/* ============================
   CSS VARIABLES & RESET
   ============================ */

:root {
    /* Colors — Light Mode (default) */
    --color-bg: #ffffff;
    --color-bg-secondary: #f8fafc;
    --color-bg-tertiary: #f1f5f9;
    --color-surface: #ffffff;
    --color-surface-hover: #f8fafc;
    --color-border: #e2e8f0;
    --color-border-light: #f1f5f9;
    --color-text-primary: #0f172a;
    --color-text-secondary: #475569;
    --color-text-tertiary: #94a3b8;
    --color-accent: #2563eb;
    --color-accent-hover: #1d4ed8;
    --color-accent-light: rgba(37, 99, 235, 0.08);
    --color-accent-glow: rgba(37, 99, 235, 0.15);
    --color-shadow: rgba(15, 23, 42, 0.04);
    --color-shadow-md: rgba(15, 23, 42, 0.08);
    --color-shadow-lg: rgba(15, 23, 42, 0.12);
    --color-overlay: rgba(15, 23, 42, 0.4);
    --color-header-bg: rgba(255, 255, 255, 0.82);
    --color-card-bg: #ffffff;
    --color-tag-bg: #f1f5f9;
    --color-tag-text: #475569;
    --color-structure-bg: #f8fafc;
    --color-structure-border: #e2e8f0;
    --color-structure-node: #ffffff;
    --color-hero-gradient-1: rgba(37, 99, 235, 0.06);
    --color-hero-gradient-2: rgba(139, 92, 246, 0.04);
    --color-grid-line: rgba(15, 23, 42, 0.03);
    --color-orb-1: rgba(37, 99, 235, 0.08);
    --color-orb-2: rgba(139, 92, 246, 0.06);

    /* Typography */
    --font-family: 'Inter', system-ui, -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;
    --font-size-6xl: 3.75rem;

    /* 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: 1120px;
    --container-padding: 1.25rem;
    --header-height: 4rem;
    --border-radius-sm: 0.5rem;
    --border-radius-md: 0.75rem;
    --border-radius-lg: 1rem;
    --border-radius-xl: 1.25rem;
    --border-radius-full: 9999px;

    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 250ms ease;
    --transition-slow: 400ms ease;
    --transition-theme: 350ms ease;
}

/* ===== Dark Mode ===== */
[data-theme="dark"] {
    --color-bg: #0b1120;
    --color-bg-secondary: #0f172a;
    --color-bg-tertiary: #1e293b;
    --color-surface: #162032;
    --color-surface-hover: #1e293b;
    --color-border: #1e293b;
    --color-border-light: #162032;
    --color-text-primary: #f1f5f9;
    --color-text-secondary: #94a3b8;
    --color-text-tertiary: #64748b;
    --color-accent: #3b82f6;
    --color-accent-hover: #60a5fa;
    --color-accent-light: rgba(59, 130, 246, 0.1);
    --color-accent-glow: rgba(59, 130, 246, 0.2);
    --color-shadow: rgba(0, 0, 0, 0.2);
    --color-shadow-md: rgba(0, 0, 0, 0.3);
    --color-shadow-lg: rgba(0, 0, 0, 0.4);
    --color-overlay: rgba(0, 0, 0, 0.6);
    --color-header-bg: rgba(11, 17, 32, 0.85);
    --color-card-bg: #162032;
    --color-tag-bg: #1e293b;
    --color-tag-text: #94a3b8;
    --color-structure-bg: #0f172a;
    --color-structure-border: #1e293b;
    --color-structure-node: #1e293b;
    --color-hero-gradient-1: rgba(59, 130, 246, 0.08);
    --color-hero-gradient-2: rgba(139, 92, 246, 0.06);
    --color-grid-line: rgba(255, 255, 255, 0.02);
    --color-orb-1: rgba(59, 130, 246, 0.12);
    --color-orb-2: rgba(139, 92, 246, 0.08);
}

