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

:root {
    --primary-color: #2563eb;
    --primary-dark: #1e40af;
    --secondary-color: #10b981;
    --background: #f8fafc;
    --card-background: #ffffff;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --border-color: #e2e8f0;
    --shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px 0 rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --azure-color: #0078d4;
    --aws-color: #ff9900;
    --gcp-color: #4285f4;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background-color: var(--background);
    color: var(--text-primary);
    line-height: 1.6;
}

/* Header & Navigation */
header {
    background: var(--card-background);
    box-shadow: var(--shadow);
    position: sticky;
    top: 0;
    z-index: 100;
}

.navbar {
    max-width: 1400px;
    margin: 0 auto;
    padding: 1rem 2rem;
}

.nav-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.logo-text {
    display: flex;
    flex-direction: column;
    gap: 0.1rem;
}

.logo-placeholder {
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    border-radius: 8px;
    color: white;
    flex-shrink: 0;
}

.logo-placeholder svg {
    width: 24px;
    height: 24px;
}

.logo h1 {
    font-size: 1.5rem;
    color: var(--primary-color);
    font-weight: 700;
    margin: 0;
    white-space: nowrap;
    line-height: 1.2;
}

.brand-tag {
    font-size: 0.7rem;
    color: var(--text-secondary);
    font-weight: 500;
    line-height: 1;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 2rem;
}

.nav-menu a {
    text-decoration: none;
    color: var(--text-secondary);
    font-weight: 500;
    transition: color 0.2s;
}

.nav-menu a:hover,
.nav-menu a.active {
    color: var(--primary-color);
}

/* Main Container */
.main-container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 2rem;
}

.content-wrapper {
    display: grid;
    grid-template-columns: 1fr 350px;
    gap: 2rem;
    margin-bottom: 3rem;
}

/* Calculator Section */
.calculator-section {
    min-width: 0;
    display: flex;
    flex-direction: column;
    gap: 2rem;
}

.calculator-card {
    background: var(--card-background);
    border-radius: 12px;
    padding: 2rem;
    box-shadow: var(--shadow-lg);
}

.analyzer-card {
    border: 2px solid var(--primary-color);
    background: linear-gradient(to bottom, var(--card-background) 0%, #f0f7ff 100%);
}

.analyzer-form {
    margin-bottom: 1rem;
}

.input-with-button {
    display: flex;
    gap: 0.75rem;
}

.input-with-button input {
    flex: 1;
}

.analyze-btn {
    background: var(--primary-color);
    color: white;
    border: none;
    padding: 0.75rem 1.5rem;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: background-color 0.2s;
    white-space: nowrap;
}

.analyze-btn:hover {
    background: var(--primary-dark);
}

.analysis-results {
    margin-top: 2rem;
    padding-top: 2rem;
    border-top: 2px solid var(--border-color);
}

.analysis-header {
    margin-bottom: 1.5rem;
}

.analysis-header h3 {
    color: var(--text-primary);
    font-size: 1.5rem;
}

.analysis-content {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.analysis-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0.75rem;
    background: var(--background);
    border-radius: 8px;
    border-left: 3px solid var(--primary-color);
}

.analysis-item.highlight {
    background: linear-gradient(to right, #e0f2fe, var(--background));
    border-left-color: var(--primary-color);
    font-weight: 600;
}

.analysis-label {
    font-weight: 600;
    color: var(--text-secondary);
}

.analysis-value {
    font-weight: 700;
    color: var(--primary-color);
    font-family: 'Courier New', monospace;
    font-size: 1.05rem;
}

.analysis-explanation,
.analysis-recommendation {
    margin-top: 1rem;
    padding: 1.25rem;
    background: var(--background);
    border-radius: 8px;
    border-left: 4px solid var(--secondary-color);
}

.analysis-explanation h4,
.analysis-recommendation h4 {
    margin-bottom: 0.75rem;
    color: var(--text-primary);
}

.analysis-explanation p,
.analysis-recommendation p {
    margin-bottom: 0.75rem;
    color: var(--text-secondary);
    line-height: 1.7;
}

.analysis-explanation ul,
.analysis-recommendation ul {
    margin-left: 1.5rem;
    margin-top: 0.5rem;
    color: var(--text-secondary);
    line-height: 1.8;
}

.analysis-explanation li,
.analysis-recommendation li {
    margin-bottom: 0.5rem;
}

.use-calculator-btn {
    margin-top: 1rem;
    background: var(--secondary-color);
    color: white;
    border: none;
    padding: 0.875rem 1.5rem;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: background-color 0.2s, transform 0.2s;
    width: 100%;
}

.use-calculator-btn:hover {
    background: #059669;
    transform: translateY(-2px);
    box-shadow: var(--shadow);
}

.calculator-card h2 {
    font-size: 1.875rem;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.subtitle {
    color: var(--text-secondary);
    margin-bottom: 2rem;
    font-size: 0.95rem;
}

.calculator-form {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.form-group {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.form-group label {
    font-weight: 600;
    color: var(--text-primary);
    font-size: 0.95rem;
}

.radio-group {
    display: flex;
    gap: 1.5rem;
    flex-wrap: wrap;
}

.radio-label {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    cursor: pointer;
    font-weight: normal;
}

.radio-label input[type="radio"] {
    cursor: pointer;
    width: 18px;
    height: 18px;
}

.info-text {
    font-size: 0.875rem;
    color: var(--text-secondary);
    font-style: italic;
}

input[type="text"],
select {
    padding: 0.75rem;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    font-size: 1rem;
    transition: border-color 0.2s;
}

input[type="text"]:focus,
select:focus {
    outline: none;
    border-color: var(--primary-color);
}

input[type="range"] {
    width: 100%;
    height: 8px;
    border-radius: 4px;
    background: var(--border-color);
    outline: none;
    -webkit-appearance: none;
    appearance: none;
}

input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 20px;
    height: 20px;
    border-radius: 50%;
    background: var(--primary-color);
    cursor: pointer;
}

input[type="range"]::-moz-range-thumb {
    appearance: none;
    width: 20px;
    height: 20px;
    border-radius: 50%;
    background: var(--primary-color);
    cursor: pointer;
    border: none;
}

input[type="range"]::-moz-range-thumb {
    width: 20px;
    height: 20px;
    border-radius: 50%;
    background: var(--primary-color);
    cursor: pointer;
    border: none;
}

