/* ==========================================================================
   Upstream Partners - Portfolio Website Styles
   Design System: Conservative Modern
   ========================================================================== */

/* --------------------------------------------------------------------------
   CSS Custom Properties (Design Tokens)
   -------------------------------------------------------------------------- */
:root {
    /* Colors */
    --color-primary: #1a365d;
    --color-secondary: #2c5282;
    --color-accent: #38a169;
    --color-background: #f7fafc;
    --color-surface: #ffffff;
    --color-text-primary: #1a202c;
    --color-text-secondary: #4a5568;
    --color-border: #e2e8f0;

    /* Typography */
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.25rem;
    --font-size-2xl: 1.5rem;
    --font-size-3xl: 1.875rem;
    --font-size-4xl: 2.25rem;
    --font-size-5xl: 3rem;

    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    --spacing-3xl: 4rem;
    --spacing-4xl: 6rem;

    /* Layout */
    --container-max-width: 1200px;
    --header-height: 72px;

    /* Border Radius */
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;

    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px 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);

    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 200ms ease;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family);
    font-size: var(--font-size-base);
    line-height: 1.6;
    color: var(--color-text-primary);
    background-color: var(--color-background);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

a {
    color: var(--color-secondary);
    text-decoration: none;
    transition: color var(--transition-fast);
}

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

ul {
    list-style: none;
}

/* --------------------------------------------------------------------------
   Accessibility
   -------------------------------------------------------------------------- */
.skip-link {
    position: absolute;
    top: -40px;
    left: 0;
    background: var(--color-primary);
    color: white;
    padding: var(--spacing-sm) var(--spacing-md);
    z-index: 1000;
    transition: top var(--transition-fast);
}

.skip-link:focus {
    top: 0;
}

/* Focus styles */
:focus-visible {
    outline: 2px solid var(--color-secondary);
    outline-offset: 2px;
}

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

/* --------------------------------------------------------------------------
   Typography
   -------------------------------------------------------------------------- */
h1, h2, h3, h4, h5, h6 {
    font-weight: 600;
    line-height: 1.3;
    color: var(--color-primary);
}

h1 {
    font-size: var(--font-size-4xl);
    font-weight: 700;
}

h2 {
    font-size: var(--font-size-3xl);
    margin-bottom: var(--spacing-xl);
}

h3 {
    font-size: var(--font-size-xl);
    margin-bottom: var(--spacing-md);
}

.section-intro {
    font-size: var(--font-size-lg);
    color: var(--color-text-secondary);
    max-width: 800px;
    margin-bottom: var(--spacing-2xl);
}

/* --------------------------------------------------------------------------
   Buttons
   -------------------------------------------------------------------------- */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-md) var(--spacing-xl);
    font-size: var(--font-size-base);
    font-weight: 600;
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: all var(--transition-base);
    border: none;
    text-decoration: none;
}

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

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

/* --------------------------------------------------------------------------
   Header
   -------------------------------------------------------------------------- */
.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: var(--header-height);
    background-color: var(--color-surface);
    box-shadow: var(--shadow-sm);
    z-index: 100;
}

.header .container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 100%;
}

.logo {
    display: flex;
    align-items: center;
    text-decoration: none;
}

.logo-text {
    font-size: var(--font-size-xl);
    font-weight: 700;
    color: var(--color-primary);
}

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

.nav-list a {
    font-size: var(--font-size-sm);
    font-weight: 500;
    color: var(--color-text-secondary);
    transition: color var(--transition-fast);
}

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

.nav-cta {
    background-color: var(--color-primary);
    color: white !important;
    padding: var(--spacing-sm) var(--spacing-lg);
    border-radius: var(--radius-sm);
}

.nav-cta:hover {
    background-color: var(--color-secondary);
    color: white !important;
}

/* Mobile Menu Toggle */
.mobile-menu-toggle {
    display: none;
    background: none;
    border: none;
    padding: var(--spacing-sm);
    cursor: pointer;
}

.hamburger {
    display: block;
    width: 24px;
    height: 2px;
    background-color: var(--color-primary);
    position: relative;
    transition: background-color var(--transition-fast);
}

.hamburger::before,
.hamburger::after {
    content: '';
    position: absolute;
    width: 24px;
    height: 2px;
    background-color: var(--color-primary);
    left: 0;
    transition: transform var(--transition-fast);
}

.hamburger::before {
    top: -7px;
}

.hamburger::after {
    top: 7px;
}

/* --------------------------------------------------------------------------
   Hero Section
   -------------------------------------------------------------------------- */
.hero {
    padding: calc(var(--header-height) + var(--spacing-4xl)) 0 var(--spacing-4xl);
    background: linear-gradient(135deg, var(--color-surface) 0%, var(--color-background) 100%);
    text-align: center;
}

.hero h1 {
    margin-bottom: var(--spacing-lg);
    max-width: 900px;
    margin-left: auto;
    margin-right: auto;
}