/* System preference fallback */
@media (prefers-color-scheme: dark) {
    [data-theme="system"] {
        --color-bg: #0b1120;
        --color-bg-secondary: #0f172a;
        --color-bg-tertiary: #1e293b;
        --color-surface: #162032;
        --color-surface-hover: #1e293b;
        --color-border: #1e293b;
        --color-border-light: #162032;
        --color-text-primary: #f1f5f9;
        --color-text-secondary: #94a3b8;
        --color-text-tertiary: #64748b;
        --color-accent: #3b82f6;
        --color-accent-hover: #60a5fa;
        --color-accent-light: rgba(59, 130, 246, 0.1);
        --color-accent-glow: rgba(59, 130, 246, 0.2);
        --color-shadow: rgba(0, 0, 0, 0.2);
        --color-shadow-md: rgba(0, 0, 0, 0.3);
        --color-shadow-lg: rgba(0, 0, 0, 0.4);
        --color-overlay: rgba(0, 0, 0, 0.6);
        --color-header-bg: rgba(11, 17, 32, 0.85);
        --color-card-bg: #162032;
        --color-tag-bg: #1e293b;
        --color-tag-text: #94a3b8;
        --color-structure-bg: #0f172a;
        --color-structure-border: #1e293b;
        --color-structure-node: #1e293b;
        --color-hero-gradient-1: rgba(59, 130, 246, 0.08);
        --color-hero-gradient-2: rgba(139, 92, 246, 0.06);
        --color-grid-line: rgba(255, 255, 255, 0.02);
        --color-orb-1: rgba(59, 130, 246, 0.12);
        --color-orb-2: rgba(139, 92, 246, 0.08);
    }
}

/* ===== Theme icon visibility ===== */
[data-theme="light"] .theme-icon.sun,
[data-theme="system"] .theme-icon.sun {
    display: block;
}
[data-theme="light"] .theme-icon.moon,
[data-theme="system"] .theme-icon.moon {
    display: none;
}
[data-theme="dark"] .theme-icon.sun {
    display: none;
}
[data-theme="dark"] .theme-icon.moon {
    display: block;
}

@media (prefers-color-scheme: dark) {
    [data-theme="system"] .theme-icon.sun {
        display: none;
    }
    [data-theme="system"] .theme-icon.moon {
        display: block;
    }
}

/* ============================
   RESET
   ============================ */

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

html {
    scroll-behavior: smooth;
    scroll-padding-top: var(--header-height);
    -webkit-text-size-adjust: 100%;
}

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-bg);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    transition: background-color var(--transition-theme), color var(--transition-theme);
    overflow-x: hidden;
}

body.menu-open {
    overflow: hidden;
}

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

ul, ol {
    list-style: none;
}

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

button {
    border: none;
    background: none;
    cursor: pointer;
    font-family: inherit;
    color: inherit;
}

/* ============================
   UTILITY
   ============================ */

.container {
    width: 100%;
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 var(--container-padding);
}

/* ============================
   HEADER
   ============================ */

.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    height: var(--header-height);
    background: var(--color-header-bg);
    backdrop-filter: blur(16px) saturate(180%);
    -webkit-backdrop-filter: blur(16px) saturate(180%);
    border-bottom: 1px solid var(--color-border);
    transition: background-color var(--transition-theme), border-color var(--transition-theme), box-shadow var(--transition-base);
}

.header--scrolled {
    box-shadow: 0 1px 12px var(--color-shadow);
}

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

/* Logo */
.header__logo {
    display: flex;
    align-items: center;
    gap: 0;
    font-weight: 700;
    font-size: var(--font-size-xl);
    color: var(--color-text-primary);
    transition: color var(--transition-theme);
    position: relative;
    z-index: 10;
}

.logo-text {
    color: var(--color-accent);
    font-weight: 800;
    font-size: var(--font-size-2xl);
    line-height: 1;
    transition: color var(--transition-theme);
}

.logo-full {
    color: var(--color-text-primary);
    transition: color var(--transition-theme);
}