.range-value {
    text-align: center;
    font-weight: 600;
    color: var(--primary-color);
    font-size: 1.125rem;
}

.calculate-btn {
    background: var(--primary-color);
    color: white;
    border: none;
    padding: 0.875rem 1.5rem;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: background-color 0.2s;
}

.calculate-btn:hover {
    background: var(--primary-dark);
}

/* Results Section */
.results-section {
    margin-top: 2rem;
    padding-top: 2rem;
    border-top: 2px solid var(--border-color);
}

.results-section h3 {
    margin-bottom: 1.5rem;
    color: var(--text-primary);
}

.results-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 1rem;
}

.result-item {
    display: flex;
    flex-direction: column;
    gap: 0.25rem;
}

.result-item.full-width {
    grid-column: 1 / -1;
}

.result-label {
    font-size: 0.875rem;
    color: var(--text-secondary);
    font-weight: 500;
}

.result-value {
    font-size: 1rem;
    color: var(--text-primary);
    font-weight: 600;
    font-family: 'Courier New', monospace;
}

/* Bit Visualization */
.bit-visualization {
    margin-top: 2rem;
    padding: 1.5rem;
    background: linear-gradient(to bottom, #f8fafc, #ffffff);
    border-radius: 12px;
    border: 2px solid var(--border-color);
}

.bit-visualization h4 {
    margin-top: 0;
    margin-bottom: 1.5rem;
    color: var(--text-primary);
    font-size: 1.125rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.bit-visualization h4::before {
    content: "🔢";
    font-size: 1.25rem;
}

.bit-visualization-container {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.bit-stats {
    display: flex;
    justify-content: center;
    gap: 2rem;
    margin-bottom: 1rem;
    padding: 0.75rem;
    background: var(--background);
    border-radius: 8px;
}

.stat-item {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.stat-label {
    font-weight: 600;
    color: var(--text-secondary);
    font-size: 0.875rem;
}

.stat-value {
    font-size: 1.125rem;
    font-weight: 700;
    color: var(--primary-color);
    font-family: 'Courier New', monospace;
}

.octet-group {
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 1rem 1.5rem;
    background: var(--card-background);
    border-radius: 8px;
    border: 1px solid var(--border-color);
    overflow-x: auto;
    min-height: 60px;
}

/* Single-line bit visualization */
.single-line-bits-container {
    display: flex;
    align-items: flex-end;
    justify-content: center;
    gap: 0.5rem;
    flex-wrap: nowrap;
    white-space: nowrap;
    padding: 0.75rem 0;
    width: 100%;
}

.octet-wrapper-stacked {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.4rem;
    flex-shrink: 0;
}

.octet-decimal-stacked {
    font-size: 0.85rem;
    font-weight: 700;
    color: var(--text-primary);
    font-family: 'Courier New', monospace;
    padding: 0.2rem 0.4rem;
    background: var(--background);
    border-radius: 4px;
    text-align: center;
    line-height: 1.2;
    border: 1px solid var(--border-color);
    min-width: 35px;
}

.bits-stacked {
    display: flex;
    align-items: center;
    gap: 0.12rem;
    flex-shrink: 0;
}

.bit-square-inline {
    width: 20px;
    height: 20px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    border: 1.5px solid transparent;
    border-radius: 3px;
    font-weight: 700;
    font-size: 0.7rem;
    cursor: help;
    transition: all 0.2s;
    font-family: 'Courier New', monospace;
    flex-shrink: 0;
    line-height: 1;
}

.bit-square-inline:hover {
    transform: scale(1.2);
    box-shadow: 0 2px 6px rgba(0, 0, 0, 0.25);
    z-index: 10;
    position: relative;
}

.bit-square-inline.network-bit {
    background: linear-gradient(135deg, #3b82f6, #2563eb);
    color: white;
    border-color: #1e40af;
}

.bit-square-inline.host-bit {
    background: linear-gradient(135deg, #10b981, #059669);
    color: white;
    border-color: #047857;
}

.dot-separator-stacked {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-secondary);
    padding: 0 0.3rem;
    display: flex;
    align-items: flex-end;
    line-height: 1;
    flex-shrink: 0;
    height: 20px;
    padding-bottom: 0.2rem;
}

.bit-square {
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    border: 2px solid var(--border-color);
    border-radius: 4px;
    font-weight: 700;
    font-size: 0.75rem;
    cursor: help;
    transition: all 0.2s;
    font-family: 'Courier New', monospace;
}

.bit-square:hover {
    transform: scale(1.1);
    box-shadow: var(--shadow);
    z-index: 10;
    position: relative;
}

.bit-square.network-bit {
    background: linear-gradient(135deg, #3b82f6, #2563eb);
    color: white;
    border-color: #1e40af;
}

.bit-square.host-bit {
    background: linear-gradient(135deg, #10b981, #059669);
    color: white;
    border-color: #047857;
}

.bit-legend {
    display: flex;
    justify-content: center;
    gap: 2rem;
    padding: 1rem;
    background: var(--background);
    border-radius: 8px;
}

.legend-item {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.legend-color {
    width: 24px;
    height: 24px;
    border-radius: 4px;
    border: 2px solid var(--border-color);
}

.legend-color.network-bit-color {
    background: linear-gradient(135deg, #3b82f6, #2563eb);
    border-color: #1e40af;
}

.legend-color.host-bit-color {
    background: linear-gradient(135deg, #10b981, #059669);
    border-color: #047857;
}

.legend-label {
    font-weight: 600;
    color: var(--text-primary);
    font-size: 0.875rem;
}

/* Subnet Division Diagram */
.subnet-division-diagram {
    margin-top: 2rem;
    padding: 1.5rem;
    background: linear-gradient(to bottom, #f8fafc, #ffffff);
    border-radius: 12px;
    border: 2px solid var(--border-color);
}