.hero-subtitle {
    font-size: var(--font-size-xl);
    color: var(--color-text-secondary);
    max-width: 700px;
    margin: 0 auto var(--spacing-lg);
}

.hero-supporting {
    font-size: var(--font-size-base);
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-xl);
}

/* --------------------------------------------------------------------------
   Services Section
   -------------------------------------------------------------------------- */
.services {
    padding: var(--spacing-4xl) 0;
    background-color: var(--color-surface);
}

.services-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--spacing-xl);
}

.service-card {
    background-color: var(--color-background);
    border-radius: var(--radius-md);
    padding: var(--spacing-xl);
    border: 1px solid var(--color-border);
    transition: box-shadow var(--transition-base);
}

.service-card:hover {
    box-shadow: var(--shadow-md);
}

.service-icon {
    width: 48px;
    height: 48px;
    background-color: var(--color-primary);
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: var(--spacing-lg);
    color: white;
}

.service-card h3 {
    color: var(--color-primary);
}

.service-card p {
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-lg);
}

.service-highlights {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
}

.service-highlights li {
    padding-left: var(--spacing-lg);
    position: relative;
    margin-bottom: var(--spacing-sm);
}

.service-highlights li::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0.6em;
    width: 6px;
    height: 6px;
    background-color: var(--color-accent);
    border-radius: 50%;
}

/* --------------------------------------------------------------------------
   Industries Section
   -------------------------------------------------------------------------- */
.industries {
    padding: var(--spacing-4xl) 0;
    background-color: var(--color-background);
}

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

.industry-card {
    background-color: var(--color-surface);
    border-radius: var(--radius-md);
    padding: var(--spacing-xl);
    border: 1px solid var(--color-border);
    text-align: center;
}

.industry-icon {
    width: 56px;
    height: 56px;
    background-color: var(--color-secondary);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto var(--spacing-lg);
    color: white;
}

.industry-card h3 {
    margin-bottom: var(--spacing-lg);
}

.industry-card ul {
    text-align: left;
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
}

.industry-card li {
    padding-left: var(--spacing-lg);
    position: relative;
    margin-bottom: var(--spacing-sm);
}

.industry-card li::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0.6em;
    width: 6px;
    height: 6px;
    background-color: var(--color-accent);
    border-radius: 50%;
}

/* --------------------------------------------------------------------------
   Case Study Section
   -------------------------------------------------------------------------- */
.case-study {
    padding: var(--spacing-4xl) 0;
    background-color: var(--color-primary);
    color: white;
}

.case-study h2 {
    color: white;
}

.case-study-content {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--spacing-xl);
}

.case-study-section {
    background-color: rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-md);
    padding: var(--spacing-xl);
}

.case-study-section h3 {
    color: var(--color-accent);
    margin-bottom: var(--spacing-md);
}

.case-study-section p,
.case-study-section li {
    color: rgba(255, 255, 255, 0.9);
}

.case-study-section ul {
    font-size: var(--font-size-sm);
}

.case-study-section li {
    padding-left: var(--spacing-lg);
    position: relative;
    margin-bottom: var(--spacing-sm);
}

.case-study-section li::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0.6em;
    width: 6px;
    height: 6px;
    background-color: var(--color-accent);
    border-radius: 50%;
}

.case-study-section ul ul {
    margin-top: var(--spacing-sm);
    margin-left: var(--spacing-md);
}

.case-study-section ul ul li::before {
    width: 4px;
    height: 4px;
    background-color: rgba(255, 255, 255, 0.5);
}

.results-list li {
    font-weight: 500;
}

/* --------------------------------------------------------------------------
   Project Spotlight Section
   -------------------------------------------------------------------------- */
.project-spotlight {
    padding: var(--spacing-4xl) 0;
    background-color: var(--color-surface);
}

.project-tabs {
    display: flex;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-xl);
    border-bottom: 2px solid var(--color-border);
    padding-bottom: var(--spacing-sm);
}

.project-tab {
    padding: var(--spacing-sm) var(--spacing-lg);
    background: none;
    border: none;
    font-size: var(--font-size-base);
    font-weight: 500;
    color: var(--color-text-secondary);
    cursor: pointer;
    border-radius: var(--radius-sm) var(--radius-sm) 0 0;
    transition: all var(--transition-fast);
    position: relative;
}

.project-tab:hover {
    color: var(--color-primary);
    background-color: var(--color-background);
}

.project-tab.active {
    color: var(--color-primary);
    font-weight: 600;
}

.project-tab.active::after {
    content: '';
    position: absolute;
    bottom: calc(-1 * var(--spacing-sm) - 2px);
    left: 0;
    right: 0;
    height: 2px;
    background-color: var(--color-primary);
}

.project-panel {
    display: none;
}

.project-panel.active {
    display: block;
}

.project-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-2xl);
    align-items: start;
}