/* Desktop Nav */
.header__nav {
    display: none;
}

@media (min-width: 768px) {
    .header__nav {
        display: flex;
    }
}

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

.nav__link {
    display: inline-flex;
    align-items: center;
    padding: 0.5rem 1rem;
    font-size: var(--font-size-sm);
    font-weight: 500;
    color: var(--color-text-secondary);
    border-radius: var(--border-radius-md);
    transition: color var(--transition-fast), background-color var(--transition-fast);
}

.nav__link:hover,
.nav__link.active {
    color: var(--color-text-primary);
    background-color: var(--color-accent-light);
}

.nav__link.active {
    color: var(--color-accent);
}

/* Header Actions */
.header__actions {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

/* Theme Toggle */
.theme-toggle {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 2.5rem;
    height: 2.5rem;
    border-radius: var(--border-radius-md);
    transition: background-color var(--transition-fast), color var(--transition-theme);
    color: var(--color-text-secondary);
}

.theme-toggle:hover {
    background-color: var(--color-accent-light);
    color: var(--color-accent);
}

.theme-icon {
    width: 1.25rem;
    height: 1.25rem;
}

/* Hamburger */
.hamburger {
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    gap: 5px;
    width: 2.5rem;
    height: 2.5rem;
    border-radius: var(--border-radius-md);
    transition: background-color var(--transition-fast);
    position: relative;
    z-index: 10;
}

.hamburger:hover {
    background-color: var(--color-accent-light);
}

@media (min-width: 768px) {
    .hamburger {
        display: none;
    }
}

.hamburger__line {
    display: block;
    width: 20px;
    height: 2px;
    background-color: var(--color-text-primary);
    border-radius: 2px;
    transition: transform var(--transition-base), opacity var(--transition-base), background-color var(--transition-theme);
}

.hamburger.active .hamburger__line:nth-child(1) {
    transform: translateY(7px) rotate(45deg);
}

.hamburger.active .hamburger__line:nth-child(2) {
    opacity: 0;
}

.hamburger.active .hamburger__line:nth-child(3) {
    transform: translateY(-7px) rotate(-45deg);
}

/* ============================
   MOBILE MENU
   ============================ */

.mobile-overlay {
    position: fixed;
    inset: 0;
    background: var(--color-overlay);
    z-index: 998;
    opacity: 0;
    visibility: hidden;
    transition: opacity var(--transition-base), visibility var(--transition-base);
}

.mobile-overlay.active {
    opacity: 1;
    visibility: visible;
}

.mobile-menu {
    position: fixed;
    top: 0;
    right: 0;
    width: min(320px, 85vw);
    height: 100vh;
    height: 100dvh;
    background: var(--color-bg);
    z-index: 999;
    padding: calc(var(--header-height) + var(--spacing-xl)) var(--spacing-xl) var(--spacing-xl);
    transform: translateX(100%);
    transition: transform var(--transition-slow), background-color var(--transition-theme);
    overflow-y: auto;
    border-left: 1px solid var(--color-border);
}

.mobile-menu.active {
    transform: translateX(0);
}

.mobile-menu__list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.mobile-menu__link {
    display: block;
    padding: 0.875rem 1rem;
    font-size: var(--font-size-lg);
    font-weight: 500;
    color: var(--color-text-secondary);
    border-radius: var(--border-radius-md);
    transition: color var(--transition-fast), background-color var(--transition-fast);
}

.mobile-menu__link:hover,
.mobile-menu__link.active {
    color: var(--color-accent);
    background-color: var(--color-accent-light);
}

@media (min-width: 768px) {
    .mobile-menu,
    .mobile-overlay {
        display: none !important;
    }
}

/* ============================
   HERO
   ============================ */

.hero {
    position: relative;
    min-height: 100vh;
    min-height: 100dvh;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
    padding: calc(var(--header-height) + var(--spacing-3xl)) 0 var(--spacing-3xl);
}

/* Hero Background */
.hero__bg {
    position: absolute;
    inset: 0;
    z-index: 0;
    overflow: hidden;
}

