@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700;800&display=swap');

:root {
    /* Revised: Light Mode for Logo Visibility */
    /* Colors */
    --bg-main: #FFFFFF;
    /* Pure White */
    --bg-surface: #F8FAFC;
    /* Light Gray for cards */
    --bg-card-hover: #F1F5F9;
    /* Slightly darker gray on hover */

    --text-primary: #0F172A;
    /* Dark Slate */
    --text-secondary: #475569;
    /* Muted Slate */

    --color-accent: #2563EB;
    /* Royal Blue */
    --color-accent-hover: #1D4ED8;
    --color-accent-secondary: #7C3AED;
    /* Deep Purple */

    --border-subtle: rgba(0, 0, 0, 0.08);

    /* Gradients */
    --gradient-primary: linear-gradient(135deg, var(--color-accent) 0%, var(--color-accent-secondary) 100%);
    --gradient-text: linear-gradient(to right, var(--text-primary), #475569);

    /* Typography */
    --font-family-sans: 'Inter', sans-serif;

    /* Spacing */
    --container-max-width: 1200px;
    --spacing-section-desktop: 100px;
    --spacing-section-mobile: 60px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-full: 9999px;

    /* Transitions */
    --transition-fast: 0.2s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-normal: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-slow: 0.5s ease-out;
}

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

html {
    scroll-behavior: smooth;
}

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

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

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

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

/* ==========================================================================
   Typography Hierachy
   ========================================================================== */
h1,
h2,
h3,
h4,
h5,
h6 {
    line-height: 1.2;
    margin-bottom: 1rem;
    font-weight: 700;
    color: var(--text-primary);
}

h1 {
    font-size: clamp(2.5rem, 5vw, 4rem);
    font-weight: 800;
    letter-spacing: -0.02em;
}

h2 {
    font-size: clamp(2rem, 4vw, 3rem);
    letter-spacing: -0.01em;
}

h3 {
    font-size: clamp(1.5rem, 3vw, 2rem);
    font-weight: 600;
}

h4 {
    font-size: clamp(1.25rem, 2vw, 1.5rem);
    font-weight: 600;
}

p {
    margin-bottom: 1.5rem;
    color: var(--text-secondary);
}

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

.text-gradient {
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    display: inline-block;
}

.subtitle {
    font-size: clamp(1.125rem, 2vw, 1.25rem);
    font-weight: 400;
    color: var(--text-secondary);
    max-width: 60ch;
}

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

@media (min-width: 768px) {
    .container {
        padding: 0 40px;
    }
}

section {
    padding: var(--spacing-section-mobile) 0;
}

@media (min-width: 768px) {
    section {
        padding: var(--spacing-section-desktop) 0;
    }
}

/* Utils */
.text-center {
    text-align: center;
}

.mb-2 {
    margin-bottom: 0.5rem;
}

.mb-4 {
    margin-bottom: 1rem;
}

.mb-8 {
    margin-bottom: 2rem;
}

.mt-8 {
    margin-top: 2rem;
}

/* ==========================================================================
   Buttons
   ========================================================================== */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.875rem 1.75rem;
    font-size: 1rem;
    font-weight: 600;
    border-radius: var(--radius-full);
    transition: all var(--transition-fast);
    cursor: pointer;
    border: none;
    gap: 0.5rem;
}

.btn-primary {
    background: var(--gradient-primary);
    color: #FFFFFF;
    box-shadow: 0 4px 14px 0 rgba(37, 99, 235, 0.3);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(37, 99, 235, 0.4);
    color: #FFFFFF;
}

.btn-outline {
    background: transparent;
    color: var(--text-primary);
    border: 2px solid var(--text-primary);
}

.btn-outline:hover {
    background: var(--text-primary);
    border-color: var(--text-primary);
    color: var(--bg-main);
}

/* ==========================================================================
   Cards
   ========================================================================== */
.card {
    background: var(--bg-surface);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-lg);
    padding: 2rem;
    transition: all var(--transition-normal);
}

.card:hover {
    transform: translateY(-5px);
    background: var(--bg-card-hover);
    border-color: rgba(37, 99, 235, 0.3);
    box-shadow: 0 10px 30px -10px rgba(0, 0, 0, 0.1);
}

/* ==========================================================================
   Header & Nav
   ========================================================================== */
.site-header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 100;
    transition: all var(--transition-fast);
    padding: 1rem 0;
}

.site-header.scrolled {
    background: rgba(255, 255, 255, 0.9);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border-subtle);
    padding: 0.75rem 0;
}

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

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

.logo img {
    height: 40px;
    width: auto;
}

.nav-links {
    display: none;
    gap: 2rem;
}

@media (min-width: 768px) {
    .nav-links {
        display: flex;
        align-items: center;
    }
}

.nav-links a {
    color: var(--text-secondary);
    font-weight: 500;
}

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

/* ==========================================================================
   Animations
   ========================================================================== */
.fade-in-up {
    opacity: 0;
    transform: translateY(20px);
    transition: opacity 0.6s ease-out, transform 0.6s ease-out;
}

.fade-in-up.visible {
    opacity: 1;
    transform: translateY(0);
}