/* ============================================
   CSS Custom Properties (Design Tokens)
   ============================================ */

:root {
    /* Light Mode Colors */
    --color-bg: #ffffff;
    --color-bg-secondary: #f8f9fa;
    --color-text: #1a1a1a;
    --color-text-secondary: #4a5568;
    --color-primary: #2563eb;
    --color-primary-hover: #1d4ed8;
    --color-border: #e2e8f0;
    --color-shadow: rgba(0, 0, 0, 0.1);

    /* Typography */
    --font-family-base: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen', 'Ubuntu', 'Cantarell', 'Fira Sans', 'Droid Sans', 'Helvetica Neue', sans-serif;
    --font-family-mono: 'SF Mono', 'Monaco', 'Inconsolata', 'Fira Code', 'Droid Sans Mono', 'Source Code Pro', monospace;

    /* Font Sizes */
    --font-size-base: 18px;
    --font-size-sm: 16px;
    --font-size-lg: 20px;
    --font-size-xl: 24px;
    --font-size-2xl: 32px;
    --font-size-3xl: 40px;

    /* Line Heights */
    --line-height-base: 1.7;
    --line-height-heading: 1.3;

    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    --spacing-2xl: 4rem;

    /* Layout */
    --max-width: 900px;
    --border-radius: 8px;

    /* Transitions */
    --transition-speed: 0.3s;
}

/* Dark Mode Colors */
[data-theme="dark"] {
    --color-bg: #0f172a;
    --color-bg-secondary: #1e293b;
    --color-text: #f1f5f9;
    --color-text-secondary: #cbd5e1;
    --color-primary: #60a5fa;
    --color-primary-hover: #93c5fd;
    --color-border: #334155;
    --color-shadow: rgba(0, 0, 0, 0.3);
}

/* ============================================
   Base Styles
   ============================================ */

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

html {
    font-size: 16px;
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family-base);
    font-size: var(--font-size-base);
    line-height: var(--line-height-base);
    color: var(--color-text);
    background-color: var(--color-bg);
    transition: background-color var(--transition-speed), color var(--transition-speed);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* ============================================
   Typography
   ============================================ */

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

h1 {
    font-size: var(--font-size-3xl);
    margin-bottom: var(--spacing-lg);
}

h2 {
    font-size: var(--font-size-2xl);
    margin-top: var(--spacing-2xl);
    margin-bottom: var(--spacing-lg);
    padding-bottom: var(--spacing-sm);
    border-bottom: 2px solid var(--color-border);
}

h3 {
    font-size: var(--font-size-xl);
    margin-top: var(--spacing-lg);
}

h4 {
    font-size: var(--font-size-lg);
    margin-top: var(--spacing-md);
}

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

.lead {
    font-size: var(--font-size-lg);
    color: var(--color-text-secondary);
    line-height: 1.6;
}

strong {
    font-weight: 600;
    color: var(--color-text);
}

em {
    font-style: italic;
}

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

a:hover {
    color: var(--color-primary-hover);
    text-decoration: underline;
}

/* ============================================
   Layout
   ============================================ */

.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

/* ============================================
   Header
   ============================================ */

.site-header {
    background-color: var(--color-bg);
    border-bottom: 1px solid var(--color-border);
    padding: var(--spacing-md) 0;
    position: sticky;
    top: 0;
    z-index: 100;
    backdrop-filter: blur(10px);
    background-color: rgba(255, 255, 255, 0.95);
    transition: background-color var(--transition-speed);
}

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

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

.site-title {
    font-size: var(--font-size-xl);
    margin: 0;
}

/* Theme Toggle Button */
.theme-toggle {
    background: none;
    border: none;
    cursor: pointer;
    padding: var(--spacing-xs);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--color-text);
    border-radius: var(--border-radius);
    transition: background-color var(--transition-speed);
}

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

.theme-toggle svg {
    width: 24px;
    height: 24px;
}

.sun-icon {
    display: none;
}

.moon-icon {
    display: block;
}

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

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

/* ============================================
   Main Content
   ============================================ */

.main-content {
    padding: var(--spacing-2xl) 0;
    min-height: calc(100vh - 200px);
}

.hero {
    margin-bottom: var(--spacing-2xl);
}

.hero h1 {
    margin-bottom: var(--spacing-md);
}

.section {
    margin-bottom: var(--spacing-2xl);
}

/* ============================================
   Experience Items
   ============================================ */

