/* ========================================
   Main Stylesheet for Personal Academic Website
   ======================================== */

/* ========================================
   1. CSS Variables & Root Styles
   ======================================== */
:root {
    /* Color Palette */
    --primary-color: #667eea;
    --primary-dark: #5a67d8;
    --primary-light: #4696eb;
    --secondary-color: #57aeff;
    --success-color: #48bb78;
    --danger-color: #f56565;
    --warning-color: #ed8936;
    --info-color: #4299e1;
    
    /* Neutral Colors */
    --gray-50: #f9fafb;
    --gray-100: #f7fafc;
    --gray-200: #edf2f7;
    --gray-300: #e2e8f0;
    --gray-400: #cbd5e0;
    --gray-500: #a0aec0;
    --gray-600: #718096;
    --gray-700: #4a5568;
    --gray-800: #2d3748;
    --gray-900: #1a202c;
    
    /* Typography */
    --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    --font-family-mono: 'Courier New', Consolas, 'Monaco', monospace;
    
    /* 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;
    
    /* Border Radius */
    --radius-sm: 0.25rem;
    --radius-md: 0.5rem;
    --radius-lg: 1rem;
    --radius-full: 9999px;
    
    /* 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);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    
    /* Transitions */
    --transition-fast: 150ms ease-in-out;
    --transition-base: 300ms ease-in-out;
    --transition-slow: 500ms ease-in-out;
    
    /* Z-index */
    --z-dropdown: 1000;
    --z-sticky: 1020;
    --z-fixed: 1030;
    --z-modal-backdrop: 1040;
    --z-modal: 1050;
    --z-popover: 1060;
    --z-tooltip: 1070;
}

/* ========================================
   2. Base Styles
   ======================================== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    font-size: 16px;
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family);
    line-height: 1.6;
    color: var(--gray-800);
    background-color: white;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* ========================================
   3. Typography
   ======================================== */
h1, h2, h3, h4, h5, h6 {
    margin-bottom: var(--spacing-md);
    font-weight: 400;
    line-height: 1.2;
    color: var(--gray-900);
}

h1 {
    font-size: 2.5rem;
    font-weight: 300;
    letter-spacing: -0.025em;
}

h2 {
    font-size: 2rem;
    font-weight: 300;
}

h3 {
    font-size: 1.5rem;
    font-weight: 400;
}

h4 {
    font-size: 1.25rem;
    font-weight: 500;
}

h5 {
    font-size: 1.125rem;
    font-weight: 500;
}

h6 {
    font-size: 1rem;
    font-weight: 600;
}

p {
    margin-bottom: var(--spacing-md);
    line-height: 1.8;
}

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

a:hover {
    color: var(--primary-dark);
    text-decoration: underline;
}

strong, b {
    font-weight: 600;
}

em, i {
    font-style: italic;
}

code {
    font-family: var(--font-family-mono);
    background-color: var(--gray-100);
    padding: 0.125rem 0.25rem;
    border-radius: var(--radius-sm);
    font-size: 0.875em;
}

pre {
    font-family: var(--font-family-mono);
    background-color: var(--gray-900);
    color: white;
    padding: var(--spacing-lg);
    border-radius: var(--radius-md);
    overflow-x: auto;
    margin-bottom: var(--spacing-lg);
}

pre code {
    background-color: transparent;
    padding: 0;
    font-size: 0.875rem;
}

blockquote {
    border-left: 4px solid var(--primary-color);
    padding-left: var(--spacing-lg);
    margin: var(--spacing-lg) 0;
    font-style: italic;
    color: var(--gray-700);
}

/* ========================================
   4. Layout Components
   ======================================== */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

.container-sm {
    max-width: 800px;
}

.container-lg {
    max-width: 1400px;
}

/* ========================================
   5. Header Styles
   ======================================== */
header {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    color: white;
    padding: var(--spacing-3xl) 0;
    text-align: center;
    box-shadow: var(--shadow-md);
    position: relative;
    overflow: hidden;
}

header::before {
    content: '';
    position: absolute;
    top: -50%;
    right: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle, rgba(255,255,255,0.1) 0%, transparent 70%);
    transform: rotate(45deg);
}

header h1 {
    color: white;
    margin-bottom: var(--spacing-sm);
    position: relative;
    z-index: 1;
}

header p {
    font-size: 1.2rem;
    opacity: 0.9;
    margin-bottom: var(--spacing-xl);
    position: relative;
    z-index: 1;
}