.hero__gradient {
    position: absolute;
    inset: 0;
    background:
        radial-gradient(ellipse 80% 60% at 50% 0%, var(--color-hero-gradient-1), transparent),
        radial-gradient(ellipse 60% 50% at 80% 50%, var(--color-hero-gradient-2), transparent);
    transition: background var(--transition-theme);
}

.hero__grid-pattern {
    position: absolute;
    inset: 0;
    background-image:
        linear-gradient(var(--color-grid-line) 1px, transparent 1px),
        linear-gradient(90deg, var(--color-grid-line) 1px, transparent 1px);
    background-size: 60px 60px;
    mask-image: radial-gradient(ellipse 70% 70% at 50% 50%, black, transparent);
    -webkit-mask-image: radial-gradient(ellipse 70% 70% at 50% 50%, black, transparent);
    transition: background-image var(--transition-theme);
}

.hero__orb {
    position: absolute;
    border-radius: 50%;
    filter: blur(80px);
    transition: background var(--transition-theme);
    animation: orbFloat 20s ease-in-out infinite;
}

.hero__orb--1 {
    width: 400px;
    height: 400px;
    top: 10%;
    left: -10%;
    background: var(--color-orb-1);
    animation-delay: 0s;
}

.hero__orb--2 {
    width: 350px;
    height: 350px;
    bottom: 10%;
    right: -5%;
    background: var(--color-orb-2);
    animation-delay: -10s;
}

@keyframes orbFloat {
    0%, 100% { transform: translate(0, 0) scale(1); }
    25% { transform: translate(30px, -20px) scale(1.05); }
    50% { transform: translate(-20px, 30px) scale(0.95); }
    75% { transform: translate(20px, 20px) scale(1.02); }
}

/* Hero Content */
.hero__content {
    position: relative;
    z-index: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
    gap: var(--spacing-lg);
}

.hero__badge {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: 0.375rem 1rem 0.375rem 0.75rem;
    background: var(--color-accent-light);
    border: 1px solid var(--color-accent-glow);
    border-radius: var(--border-radius-full);
    font-size: var(--font-size-sm);
    font-weight: 500;
    color: var(--color-accent);
    transition: background var(--transition-theme), border-color var(--transition-theme), color var(--transition-theme);
}

.badge__dot {
    width: 8px;
    height: 8px;
    background: var(--color-accent);
    border-radius: 50%;
    animation: pulse 2s ease-in-out infinite;
    transition: background var(--transition-theme);
}

@keyframes pulse {
    0%, 100% { opacity: 1; transform: scale(1); }
    50% { opacity: 0.5; transform: scale(0.8); }
}

.hero__title {
    font-size: clamp(var(--font-size-3xl), 7vw, var(--font-size-6xl));
    font-weight: 800;
    line-height: 1.1;
    letter-spacing: -0.03em;
    color: var(--color-text-primary);
    transition: color var(--transition-theme);
}

.hero__name {
    background: linear-gradient(135deg, var(--color-accent), #8b5cf6);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero__subtitle {
    font-size: clamp(var(--font-size-lg), 3vw, var(--font-size-2xl));
    font-weight: 500;
    color: var(--color-text-secondary);
    letter-spacing: -0.01em;
    transition: color var(--transition-theme);
}

.hero__description {
    max-width: 520px;
    font-size: var(--font-size-base);
    color: var(--color-text-tertiary);
    line-height: 1.7;
    transition: color var(--transition-theme);
}

.hero__actions {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-md);
    margin-top: var(--spacing-sm);
}

/* Scroll Indicator */
.hero__scroll {
    position: absolute;
    bottom: 2rem;
    left: 50%;
    transform: translateX(-50%);
}

.scroll-indicator {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-sm);
    color: var(--color-text-tertiary);
    font-size: var(--font-size-xs);
    font-weight: 500;
    letter-spacing: 0.05em;
    text-transform: uppercase;
    transition: color var(--transition-fast);
}

