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

:root {
    --primary: #4F46E5;
    --primary-dark: #4338CA;
    --primary-light: #6366F1;
    --success: #10B981;
    --error: #EF4444;
    --warning: #F59E0B;

    --bg-primary: #FFFFFF;
    --bg-secondary: #F9FAFB;
    --bg-tertiary: #F3F4F6;
    --bg-code: #1E293B;
    --bg-output: #0F172A;

    --text-primary: #111827;
    --text-secondary: #6B7280;
    --text-tertiary: #9CA3AF;
    --text-code: #E2E8F0;

    --border-color: #E5E7EB;
    --border-focus: #4F46E5;

    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1);

    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;

    --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    --font-mono: 'SF Mono', Monaco, 'Cascadia Code', 'Roboto Mono', Consolas, 'Courier New', monospace;

    --spacing-xs: 4px;
    --spacing-sm: 8px;
    --spacing-md: 16px;
    --spacing-lg: 24px;
    --spacing-xl: 32px;
    --spacing-2xl: 48px;

    --header-height: 64px;
    --container-max: 1280px;
}

[data-theme="dark"] {
    --bg-primary: #0F172A;
    --bg-secondary: #1E293B;
    --bg-tertiary: #334155;
    --bg-code: #1E293B;
    --bg-output: #0F172A;

    --text-primary: #F1F5F9;
    --text-secondary: #CBD5E1;
    --text-tertiary: #94A3B8;
    --text-code: #E2E8F0;

    --border-color: #334155;
}

html {
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: var(--font-sans);
    color: var(--text-primary);
    background: var(--bg-primary);
    line-height: 1.6;
    overflow-x: hidden;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
    font-weight: 700;
    line-height: 1.2;
    margin-bottom: var(--spacing-md);
    color: var(--text-primary);
}

h1 { font-size: 2.5rem; }
h2 { font-size: 2rem; }
h3 { font-size: 1.5rem; }
h4 { font-size: 1.25rem; }
h5 { font-size: 1.125rem; }
h6 { font-size: 1rem; }

p {
    margin-bottom: var(--spacing-md);
    color: var(--text-secondary);
}

a {
    color: var(--primary);
    text-decoration: none;
    transition: color 0.2s;
}

a:hover {
    color: var(--primary-dark);
}

/* Layout */
.container {
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

/* Header */
.header {
    background: var(--bg-primary);
    border-bottom: 1px solid var(--border-color);
    height: var(--header-height);
    position: sticky;
    top: 0;
    z-index: 1000;
    backdrop-filter: blur(8px);
    background: rgba(255, 255, 255, 0.95);
}

[data-theme="dark"] .header {
    background: rgba(15, 23, 42, 0.95);
}

.header-content {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: var(--header-height);
}

.logo {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-size: 1.125rem;
    font-weight: 700;
    color: var(--text-primary);
}

.logo svg {
    flex-shrink: 0;
}

.nav {
    display: flex;
    gap: var(--spacing-lg);
    align-items: center;
}

.nav a {
    color: var(--text-secondary);
    font-weight: 500;
    font-size: 0.9375rem;
    transition: color 0.2s;
}

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

.theme-toggle {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all 0.2s;
}

.theme-toggle:hover {
    background: var(--bg-tertiary);
}

.theme-toggle .sun-icon {
    display: none;
}

.theme-toggle .moon-icon {
    display: block;
}

[data-theme="dark"] .theme-toggle .sun-icon {
    display: block;
}

[data-theme="dark"] .theme-toggle .moon-icon {
    display: none;
}

/* Hero */
.hero {
    padding: var(--spacing-2xl) 0;
    background: linear-gradient(180deg, var(--bg-secondary) 0%, var(--bg-primary) 100%);
}

.hero-content {
    text-align: center;
    max-width: 800px;
    margin: 0 auto;
}

.hero h1 {
    font-size: 3rem;
    margin-bottom: var(--spacing-md);
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-light) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: 1.25rem;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-xl);
}

.trust-badges {
    display: flex;
    gap: var(--spacing-lg);
    justify-content: center;
    flex-wrap: wrap;
}

