/* GradIn - Main Stylesheet */

/* CSS Variables */
:root {
    --indigo: #5856D6;
    --indigo-dark: #4341C7;
    --indigo-light: #7674E8;
    --background: #FFFFFF;
    --text-primary: #000000;
    --text-secondary: #6B6B6B;
    --border: #e0e0e0;
    --green: #34C759;
    --code-bg: #F5F5F5;
}

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

html, body {
    margin: 0;
    padding: 0;
    width: 100%;
    overflow-x: hidden;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--background);
    margin: 0;
    padding: 0;
}

/* Container */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

/* Top Navigation Bar */
.top-nav {
  background: white;
  padding: 12px 0;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.08);
  position: sticky;
  top: 0;
  z-index: 1000;
}
.top-nav .container {
  display: flex;
  justify-content: space-between;
  align-items: center;
}
.top-nav a {
  display: inline-block;
  line-height: 0;
  text-decoration: none;
}
.nav-logo {
  height: 50px;
  width: auto;
  border-radius: 10px;
  border: 2px solid var(--border);
  display: block;
}
.nav-app-store {
  height: 40px;
  width: auto;
  display: block;
  transition: opacity 0.3s;
  cursor: pointer;
}
.nav-app-store:hover {
  opacity: 0.8;
}

/* Header */
header {
    background: var(--indigo);
    color: white;
    padding: 80px 20px;
    text-align: center;
}

header h1 {
    font-size: 3.5rem;
    font-weight: 700;
    margin-bottom: 20px;
}

header p {
    font-size: 1.3rem;
    opacity: 0.95;
    max-width: 600px;
    margin: 0 auto;
}

/* Navigation Menu */
nav {
    background: white;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    position: sticky;
    top: 0;
    z-index: 100;
}

nav ul {
    list-style: none;
    display: flex;
    justify-content: center;
    padding: 20px 0;
    flex-wrap: wrap;
}

nav a {
    color: var(--text-primary);
    text-decoration: none;
    padding: 10px 20px;
    margin: 0 10px;
    border-radius: 8px;
    transition: all 0.3s;
    font-weight: 500;
}

nav a:hover {
    background: var(--indigo);
    color: white;
}

/* Sections */
section {
    padding: 60px 0;
}

section h2 {
    font-size: 2.5rem;
    color: var(--text-primary);
    margin-bottom: 30px;
    text-align: center;
}

section h3 {
    font-size: 1.8rem;
    color: var(--text-primary);
    margin-top: 30px;
    margin-bottom: 15px;
}

section p, section li {
    font-size: 1.1rem;
    color: var(--text-secondary);
    margin-bottom: 15px;
}

/* Links */
a {
    text-decoration: none;
}

.back-link {
    display: inline-block;
    color: var(--indigo);
    text-decoration: none;
    margin-top: 0;
    margin-bottom: 30px;
    font-weight: 500;
}

.back-link:hover {
    text-decoration: underline;
}

/* Utility Classes */
.highlight {
    color: var(--indigo);
    font-weight: 600;
}

ul {
    list-style: none;
    padding-left: 0;
}

/* Footer */
footer {
    background: #F9F9F9;
    text-align: center;
    padding: 30px 0;
    color: var(--text-secondary);
    margin-top: 60px;
}

footer a {
    color: var(--indigo);
    text-decoration: none;
}

footer a:hover {
    text-decoration: underline;
}

/* Mobile Optimization */
@media (max-width: 768px) {
    .container {
        padding: 0 16px;
    }

    header h1 {
        font-size: 2rem;
    }

    header p {
        font-size: 1.1rem;
    }

    section h2 {
        font-size: 2rem;
    }

    nav a {
        padding: 8px 15px;
        margin: 5px;
        font-size: 0.9rem;
    }
}

@media (max-width: 600px) {
    .nav-logo {
        height: 50px;
    }

    .nav-app-store {
        height: 40px;
    }

    header {
        padding: 50px 15px;
    }

    header h1 {
        font-size: 2rem;
    }

    header p {
        font-size: 1.1rem;
    }

    nav {
        display: none;
    }

    section:first-of-type {
        padding-top: 40px;
    }

    section {
        padding: 40px 0;
    }

    section h2 {
        font-size: 1.6rem;
    }

    section p {
        font-size: 1rem;
    }
}