.scroll-indicator:hover {
    color: var(--color-accent);
}

.scroll-indicator__mouse {
    width: 24px;
    height: 38px;
    border: 2px solid var(--color-text-tertiary);
    border-radius: 12px;
    display: flex;
    justify-content: center;
    padding-top: 8px;
    transition: border-color var(--transition-fast);
}

.scroll-indicator:hover .scroll-indicator__mouse {
    border-color: var(--color-accent);
}

.scroll-indicator__wheel {
    width: 3px;
    height: 8px;
    background: var(--color-text-tertiary);
    border-radius: 2px;
    animation: scrollWheel 2s ease-in-out infinite;
    transition: background var(--transition-fast);
}

.scroll-indicator:hover .scroll-indicator__wheel {
    background: var(--color-accent);
}

@keyframes scrollWheel {
    0% { opacity: 1; transform: translateY(0); }
    100% { opacity: 0; transform: translateY(10px); }
}

@media (max-height: 700px) {
    .hero__scroll { display: none; }
}

/* ============================
   BUTTONS
   ============================ */

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    padding: 0.75rem 1.5rem;
    font-size: var(--font-size-sm);
    font-weight: 600;
    border-radius: var(--border-radius-md);
    transition: all var(--transition-base);
    white-space: nowrap;
    position: relative;
    overflow: hidden;
}

.btn__icon {
    width: 1rem;
    height: 1rem;
    flex-shrink: 0;
}

.btn--primary {
    background: var(--color-accent);
    color: #ffffff;
    box-shadow: 0 2px 8px rgba(37, 99, 235, 0.25), 0 0 0 0 rgba(37, 99, 235, 0);
}

.btn--primary:hover {
    background: var(--color-accent-hover);
    box-shadow: 0 4px 16px rgba(37, 99, 235, 0.35), 0 0 0 0 rgba(37, 99, 235, 0);
    transform: translateY(-1px);
}

.btn--primary:active {
    transform: translateY(0);
}

.btn--secondary {
    background: var(--color-surface);
    color: var(--color-text-primary);
    border: 1px solid var(--color-border);
    box-shadow: 0 1px 3px var(--color-shadow);
}

.btn--secondary:hover {
    background: var(--color-surface-hover);
    border-color: var(--color-accent);
    color: var(--color-accent);
    box-shadow: 0 2px 8px var(--color-shadow-md);
    transform: translateY(-1px);
}

.btn--secondary:active {
    transform: translateY(0);
}

.btn--lg {
    padding: 1rem 2rem;
    font-size: var(--font-size-base);
    border-radius: var(--border-radius-lg);
}

.btn--lg .btn__icon {
    width: 1.125rem;
    height: 1.125rem;
}

/* ============================
   SECTIONS
   ============================ */

.projects,
.contact {
    padding: var(--spacing-4xl) 0;
    transition: background-color var(--transition-theme);
}

.projects {
    background: var(--color-bg-secondary);
}

.contact {
    background: var(--color-bg);
}

/* Section Header */
.section-header {
    text-align: center;
    margin-bottom: var(--spacing-3xl);
}

.section-label {
    display: inline-block;
    font-size: var(--font-size-sm);
    font-weight: 600;
    color: var(--color-accent);
    letter-spacing: 0.02em;
    margin-bottom: var(--spacing-sm);
    transition: color var(--transition-theme);
}

.section-title {
    font-size: clamp(var(--font-size-2xl), 4vw, var(--font-size-4xl));
    font-weight: 800;
    letter-spacing: -0.03em;
    line-height: 1.2;
    color: var(--color-text-primary);
    margin-bottom: var(--spacing-md);
    transition: color var(--transition-theme);
}

.section-description {
    max-width: 480px;
    margin: 0 auto;
    font-size: var(--font-size-base);
    color: var(--color-text-secondary);
    line-height: 1.7;
    transition: color var(--transition-theme);
}

/* ============================
   PROJECT CARDS
   ============================ */

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

@media (min-width: 768px) {
    .projects__grid {
        grid-template-columns: repeat(2, 1fr);
        gap: var(--spacing-xl);
    }
}

