:root {
    --bg-editor: #282c34;
    --bg-sidebar: #21252b;
    --bg-gutter: #282c34;
    --fg-text: #abb2bf;
    --fg-comment: #5c6370;
    --fg-gutter: #495162;

    --color-keyword: #c678dd;
    --color-function: #61afef;
    --color-string: #98c379;
    --color-variable: #e06c75;
    --color-number: #d19a66;

    --border: #181a1f;
    --hover-item: #2c313a;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

body {
    background-color: var(--bg-editor);
    color: var(--fg-text);
    font-family: 'Fira Code', 'Menlo', 'Consolas', monospace;
    height: 100vh;
    display: flex;
    overflow: hidden;
}

aside {
    width: 80px;
    background-color: var(--bg-sidebar);
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 20px 0;
    border-right: 1px solid var(--border);
    z-index: 30;
    flex-shrink: 0;
}

.brand-logo {
    width: 64px;       
    height: auto;
    display: block;
    margin-bottom: 25px;
}

#group-edit, #group-read {
    width: 100%;
    display: flex;
    flex-direction: column;
    align-items: center;
}

.tool-btn {
    background: none;
    border: none;
    color: var(--fg-comment);
    text-decoration: none;
    
    width: 42px;
    height: 42px;
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 0; 
    
    cursor: pointer;
    border-radius: 10px;
    margin-bottom: 12px;
    transition: all 0.2s ease;
    position: relative;
}

.tool-btn i {
    font-size: 22px; 
}

.tool-btn:hover { background-color: var(--hover-item); color: var(--fg-text); }
.tool-btn.accent { color: var(--color-function); }
.tool-btn.success { color: var(--color-string); }

.tool-btn:hover::after {
    content: attr(aria-label); position: absolute; left: 60px; top: 50%;
    transform: translateY(-50%); background: var(--bg-sidebar);
    border: 1px solid var(--border); color: var(--fg-text);
    padding: 6px 10px; border-radius: 4px; font-size: 11px;
    white-space: nowrap; pointer-events: none; z-index: 100;
    box-shadow: 0 4px 6px rgba(0,0,0,0.3);
}

.spacer { flex-grow: 1; }

main {
    flex-grow: 1;
    position: relative;
    display: flex;
    flex-direction: column;
    overflow: hidden;
    width: calc(100% - 80px);
}

#editor {
    flex-grow: 1;
    background: var(--bg-editor);
    border: none;
    color: var(--fg-text);
    padding: 20px;
    white-space: pre;
    overflow: auto;
    resize: none;
    outline: none;
    font-family: inherit;
    font-size: 13px;
    line-height: 1.5;
    display: block;
}

#viewer-container {
    display: none;
    flex-grow: 1;
    overflow: auto;
    position: relative;
}

.viewer-layout {
    display: flex;
    min-height: 100%;
    min-width: 100%;
}

.gutter {
    background-color: var(--bg-gutter);
    color: var(--fg-gutter);
    padding: 20px 15px 20px 0; 
    text-align: right;
    border-right: 1px solid var(--border);
    user-select: none;
    flex-shrink: 0;
    min-width: 50px;
    font-size: 13px;
    line-height: 1.5;
}

.code-pane {
    flex-grow: 1;
    padding: 20px;
    overflow-x: visible;
}

pre[class*="language-"], code[class*="language-"] {
    color: var(--fg-text);
    font-family: inherit;
    font-size: 13px;
    line-height: 1.5;
    direction: ltr;
    text-align: left;
    white-space: pre;
    word-spacing: normal;
    tab-size: 4;
    background: transparent !important;
    border: none !important;
    margin: 0 !important;
    padding: 0 !important;
    box-shadow: none !important;
}

footer {
    height: 32px;
    background-color: var(--bg-sidebar);
    border-top: 1px solid var(--border);
    display: flex;
    align-items: center;
    justify-content: flex-end;
    padding: 0 20px;
    font-size: 11px;
    gap: 20px;
    user-select: none;
    color: var(--fg-comment);
    flex-shrink: 0;
}

.stat { display: flex; align-items: center; gap: 6px; }

#toast {
    position: fixed; top: -50px; left: 50%; transform: translateX(-50%);
    background-color: var(--color-function); color: #fff; padding: 8px 20px;
    border-radius: 4px; font-weight: 600; font-size: 13px;
    transition: top 0.3s ease; z-index: 1000;
}
#toast.show { top: 20px; }

::-webkit-scrollbar { width: 10px; height: 10px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: #4b5263; border-radius: 5px; }
::-webkit-scrollbar-thumb:hover { background: #5c6370; }
::-webkit-scrollbar-corner { background: transparent; }

/* Error Page Styles */
.error-container {
    text-align: center;
}

.error-code {
    font-size: 8rem;
    font-weight: 800;
    margin: 0;
    background: linear-gradient(135deg, #fff 0%, #555 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    line-height: 1;
}

.error-message {
    font-size: 1.2rem;
    color: var(--fg-text);
    margin: 20px 0 40px;
    max-width: 500px;
}

.btn-back {
    display: inline-block;
    padding: 12px 24px;
    background-color: var(--color-function);
    color: #fff;
    text-decoration: none;
    border-radius: 8px;
    font-weight: 600;
    font-size: 14px;
    transition: opacity 0.2s;
}

.btn-back:hover {
    opacity: 0.8;
}

@media screen and (max-width: 480px) {
    .error-code { font-size: 5rem; }
    .error-message { font-size: 1rem; }
}