/* Student Performance Tracker - Modern CSS Styling */

/* Import Google Fonts */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&display=swap');

/* CSS Variables for theming */
:root {
    --primary-color: #6366f1;
    --primary-dark: #4f46e5;
    --primary-light: #818cf8;
    --secondary-color: #8b5cf6;
    --success-color: #10b981;
    --warning-color: #f59e0b;
    --error-color: #ef4444;
    --info-color: #3b82f6;

    --bg-primary: #ffffff;
    --bg-secondary: #f9fafb;
    --bg-tertiary: #f3f4f6;
    --bg-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --header-bg: rgba(255, 255, 255, 0.95);

    --text-primary: #111827;
    --text-secondary: #6b7280;
    --text-light: #9ca3af;

    --border-color: #e5e7eb;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1);

    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
}

/* Dark Mode Variables */
[data-theme="dark"] {
    --bg-primary: #1f2937;
    --bg-secondary: #111827;
    --bg-tertiary: #374151;
    --bg-gradient: linear-gradient(135deg, #1e293b 0%, #0f172a 100%);
    --header-bg: rgba(31, 41, 55, 0.95);

    --text-primary: #f9fafb;
    --text-secondary: #d1d5db;
    --text-light: #9ca3af;

    --border-color: #374151;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.5);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.6);
}

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    background: var(--bg-gradient);
    min-height: 100vh;
    color: var(--text-primary);
    line-height: 1.6;
    transition: background 0.3s ease, color 0.3s ease;
}

/* Container */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem 1rem;
}

/* Header */
header {
    background: var(--header-bg);
    backdrop-filter: blur(10px);
    box-shadow: var(--shadow-md);
    position: sticky;
    top: 0;
    z-index: 100;
    transition: background 0.3s ease, box-shadow 0.3s ease;
}

.header-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

/* Navigation */
nav ul {
    list-style: none;
    display: flex;
    gap: 2rem;
    align-items: center;
}

nav a {
    text-decoration: none;
    color: var(--text-secondary);
    font-weight: 500;
    transition: color 0.3s ease;
    position: relative;
}

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

nav a::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--primary-color);
    transition: width 0.3s ease;
}

nav a:hover::after {
    width: 100%;
}

/* Cards */
.card {
    background: var(--bg-primary);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    padding: 2rem;
    margin-bottom: 2rem;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

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

.card-header {
    margin-bottom: 1.5rem;
    padding-bottom: 1rem;
    border-bottom: 2px solid var(--bg-tertiary);
}

.card-title {
    font-size: 1.75rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 0.5rem;
}

.card-subtitle {
    color: var(--text-secondary);
    font-size: 0.95rem;
}

/* Dashboard Stats */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1.5rem;
    margin-bottom: 2rem;
}

.stat-card {
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    color: white;
    padding: 1.5rem;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    transition: transform 0.3s ease;
}

.stat-card:hover {
    transform: translateY(-5px);
}

.stat-card.success {
    background: linear-gradient(135deg, var(--success-color), #059669);
}

.stat-card.warning {
    background: linear-gradient(135deg, var(--warning-color), #d97706);
}

.stat-card.info {
    background: linear-gradient(135deg, var(--info-color), #2563eb);
}

.stat-value {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
}

.stat-label {
    font-size: 0.95rem;
    opacity: 0.9;
}

/* Forms */
.form-group {
    margin-bottom: 1.5rem;
}

label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
    color: var(--text-primary);
}

input[type="text"],
input[type="number"],
select,
textarea {
    width: 100%;
    padding: 0.75rem 1rem;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    font-size: 1rem;
    font-family: inherit;
    background: var(--bg-primary);
    color: var(--text-primary);
    transition: border-color 0.3s ease, box-shadow 0.3s ease, background 0.3s ease, color 0.3s ease;
}

input[type="text"]:focus,
input[type="number"]:focus,
select:focus,
textarea:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: var(--radius-md);
    font-size: 1rem;
    font-weight: 600;
    text-decoration: none;
    cursor: pointer;
    transition: all 0.3s ease;
    text-align: center;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    color: white;
}

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

.btn-secondary {
    background: var(--bg-tertiary);
    color: var(--text-primary);
}

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

.btn-success {
    background: linear-gradient(135deg, var(--success-color), #059669);
    color: white;
}

.btn-danger {
    background: linear-gradient(135deg, var(--error-color), #dc2626);
    color: white;
}