.project-card {
    background: var(--color-card-bg);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius-xl);
    padding: var(--spacing-xl);
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
    transition: all var(--transition-base);
    position: relative;
    overflow: hidden;
}

.project-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: linear-gradient(90deg, var(--color-accent), #8b5cf6);
    opacity: 0;
    transition: opacity var(--transition-base);
}

.project-card:hover {
    border-color: var(--color-accent-glow);
    box-shadow: 0 8px 32px var(--color-shadow-md), 0 0 0 1px var(--color-accent-glow);
    transform: translateY(-4px);
}

.project-card:hover::before {
    opacity: 1;
}

/* Card Header */
.project-card__header {
    display: flex;
    align-items: flex-start;
    justify-content: space-between;
}

.project-card__icon {
    width: 3rem;
    height: 3rem;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--color-accent-light);
    border-radius: var(--border-radius-md);
    color: var(--color-accent);
    transition: background var(--transition-theme), color var(--transition-theme);
}

.project-card__icon svg {
    width: 1.5rem;
    height: 1.5rem;
}

.project-card__external {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 2.25rem;
    height: 2.25rem;
    border-radius: var(--border-radius-sm);
    color: var(--color-text-tertiary);
    transition: color var(--transition-fast), background var(--transition-fast);
}

.project-card__external:hover {
    color: var(--color-accent);
    background: var(--color-accent-light);
}

.project-card__external svg {
    width: 1.125rem;
    height: 1.125rem;
}

.project-card__badge {
    display: inline-flex;
    align-items: center;
    padding: 0.25rem 0.75rem;
    background: var(--color-accent-light);
    color: var(--color-accent);
    font-size: var(--font-size-xs);
    font-weight: 600;
    border-radius: var(--border-radius-full);
    transition: background var(--transition-theme), color var(--transition-theme);
}

/* Card Body */
.project-card__body {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.project-card__title {
    font-size: var(--font-size-xl);
    font-weight: 700;
    color: var(--color-text-primary);
    letter-spacing: -0.02em;
    transition: color var(--transition-theme);
}

.project-card__description {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
    line-height: 1.7;
    transition: color var(--transition-theme);
}

/* Structure Visual */
.project-card__structure {
    margin-top: var(--spacing-md);
    padding: var(--spacing-lg);
    background: var(--color-structure-bg);
    border: 1px solid var(--color-structure-border);
    border-radius: var(--border-radius-md);
    transition: background var(--transition-theme), border-color var(--transition-theme);
}

.structure-label {
    font-size: var(--font-size-xs);
    font-weight: 600;
    color: var(--color-text-tertiary);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: var(--spacing-md);
    transition: color var(--transition-theme);
}

.structure-visual {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-md);
}

.structure-node {
    display: inline-flex;
    align-items: center;
    padding: 0.5rem 1rem;
    background: var(--color-structure-node);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius-sm);
    font-size: var(--font-size-sm);
    font-weight: 500;
    font-family: 'SF Mono', 'Fira Code', 'Fira Mono', 'Roboto Mono', monospace;
    color: var(--color-text-secondary);
    transition: all var(--transition-theme);
}

.structure-node--root {
    color: var(--color-accent);
    border-color: var(--color-accent-glow);
    background: var(--color-accent-light);
    font-weight: 600;
}

.structure-branches {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: var(--spacing-sm);
    position: relative;
}

.structure-branches::before {
    content: '';
    position: absolute;
    top: -var(--spacing-md);
    left: 50%;
    width: 1px;
    height: var(--spacing-md);
    background: var(--color-border);
}

.structure-node--more {
    color: var(--color-text-tertiary);
    border-style: dashed;
}

/* Card Footer */
.project-card__footer {
    display: flex;
    align-items: center;
    justify-content: space-between;
    flex-wrap: wrap;
    gap: var(--spacing-md);
    padding-top: var(--spacing-md);
    border-top: 1px solid var(--color-border);
    transition: border-color var(--transition-theme);
}

