/* CSS Custom Properties for Design System */
:root {
    --color-primary: #7868E6;
    --color-primary-light: #B8B5FF;
    --color-secondary: #E4FBFF;
    --color-accent: #FFB4B4;
    --color-background: #EDEEF7;
    --color-white: #FFFFFF;
    --color-text: #333333;
    --color-text-light: #666666;
    --color-border: #E0E0E0;
    --color-shadow: rgba(120, 104, 230, 0.1);
    --color-error: #FF6B6B;
    --color-success: #51CF66;
    --color-warning: #FFD43B;
    
    --font-family-primary: 'Segoe UI', Tahoma, Geneva, Verdana, 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;
    
    --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-sm: 0.25rem;
    --border-radius-md: 0.5rem;
    --border-radius-lg: 1rem;
    --border-radius-xl: 1.5rem;
    
    --shadow-sm: 0 1px 2px 0 var(--color-shadow);
    --shadow-md: 0 4px 6px -1px var(--color-shadow);
    --shadow-lg: 0 10px 15px -3px var(--color-shadow);
    --shadow-xl: 0 20px 25px -5px var(--color-shadow);
    
    --transition-fast: 0.15s ease-in-out;
    --transition-base: 0.3s ease-in-out;
    --transition-slow: 0.5s ease-in-out;
}

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

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

body {
    font-family: var(--font-family-primary);
    font-size: var(--font-size-base);
    line-height: 1.6;
    color: var(--color-text);
    background-color: var(--color-background);
    background-image: 
        radial-gradient(circle at 1px 1px, rgba(120, 104, 230, 0.05) 1px, transparent 0);
    background-size: 20px 20px;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* Paper Texture Effect */
.paper-texture {
    position: relative;
    background: var(--color-white);
    background-image: 
        radial-gradient(circle at 1px 1px, rgba(0, 0, 0, 0.02) 1px, transparent 0),
        linear-gradient(90deg, rgba(0, 0, 0, 0.01) 1px, transparent 1px),
        linear-gradient(0deg, rgba(0, 0, 0, 0.01) 1px, transparent 1px);
    background-size: 20px 20px, 20px 20px, 20px 20px;
}

.paper-texture::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: 
        radial-gradient(ellipse at top left, rgba(184, 181, 255, 0.05) 0%, transparent 50%),
        radial-gradient(ellipse at top right, rgba(228, 251, 255, 0.05) 0%, transparent 50%),
        radial-gradient(ellipse at bottom left, rgba(255, 180, 180, 0.05) 0%, transparent 50%);
    pointer-events: none;
}

/* Utility Classes */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

/* Header Styles */
.header {
    background: var(--color-white);
    box-shadow: var(--shadow-sm);
    position: sticky;
    top: 0;
    z-index: 100;
    border-bottom: 1px solid var(--color-border);
}

.header .container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--spacing-md);
    flex-wrap: wrap;
    gap: var(--spacing-md);
}

.header__title {
    font-size: var(--font-size-2xl);
    font-weight: 700;
    color: var(--color-primary);
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.header__icon {
    font-size: var(--font-size-3xl);
}

/* Navigation Styles */
.nav__list {
    display: flex;
    list-style: none;
    gap: var(--spacing-sm);
    flex-wrap: wrap;
}

.nav__link {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    padding: var(--spacing-sm) var(--spacing-md);
    text-decoration: none;
    color: var(--color-text);
    border-radius: var(--border-radius-md);
    transition: all var(--transition-base);
    font-weight: 500;
    white-space: nowrap;
}

.nav__link:hover,
.nav__link:focus {
    background-color: var(--color-primary-light);
    color: var(--color-primary);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
    outline: none;
}

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

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

/* Main Content */
.main {
    flex: 1;
    padding: var(--spacing-2xl) 0;
}

/* Hero Section */
.hero {
    text-align: center;
    margin-bottom: var(--spacing-3xl);
    padding: var(--spacing-2xl) var(--spacing-md);
    background: var(--color-white);
    border-radius: var(--border-radius-xl);
    box-shadow: var(--shadow-lg);
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(135deg, var(--color-primary-light) 0%, var(--color-secondary) 100%);
    opacity: 0.1;
    pointer-events: none;
}

.hero__title {
    font-size: var(--font-size-4xl);
    font-weight: 700;
    color: var(--color-primary);
    margin-bottom: var(--spacing-lg);
    position: relative;
    z-index: 1;
}

.hero__description {
    font-size: var(--font-size-lg);
    color: var(--color-text-light);
    max-width: 600px;
    margin: 0 auto;
    position: relative;
    z-index: 1;
}

/* Features Section */
.features {
    margin-bottom: var(--spacing-3xl);
}

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

.feature-card {
    background: var(--color-white);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-xl);
    box-shadow: var(--shadow-md);
    transition: all var(--transition-base);
    text-align: center;
    position: relative;
    overflow: hidden;
}