.diagram-header {
    margin-bottom: 1.5rem;
}

.diagram-header h4 {
    margin-bottom: 1rem;
    color: var(--text-primary);
    font-size: 1.125rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.diagram-header h4::before {
    content: "📦";
    font-size: 1.25rem;
}

.division-summary {
    display: flex;
    gap: 2rem;
    flex-wrap: wrap;
}

.summary-item {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.75rem 1rem;
    background: var(--card-background);
    border-radius: 8px;
    border-left: 3px solid var(--primary-color);
}

.summary-label {
    font-weight: 600;
    color: var(--text-secondary);
    font-size: 0.875rem;
}

.summary-value {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--primary-color);
    font-family: 'Courier New', monospace;
}

.subnets-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
    gap: 1rem;
    margin-bottom: 1rem;
    max-height: 600px;
    overflow-y: auto;
    padding: 0.5rem;
}

.subnet-box {
    background: var(--card-background);
    border: 2px solid var(--border-color);
    border-radius: 8px;
    padding: 1rem;
    text-align: center;
    transition: all 0.3s ease;
    animation: fadeInUp 0.4s ease-out forwards;
    opacity: 0;
    transform: translateY(10px);
}

.subnet-box:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary-color);
}

@keyframes fadeInUp {
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.subnet-box.subnet-small {
    border-left-color: #ef4444;
    background: linear-gradient(to bottom, #fef2f2, var(--card-background));
}

.subnet-box.subnet-small-medium {
    border-left-color: #f59e0b;
    background: linear-gradient(to bottom, #fffbeb, var(--card-background));
}

.subnet-box.subnet-medium {
    border-left-color: #10b981;
    background: linear-gradient(to bottom, #f0fdf4, var(--card-background));
}

.subnet-box.subnet-large {
    border-left-color: #3b82f6;
    background: linear-gradient(to bottom, #eff6ff, var(--card-background));
}

.subnet-box.subnet-selected {
    border: 3px solid var(--primary-color);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.2), var(--shadow-lg);
    transform: scale(1.05);
    z-index: 10;
    position: relative;
}

.subnet-box.subnet-selected:hover {
    transform: scale(1.08);
}

.selected-badge {
    display: inline-block;
    background: var(--primary-color);
    color: white;
    font-size: 0.65rem;
    padding: 0.2rem 0.5rem;
    border-radius: 12px;
    margin-left: 0.5rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.subnet-network-info {
    margin-top: 0.75rem;
    padding-top: 0.75rem;
    border-top: 1px solid var(--border-color);
    font-size: 0.75rem;
    text-align: left;
}

.network-id,
.broadcast-id {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    margin-bottom: 0.75rem;
    padding: 0.5rem;
    background: var(--background);
    border-radius: 4px;
    width: 100%;
}

.network-id:last-child,
.broadcast-id:last-child {
    margin-bottom: 0;
}

.info-label {
    font-weight: 600;
    color: var(--text-secondary);
    font-size: 0.7rem;
    margin-bottom: 0.25rem;
    display: block;
}

.info-value {
    font-family: 'Courier New', monospace;
    font-weight: 600;
    color: var(--primary-color);
    font-size: 0.8rem;
    display: block;
    word-break: break-all;
}

/* Class Mismatch Message */
.class-mismatch-message {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.875rem 1rem;
    margin: 1rem 0;
    background: linear-gradient(to right, #dbeafe, #e0f2fe);
    border-left: 4px solid var(--primary-color);
    border-radius: 8px;
    font-size: 0.875rem;
    color: var(--text-primary);
    animation: slideIn 0.3s ease-out;
}

@keyframes slideIn {
    from {
        opacity: 0;
        transform: translateX(-10px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

.message-icon {
    font-size: 1.25rem;
    flex-shrink: 0;
}

.message-text {
    flex: 1;
    line-height: 1.5;
}

.message-text strong {
    color: var(--primary-color);
    font-weight: 700;
}

.message-close {
    background: none;
    border: none;
    font-size: 1.5rem;
    color: var(--text-secondary);
    cursor: pointer;
    padding: 0;
    width: 24px;
    height: 24px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 4px;
    transition: all 0.2s;
    flex-shrink: 0;
}

.message-close:hover {
    background: rgba(0, 0, 0, 0.1);
    color: var(--text-primary);
}

.subnet-number {
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.subnet-hosts {
    margin: 0.75rem 0;
}

.hosts-value {
    display: block;
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
    font-family: 'Courier New', monospace;
    line-height: 1.2;
}

.hosts-label {
    display: block;
    font-size: 0.75rem;
    color: var(--text-secondary);
    margin-top: 0.25rem;
}

.subnet-details {
    display: flex;
    justify-content: space-around;
    margin-top: 0.75rem;
    padding-top: 0.75rem;
    border-top: 1px solid var(--border-color);
    font-size: 0.7rem;
    color: var(--text-secondary);
}

.detail-item {
    font-size: 0.7rem;
}

.more-subnets-message {
    grid-column: 1 / -1;
    padding: 2rem;
    text-align: center;
    background: var(--background);
    border-radius: 8px;
    border: 2px dashed var(--border-color);
}

.more-subnets-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.5rem;
}

.more-subnets-icon {
    font-size: 2rem;
    color: var(--text-secondary);
    line-height: 1;
}

.more-subnets-message p {
    margin: 0;
    color: var(--text-secondary);
    font-size: 0.875rem;
}

/* CIDR Calculator - Subnets Table */
.table-container {
    overflow-x: auto;
    margin-top: 1rem;
    border-radius: 8px;
    border: 1px solid var(--border-color);
}

.subnets-table {
    width: 100%;
    border-collapse: collapse;
    background: var(--card-background);
    font-size: 0.875rem;
}

.subnets-table thead {
    background: var(--background);
    position: sticky;
    top: 0;
    z-index: 10;
}

.subnets-table th {
    padding: 0.875rem 1rem;
    text-align: left;
    font-weight: 600;
    color: var(--text-primary);
    border-bottom: 2px solid var(--border-color);
    white-space: nowrap;
    font-size: 0.8rem;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.subnets-table td {
    padding: 0.875rem 1rem;
    border-bottom: 1px solid var(--border-color);
    color: var(--text-primary);
}

