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

:root {
    --color-bg: #f5f5f5;
    --color-surface: #ffffff;
    --color-primary: #1a3a5c;
    --color-primary-light: #2a5a8c;
    --color-accent: #d4a017;
    --color-text: #333333;
    --color-text-light: #666666;
    --color-border: #e0e0e0;
    --max-width: 1100px;
    --header-height: 70px;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen,
        Ubuntu, Cantarell, sans-serif;
    background: var(--color-bg);
    color: var(--color-text);
    line-height: 1.6;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

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

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

a:hover {
    text-decoration: underline;
}

/* ===== Layout ===== */
.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 24px;
}

/* ===== Header ===== */
header {
    background: var(--color-primary);
    color: #fff;
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.15);
}

.header-inner {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 24px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: var(--header-height);
}

.logo {
    display: flex;
    align-items: center;
    flex-shrink: 0;
}

.logo:hover {
    text-decoration: none;
}

.logo img {
    height: 50px;
    width: auto;
}

/* ===== Navigation ===== */
.mobile-menu-btn {
    display: none;
    background: none;
    border: none;
    color: #fff;
    font-size: 1.6rem;
    cursor: pointer;
    padding: 4px 8px;
}

.nav-tabs {
    list-style: none;
    display: flex;
    gap: 4px;
}

.nav-tabs a {
    color: rgba(255, 255, 255, 0.8);
    padding: 8px 16px;
    border-radius: 4px;
    font-size: 0.95rem;
    font-weight: 500;
    transition: background 0.2s, color 0.2s;
    white-space: nowrap;
}

.nav-tabs a:hover {
    color: #fff;
    background: rgba(255, 255, 255, 0.1);
    text-decoration: none;
}

.nav-tabs a.active {
    color: #fff;
    background: rgba(255, 255, 255, 0.2);
}

/* ===== Tab Content ===== */
.tab-content {
    display: none;
    padding: 48px 0 64px;
    animation: fadeIn 0.3s ease;
}

.tab-content.active {
    display: block;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(8px); }
    to { opacity: 1; transform: translateY(0); }
}

main {
    flex: 1;
}

h2 {
    font-size: 2rem;
    color: var(--color-primary);
    margin-bottom: 16px;
}

h3 {
    font-size: 1.25rem;
    color: var(--color-primary);
    margin-bottom: 8px;
}

.section-intro {
    font-size: 1.1rem;
    color: var(--color-text-light);
    margin-bottom: 32px;
    max-width: 720px;
}

/* ===== About ===== */
.about-grid {
    display: grid;
    grid-template-columns: 1fr 1.5fr;
    gap: 40px;
    align-items: start;
}

.about-text p {
    margin-bottom: 16px;
    font-size: 1.05rem;
}

.capabilities-summary {
    margin-top: 24px;
    padding: 24px;
    background: var(--color-surface);
    border-radius: 8px;
    border: 1px solid var(--color-border);
}

.capabilities-summary h3 {
    margin-bottom: 12px;
}

.capabilities-summary ul {
    list-style: none;
    padding: 0;
}

.capabilities-summary li {
    padding: 8px 0;
    border-bottom: 1px solid var(--color-border);
}

.capabilities-summary li:last-child {
    border-bottom: none;
}

.capabilities-summary a {
    font-weight: 600;
}

.about-images {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 14px;
    max-width: 720px;
}

.about-images img {
    border-radius: 6px;
    box-shadow: 0 2px 12px rgba(0, 0, 0, 0.1);
    width: 100%;
    aspect-ratio: 4 / 3;
    object-fit: cover;
    image-rendering: smooth;
    -webkit-backface-visibility: hidden;
    transform: translateZ(0);
}

/* ===== PCBA Process Grid ===== */
.process-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 24px;
}

.process-step {
    background: var(--color-surface);
    border-radius: 8px;
    overflow: hidden;
    border: 1px solid var(--color-border);
    transition: box-shadow 0.2s;
}

.process-step:hover {
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.1);
}

.process-step img {
    width: 100%;
    height: 240px;
    object-fit: cover;
}

.process-step h3,
.process-step p {
    padding: 0 20px;
}

.process-step h3 {
    margin-top: 16px;
    margin-bottom: 8px;
}

.process-step p {
    color: var(--color-text-light);
    padding-bottom: 20px;
    font-size: 0.95rem;
}

/* ===== PCB Design ===== */
.design-layout {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 40px;
    align-items: start;
}

.design-text ul {
    margin: 12px 0 20px 20px;
}

.design-text li {
    margin-bottom: 6px;
}

.design-text p {
    margin-bottom: 16px;
}

.design-image img {
    border-radius: 8px;
    box-shadow: 0 2px 12px rgba(0, 0, 0, 0.1);
}