.experience-item {
    margin-bottom: var(--spacing-xl);
    padding: var(--spacing-lg);
    background-color: var(--color-bg-secondary);
    border-radius: var(--border-radius);
    border-left: 4px solid var(--color-primary);
}

.experience-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-md);
}

.experience-title {
    flex: 1;
}

.company-logo {
    flex-shrink: 0;
}

.company-logo svg {
    display: block;
}

[data-theme="dark"] .company-logo rect {
    fill: #334155;
}

[data-theme="dark"] .company-logo text {
    fill: #94a3b8;
}

.experience-item h3 {
    margin-top: 0;
    display: flex;
    flex-wrap: wrap;
    align-items: baseline;
    gap: var(--spacing-sm);
}

.date {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
    font-weight: 400;
}

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

/* ============================================
   Education
   ============================================ */

.education-item {
    margin-bottom: var(--spacing-lg);
}

.education-item h3 {
    margin-bottom: var(--spacing-xs);
}

.institution {
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-sm);
}

/* ============================================
   Skills Grid
   ============================================ */

.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--spacing-lg);
    margin-top: var(--spacing-lg);
}

.skill-category {
    padding: var(--spacing-md);
    background-color: var(--color-bg-secondary);
    border-radius: var(--border-radius);
}

.skill-category h3 {
    font-size: var(--font-size-lg);
    margin-top: 0;
    margin-bottom: var(--spacing-sm);
    color: var(--color-primary);
}

.skill-category p {
    margin: 0;
    color: var(--color-text-secondary);
}

/* ============================================
   Lists
   ============================================ */

ul, ol {
    margin-bottom: var(--spacing-md);
    padding-left: var(--spacing-lg);
}

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

li:last-child {
    margin-bottom: 0;
}

ul.testimonials li {
    margin-bottom: var(--spacing-md);
}

/* ============================================
   Call to Action
   ============================================ */

.cta {
    text-align: center;
    padding: var(--spacing-xl) 0;
}

.cta hr {
    border: none;
    border-top: 1px solid var(--color-border);
    margin: var(--spacing-xl) auto;
    max-width: 200px;
}

/* ============================================
   Footer
   ============================================ */

.site-footer {
    background-color: var(--color-bg-secondary);
    border-top: 1px solid var(--color-border);
    padding: var(--spacing-xl) 0;
    color: var(--color-text-secondary);
}

.footer-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-lg);
}

.footer-links {
    display: flex;
    gap: var(--spacing-xl);
    flex-wrap: wrap;
    justify-content: center;
}

.footer-link {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-xs);
    color: var(--color-text);
    transition: color var(--transition-speed), transform var(--transition-speed);
    text-decoration: none;
}

.footer-link:hover {
    color: var(--color-primary);
    transform: translateY(-2px);
    text-decoration: none;
}

.footer-link svg {
    width: 32px;
    height: 32px;
}

.footer-link span {
    font-size: var(--font-size-sm);
    font-weight: 500;
}

.footer-copyright {
    margin: 0;
    text-align: center;
}

/* ============================================
   Responsive Design
   ============================================ */

@media (max-width: 768px) {
    :root {
        --font-size-base: 16px;
        --font-size-2xl: 28px;
        --font-size-3xl: 32px;
    }

    .container {
        padding: 0 var(--spacing-sm);
    }

    .experience-item {
        padding: var(--spacing-md);
    }

    .experience-header {
        flex-direction: column-reverse;
        align-items: center;
    }

    .company-logo svg {
        width: 60px;
        height: 60px;
    }

    .experience-item h3 {
        flex-direction: column;
        gap: var(--spacing-xs);
    }

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

    .footer-links {
        gap: var(--spacing-lg);
    }
}

@media (max-width: 480px) {
    :root {
        --font-size-base: 16px;
        --font-size-2xl: 24px;
        --font-size-3xl: 28px;
    }
}

/* ============================================
   Print Styles
   ============================================ */

@media print {
    .site-header,
    .site-footer,
    .theme-toggle {
        display: none;
    }

    body {
        font-size: 12pt;
        line-height: 1.5;
    }

    .experience-item {
        page-break-inside: avoid;
    }
}