.subnets-table tbody tr:hover {
    background: var(--background);
}

.subnets-table tbody tr:last-child td {
    border-bottom: none;
}

.subnets-table code {
    background: var(--background);
    padding: 0.25rem 0.5rem;
    border-radius: 4px;
    font-family: 'Courier New', monospace;
    font-size: 0.85rem;
    color: var(--primary-color);
    font-weight: 600;
}

.subnets-table td:first-child {
    font-weight: 600;
    color: var(--primary-color);
}

/* CIDR Calculator - Subnet Division Control */
.subnet-division-control {
    margin-top: 2rem;
    padding-top: 2rem;
    border-top: 2px solid var(--border-color);
}

.division-control-header h4 {
    margin: 0 0 1rem 0;
    color: var(--primary-color);
    font-size: 1.125rem;
}

.division-control-content {
    display: flex;
    gap: 1rem;
    align-items: flex-end;
}

.division-control-content .form-group {
    flex: 1;
    margin: 0;
}

.divide-btn {
    padding: 0.875rem 2rem;
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    color: white;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
    white-space: nowrap;
}

.divide-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(37, 99, 235, 0.3);
}

.divide-btn:active {
    transform: translateY(0);
}

/* CIDR Calculator - Subnet Selector */
.subnet-selector {
    margin: 0.75rem 0;
}

.subnet-select {
    width: 100%;
    padding: 0.875rem 1rem;
    font-size: 1rem;
    font-family: inherit;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    background: var(--card-background);
    color: var(--text-primary);
    cursor: pointer;
    transition: all 0.2s;
    appearance: none;
    -webkit-appearance: none;
    -moz-appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%232563eb' d='M6 9L1 4h10z'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 1rem center;
    background-size: 12px;
    padding-right: 2.5rem;
}

.subnet-select:hover {
    border-color: var(--primary-color);
}

.subnet-select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.subnet-select option {
    padding: 0.5rem;
    background: var(--card-background);
    color: var(--text-primary);
}

/* CIDR Calculator - Subnet Box Styles */
.subnet-box-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 0.75rem;
    padding-bottom: 0.75rem;
    border-bottom: 1px solid var(--border-color);
}

.subnet-box-content {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.subnet-info-line {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    gap: 0.25rem;
}

.subnet-label {
    font-size: 0.7rem;
    font-weight: 600;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.subnet-value {
    font-family: 'Courier New', monospace;
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--primary-color);
    word-break: break-all;
}

/* CIDR Explanation Styles */
.explanation-content {
    padding: 1.25rem;
    background: var(--background);
    border-radius: 8px;
    border-left: 4px solid var(--primary-color);
}

.explanation-content h4 {
    margin: 0 0 1rem 0;
    color: var(--primary-color);
    font-size: 1.125rem;
}

.explanation-content p {
    margin: 0.75rem 0;
    line-height: 1.6;
    color: var(--text-primary);
}

.explanation-content ul {
    margin: 0.75rem 0;
    padding-left: 1.5rem;
}

.explanation-content li {
    margin: 0.5rem 0;
    line-height: 1.6;
}

.explanation-content strong {
    color: var(--primary-color);
    font-weight: 600;
}

.explanation-content sup {
    font-size: 0.7em;
    vertical-align: super;
}

.info-note {
    margin-top: 1rem;
    padding: 0.875rem;
    background: rgba(37, 99, 235, 0.1);
    border-radius: 6px;
    border-left: 3px solid var(--primary-color);
    font-size: 0.875rem;
    color: var(--text-primary);
}

/* Responsive Table */
@media (max-width: 768px) {
    .table-container {
        margin: 0 -1rem;
        border-left: none;
        border-right: none;
        border-radius: 0;
    }

    .subnets-table {
        font-size: 0.75rem;
    }

    .subnets-table th,
    .subnets-table td {
        padding: 0.625rem 0.75rem;
    }

    .subnets-table th {
        font-size: 0.7rem;
    }

    .subnets-table code {
        font-size: 0.75rem;
        padding: 0.2rem 0.4rem;
    }

    .subnet-box-header {
        flex-direction: column;
        align-items: flex-start;
        gap: 0.5rem;
    }
}

/* Nested Subnet Division Styles */
.subnet-divide-section {
    margin-top: 0.75rem;
    padding-top: 0.75rem;
    border-top: 1px solid var(--border-color);
}

.divide-further-btn {
    width: 100%;
    padding: 0.625rem 1rem;
    background: linear-gradient(135deg, var(--secondary-color), #059669);
    color: white;
    border: none;
    border-radius: 6px;
    font-size: 0.875rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
}

.divide-further-btn:hover {
    background: linear-gradient(135deg, #059669, #047857);
    transform: translateY(-1px);
    box-shadow: 0 4px 6px rgba(16, 185, 129, 0.3);
}

.divide-further-btn:active {
    transform: translateY(0);
}

.cannot-divide {
    font-size: 0.75rem;
    color: var(--text-secondary);
    font-style: italic;
    text-align: center;
    padding: 0.5rem;
}

.divide-form {
    display: flex;
    gap: 0.5rem;
    margin-top: 0.5rem;
    padding: 0.75rem;
    background: var(--background);
    border-radius: 6px;
    border: 1px solid var(--border-color);
}

.divide-input {
    flex: 1;
    padding: 0.5rem;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    font-size: 0.875rem;
    font-family: 'Courier New', monospace;
}

.divide-input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.divide-submit-btn {
    padding: 0.5rem 1rem;
    background: var(--primary-color);
    color: white;
    border: none;
    border-radius: 4px;
    font-size: 0.875rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
}

.divide-submit-btn:hover {
    background: var(--primary-dark);
}

/* Nested Subnet Rows in Table */
.nested-subnet-row {
    background: var(--background) !important;
}

.nested-subnet-row:hover {
    background: #f1f5f9 !important;
}

.nested-indicator {
    color: var(--secondary-color);
    font-weight: 700;
    margin-right: 0.25rem;
    font-size: 0.9rem;
}

