background-color: var(--color-bg-preview);
}

.preview {
    padding: 24px 32px;
    min-height: 100%;
}

.preview.markdown-body {
    background-color: var(--color-bg-preview);
    color: #1f2328;
}

.preview .task-list-item {
    list-style-type: none;
}

.preview .task-list-item input[type="checkbox"] {
    margin-right: 6px;
}

/* ============================================================
   Scrollbar Styling (Webkit)
   ============================================================ */
.editor::-webkit-scrollbar,
.pane--preview::-webkit-scrollbar {
    width: 10px;
}

.editor::-webkit-scrollbar-track {
    background: var(--color-bg-editor);
}

.editor::-webkit-scrollbar-thumb {
    background-color: #484f58;
    border-radius: 5px;
    border: 2px solid var(--color-bg-editor);
}

.pane--preview::-webkit-scrollbar-track {
    background: var(--color-bg-preview);
}

.pane--preview::-webkit-scrollbar-thumb {
    background-color: #c0c8d0;
    border-radius: 5px;
    border: 2px solid var(--color-bg-preview);
}

/* ============================================================
   Drop Overlay (Drag & Drop)
   ============================================================ */
.drop-overlay {
    display: none;
    position: absolute;
    inset: 0;
    z-index: 20;
    background-color: rgba(88, 166, 255, 0.08);
    border: 3px dashed var(--color-accent);
    border-radius: 8px;
    margin: 6px;
    pointer-events: none;
    align-items: center;
    justify-content: center;
}

.drop-overlay--visible {
    display: flex;
}

.drop-overlay__content {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 12px;
    color: var(--color-accent);
    font-size: 0.9375rem;
    font-weight: 600;
    user-select: none;
}

.drop-overlay__icon {
    opacity: 0.85;
}

/* ============================================================
   View Mode (Preview Full-Width)
   ============================================================ */
body.view-mode .pane--editor {
    display: none;
}

body.view-mode .pane--preview {
    width: 100%;
    border-left: none;
}

body.view-mode .btn--reset {
    display: none;
}

body.view-mode .btn--view {
    background-color: var(--color-accent);
    color: #ffffff;
    border-color: var(--color-accent);
}

body.view-mode .btn--view:hover {
    background-color: #4393e6;
    border-color: #4393e6;
}

/* ============================================================
   Responsive: Mobile (768px 以下)
   ============================================================ */
@media screen and (max-width: 768px) {
    :root {
        --tabs-height: 40px;
        --header-height: auto;
    }

    .tabs {
        display: flex;
    }

    .header {
        padding: 10px 12px;
        align-items: flex-start;
        flex-direction: column;
    }

    .header__title {
        font-size: 1rem;
    }

    .header__actions {
        width: 100%;
        gap: 6px;
    }

    .filename-input {
        display: none;
    }

    .btn {
        height: 28px;
        padding: 0 10px;
        font-size: 0.75rem;
    }

    .main {
        position: relative;
    }

    .pane {
        position: absolute;
        top: 0;
        left: 0;
        width: 100%;
        height: 100%;
        display: none;
    }

    .pane--editor {
        border-right: none;
    }

    .pane--active {
        display: block;
    }

    .editor {
        font-size: 0.8125rem;
        padding: 16px;
    }

    .preview {
        padding: 16px;
    }

    .btn--view {
        display: none;
    }
}

/* ============================================================
   Print / PDF Export Helper
   ============================================================ */
@media print {
    .header,
    .tabs,
    .pane--editor {
        display: none !important;
    }

    .main {
        display: block;
    }

    .pane--preview {
        width: 100%;
        overflow: visible;
    }
}