/* =========================================
   1. RESET & VARIABLES
   ========================================= */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --bg-page: #fafafa;
    --bg-card: #ffffff;
    --border-card: #e0e0e0;
    --text-primary: #1a1a1a;
    --text-secondary: #666666;
    --accent: #0066cc;
    --accent-hover: #0052a3;
    --bg-output: #f5f5f5;
    --font-mono: 'Courier New', Courier, monospace;
    --font-ui: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
}

body {
    font-family: var(--font-ui);
    background-color: var(--bg-page);
    color: var(--text-primary);
    line-height: 1.6;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

main {
    flex: 1;
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem;
    width: 100%;
}

/* =========================================
   2. HEADER & FOOTER
   ========================================= */
.main-nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1.5rem 2rem;
    background-color: var(--bg-card);
    border-bottom: 1px solid var(--border-card);
}

.nav-logo {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text-primary);
    text-decoration: none;
    letter-spacing: -0.5px;
}

.nav-link {
    color: var(--accent);
    text-decoration: none;
    font-weight: 500;
}

.nav-link:hover {
    color: var(--accent-hover);
    text-decoration: underline;
}

.main-footer {
    text-align: center;
    padding: 2rem;
    color: var(--text-secondary);
    font-size: 0.875rem;
    border-top: 1px solid var(--border-card);
    background-color: var(--bg-card);
    margin-top: auto;
}

/* =========================================
   3. HOMEPAGE: HERO & FILTERS
   ========================================= */
.hero {
    text-align: center;
    margin-bottom: 3rem;
    padding: 2rem 0;
}

.hero h1 {
    font-size: 2.5rem;
    margin-bottom: 0.75rem;
    color: var(--text-primary);
}

.hero p {
    font-size: 1.125rem;
    color: var(--text-secondary);
    max-width: 600px;
    margin: 0 auto;
}

.filters {
    display: flex;
    gap: 0.75rem;
    margin-bottom: 2rem;
    flex-wrap: wrap;
    justify-content: center;
}

.filter-btn {
    padding: 0.5rem 1.25rem;
    border: 1px solid var(--border-card);
    background-color: var(--bg-card);
    color: var(--text-primary);
    cursor: pointer;
    border-radius: 6px;
    font-size: 0.9375rem;
    font-weight: 500;
    transition: all 0.2s ease;
}

.filter-btn:hover {
    border-color: var(--accent);
    color: var(--accent);
}

.filter-btn.active {
    background-color: var(--accent);
    color: white;
    border-color: var(--accent);
}

/* =========================================
   4. HOMEPAGE: TOOLS GRID
   ========================================= */
.tools-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: 1.5rem;
}

.tool-card {
    background-color: var(--bg-card);
    border: 1px solid var(--border-card);
    border-radius: 8px;
    padding: 1.5rem;
    transition: transform 0.2s, box-shadow 0.2s;
    display: flex;
    flex-direction: column;
}

.tool-card:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 16px rgba(0, 0, 0, 0.08);
    border-color: var(--accent);
}

.tool-card.tool-wip {
    opacity: 0.7;
}

.tool-card.tool-wip:hover {
    transform: none;
    box-shadow: none;
    border-color: var(--border-card);
}

.tool-category {
    display: inline-block;
    font-size: 0.75rem;
    font-weight: 700;
    color: var(--accent);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-bottom: 0.75rem;
}

.tool-card h2 {
    font-size: 1.25rem;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.tool-card p {
    color: var(--text-secondary);
    font-size: 0.9375rem;
    margin-bottom: 1.5rem;
    flex-grow: 1;
}

.tool-link {
    display: inline-flex;
    align-items: center;
    color: var(--accent);
    text-decoration: none;
    font-weight: 600;
    font-size: 0.9375rem;
    transition: color 0.2s;
}

.tool-link:hover {
    color: var(--accent-hover);
}

.tool-badge {
    display: inline-block;
    padding: 0.375rem 0.75rem;
    background-color: var(--bg-output);
    color: var(--text-secondary);
    font-size: 0.875rem;
    font-weight: 600;
    border-radius: 4px;
    align-self: flex-start;
}

/* =========================================
   5. TOOL PAGES: COMMON LAYOUT
   ========================================= */
.back-link {
    display: inline-flex;
    align-items: center;
    color: var(--accent);
    text-decoration: none;
    margin-bottom: 1.5rem;
    font-weight: 500;
    transition: color 0.2s;
}

.back-link:hover {
    color: var(--accent-hover);
}

.tool-header {
    margin-bottom: 2rem;
    border-bottom: 1px solid var(--border-card);
    padding-bottom: 1.5rem;
}

.tool-header h1 {
    font-size: 2rem;
    margin-bottom: 0.5rem;
}

.tool-header p {
    color: var(--text-secondary);
    font-size: 1.0625rem;
}

.how-to {
    background-color: var(--bg-card);
    border: 1px solid var(--border-card);
    border-radius: 8px;
    padding: 1.5rem;
    margin-bottom: 2rem;
}

.how-to h2 {
    font-size: 1.125rem;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.how-to ol {
    padding-left: 1.5rem;
}

.how-to li {
    margin-bottom: 0.5rem;
    color: var(--text-secondary);
}

.tool-area {
    background-color: var(--bg-card);
    border: 1px solid var(--border-card);
    border-radius: 8px;
    padding: 1.5rem;
}

.input-label {
    display: block;
    font-size: 0.8125rem;
    font-weight: 700;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

textarea {
    width: 100%;
    padding: 1rem;
    border: 1px solid var(--border-card);
    border-radius: 6px;
    font-family: var(--font-mono);
    font-size: 0.9375rem;
    resize: vertical;
    margin-bottom: 1rem;
    background-color: var(--bg-page);
    transition: border-color 0.2s;
}

textarea:focus {
    outline: none;
    border-color: var(--accent);
    background-color: var(--bg-card);
}