.feature-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(90deg, var(--color-primary), var(--color-primary-light));
}

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

.feature-card__icon {
    font-size: var(--font-size-4xl);
    margin-bottom: var(--spacing-lg);
}

.feature-card__title {
    font-size: var(--font-size-xl);
    font-weight: 600;
    color: var(--color-primary);
    margin-bottom: var(--spacing-md);
}

.feature-card__description {
    color: var(--color-text-light);
    margin-bottom: var(--spacing-lg);
    line-height: 1.7;
}

.feature-card__link {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-xs);
    padding: var(--spacing-sm) var(--spacing-lg);
    background: var(--color-primary);
    color: var(--color-white);
    text-decoration: none;
    border-radius: var(--border-radius-md);
    font-weight: 500;
    transition: all var(--transition-base);
}

.feature-card__link:hover,
.feature-card__link:focus {
    background: var(--color-primary-light);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
    outline: none;
}

/* Stats Section */
.stats {
    margin-bottom: var(--spacing-3xl);
}

.stats__grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--spacing-lg);
}

.stat-card {
    background: var(--color-white);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-xl);
    text-align: center;
    box-shadow: var(--shadow-md);
    transition: all var(--transition-base);
}

.stat-card:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-lg);
}

.stat-card__number {
    font-size: var(--font-size-4xl);
    font-weight: 700;
    color: var(--color-primary);
    margin-bottom: var(--spacing-sm);
}

.stat-card__label {
    font-size: var(--font-size-sm);
    color: var(--color-text-light);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    font-weight: 500;
}

/* Section Titles */
.section__title {
    font-size: var(--font-size-2xl);
    font-weight: 600;
    color: var(--color-primary);
    margin-bottom: var(--spacing-xl);
    text-align: center;
    position: relative;
}

.section__title::after {
    content: '';
    position: absolute;
    bottom: -var(--spacing-sm);
    left: 50%;
    transform: translateX(-50%);
    width: 60px;
    height: 3px;
    background: linear-gradient(90deg, var(--color-primary), var(--color-primary-light));
    border-radius: var(--border-radius-sm);
}

/* Recent Activity */
.recent-activity {
    background: var(--color-white);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-xl);
    box-shadow: var(--shadow-md);
}

.activity-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.activity-item {
    padding: var(--spacing-md);
    border-left: 4px solid var(--color-primary-light);
    background: var(--color-background);
    border-radius: var(--border-radius-md);
    transition: all var(--transition-base);
}

.activity-item:hover {
    border-left-color: var(--color-primary);
    background: var(--color-secondary);
}

.activity-item--empty {
    text-align: center;
    color: var(--color-text-light);
    border-left-color: var(--color-border);
    font-style: italic;
}

/* Form Styles */
.form {
    background: var(--color-white);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-xl);
    box-shadow: var(--shadow-md);
    margin-bottom: var(--spacing-xl);
}

.form__group {
    margin-bottom: var(--spacing-lg);
}

.form__label {
    display: block;
    margin-bottom: var(--spacing-sm);
    font-weight: 500;
    color: var(--color-text);
}

.form__input,
.form__textarea,
.form__select {
    width: 100%;
    padding: var(--spacing-md);
    border: 2px solid var(--color-border);
    border-radius: var(--border-radius-md);
    font-size: var(--font-size-base);
    font-family: inherit;
    transition: all var(--transition-base);
    background: var(--color-white);
}

.form__input:focus,
.form__textarea:focus,
.form__select:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: 0 0 0 3px rgba(120, 104, 230, 0.1);
}

.form__input:invalid,
.form__textarea:invalid,
.form__select:invalid {
    border-color: var(--color-error);
}

.form__textarea {
    min-height: 120px;
    resize: vertical;
}

.form__error {
    color: var(--color-error);
    font-size: var(--font-size-sm);
    margin-top: var(--spacing-xs);
    display: none;
}

.form__error--visible {
    display: block;
}

/* Button Styles */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-xs);
    padding: var(--spacing-md) var(--spacing-lg);
    border: none;
    border-radius: var(--border-radius-md);
    font-size: var(--font-size-base);
    font-weight: 500;
    text-decoration: none;
    cursor: pointer;
    transition: all var(--transition-base);
    white-space: nowrap;
    font-family: inherit;
}

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

.btn--primary:hover,
.btn--primary:focus {
    background: var(--color-primary-light);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
    outline: none;
}

.btn--secondary {
    background: var(--color-secondary);
    color: var(--color-primary);
    border: 2px solid var(--color-primary-light);
}

.btn--secondary:hover,
.btn--secondary:focus {
    background: var(--color-primary-light);
    color: var(--color-white);
    outline: none;
}