.btn-sm {
    padding: 0.5rem 1rem;
    font-size: 0.875rem;
}

.btn-block {
    display: block;
    width: 100%;
}

/* Tables */
.table-container {
    overflow-x: auto;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
}

table {
    width: 100%;
    border-collapse: collapse;
    background: var(--bg-primary);
}

thead {
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    color: white;
}

th {
    padding: 1rem;
    text-align: left;
    font-weight: 600;
}

td {
    padding: 1rem;
    border-bottom: 1px solid var(--border-color);
}

tbody tr {
    transition: background-color 0.2s ease;
}

tbody tr:hover {
    background-color: var(--bg-secondary);
}

/* Badges */
.badge {
    display: inline-block;
    padding: 0.25rem 0.75rem;
    border-radius: 9999px;
    font-size: 0.875rem;
    font-weight: 600;
}

.badge-success {
    background-color: #d1fae5;
    color: #065f46;
}

.badge-warning {
    background-color: #fef3c7;
    color: #92400e;
}

.badge-danger {
    background-color: #fee2e2;
    color: #991b1b;
}

.badge-info {
    background-color: #dbeafe;
    color: #1e40af;
}

/* Grade Display */
.grade-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0.75rem;
    margin-bottom: 0.5rem;
    background: var(--bg-secondary);
    border-radius: var(--radius-md);
    border-left: 4px solid var(--primary-color);
}

.grade-subject {
    font-weight: 600;
    color: var(--text-primary);
}

.grade-value {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--primary-color);
}

/* Flash Messages */
.flash-messages {
    position: fixed;
    top: 80px;
    right: 20px;
    z-index: 1000;
    max-width: 400px;
}

.alert {
    padding: 1rem 1.5rem;
    border-radius: var(--radius-md);
    margin-bottom: 1rem;
    box-shadow: var(--shadow-lg);
    animation: slideIn 0.3s ease;
}

@keyframes slideIn {
    from {
        transform: translateX(400px);
        opacity: 0;
    }

    to {
        transform: translateX(0);
        opacity: 1;
    }
}

.alert-success {
    background-color: #d1fae5;
    color: #065f46;
    border-left: 4px solid var(--success-color);
}

.alert-error {
    background-color: #fee2e2;
    color: #991b1b;
    border-left: 4px solid var(--error-color);
}

.alert-warning {
    background-color: #fef3c7;
    color: #92400e;
    border-left: 4px solid var(--warning-color);
}

.alert-info {
    background-color: #dbeafe;
    color: #1e40af;
    border-left: 4px solid var(--info-color);
}

/* Action Buttons Group */
.action-buttons {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
}

/* Empty State */
.empty-state {
    text-align: center;
    padding: 3rem 1rem;
    color: var(--text-secondary);
}

.empty-state-icon {
    font-size: 4rem;
    margin-bottom: 1rem;
    opacity: 0.5;
}

.empty-state-text {
    font-size: 1.25rem;
    margin-bottom: 1rem;
}

/* Dynamic Grade Inputs */
.grade-input-group {
    display: grid;
    grid-template-columns: 2fr 1fr auto;
    gap: 1rem;
    align-items: end;
    margin-bottom: 1rem;
}

.remove-btn {
    background: var(--error-color);
    color: white;
    border: none;
    padding: 0.75rem 1rem;
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: background-color 0.3s ease;
}

.remove-btn:hover {
    background: #dc2626;
}

/* Theme Toggle Button */
.theme-toggle {
    background: var(--bg-tertiary);
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: 0.5rem 0.75rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    transition: all 0.3s ease;
    font-size: 1.2rem;
}

.theme-toggle:hover {
    background: var(--primary-color);
    border-color: var(--primary-color);
    transform: scale(1.05);
}

.theme-toggle:hover .theme-icon {
    transform: rotate(180deg);
}

.theme-icon {
    transition: transform 0.5s ease;
    display: inline-block;
}

/* Responsive Design */
@media (max-width: 768px) {
    .header-content {
        flex-direction: column;
        gap: 1rem;
    }

    nav ul {
        flex-direction: column;
        gap: 0.5rem;
    }

    .stats-grid {
        grid-template-columns: 1fr;
    }

    .grade-input-group {
        grid-template-columns: 1fr;
    }

    .action-buttons {
        flex-direction: column;
    }

    .btn {
        width: 100%;
    }
}

/* Loading Animation */
.loading {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 3px solid rgba(255, 255, 255, 0.3);
    border-radius: 50%;
    border-top-color: white;
    animation: spin 1s ease-in-out infinite;
}

@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}

/* Utility Classes */
.text-center {
    text-align: center;
}

.text-right {
    text-align: right;
}

.mt-1 {
    margin-top: 0.5rem;
}

.mt-2 {
    margin-top: 1rem;
}

.mt-3 {
    margin-top: 1.5rem;
}

.mb-1 {
    margin-bottom: 0.5rem;
}

.mb-2 {
    margin-bottom: 1rem;
}

.mb-3 {
    margin-bottom: 1.5rem;
}

.p-1 {
    padding: 0.5rem;
}

.p-2 {
    padding: 1rem;
}

.p-3 {
    padding: 1.5rem;
}