/* Nested Division Message */
.nested-division-message {
    margin-bottom: 1.5rem;
    padding: 1rem;
    background: linear-gradient(to right, #d1fae5, #a7f3d0);
    border-left: 4px solid var(--secondary-color);
    border-radius: 8px;
    animation: slideIn 0.3s ease-out;
}

.nested-division-message .message-content {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.nested-division-message strong {
    color: var(--secondary-color);
    font-size: 0.95rem;
}

.nested-division-message p {
    margin: 0;
    font-size: 0.875rem;
    color: var(--text-primary);
}

/* CIDR Calculator - Horizontal Subnet Cards */
.subnets-container {
    display: flex;
    flex-direction: column;
    gap: 1rem;
    margin-top: 1.5rem;
}

.subnet-card-horizontal {
    background: var(--card-background);
    border: 2px solid var(--border-color);
    border-radius: 12px;
    padding: 1.25rem;
    transition: all 0.2s;
    position: relative;
}

.subnet-card-horizontal:hover {
    border-color: var(--primary-color);
    box-shadow: 0 4px 12px rgba(37, 99, 235, 0.1);
}

.subnet-card-horizontal.level-0 {
    border-left: 4px solid var(--primary-color);
}

.subnet-card-horizontal.level-1 {
    border-left: 4px solid var(--secondary-color);
    background: #f0fdf4;
}

.subnet-card-horizontal.level-2 {
    border-left: 4px solid #f59e0b;
    background: #fffbeb;
}

.subnet-card-content {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.subnet-card-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 0.75rem;
    padding-bottom: 0.75rem;
    border-bottom: 1px solid var(--border-color);
}

.subnet-card-title {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.subnet-number {
    font-size: 1.125rem;
    font-weight: 700;
    color: var(--primary-color);
}

.subnet-level-badge {
    font-size: 0.75rem;
    padding: 0.25rem 0.5rem;
    background: var(--secondary-color);
    color: white;
    border-radius: 12px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.subnet-card-cidr {
    font-family: 'Courier New', monospace;
    font-size: 0.95rem;
    font-weight: 600;
    color: var(--text-secondary);
    background: var(--background);
    padding: 0.375rem 0.75rem;
    border-radius: 6px;
}

.subnet-card-body {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.subnet-info-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 0.75rem;
}

.subnet-info-item {
    display: flex;
    flex-direction: column;
    gap: 0.25rem;
}

.subnet-info-label {
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.subnet-info-value {
    font-family: 'Courier New', monospace;
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--text-primary);
}

.subnet-info-value.highlight {
    color: var(--primary-color);
    font-size: 1rem;
}

.subnet-card-footer {
    padding-top: 0.75rem;
    border-top: 1px solid var(--border-color);
}

.subnet-divide-control {
    display: flex;
    gap: 0.75rem;
    align-items: center;
}

.subnet-divide-select {
    flex: 1;
    padding: 0.625rem 0.875rem;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    font-size: 0.875rem;
    background: var(--card-background);
    color: var(--text-primary);
    cursor: pointer;
}

.subnet-divide-btn {
    padding: 0.625rem 1.25rem;
    background: linear-gradient(135deg, var(--secondary-color), #059669);
    color: white;
    border: none;
    border-radius: 6px;
    font-size: 0.875rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
    white-space: nowrap;
}

.subnet-divide-btn:hover {
    background: linear-gradient(135deg, #059669, #047857);
    transform: translateY(-1px);
    box-shadow: 0 2px 8px rgba(16, 185, 129, 0.3);
}

.cannot-divide-msg {
    font-size: 0.875rem;
    color: var(--text-secondary);
    font-style: italic;
}

.divided-msg {
    font-size: 0.875rem;
    color: var(--secondary-color);
    font-weight: 600;
}

/* Nested Subnet Children */
.subnet-children {
    margin-top: 1rem;
    padding-left: 1rem;
    border-left: 2px dashed var(--border-color);
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
    position: relative;
}

.subnet-children .subnet-card-horizontal {
    margin-left: 0;
}

/* Compact view for deep nesting */
.subnet-card-content.compact-view {
    padding: 0.875rem;
}

.subnet-card-content.compact-view .subnet-card-header {
    flex-wrap: wrap;
    gap: 0.5rem;
}

.subnet-card-content.compact-view .subnet-info-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: 0.5rem;
}

.subnet-card-content.compact-view .subnet-info-label {
    font-size: 0.7rem;
}

.subnet-card-content.compact-view .subnet-info-value {
    font-size: 0.85rem;
}

.subnet-card-content.compact-view .subnet-card-cidr {
    font-size: 0.85rem;
    padding: 0.25rem 0.5rem;
}

/* Visual hierarchy indicator for deep levels */
.subnet-card-horizontal.level-4,
.subnet-card-horizontal.level-5,
.subnet-card-horizontal.level-6 {
    border-left-width: 3px;
}

.subnet-card-horizontal.level-4 {
    border-left-color: #f59e0b;
}

.subnet-card-horizontal.level-5 {
    border-left-color: #ef4444;
}

.subnet-card-horizontal.level-6 {
    border-left-color: #8b5cf6;
}

/* Prevent horizontal overflow for deep nesting */
.subnets-container {
    overflow-x: auto;
    max-width: 100%;
}

.subnet-card-horizontal {
    min-width: 0;
    flex-shrink: 0;
}

/* Better wrapping for deep levels */
@media (max-width: 1024px) {
    .subnet-card-content {
        margin-left: 0 !important;
    }
    
    .subnet-children {
        padding-left: 0.5rem;
        margin-left: 0.5rem;
    }
    
    .subnet-card-horizontal.level-3,
    .subnet-card-horizontal.level-4,
    .subnet-card-horizontal.level-5,
    .subnet-card-horizontal.level-6 {
        border-left-width: 4px;
    }
}

/* Responsive adjustments */
@media (max-width: 768px) {
    .division-control-content {
        flex-direction: column;
        align-items: stretch;
    }
    
    .divide-btn {
        width: 100%;
    }
    
    .subnet-card-header {
        flex-direction: column;
        align-items: flex-start;
    }
    