/* ===== Programming ===== */
.programming-layout {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 40px;
    align-items: start;
}

.programming-image img {
    width: 100%;
    border-radius: 8px;
    box-shadow: 0 2px 12px rgba(0, 0, 0, 0.1);
}

.service-card {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: 8px;
    padding: 24px;
    margin-bottom: 20px;
}

.service-card p {
    color: var(--color-text-light);
}

.github-link {
    display: inline-block;
    margin-top: 8px;
    padding: 10px 20px;
    background: var(--color-primary);
    color: #fff;
    border-radius: 6px;
    font-weight: 600;
    transition: background 0.2s;
}

.github-link:hover {
    background: var(--color-primary-light);
    text-decoration: none;
    color: #fff;
}

/* ===== Milling ===== */
.milling-layout {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 40px;
    align-items: start;
}

.milling-text ul {
    margin: 12px 0 20px 20px;
}

.milling-text li {
    margin-bottom: 6px;
}

.milling-text p {
    margin-bottom: 16px;
}

.milling-images {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 12px;
}

.milling-images img {
    border-radius: 8px;
    box-shadow: 0 2px 12px rgba(0, 0, 0, 0.1);
    width: 100%;
    height: auto;
}

.gallery-heading {
    margin-top: 40px;
    margin-bottom: 16px;
}

.milling-gallery {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 16px;
}

.milling-gallery img {
    border-radius: 8px;
    box-shadow: 0 2px 12px rgba(0, 0, 0, 0.1);
    width: 100%;
    height: 280px;
    object-fit: cover;
}

/* ===== Contact ===== */
.contact-layout {
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: 40px;
    align-items: start;
}

.form-group {
    margin-bottom: 20px;
}

.form-group label {
    display: block;
    font-weight: 600;
    margin-bottom: 6px;
    color: var(--color-primary);
}

.form-group input,
.form-group textarea {
    width: 100%;
    padding: 10px 14px;
    border: 1px solid var(--color-border);
    border-radius: 6px;
    font-size: 1rem;
    font-family: inherit;
    background: var(--color-surface);
    transition: border-color 0.2s;
}

.form-group input:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--color-primary-light);
    box-shadow: 0 0 0 3px rgba(26, 58, 92, 0.1);
}

.submit-btn {
    padding: 12px 32px;
    background: var(--color-primary);
    color: #fff;
    border: none;
    border-radius: 6px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: background 0.2s;
}

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

.contact-info {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: 8px;
    padding: 24px;
}

.contact-info h3 {
    margin-bottom: 12px;
}

.contact-info p {
    color: var(--color-text-light);
    margin-bottom: 8px;
}

/* ===== Lightbox ===== */
.lightbox-overlay {
    display: none;
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.85);
    z-index: 200;
    justify-content: center;
    align-items: center;
    cursor: pointer;
}

.lightbox-overlay.open {
    display: flex;
}

.lightbox-close {
    position: absolute;
    top: 16px;
    right: 24px;
    background: none;
    border: none;
    color: #fff;
    font-size: 2.5rem;
    cursor: pointer;
    line-height: 1;
    padding: 4px 12px;
    opacity: 0.8;
    transition: opacity 0.2s;
}

.lightbox-close:hover {
    opacity: 1;
}

.lightbox-overlay img {
    max-width: 90vw;
    max-height: 90vh;
    border-radius: 4px;
    box-shadow: 0 4px 32px rgba(0, 0, 0, 0.5);
}

/* ===== Footer ===== */
footer {
    background: var(--color-primary);
    color: rgba(255, 255, 255, 0.7);
    text-align: center;
    padding: 20px 0;
    font-size: 0.9rem;
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
    :root {
        --header-height: auto;
    }

    .header-inner {
        flex-wrap: wrap;
        padding: 12px 16px;
    }

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

    .nav-tabs {
        display: none;
        flex-direction: column;
        width: 100%;
        padding: 8px 0;
        gap: 2px;
    }

    .nav-tabs.open {
        display: flex;
    }

    .nav-tabs a {
        display: block;
        padding: 10px 12px;
    }

    .about-grid,
    .design-layout,
    .programming-layout,
    .milling-layout,
    .contact-layout {
        grid-template-columns: 1fr;
    }

    .process-grid,
    .milling-gallery {
        grid-template-columns: 1fr;
    }

    h2 {
        font-size: 1.6rem;
    }

    .tab-content {
        padding: 32px 0 48px;
    }
}