.badge {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm) var(--spacing-md);
    background: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    font-size: 0.9375rem;
    font-weight: 500;
    color: var(--text-primary);
}

.badge svg {
    color: var(--primary);
    flex-shrink: 0;
}

/* Compiler Section */
.compiler-section {
    padding: var(--spacing-2xl) 0;
}

.compiler-wrapper {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-lg);
}

.compiler-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-md);
    background: var(--bg-tertiary);
    border-bottom: 1px solid var(--border-color);
    gap: var(--spacing-md);
    flex-wrap: wrap;
}

.compiler-controls {
    display: flex;
    gap: var(--spacing-sm);
    align-items: center;
    flex-wrap: wrap;
}

.editor-settings {
    display: flex;
    gap: var(--spacing-sm);
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm) var(--spacing-md);
    font-size: 0.9375rem;
    font-weight: 600;
    border-radius: var(--radius-md);
    border: none;
    cursor: pointer;
    transition: all 0.2s;
    font-family: var(--font-sans);
}

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

.btn-primary:hover {
    background: var(--primary-dark);
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

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

.btn-secondary:hover {
    background: var(--bg-secondary);
}

.icon-btn {
    background: transparent;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all 0.2s;
    color: var(--text-secondary);
    font-size: 0.875rem;
    font-weight: 600;
}

.icon-btn:hover {
    background: var(--bg-secondary);
    color: var(--text-primary);
}

.php-version-selector {
    padding: var(--spacing-sm) var(--spacing-md);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    background: var(--bg-primary);
    color: var(--text-primary);
    font-size: 0.9375rem;
    font-weight: 500;
    font-family: var(--font-sans);
    cursor: pointer;
}

/* Compiler Body */
.compiler-body {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1px;
    background: var(--border-color);
    min-height: 500px;
}

.editor-panel,
.output-panel {
    background: var(--bg-primary);
    display: flex;
    flex-direction: column;
}

.panel-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-sm) var(--spacing-md);
    background: var(--bg-tertiary);
    border-bottom: 1px solid var(--border-color);
}

.panel-title {
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.code-editor {
    flex: 1;
    padding: var(--spacing-md);
    font-family: var(--font-mono);
    font-size: 14px;
    line-height: 1.6;
    background: var(--bg-code);
    color: var(--text-code);
    border: none;
    resize: none;
    outline: none;
    tab-size: 4;
}

.output-content {
    flex: 1;
    padding: var(--spacing-md);
    font-family: var(--font-mono);
    font-size: 14px;
    line-height: 1.6;
    background: var(--bg-output);
    color: var(--text-code);
    overflow: auto;
    white-space: pre-wrap;
    word-wrap: break-word;
}

.execution-info {
    padding: var(--spacing-sm) var(--spacing-md);
    background: var(--bg-tertiary);
    border-top: 1px solid var(--border-color);
    font-size: 0.8125rem;
    color: var(--text-secondary);
    display: none;
}

.execution-info.show {
    display: block;
}

/* Content Section */
.content-section {
    padding: var(--spacing-2xl) 0;
    background: var(--bg-secondary);
}

.content-grid {
    display: grid;
    grid-template-columns: 1fr 320px;
    gap: var(--spacing-xl);
}

.content-article {
    background: var(--bg-primary);
    padding: var(--spacing-xl);
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-color);
}

.content-article h2 {
    margin-top: var(--spacing-xl);
}

.content-article h2:first-child {
    margin-top: 0;
}

.content-article h3 {
    margin-top: var(--spacing-lg);
    font-size: 1.375rem;
}

.feature-list {
    list-style: none;
    padding: 0;
}

.feature-list li {
    padding: var(--spacing-sm) 0;
    color: var(--text-secondary);
}

.feature-list li strong {
    color: var(--text-primary);
}

/* Sidebar */
.sidebar {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
}

.sidebar-card {
    background: var(--bg-primary);
    padding: var(--spacing-lg);
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-color);
}

.sidebar-card h3 {
    font-size: 1.125rem;
    margin-bottom: var(--spacing-md);
}

.example-links {
    list-style: none;
    padding: 0;
}

.example-links li {
    margin-bottom: var(--spacing-sm);
}

.example-links a {
    color: var(--text-secondary);
    font-size: 0.9375rem;
    transition: color 0.2s;
}