    .subnet-info-grid {
        grid-template-columns: 1fr;
    }
    
    .subnet-divide-control {
        flex-direction: column;
    }
    
    .subnet-divide-btn {
        width: 100%;
    }
    
    .subnet-children {
        padding-left: 0.5rem;
    }
}

/* Pagination Controls */
.pagination-controls {
    display: flex;
    flex-direction: column;
    gap: 1rem;
    padding: 1.5rem;
    background: var(--background);
    border-radius: 8px;
    margin: 1.5rem 0;
    border: 1px solid var(--border-color);
}

.pagination-top {
    margin-bottom: 0;
}

.pagination-bottom {
    margin-top: 0;
}

.pagination-info {
    text-align: center;
    font-size: 0.875rem;
    color: var(--text-secondary);
    font-weight: 500;
}

.pagination-buttons {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 0.5rem;
    flex-wrap: wrap;
}

.pagination-numbers {
    display: flex;
    gap: 0.25rem;
    align-items: center;
}

.pagination-btn {
    padding: 0.5rem 0.875rem;
    border: 1px solid var(--border-color);
    background: var(--card-background);
    color: var(--text-primary);
    border-radius: 6px;
    font-size: 0.875rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s;
    min-width: 40px;
}

.pagination-btn:hover:not(:disabled) {
    background: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
    transform: translateY(-1px);
}

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

.pagination-btn.active {
    background: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
    font-weight: 700;
}

.pagination-ellipsis {
    padding: 0 0.5rem;
    color: var(--text-secondary);
    font-weight: 600;
}

@media (max-width: 768px) {
    .pagination-buttons {
        flex-direction: column;
        width: 100%;
    }
    
    .pagination-btn {
        width: 100%;
    }
    
    .pagination-numbers {
        width: 100%;
        justify-content: center;
        flex-wrap: wrap;
    }
}

.more-subnets-note {
    font-weight: 600;
    color: var(--primary-color) !important;
    margin-top: 0.5rem !important;
}

.diagram-footer {
    margin-top: 1.5rem;
    padding-top: 1rem;
    border-top: 1px solid var(--border-color);
}

.diagram-note {
    font-size: 0.875rem;
    color: var(--text-secondary);
    line-height: 1.6;
    margin: 0;
}

/* Subnetting Explanation Section - Top */
.subnetting-explanation-top {
    margin-top: 2rem;
    margin-bottom: 2rem;
    padding: 1.5rem;
    background: linear-gradient(to bottom, #f0f9ff, #ffffff);
    border-radius: 12px;
    border: 2px solid var(--primary-color);
    box-shadow: var(--shadow);
}

.explanation-content-top h4 {
    margin-top: 0;
    margin-bottom: 1rem;
    color: var(--text-primary);
    font-size: 1.25rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.main-explanation {
    font-size: 1.125rem;
    margin-bottom: 1.5rem;
    color: var(--text-primary);
    line-height: 1.7;
    padding: 1rem;
    background: var(--card-background);
    border-radius: 8px;
    border-left: 4px solid var(--primary-color);
}

/* Subnetting Explanation Section - Bottom */
.subnetting-explanation {
    margin-top: 2rem;
    padding: 1.5rem;
    background: linear-gradient(to bottom, #fef3c7, #ffffff);
    border-radius: 12px;
    border: 2px solid #f59e0b;
}

.explanation-content h5 {
    margin-top: 0;
    margin-bottom: 1rem;
    color: var(--text-primary);
    font-size: 1.125rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.explanation-content > p {
    margin-bottom: 1.5rem;
    color: var(--text-secondary);
    line-height: 1.7;
}

.explanation-points {
    display: flex;
    flex-direction: column;
    gap: 1rem;
    margin-bottom: 2rem;
}

.point-item {
    display: flex;
    gap: 1rem;
    padding: 1rem;
    background: var(--card-background);
    border-radius: 8px;
    border-left: 4px solid var(--secondary-color);
}

.point-icon {
    font-size: 1.5rem;
    flex-shrink: 0;
}

.point-content {
    flex: 1;
    color: var(--text-secondary);
    line-height: 1.6;
}

.point-content strong {
    color: var(--text-primary);
}

.overlap-prevention {
    display: flex;
    flex-direction: column;
    gap: 1rem;
    margin-top: 1.5rem;
}

.prevention-rule {
    display: flex;
    gap: 1rem;
    padding: 1rem;
    background: var(--card-background);
    border-radius: 8px;
    border-left: 4px solid #f59e0b;
}

.rule-number {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 32px;
    height: 32px;
    background: #f59e0b;
    color: white;
    border-radius: 50%;
    font-weight: 700;
    font-size: 0.875rem;
    flex-shrink: 0;
}

.rule-content {
    flex: 1;
    color: var(--text-secondary);
    line-height: 1.6;
}

.rule-content strong {
    color: var(--text-primary);
}

.subnet-bits-explanation {
    margin: 1.5rem 0;
    padding: 1rem;
    background: var(--card-background);
    border-radius: 8px;
    border: 2px solid var(--border-color);
}

.bits-calculation {
    color: var(--text-secondary);
    line-height: 1.7;
}

.calculation-formula {
    margin: 0.75rem 0;
    padding: 1rem;
    background: linear-gradient(to right, #eff6ff, #f0f9ff);
    border-radius: 8px;
    text-align: center;
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--primary-color);
    font-family: 'Courier New', monospace;
    border: 2px solid var(--primary-color);
}

.calculation-formula sup {
    font-size: 0.8em;
    vertical-align: super;
}

.formula-explanation {
    font-size: 0.875rem;
    color: var(--text-secondary);
    font-style: italic;
    margin-top: 0.5rem;
}

/* Public IP Warning */
.public-ip-warning {
    margin: 1.5rem 0;
    padding: 1.5rem;
    background: linear-gradient(to bottom, #fef2f2, #fff7ed);
    border-radius: 12px;
    border: 2px solid #ef4444;
    box-shadow: 0 4px 6px rgba(239, 68, 68, 0.1);
}

.warning-header {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-bottom: 1rem;
    padding-bottom: 1rem;
    border-bottom: 2px solid #fecaca;
}