.project-description h3 {
    margin-bottom: var(--spacing-md);
}

.project-description p {
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-lg);
}

.tech-highlights {
    margin-bottom: var(--spacing-xl);
}

.tech-highlights li {
    padding-left: var(--spacing-lg);
    position: relative;
    margin-bottom: var(--spacing-sm);
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
}

.tech-highlights li::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0.6em;
    width: 6px;
    height: 6px;
    background-color: var(--color-accent);
    border-radius: 50%;
}

.project-link {
    display: inline-flex;
    align-items: center;
    font-weight: 600;
    color: var(--color-secondary);
}

.project-link:hover {
    color: var(--color-primary);
}

.project-why {
    background-color: var(--color-background);
    border-radius: var(--radius-md);
    padding: var(--spacing-xl);
    border-left: 4px solid var(--color-accent);
}

.project-why h3 {
    color: var(--color-primary);
}

.project-why p {
    color: var(--color-text-secondary);
    margin-bottom: 0;
}

/* --------------------------------------------------------------------------
   About Section
   -------------------------------------------------------------------------- */
.about {
    padding: var(--spacing-4xl) 0;
    background-color: var(--color-background);
}

.about-content {
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: var(--spacing-2xl);
}

.about-bio h3 {
    margin-bottom: var(--spacing-lg);
}

.about-bio p {
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-lg);
}

.about-bio p:last-child {
    margin-bottom: 0;
}

.about-credentials {
    background-color: var(--color-surface);
    border-radius: var(--radius-md);
    padding: var(--spacing-xl);
    border: 1px solid var(--color-border);
}

.about-credentials h3 {
    margin-bottom: var(--spacing-lg);
}

.about-credentials ul {
    margin-bottom: var(--spacing-xl);
}

.about-credentials li {
    padding-left: var(--spacing-lg);
    position: relative;
    margin-bottom: var(--spacing-sm);
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
}

.about-credentials li::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0.6em;
    width: 6px;
    height: 6px;
    background-color: var(--color-accent);
    border-radius: 50%;
}

.linkedin-link {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-size: var(--font-size-sm);
    font-weight: 600;
    color: var(--color-secondary);
}

.linkedin-link:hover {
    color: var(--color-primary);
}

/* --------------------------------------------------------------------------
   Contact Section
   -------------------------------------------------------------------------- */
.contact {
    padding: var(--spacing-4xl) 0;
    background-color: var(--color-surface);
    text-align: center;
}

.contact .section-intro {
    margin-left: auto;
    margin-right: auto;
}

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

.contact-link {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-md) var(--spacing-xl);
    background-color: var(--color-background);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    font-weight: 500;
    color: var(--color-text-primary);
    transition: all var(--transition-base);
}

.contact-link:hover {
    border-color: var(--color-secondary);
    color: var(--color-secondary);
}

.contact-link svg {
    flex-shrink: 0;
}

/* --------------------------------------------------------------------------
   Footer
   -------------------------------------------------------------------------- */
.footer {
    padding: var(--spacing-xl) 0;
    background-color: var(--color-primary);
    color: rgba(255, 255, 255, 0.8);
}

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

.footer p {
    font-size: var(--font-size-sm);
}

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

.footer-links a {
    color: rgba(255, 255, 255, 0.8);
    transition: color var(--transition-fast);
}

.footer-links a:hover {
    color: white;
}

/* --------------------------------------------------------------------------
   Responsive Design
   -------------------------------------------------------------------------- */

/* Tablet (768px - 1024px) */
@media (max-width: 1024px) {
    .services-grid {
        grid-template-columns: 1fr;
    }

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

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

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

/* Mobile (< 768px) */
@media (max-width: 768px) {
    :root {
        --font-size-4xl: 1.875rem;
        --font-size-3xl: 1.5rem;
        --font-size-2xl: 1.25rem;
    }

    .mobile-menu-toggle {
        display: block;
    }

    .nav {
        position: fixed;
        top: var(--header-height);
        left: 0;
        right: 0;
        background-color: var(--color-surface);
        padding: var(--spacing-lg);
        box-shadow: var(--shadow-md);
        transform: translateY(-100%);
        opacity: 0;
        visibility: hidden;
        transition: all var(--transition-base);
    }

    .nav-open {
        transform: translateY(0);
        opacity: 1;
        visibility: visible;
    }

    .nav-list {
        flex-direction: column;
        gap: var(--spacing-md);
    }

    .nav-list a {
        display: block;
        padding: var(--spacing-sm) 0;
    }

    .nav-cta {
        text-align: center;
        display: block;
        margin-top: var(--spacing-md);
    }

    .hero {
        padding: calc(var(--header-height) + var(--spacing-2xl)) 0 var(--spacing-2xl);
    }

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

    .contact-methods {
        flex-direction: column;
        align-items: center;
    }

    .contact-link {
        width: 100%;
        max-width: 300px;
        justify-content: center;
    }

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