:root {
    --bg-color: #f4f7fa;
    --surface-color: #ffffff;
    --primary-color: #007aff;
    --primary-hover-color: #0056b3;
    --text-color: #212529;
    --text-muted-color: #6c757d;
    --border-color: #e9ecef;
    --success-color: #28a745;
    --error-color: #dc3545;
    --skeleton-color: #e0e0e0;
    --shadow-sm: 0 1px 3px rgba(0,0,0,0.05);
    --border-radius: 12px;
}

* { box-sizing: border-box; margin: 0; padding: 0; }
html, body { height: 100%; }
body { font-family: 'Inter', sans-serif; background-color: var(--bg-color); color: var(--text-color); line-height: 1.6; }
.app-container { display: flex; height: 100%; }

@keyframes fadeInSlideUp { from { opacity: 0; transform: translateY(10px); } to { opacity: 1; transform: translateY(0); } }
@keyframes spin { from { transform: rotate(0deg); } to { transform: rotate(360deg); } }
@keyframes pulse { 50% { opacity: .5; } }

/* --- Sidebar Navigation --- */
.sidebar { width: 240px; background-color: var(--surface-color); border-right: 1px solid var(--border-color); padding: 2rem 1rem; display: flex; flex-direction: column; flex-shrink: 0; transition: width 0.3s ease; position: relative; }
.sidebar-header { display: flex; align-items: center; gap: 12px; padding: 0 1rem; margin-bottom: 2.5rem; overflow: hidden; }
.logo-icon { width: 36px; height: 36px; color: var(--primary-color); flex-shrink: 0; }
.sidebar-header h1 { font-size: 1.5rem; font-weight: 700; color: var(--text-color); white-space: nowrap; }
#menu-toggle { display: none; }
.tool-menu { list-style: none; }
.tool-item { margin-bottom: 8px; }
.tool-item a { display: flex; align-items: center; gap: 16px; padding: 14px 16px; border-radius: 8px; color: var(--text-muted-color); font-weight: 500; transition: all 0.2s ease; overflow: hidden; text-decoration: none; }
.tool-item .icon { width: 22px; height: 22px; flex-shrink: 0; }
.tool-item span { white-space: nowrap; }
.tool-item a:hover { background-color: #f0f0f5; color: var(--text-color); }
.tool-item.active a { background-color: var(--primary-color); color: #fff; font-weight: 600; }

/* --- Main Content & Form Styling --- */
.main-content { flex-grow: 1; padding: 2rem 3rem; overflow-y: auto; display: none; }
.main-content.active { display: block; animation: fadeInSlideUp 0.4s ease-out; }
.content-header { margin-bottom: 2rem; }
.content-header h1 { font-size: 2.25rem; font-weight: 700; margin-bottom: 0.25rem; }
.content-header p { font-size: 1.1rem; color: var(--text-muted-color); }
.lookup-form { display: flex; gap: 1rem; margin-bottom: 2.5rem; align-items: stretch; }
.lookup-input, .lookup-form select { flex-grow: 1; padding: 0.9rem 1.25rem; font-size: 1rem; border: 1px solid var(--border-color); border-radius: 8px; background-color: var(--surface-color); color: var(--text-color); transition: border-color 0.3s ease, box-shadow 0.3s ease; -webkit-appearance: none; appearance: none; }
.lookup-input:focus, .lookup-form select:focus { outline: none; border-color: var(--primary-color); box-shadow: 0 0 0 3px rgba(0, 123, 255, 0.25); }
.form-group { position: relative; flex-shrink: 0; }
.form-group select { padding-right: 2.5rem; flex-grow: 0; min-width: 120px; }
.form-group::after { content: '▼'; font-size: 0.7rem; color: var(--text-muted-color); position: absolute; right: 1rem; top: 50%; transform: translateY(-50%); pointer-events: none; }
.lookup-button { padding: 0.9rem 2rem; font-size: 1rem; font-weight: 600; border: none; border-radius: 8px; background-color: var(--primary-color); color: #fff; cursor: pointer; transition: background-color 0.3s ease; display: flex; align-items: center; gap: 8px; flex-shrink: 0; }
.lookup-button:disabled { background-color: #a0c9ff; cursor: not-allowed; }
.btn-spinner { width: 18px; height: 18px; border: 3px solid rgba(255,255,255,0.3); border-top-color: #fff; border-radius: 50%; animation: spin 1s linear infinite; }