.warning-icon {
    font-size: 2rem;
    line-height: 1;
}

.warning-header h5 {
    margin: 0;
    color: #dc2626;
    font-size: 1.25rem;
    font-weight: 700;
}

.warning-content {
    color: var(--text-secondary);
    line-height: 1.7;
}

.warning-content > p {
    margin-bottom: 1rem;
    font-size: 1rem;
    color: var(--text-primary);
}

.warning-points {
    display: flex;
    flex-direction: column;
    gap: 1rem;
    margin: 1.5rem 0;
}

.warning-point {
    display: flex;
    gap: 1rem;
    padding: 1rem;
    background: var(--card-background);
    border-radius: 8px;
    border-left: 4px solid #ef4444;
}

.warning-point-icon {
    font-size: 1.5rem;
    flex-shrink: 0;
}

.warning-point-text {
    flex: 1;
    color: var(--text-secondary);
    line-height: 1.7;
}

.warning-point-text strong {
    color: var(--text-primary);
}

.warning-point-text ul {
    margin-top: 0.5rem;
    margin-left: 1.5rem;
    margin-bottom: 0;
}

.warning-point-text li {
    margin-bottom: 0.25rem;
}

.warning-footer {
    margin-top: 1.5rem;
    padding: 1rem;
    background: #fee2e2;
    border-radius: 8px;
    border-left: 4px solid #dc2626;
    color: #991b1b;
    font-weight: 600;
    line-height: 1.6;
}

.example-box {
    margin-top: 1.5rem;
    padding: 1rem;
    background: #fef3c7;
    border-left: 4px solid #f59e0b;
    border-radius: 8px;
    color: var(--text-secondary);
    line-height: 1.7;
    font-size: 0.9rem;
}

.example-box strong {
    color: var(--text-primary);
}

.example-box .correct {
    color: #059669;
    font-weight: 600;
}

.example-box .wrong {
    color: #dc2626;
    font-weight: 600;
}

.selected-subnet-note {
    color: #f59e0b !important;
    font-weight: 600 !important;
}

/* Cloud Helpers Section */
.cloud-helpers-section {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.cloud-helpers-section h2 {
    font-size: 1.5rem;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.cloud-cards {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.cloud-card {
    background: var(--card-background);
    border-radius: 12px;
    padding: 1.5rem;
    text-decoration: none;
    color: var(--text-primary);
    box-shadow: var(--shadow);
    transition: all 0.3s ease;
    border: 2px solid transparent;
    position: relative;
    overflow: hidden;
}

.cloud-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
    border-color: currentColor;
}

.cloud-card.azure-card {
    border-left: 4px solid var(--azure-color);
}

.cloud-card.aws-card {
    border-left: 4px solid var(--aws-color);
}

.cloud-card.gcp-card {
    border-left: 4px solid var(--gcp-color);
}

.cloud-icon {
    width: 48px;
    height: 48px;
    margin-bottom: 1rem;
    color: currentColor;
}

.cloud-card.azure-card .cloud-icon {
    color: var(--azure-color);
}

.cloud-card.aws-card .cloud-icon {
    color: var(--aws-color);
}

.cloud-card.gcp-card .cloud-icon {
    color: var(--gcp-color);
}

.cloud-icon svg {
    width: 100%;
    height: 100%;
}

.cloud-card h3 {
    font-size: 1.25rem;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.cloud-card p {
    font-size: 0.875rem;
    color: var(--text-secondary);
    line-height: 1.5;
}

.card-arrow {
    position: absolute;
    top: 1.5rem;
    right: 1.5rem;
    font-size: 1.5rem;
    color: var(--text-secondary);
    transition: transform 0.3s ease;
}

.cloud-card:hover .card-arrow {
    transform: translateX(4px);
}

/* Tutorial Section */
.tutorial-section {
    margin-top: 3rem;
}

.tutorial-card {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    border-radius: 12px;
    padding: 3rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    box-shadow: var(--shadow-lg);
    color: white;
}

.tutorial-content {
    flex: 1;
    max-width: 600px;
}

.tutorial-content h2 {
    font-size: 2rem;
    margin-bottom: 1rem;
}

.tutorial-content p {
    font-size: 1.125rem;
    margin-bottom: 1.5rem;
    opacity: 0.95;
    line-height: 1.7;
}

.tutorial-btn {
    display: inline-block;
    background: white;
    color: var(--primary-color);
    padding: 0.875rem 2rem;
    border-radius: 8px;
    text-decoration: none;
    font-weight: 600;
    transition: transform 0.2s, box-shadow 0.2s;
}

.tutorial-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
}

.tutorial-visual {
    display: flex;
    align-items: center;
    justify-content: center;
}

.tutorial-icon {
    font-size: 6rem;
    opacity: 0.9;
}

/* Footer */
footer {
    background: var(--card-background);
    padding: 2rem;
    text-align: center;
    color: var(--text-secondary);
    margin-top: 3rem;
    border-top: 1px solid var(--border-color);
}

.footer-content {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    align-items: center;
}

.footer-content p {
    margin: 0;
    font-size: 0.875rem;
}

.powered-by {
    color: var(--text-secondary);
    font-size: 0.875rem;
}

.powered-by strong {
    color: var(--primary-color);
    font-weight: 600;
}

.brand-name {
    color: var(--text-secondary);
    font-size: 0.875rem;
    font-style: italic;
}

.brand-name strong {
    color: var(--secondary-color);
    font-weight: 600;
}

/* Placeholder Pages */
.page-header {
    text-align: center;
    margin-bottom: 3rem;
    padding: 2rem 0;
}

.page-header h1 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.page-subtitle {
    font-size: 1.125rem;
    color: var(--text-secondary);
}

.placeholder-content {
    max-width: 800px;
    margin: 0 auto;
}

.placeholder-card {
    background: var(--card-background);
    border-radius: 12px;
    padding: 3rem;
    box-shadow: var(--shadow-lg);
    text-align: center;
}

.placeholder-card h2 {
    font-size: 2rem;
    margin-bottom: 1.5rem;
    color: var(--text-primary);
}