.project-card__tags {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-xs);
}

.tag {
    display: inline-flex;
    align-items: center;
    padding: 0.25rem 0.625rem;
    background: var(--color-tag-bg);
    color: var(--color-tag-text);
    font-size: var(--font-size-xs);
    font-weight: 500;
    border-radius: var(--border-radius-full);
    transition: background var(--transition-theme), color var(--transition-theme);
}

.project-card__link {
    display: inline-flex;
    align-items: center;
    gap: 0.375rem;
    font-size: var(--font-size-sm);
    font-weight: 600;
    color: var(--color-accent);
    transition: gap var(--transition-fast);
}

.project-card__link:hover {
    gap: 0.625rem;
}

.project-card__link svg {
    width: 1rem;
    height: 1rem;
    transition: transform var(--transition-fast);
}

.project-card__link:hover svg {
    transform: translateX(2px);
}

/* ============================
   CONTACT
   ============================ */

.contact__card {
    max-width: 480px;
    margin: 0 auto;
    text-align: center;
    padding: var(--spacing-3xl) var(--spacing-xl);
    background: var(--color-card-bg);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius-xl);
    transition: all var(--transition-theme);
}

.contact__icon-wrap {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 4rem;
    height: 4rem;
    background: var(--color-accent-light);
    border-radius: var(--border-radius-lg);
    margin-bottom: var(--spacing-lg);
    transition: background var(--transition-theme);
}

.contact__icon {
    width: 1.75rem;
    height: 1.75rem;
    color: var(--color-accent);
    transition: color var(--transition-theme);
}

.contact__title {
    font-size: var(--font-size-xl);
    font-weight: 700;
    color: var(--color-text-primary);
    margin-bottom: var(--spacing-sm);
    transition: color var(--transition-theme);
}

.contact__text {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
    line-height: 1.7;
    margin-bottom: var(--spacing-xl);
    transition: color var(--transition-theme);
}

.contact__btn {
    width: 100%;
    max-width: 320px;
}

/* ============================
   FOOTER
   ============================ */

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

.footer__inner {
    text-align: center;
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xs);
}

.footer__text {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
    transition: color var(--transition-theme);
}

.footer__sub {
    font-size: var(--font-size-xs);
    color: var(--color-text-tertiary);
    transition: color var(--transition-theme);
}

/* ============================
   ANIMATIONS
   ============================ */

/* Initial load animations */
.animate-in {
    opacity: 0;
    transform: translateY(20px);
    animation: fadeInUp 0.6s ease forwards;
    animation-delay: var(--delay, 0s);
}

@keyframes fadeInUp {
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Scroll animations */
.animate-on-scroll {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.7s ease, transform 0.7s ease;
    transition-delay: calc(var(--stagger, 0) * 0.12s);
}

.animate-on-scroll.visible {
    opacity: 1;
    transform: translateY(0);
}

/* ============================
   RESPONSIVE
   ============================ */

/* 320px and up — Mobile first, base styles above handle this */

@media (min-width: 480px) {
    :root {
        --container-padding: 1.5rem;
    }
}

@media (min-width: 768px) {
    :root {
        --container-padding: 2rem;
        --header-height: 4.5rem;
    }

    .hero__description {
        font-size: var(--font-size-lg);
    }

    .projects,
    .contact {
        padding: var(--spacing-4xl) 0 calc(var(--spacing-4xl) + var(--spacing-xl));
    }

    .contact__card {
        padding: var(--spacing-3xl) var(--spacing-3xl);
    }
}

@media (min-width: 1024px) {
    :root {
        --container-padding: 2.5rem;
    }
}

/* ============================
   FOCUS STYLES (Accessibility)
   ============================ */

:focus-visible {
    outline: 2px solid var(--color-accent);
    outline-offset: 2px;
    border-radius: var(--border-radius-sm);
}

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

    html {
        scroll-behavior: auto;
    }
}