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

.btn--danger:hover,
.btn--danger:focus {
    background: #ff5252;
    outline: none;
}

.btn--small {
    padding: var(--spacing-sm) var(--spacing-md);
    font-size: var(--font-size-sm);
}

.btn--large {
    padding: var(--spacing-lg) var(--spacing-xl);
    font-size: var(--font-size-lg);
}

.btn:disabled {
    opacity: 0.6;
    cursor: not-allowed;
    transform: none;
}

/* Modal Styles */
.modal {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.5);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    opacity: 0;
    visibility: hidden;
    transition: all var(--transition-base);
}

.modal--visible {
    opacity: 1;
    visibility: visible;
}

.modal__content {
    background: var(--color-white);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-xl);
    max-width: 500px;
    width: 90%;
    max-height: 90vh;
    overflow-y: auto;
    box-shadow: var(--shadow-xl);
    transform: scale(0.9);
    transition: all var(--transition-base);
}

.modal--visible .modal__content {
    transform: scale(1);
}

.modal__header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: var(--spacing-lg);
    padding-bottom: var(--spacing-md);
    border-bottom: 1px solid var(--color-border);
}

.modal__title {
    font-size: var(--font-size-xl);
    font-weight: 600;
    color: var(--color-primary);
}

.modal__close {
    background: none;
    border: none;
    font-size: var(--font-size-xl);
    cursor: pointer;
    color: var(--color-text-light);
    transition: color var(--transition-base);
    padding: var(--spacing-xs);
}

.modal__close:hover,
.modal__close:focus {
    color: var(--color-error);
    outline: none;
}

/* Footer Styles */
.footer {
    background: var(--color-primary);
    color: var(--color-white);
    padding: var(--spacing-lg) 0;
    margin-top: auto;
}

.footer__text {
    text-align: center;
    font-size: var(--font-size-sm);
}

.footer__link {
    color: var(--color-primary-light);
    text-decoration: none;
    transition: color var(--transition-base);
}

.footer__link:hover,
.footer__link:focus {
    color: var(--color-white);
    outline: none;
}

/* Loading Styles */
.loading {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    color: var(--color-text-light);
}

.loading__spinner {
    width: 20px;
    height: 20px;
    border: 2px solid var(--color-border);
    border-top: 2px solid var(--color-primary);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

/* Alert Styles */
.alert {
    padding: var(--spacing-md);
    border-radius: var(--border-radius-md);
    margin-bottom: var(--spacing-md);
    border: 1px solid;
}

.alert--success {
    background: rgba(81, 207, 102, 0.1);
    border-color: var(--color-success);
    color: #2b8a3e;
}

.alert--error {
    background: rgba(255, 107, 107, 0.1);
    border-color: var(--color-error);
    color: #c92a2a;
}

.alert--warning {
    background: rgba(255, 212, 59, 0.1);
    border-color: var(--color-warning);
    color: #e67700;
}

.alert--info {
    background: rgba(120, 104, 230, 0.1);
    border-color: var(--color-primary);
    color: var(--color-primary);
}

/* Responsive Design */
@media (max-width: 768px) {
    .header .container {
        flex-direction: column;
        align-items: stretch;
    }
    
    .header__title {
        justify-content: center;
        margin-bottom: var(--spacing-sm);
    }
    
    .nav__list {
        justify-content: center;
    }
    
    .hero__title {
        font-size: var(--font-size-3xl);
    }
    
    .features__grid {
        grid-template-columns: 1fr;
    }
    
    .stats__grid {
        grid-template-columns: 1fr;
    }
    
    .container {
        padding: 0 var(--spacing-sm);
    }
    
    .modal__content {
        width: 95%;
        padding: var(--spacing-lg);
    }
}

@media (max-width: 480px) {
    .nav__list {
        flex-direction: column;
        gap: var(--spacing-xs);
    }
    
    .nav__link {
        justify-content: center;
        padding: var(--spacing-md);
    }
    
    .hero {
        padding: var(--spacing-lg) var(--spacing-md);
    }
    
    .hero__title {
        font-size: var(--font-size-2xl);
    }
    
    .feature-card {
        padding: var(--spacing-lg);
    }
    
    .btn {
        width: 100%;
        justify-content: center;
    }
}

/* Print Styles */
@media print {
    .header,
    .footer,
    .nav,
    .btn {
        display: none;
    }
    
    .main {
        padding: 0;
    }
    
    .container {
        max-width: none;
        padding: 0;
    }
    
    .feature-card,
    .stat-card,
    .activity-item {
        box-shadow: none;
        border: 1px solid var(--color-border);
    }
}

/* High Contrast Mode */
@media (prefers-contrast: high) {
    :root {
        --color-primary: #000080;
        --color-text: #000000;
        --color-background: #ffffff;
        --color-border: #000000;
    }
}

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