.example-links a:hover {
    color: var(--primary);
}

.numbered-list {
    padding-left: var(--spacing-lg);
    color: var(--text-secondary);
    font-size: 0.9375rem;
}

.numbered-list li {
    margin-bottom: var(--spacing-sm);
}

.link-with-arrow {
    display: inline-block;
    margin-top: var(--spacing-md);
    font-weight: 600;
    font-size: 0.9375rem;
}

/* FAQ Section */
.faq-section {
    padding: var(--spacing-2xl) 0;
}

.faq-section h2 {
    text-align: center;
    margin-bottom: var(--spacing-xl);
}

.faq-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: var(--spacing-lg);
}

.faq-item {
    background: var(--bg-secondary);
    padding: var(--spacing-lg);
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-color);
}

.faq-item h3 {
    font-size: 1.125rem;
    margin-bottom: var(--spacing-sm);
}

.faq-item p {
    margin-bottom: 0;
    font-size: 0.9375rem;
}

/* Footer */
.footer {
    background: var(--bg-secondary);
    border-top: 1px solid var(--border-color);
    padding: var(--spacing-2xl) 0 var(--spacing-lg);
}

.footer-content {
    display: grid;
    grid-template-columns: 1.5fr 3fr;
    gap: var(--spacing-xl);
    margin-bottom: var(--spacing-xl);
}

.footer-brand .logo {
    margin-bottom: var(--spacing-md);
}

.footer-tagline {
    font-size: 0.9375rem;
    color: var(--text-secondary);
}

.footer-links {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--spacing-lg);
}

.footer-column h4 {
    font-size: 0.875rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: var(--spacing-md);
    color: var(--text-primary);
}

.footer-column ul {
    list-style: none;
}

.footer-column li {
    margin-bottom: var(--spacing-sm);
}

.footer-column a {
    color: var(--text-secondary);
    font-size: 0.9375rem;
}

.footer-column a:hover {
    color: var(--primary);
}

.footer-bottom {
    padding-top: var(--spacing-lg);
    border-top: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 0.875rem;
    color: var(--text-tertiary);
}

.footer-note {
    margin: 0;
}

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

    .compiler-body {
        grid-template-columns: 1fr;
    }

    .nav {
        display: none;
    }
}

@media (max-width: 768px) {
    .hero h1 {
        font-size: 2rem;
    }

    .hero-subtitle {
        font-size: 1rem;
    }

    .trust-badges {
        flex-direction: column;
        align-items: center;
    }

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

    .footer-content {
        grid-template-columns: 1fr;
    }

    .footer-links {
        grid-template-columns: 1fr;
    }

    .footer-bottom {
        flex-direction: column;
        gap: var(--spacing-sm);
        text-align: center;
    }

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

/* Performance Optimizations */
@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

/* Print Styles */
@media print {
    .header,
    .footer,
    .sidebar,
    .compiler-controls,
    .editor-settings {
        display: none;
    }

    .compiler-body {
        grid-template-columns: 1fr;
    }
}

/* Syntax Highlighting (Basic) */
.output-content.error {
    color: var(--error);
}

.output-content.success {
    color: var(--success);
}

/* Loading State */
.btn-primary.loading {
    position: relative;
    color: transparent;
}

.btn-primary.loading::after {
    content: '';
    position: absolute;
    width: 16px;
    height: 16px;
    top: 50%;
    left: 50%;
    margin-left: -8px;
    margin-top: -8px;
    border: 2px solid white;
    border-radius: 50%;
    border-top-color: transparent;
    animation: spinner 0.6s linear infinite;
}

@keyframes spinner {
    to { transform: rotate(360deg); }
}

/* Selection */
::selection {
    background: var(--primary-light);
    color: white;
}

/* Focus Styles */
button:focus-visible,
select:focus-visible,
textarea:focus-visible {
    outline: 2px solid var(--border-focus);
    outline-offset: 2px;
}

/* Scrollbar */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

::-webkit-scrollbar-track {
    background: var(--bg-tertiary);
}

::-webkit-scrollbar-thumb {
    background: var(--text-tertiary);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--text-secondary);
}