.controls {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.5rem;
    flex-wrap: wrap;
    gap: 1rem;
}

.control-left,
.control-right {
    display: flex;
    gap: 0.75rem;
    align-items: center;
}

select {
    padding: 0.625rem 1rem;
    border: 1px solid var(--border-card);
    border-radius: 6px;
    background-color: var(--bg-card);
    font-size: 0.9375rem;
    cursor: pointer;
    transition: border-color 0.2s;
}

select:focus {
    outline: none;
    border-color: var(--accent);
}

.btn {
    padding: 0.625rem 1.25rem;
    border: none;
    border-radius: 6px;
    font-size: 0.9375rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
}

.btn-primary {
    background-color: var(--accent);
    color: white;
}

.btn-primary:hover {
    background-color: var(--accent-hover);
}

.btn-secondary {
    background-color: var(--bg-output);
    color: var(--text-primary);
    border: 1px solid var(--border-card);
}

.btn-secondary:hover {
    background-color: var(--border-card);
}

.btn:disabled {
    opacity: 0.6;
    cursor: not-allowed;
}

pre {
    background-color: var(--bg-output);
    border: 1px solid var(--border-card);
    border-radius: 6px;
    padding: 1rem;
    overflow-x: auto;
    min-height: 100px;
}

pre code {
    font-family: var(--font-mono);
    font-size: 0.9375rem;
    white-space: pre-wrap;
    word-wrap: break-word;
    color: var(--text-primary);
}

.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border-width: 0;
}

/* =========================================
   6. CRON GENERATOR SPECIFIC
   ========================================= */
.cron-builders {
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    gap: 1rem;
    margin-bottom: 1.5rem;
}

.cron-field label {
    display: block;
    font-size: 0.8125rem;
    font-weight: 600;
    color: var(--text-secondary);
    margin-bottom: 0.375rem;
}

.cron-field select {
    width: 100%;
}

.cron-expression-box {
    display: flex;
    gap: 1rem;
    align-items: center;
    margin-bottom: 1.5rem;
    flex-wrap: wrap;
}

.cron-input {
    flex: 1;
    padding: 0.75rem;
    font-family: var(--font-mono);
    font-size: 1.125rem;
    font-weight: 600;
    border: 1px solid var(--border-card);
    border-radius: 6px;
    background-color: var(--bg-output);
    text-align: center;
    min-width: 200px;
    color: var(--text-primary);
}

.cron-description {
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: 1.5rem;
    color: var(--accent);
    padding: 1rem;
    background-color: rgba(0, 102, 204, 0.05);
    border-radius: 6px;
    border-left: 4px solid var(--accent);
}

/* =========================================
   7. SUBNET CALCULATOR SPECIFIC
   ========================================= */
.subnet-inputs {
    display: flex;
    gap: 1.5rem;
    margin-bottom: 1.5rem;
    flex-wrap: wrap;
}

.input-group {
    flex: 1;
    min-width: 200px;
}

.text-input {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--border-card);
    border-radius: 6px;
    font-family: var(--font-mono);
    font-size: 1rem;
    background-color: var(--bg-page);
    transition: border-color 0.2s;
}

.text-input:focus {
    outline: none;
    border-color: var(--accent);
    background-color: var(--bg-card);
}

.error-message {
    background-color: #fee2e2;
    color: #b91c1c;
    padding: 0.875rem;
    border-radius: 6px;
    margin-bottom: 1.5rem;
    font-size: 0.9375rem;
    font-weight: 500;
    border: 1px solid #fecaca;
}

.subnet-results {
    transition: opacity 0.3s;
}

.result-row {
    display: flex;
    align-items: center;
    padding: 0.875rem 0;
    border-bottom: 1px solid var(--border-card);
    gap: 1rem;
    flex-wrap: wrap;
}

.result-row:last-of-type {
    border-bottom: none;
}

.result-label {
    flex: 1;
    font-weight: 600;
    color: var(--text-secondary);
    min-width: 160px;
    font-size: 0.9375rem;
}

.result-value {
    flex: 2;
    font-family: var(--font-mono);
    color: var(--text-primary);
    font-weight: 600;
    min-width: 180px;
    font-size: 0.9375rem;
}

.btn-copy {
    padding: 0.375rem 0.875rem;
    font-size: 0.8125rem;
    font-weight: 600;
    background-color: transparent;
    border: 1px solid var(--border-card);
    border-radius: 4px;
    cursor: pointer;
    color: var(--text-secondary);
    transition: all 0.2s;
}

.btn-copy:hover {
    border-color: var(--accent);
    color: var(--accent);
    background-color: rgba(0, 102, 204, 0.05);
}

.binary-section {
    margin-top: 2rem;
    padding-top: 1.5rem;
    border-top: 2px solid var(--border-card);
}

/* =========================================
   8. RESPONSIVE DESIGN
   ========================================= */
@media (max-width: 768px) {
    .main-nav {
        padding: 1rem;
    }

    .hero h1 {
        font-size: 2rem;
    }

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

    .controls {
        flex-direction: column;
        align-items: stretch;
    }

    .control-left,
    .control-right {
        justify-content: center;
        width: 100%;
    }

    .btn {
        flex: 1;
        text-align: center;
    }

    .cron-builders {
        grid-template-columns: repeat(2, 1fr);
    }

    .cron-builders .cron-field:last-child {
        grid-column: span 2;
    }

    .result-row {
        flex-direction: column;
        align-items: flex-start;
        gap: 0.375rem;
    }

    .btn-copy {
        align-self: flex-end;
        margin-top: 0.25rem;
    }
}