.placeholder-card p {
    font-size: 1.125rem;
    color: var(--text-secondary);
    margin-bottom: 1rem;
    line-height: 1.7;
}

.placeholder-card ul {
    text-align: left;
    max-width: 600px;
    margin: 2rem auto;
    list-style: none;
}

.placeholder-card ul li {
    padding: 0.75rem 0;
    padding-left: 2rem;
    position: relative;
    color: var(--text-secondary);
    font-size: 1rem;
}

.placeholder-card ul li::before {
    content: "✓";
    position: absolute;
    left: 0;
    color: var(--primary-color);
    font-weight: bold;
    font-size: 1.25rem;
}

.back-btn {
    display: inline-block;
    margin-top: 2rem;
    padding: 0.875rem 2rem;
    background: var(--primary-color);
    color: white;
    text-decoration: none;
    border-radius: 8px;
    font-weight: 600;
    transition: background-color 0.2s;
}

.back-btn:hover {
    background: var(--primary-dark);
}

/* Responsive Design */
@media (max-width: 1024px) {
    .content-wrapper {
        grid-template-columns: 1fr;
    }

    .cloud-helpers-section {
        order: 1;
    }

    .calculator-section {
        order: -1;
    }

    .cloud-cards {
        display: grid;
        grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    }
}

@media (max-width: 768px) {
    .nav-container {
        flex-direction: column;
        gap: 1rem;
    }

    .nav-menu {
        gap: 1rem;
    }

    .main-container {
        padding: 1rem;
    }

    .calculator-card {
        padding: 1.5rem;
    }

    .tutorial-card {
        flex-direction: column;
        text-align: center;
        padding: 2rem;
    }

    .tutorial-visual {
        margin-top: 1.5rem;
    }

    .tutorial-icon {
        font-size: 4rem;
    }

    .results-grid {
        grid-template-columns: 1fr;
    }

    .page-header h1 {
        font-size: 2rem;
    }

    .placeholder-card {
        padding: 2rem 1.5rem;
    }

    .subnets-grid {
        grid-template-columns: repeat(auto-fill, minmax(120px, 1fr));
        gap: 0.75rem;
        max-height: 400px;
    }

    .subnet-division-diagram {
        padding: 1rem;
    }

    .division-summary {
        flex-direction: column;
        gap: 0.75rem;
    }

    .subnet-box {
        padding: 0.75rem;
    }

    .hosts-value {
        font-size: 1.25rem;
    }

    .subnet-network-info {
        font-size: 0.7rem;
    }

    .info-value {
        font-size: 0.7rem;
        word-break: break-all;
    }

    .explanation-points,
    .overlap-prevention {
        gap: 0.75rem;
    }

    .point-item,
    .prevention-rule {
        padding: 0.75rem;
        flex-direction: column;
        gap: 0.5rem;
    }

    .point-icon {
        font-size: 1.25rem;
    }

    .subnetting-explanation {
        padding: 1rem;
    }

    .bit-stats {
        flex-direction: column;
        gap: 0.75rem;
    }

    .octet-group {
        padding: 0.75rem 1rem;
        overflow-x: auto;
        -webkit-overflow-scrolling: touch;
    }

    .single-line-bits-container {
        gap: 0.4rem;
        padding: 0.5rem 0;
        overflow-x: auto;
        -webkit-overflow-scrolling: touch;
        justify-content: flex-start;
    }

    .octet-wrapper-stacked {
        gap: 0.3rem;
    }

    .octet-decimal-stacked {
        font-size: 0.75rem;
        padding: 0.15rem 0.3rem;
        min-width: 30px;
    }

    .bit-square-inline {
        width: 18px;
        height: 18px;
        font-size: 0.65rem;
    }

    .bits-stacked {
        gap: 0.1rem;
    }

    .dot-separator-stacked {
        font-size: 1.3rem;
        padding: 0 0.2rem;
        height: 18px;
        padding-bottom: 0.15rem;
    }

    .analyzer-card {
        padding: 1.25rem;
    }

    .analyzer-card h2 {
        font-size: 1.25rem;
    }

    .input-with-button {
        flex-direction: column;
    }

    .analyze-btn {
        width: 100%;
    }

    .analysis-results {
        padding-top: 1.5rem;
        margin-top: 1.5rem;
    }

    .analysis-item {
        flex-direction: column;
        align-items: flex-start;
        gap: 0.5rem;
    }

    .analysis-explanation,
    .analysis-recommendation {
        padding: 1rem;
    }

    .public-ip-warning {
        padding: 1rem;
        margin: 1rem 0;
    }

    .warning-header h5 {
        font-size: 1.125rem;
    }

    .warning-points {
        gap: 0.75rem;
        margin: 1rem 0;
    }

    .warning-point {
        padding: 0.75rem;
        gap: 0.75rem;
    }

    .warning-point-icon {
        font-size: 1.25rem;
    }

    .warning-footer {
        padding: 0.75rem;
        margin-top: 1rem;
        font-size: 0.875rem;
    }
}

/* Additional optimizations for very small screens */
@media (max-width: 480px) {
    html {
        -webkit-text-size-adjust: 100%;
    }

    body {
        font-size: 14px;
    }

    .main-container {
        padding: 0.75rem;
    }

    .calculator-card {
        padding: 1rem;
    }

    .logo h1 {
        font-size: 1rem;
    }

    .brand-tag {
        font-size: 0.6rem;
    }

    .footer-content {
        gap: 0.4rem;
    }

    .footer-content p {
        font-size: 0.8rem;
    }

    .single-line-bits-container {
        gap: 0.25rem;
    }

    .octet-decimal-stacked {
        font-size: 0.65rem;
        min-width: 25px;
        padding: 0.1rem 0.2rem;
    }

    .bit-square-inline {
        width: 14px;
        height: 14px;
        font-size: 0.55rem;
    }

    .dot-separator-stacked {
        font-size: 1rem;
        padding: 0 0.1rem;
    }

    .cloud-card {
        padding: 1rem;
    }

    .tutorial-card {
        padding: 1.25rem;
    }

    .tutorial-content h2 {
        font-size: 1.25rem;
    }

    .tutorial-content p {
        font-size: 0.95rem;
    }
}