/* ========================================
   6. Navigation
   ======================================== */
nav {
    position: relative;
    z-index: 1;
}

nav ul {
    list-style: none;
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: var(--spacing-xl);
}

nav a {
    color: white;
    text-decoration: none;
    font-size: 1.1rem;
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--radius-full);
    transition: all var(--transition-base);
    display: inline-block;
    position: relative;
}

nav a::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 50%;
    width: 0;
    height: 2px;
    background-color: white;
    transition: all var(--transition-base);
    transform: translateX(-50%);
}

nav a:hover,
nav a.active {
    background-color: rgba(255, 255, 255, 0.2);
    transform: translateY(-2px);
}

nav a:hover::after,
nav a.active::after {
    width: 80%;
}

/* ========================================
   7. Card Components
   ======================================== */
.card {
    background: white;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    padding: var(--spacing-xl);
    transition: all var(--transition-base);
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-xl);
}

.card h3 {
    color: var(--gray-800);
    margin-bottom: var(--spacing-md);
}

.card p {
    color: var(--gray-600);
    margin-bottom: var(--spacing-sm);
}

.card-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--spacing-xl);
}

/* ========================================
   8. Buttons
   ======================================== */
.btn {
    display: inline-block;
    padding: var(--spacing-sm) var(--spacing-xl);
    border: none;
    border-radius: var(--radius-full);
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    transition: all var(--transition-base);
    text-decoration: none;
    text-align: center;
}

.btn:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.btn:active {
    transform: translateY(0);
    box-shadow: var(--shadow-md);
}

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

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

.btn-secondary {
    background-color: var(--gray-200);
    color: var(--gray-800);
}

.btn-secondary:hover {
    background-color: var(--gray-300);
}

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

.btn-success:hover {
    background-color: #38a169;
}

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

.btn-danger:hover {
    background-color: #e53e3e;
}

/* ========================================
   9. Forms
   ======================================== */
.form-group {
    margin-bottom: var(--spacing-lg);
}

label {
    display: block;
    color: var(--gray-700);
    margin-bottom: var(--spacing-sm);
    font-weight: 500;
}

input[type="text"],
input[type="email"],
input[type="password"],
input[type="number"],
textarea,
select {
    width: 100%;
    padding: var(--spacing-sm) var(--spacing-md);
    border: 1px solid var(--gray-300);
    border-radius: var(--radius-md);
    font-size: 1rem;
    transition: all var(--transition-fast);
}

input[type="text"]:focus,
input[type="email"]:focus,
input[type="password"]:focus,
input[type="number"]:focus,
textarea:focus,
select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

textarea {
    resize: vertical;
    min-height: 120px;
}

input[type="range"] {
    width: 100%;
    height: 6px;
    border-radius: var(--radius-sm);
    background: var(--gray-300);
    outline: none;
    -webkit-appearance: none;
}

input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 18px;
    height: 18px;
    border-radius: 50%;
    background: var(--primary-color);
    cursor: pointer;
    transition: all var(--transition-fast);
}

input[type="range"]::-webkit-slider-thumb:hover {
    transform: scale(1.2);
    box-shadow: var(--shadow-md);
}

input[type="range"]::-moz-range-thumb {
    width: 18px;
    height: 18px;
    border-radius: 50%;
    background: var(--primary-color);
    cursor: pointer;
    border: none;
    transition: all var(--transition-fast);
}

input[type="range"]::-moz-range-thumb:hover {
    transform: scale(1.2);
    box-shadow: var(--shadow-md);
}