/* --- Global DNS Checker Specific Styles --- */
.progress-bar-container { height: 4px; background-color: var(--border-color); border-radius: 2px; overflow: hidden; margin-bottom: 1.5rem; display: none; }
.progress-bar { width: 0%; height: 100%; background-color: var(--primary-color); transition: width 0.3s ease; }
.dns-checker-layout { display: grid; grid-template-columns: 2fr 1fr; gap: 2rem; align-items: flex-start; }
#map-container { position: sticky; top: 2rem; height: 500px; }
#map { width:100%; height:100%; border-radius: var(--border-radius); border: 1px solid var(--border-color); box-shadow: var(--shadow-sm); }
.location-card { display: flex; align-items: center; gap: 1rem; padding: 1rem; background-color: var(--surface-color); border: 1px solid var(--border-color); border-radius: 8px; margin-bottom: 1rem; opacity: 0; animation: fadeInSlideUp 0.5s ease-out forwards; }
.location-info { display: flex; align-items: center; gap: 12px; flex-basis: 30%; flex-shrink: 0; }
.location-flag { width: 24px; height: 18px; border-radius: 3px; box-shadow: 0 0 2px rgba(0,0,0,0.2); }
.location-name { font-weight: 600; }
.location-result { flex-grow: 1; margin: 0 1rem; }
.location-result pre { font-family: 'SF Mono', 'Menlo', monospace; font-size: 0.9rem; white-space: pre-wrap; word-break: break-all; }
.location-result .error { color: var(--text-muted-color); font-style: italic; }
.location-status { display: flex; align-items: center; gap: 8px; }
.copy-btn { cursor: pointer; background: none; border: none; color: var(--text-muted-color); transition: color 0.2s; padding: 0; } .copy-btn:hover { color: var(--primary-color); }
.status-icon { width: 24px; height: 24px; } .status-icon.success { color: var(--success-color); } .status-icon.fail { color: var(--error-color); }

/* --- Other Tool Styles & Skeleton Loader --- */
.results-container { display: flex; flex-direction: column; gap: 1.5rem; }
.placeholder { text-align: center; padding: 4rem 2rem; border: 2px dashed var(--border-color); border-radius: var(--border-radius); color: var(--text-muted-color); }
.result-card { background-color: var(--surface-color); border: 1px solid var(--border-color); border-radius: var(--border-radius); box-shadow: var(--shadow-sm); overflow: hidden; animation: fadeInSlideUp 0.4s ease-out; }
.result-header { padding: 1rem 1.5rem; background-color: #f8f9fa; border-bottom: 1px solid var(--border-color); font-weight: 600; font-size: 1.1rem; }
.result-content { padding: 1.5rem; }
.info-list { font-family: 'SF Mono', 'Menlo', monospace; font-size: 0.9rem; } .info-item { display: flex; padding: 0.5rem 0; border-bottom: 1px solid var(--border-color); } .info-item:last-child { border-bottom: none; } .info-label { color: var(--text-muted-color); width: 200px; flex-shrink: 0; } .info-value { font-weight: 600; word-break: break-all; }
.accordion .result-header { cursor: pointer; display: flex; justify-content: space-between; align-items: center; }
.accordion .result-header::after { content: '▲'; font-size: 0.8em; transform: rotate(180deg); transition: transform 0.3s ease; }
.accordion.collapsed .result-header::after { transform: rotate(0deg); } .accordion.collapsed .result-content { display: none; }
.skeleton { animation: pulse 1.5s cubic-bezier(0.4, 0, 0.6, 1) infinite; background-color: var(--skeleton-color); border-radius: 4px; }

/* --- Responsive Design & Menu Toggle --- */
@media (min-width: 993px) {
    #menu-toggle { display: block; position: absolute; top: 1.5rem; right: -16px; width: 32px; height: 32px; background-color: var(--surface-color); border: 1px solid var(--border-color); border-radius: 50%; display: flex; align-items: center; justify-content: center; cursor: pointer; box-shadow: var(--shadow-sm); z-index: 10; transition: transform 0.3s ease; }
    .sidebar-collapsed #menu-toggle { transform: rotate(0deg); } .sidebar:not(.sidebar-collapsed) #menu-toggle { transform: rotate(180deg); }
    .sidebar-collapsed { width: 88px; } .sidebar-collapsed .sidebar-header h1, .sidebar-collapsed .tool-item span { display: none; } .sidebar-collapsed .tool-item a { justify-content: center; }
}
@media (max-width: 1200px) { .dns-checker-layout { grid-template-columns: 1fr; } #map-container { position: static; height: 400px; order: 2; } }
@media (max-width: 992px) { .main-content { padding: 2rem; } .sidebar { width: 88px; } .sidebar-header { justify-content: center; padding: 0; } .sidebar-header h1, .tool-item span { display: none; } .tool-item a { justify-content: center; } }
@media (max-width: 768px) {
    .app-container { flex-direction: column; height: auto; }
    .sidebar { width: 100%; height: auto; flex-direction: row; align-items: center; border-right: none; border-bottom: 1px solid var(--border-color); padding: 0 1rem; min-height: 60px; }
    .sidebar-header { margin-bottom: 0; }
    .tool-menu { display: flex; margin-left: auto; gap: 0.5rem; } .tool-item { margin: 0; } .tool-item a { padding: 10px; } .tool-item .icon { width: 24px; height: 24px; }
    .main-content { padding: 1.5rem; min-height: calc(100vh - 60px); } .content-header h1 { font-size: 1.75rem; }
    .lookup-form { flex-direction: column; } .lookup-form > *, .form-group > select { width: 100%; }
}