/* ========================================
   10. Tables
   ======================================== */
table {
    width: 100%;
    border-collapse: collapse;
    margin-bottom: var(--spacing-lg);
}

th, td {
    padding: var(--spacing-md);
    text-align: left;
    border-bottom: 1px solid var(--gray-300);
}

th {
    background-color: var(--gray-100);
    font-weight: 600;
    color: var(--gray-800);
}

tr:hover {
    background-color: var(--gray-50);
}

/* ========================================
   11. Lists
   ======================================== */
ul, ol {
    margin-bottom: var(--spacing-md);
    padding-left: var(--spacing-xl);
}

li {
    margin-bottom: var(--spacing-sm);
}

ul.unstyled,
ol.unstyled {
    list-style: none;
    padding-left: 0;
}

/* ========================================
   12. Utility Classes
   ======================================== */
/* Text Alignment */
.text-left { text-align: left; }
.text-center { text-align: center; }
.text-right { text-align: right; }
.text-justify { text-align: justify; }

/* Text Colors */
.text-primary { color: var(--primary-color); }
.text-secondary { color: var(--secondary-color); }
.text-success { color: var(--success-color); }
.text-danger { color: var(--danger-color); }
.text-warning { color: var(--warning-color); }
.text-info { color: var(--info-color); }
.text-muted { color: var(--gray-600); }

/* Background Colors */
.bg-primary { background-color: var(--primary-color); color: white; }
.bg-secondary { background-color: var(--secondary-color); color: white; }
.bg-success { background-color: var(--success-color); color: white; }
.bg-danger { background-color: var(--danger-color); color: white; }
.bg-warning { background-color: var(--warning-color); color: white; }
.bg-info { background-color: var(--info-color); color: white; }
.bg-light { background-color: var(--gray-100); }
.bg-dark { background-color: var(--gray-800); color: white; }

/* Spacing */
.mt-0 { margin-top: 0; }
.mt-1 { margin-top: var(--spacing-sm); }
.mt-2 { margin-top: var(--spacing-md); }
.mt-3 { margin-top: var(--spacing-lg); }
.mt-4 { margin-top: var(--spacing-xl); }
.mt-5 { margin-top: var(--spacing-2xl); }

.mb-0 { margin-bottom: 0; }
.mb-1 { margin-bottom: var(--spacing-sm); }
.mb-2 { margin-bottom: var(--spacing-md); }
.mb-3 { margin-bottom: var(--spacing-lg); }
.mb-4 { margin-bottom: var(--spacing-xl); }
.mb-5 { margin-bottom: var(--spacing-2xl); }

.my-0 { margin-top: 0; margin-bottom: 0; }
.my-1 { margin-top: var(--spacing-sm); margin-bottom: var(--spacing-sm); }
.my-2 { margin-top: var(--spacing-md); margin-bottom: var(--spacing-md); }
.my-3 { margin-top: var(--spacing-lg); margin-bottom: var(--spacing-lg); }
.my-4 { margin-top: var(--spacing-xl); margin-bottom: var(--spacing-xl); }
.my-5 { margin-top: var(--spacing-2xl); margin-bottom: var(--spacing-2xl); }

.mx-auto { margin-left: auto; margin-right: auto; }

.p-0 { padding: 0; }
.p-1 { padding: var(--spacing-sm); }
.p-2 { padding: var(--spacing-md); }
.p-3 { padding: var(--spacing-lg); }
.p-4 { padding: var(--spacing-xl); }
.p-5 { padding: var(--spacing-2xl); }

/* Display */
.d-none { display: none; }
.d-block { display: block; }
.d-inline { display: inline; }
.d-inline-block { display: inline-block; }
.d-flex { display: flex; }
.d-grid { display: grid; }

/* Flexbox */
.flex-row { flex-direction: row; }
.flex-column { flex-direction: column; }
.flex-wrap { flex-wrap: wrap; }
.justify-start { justify-content: flex-start; }
.justify-center { justify-content: center; }
.justify-end { justify-content: flex-end; }
.justify-between { justify-content: space-between; }
.justify-around { justify-content: space-around; }
.align-start { align-items: flex-start; }
.align-center { align-items: center; }
.align-end { align-items: flex-end; }
.gap-1 { gap: var(--spacing-sm); }
.gap-2 { gap: var(--spacing-md); }
.gap-3 { gap: var(--spacing-lg); }
.gap-4 { gap: var(--spacing-xl); }

/* Borders */
.border { border: 1px solid var(--gray-300); }
.border-top { border-top: 1px solid var(--gray-300); }
.border-bottom { border-bottom: 1px solid var(--gray-300); }
.border-left { border-left: 1px solid var(--gray-300); }
.border-right { border-right: 1px solid var(--gray-300); }
.rounded { border-radius: var(--radius-md); }
.rounded-lg { border-radius: var(--radius-lg); }
.rounded-full { border-radius: var(--radius-full); }

/* Shadows */
.shadow-sm { box-shadow: var(--shadow-sm); }
.shadow { box-shadow: var(--shadow-md); }
.shadow-lg { box-shadow: var(--shadow-lg); }
.shadow-xl { box-shadow: var(--shadow-xl); }

/* ========================================
   13. Special Components
   ======================================== */
/* Hero Section */
.hero-section {
    display: grid;
    grid-template-columns: 1fr 2fr;
    gap: var(--spacing-3xl);
    align-items: start;
    margin-bottom: var(--spacing-3xl);
}

.profile-image {
    width: 250px;
    height: 250px;
    border-radius: 50%;
    overflow: hidden;
    box-shadow: var(--shadow-xl);
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    display: flex;
    align-items: center;
    justify-content: center;
}

.profile-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

/* Info Cards */
.info-cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-xl);
    margin-top: var(--spacing-3xl);
}

/* Contact Info */
.contact-info {
    background: linear-gradient(135deg, var(--gray-100) 0%, var(--gray-200) 100%);
    padding: var(--spacing-2xl);
    border-radius: var(--radius-lg);
    text-align: center;
    margin: var(--spacing-3xl) 0;
}

.contact-details {
    display: flex;
    justify-content: center;
    gap: var(--spacing-2xl);
    flex-wrap: wrap;
    margin-top: var(--spacing-lg);
}

/* Footer */
footer {
    background: var(--gray-800);
    color: white;
    text-align: center;
    padding: var(--spacing-xl) 0;
    margin-top: var(--spacing-3xl);
}

footer p {
    opacity: 0.8;
    font-size: 0.9rem;
    margin-bottom: 0;
}

/* ========================================
   14. Animations
   ======================================== */
@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes slideIn {
    from {
        transform: translateX(-100%);
    }
    to {
        transform: translateX(0);
    }
}

@keyframes pulse {
    0% {
        transform: scale(1);
    }
    50% {
        transform: scale(1.05);
    }
    100% {
        transform: scale(1);
    }
}

.animate-fadeIn {
    animation: fadeIn 0.6s ease-out;
}

.animate-slideIn {
    animation: slideIn 0.6s ease-out;
}

.animate-pulse {
    animation: pulse 2s infinite;
}

/* ========================================
   15. Responsive Design
   ======================================== */
@media (max-width: 768px) {
    /* Typography */
    h1 { font-size: 2rem; }
    h2 { font-size: 1.5rem; }
    h3 { font-size: 1.25rem; }
    
    /* Navigation */
    nav ul {
        flex-direction: column;
        gap: var(--spacing-sm);
    }
    
    nav a {
        width: 100%;
        text-align: center;
    }
    
    /* Hero Section */
    .hero-section {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .profile-image {
        margin: 0 auto;
    }
    
    /* Cards */
    .card-grid {
        grid-template-columns: 1fr;
    }
    
    /* Contact Details */
    .contact-details {
        flex-direction: column;
        gap: var(--spacing-md);
    }
    
    /* Container padding */
    .container {
        padding: 0 var(--spacing-md);
    }
    
    /* Header */
    header {
        padding: var(--spacing-2xl) 0;
    }
}

@media (max-width: 480px) {
    /* Further mobile optimizations */
    .btn {
        width: 100%;
        padding: var(--spacing-md) var(--spacing-lg);
    }
    
    .info-cards {
        grid-template-columns: 1fr;
    }
}

/* ========================================
   16. Print Styles
   ======================================== */
@media print {
    body {
        font-size: 12pt;
        line-height: 1.5;
        color: black;
        background: white;
    }
    
    header,
    nav,
    footer {
        display: none;
    }
    
    a {
        color: black;
        text-decoration: underline;
    }
    
    .card {
        box-shadow: none;
        border: 1px solid #000;
        page-break-inside: avoid;
    }
    
    .no-print {
        display: none;
    }
}