/* ============================================
   IELTS Writing Scoring - Professional Design System
   ============================================ */

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

/* ============================================
   CSS Variables - Design Tokens
   ============================================ */
:root {
    /* Light Mode Colors */
    --bg-primary: #ffffff;
    --bg-secondary: #f8f9fa;
    --bg-tertiary: #e9ecef;
    --bg-card: #ffffff;
    --bg-input: #f8f9fa;
    --bg-hover: #f1f3f5;

    /* Text Colors */
    --text-primary: #212529;
    --text-secondary: #6c757d;
    --text-tertiary: #adb5bd;

    /* Accent Colors */
    --accent-primary: #6366f1;
    --accent-secondary: #8b5cf6;
    --accent-hover: #4f46e5;
    --accent-light: #eef2ff;

    /* Status Colors */
    --success: #10b981;
    --warning: #f59e0b;
    --error: #ef4444;
    --info: #3b82f6;

    /* Borders */
    --border-color: #e5e7eb;
    --border-radius: 12px;
    --border-radius-sm: 8px;
    --border-radius-lg: 16px;

    /* 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);

    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;

    /* Typography */
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', 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: 2rem;

    /* Transitions */
    --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-base: 250ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-slow: 350ms cubic-bezier(0.4, 0, 0.2, 1);
}

/* Dark Mode Colors */
[data-theme="dark"] {
    --bg-primary: #0f172a;
    --bg-secondary: #1e293b;
    --bg-tertiary: #334155;
    --bg-card: #1e293b;
    --bg-input: #334155;
    --bg-hover: #475569;

    --text-primary: #f1f5f9;
    --text-secondary: #cbd5e1;
    --text-tertiary: #64748b;

    --accent-primary: #818cf8;
    --accent-secondary: #a78bfa;
    --accent-hover: #6366f1;
    --accent-light: #312e81;

    --border-color: #334155;

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

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

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

body {
    font-family: var(--font-family);
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    transition: background-color var(--transition-base), color var(--transition-base);
    min-height: 100vh;
}

/* ============================================
   Layout
   ============================================ */
.container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

.main-layout {
    display: grid;
    grid-template-columns: 1fr;
    gap: var(--spacing-xl);
    padding: var(--spacing-xl) 0;
}

@media (min-width: 1024px) {
    .main-layout {
        grid-template-columns: 1fr 350px;
    }
}

/* ============================================
   Header
   ============================================ */
.header {
    background: var(--bg-card);
    border-bottom: 1px solid var(--border-color);
    padding: var(--spacing-lg) 0;
    position: sticky;
    top: 0;
    z-index: 100;
    backdrop-filter: blur(10px);
    background: rgba(255, 255, 255, 0.8);
    box-shadow: var(--shadow-sm);
}

[data-theme="dark"] .header {
    background: rgba(15, 23, 42, 0.8);
}

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

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

.header-actions {
    display: flex;
    gap: var(--spacing-md);
    align-items: center;
}

/* ============================================
   Buttons
   ============================================ */
.btn {
    padding: var(--spacing-sm) var(--spacing-lg);
    border: none;
    border-radius: var(--border-radius-sm);
    font-family: var(--font-family);
    font-size: var(--font-size-sm);
    font-weight: 500;
    cursor: pointer;
    transition: all var(--transition-fast);
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    text-decoration: none;
}

.btn-primary {
    background: linear-gradient(135deg, var(--accent-primary), var(--accent-secondary));
    color: white;
    box-shadow: var(--shadow-md);
}

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

.btn-secondary {
    background: var(--bg-secondary);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
}

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

.btn-icon {
    width: 40px;
    height: 40px;
    padding: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 50%;
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
}

.btn-icon:hover {
    background: var(--bg-hover);
    transform: rotate(180deg);
}

/* ============================================
   Cards
   ============================================ */
.card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    padding: var(--spacing-xl);
    box-shadow: var(--shadow-sm);
    transition: all var(--transition-base);
}

.card:hover {
    box-shadow: var(--shadow-md);
}

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

.card-title {
    font-size: var(--font-size-xl);
    font-weight: 600;
    margin-bottom: var(--spacing-sm);
}

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

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

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

.form-input,
.form-textarea,
.form-select {
    width: 100%;
    padding: var(--spacing-md);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-sm);
    background: var(--bg-input);
    color: var(--text-primary);
    font-family: var(--font-family);
    font-size: var(--font-size-base);
    transition: all var(--transition-fast);
}

.form-input:focus,
.form-textarea:focus,
.form-select:focus {
    outline: none;
    border-color: var(--accent-primary);
    box-shadow: 0 0 0 3px var(--accent-light);
}

.form-textarea {
    resize: vertical;
    min-height: 150px;
}

/* ============================================
   Score Display
   ============================================ */
.score-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-lg);
    margin-top: var(--spacing-xl);
}

.score-card {
    background: linear-gradient(135deg, var(--accent-light), transparent);
    border: 2px solid var(--accent-primary);
    border-radius: var(--border-radius);
    padding: var(--spacing-lg);
    transition: transform var(--transition-base);
}

.score-card:hover {
    transform: translateY(-4px);
}

.score-value {
    font-size: var(--font-size-3xl);
    font-weight: 700;
    color: var(--accent-primary);
    margin-bottom: var(--spacing-sm);
}

.score-label {
    font-size: var(--font-size-sm);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-md);
}

.score-feedback {
    font-size: var(--font-size-sm);
    color: var(--text-secondary);
    line-height: 1.6;
}

/* ============================================
   History Panel
   ============================================ */
.history-panel {
    position: sticky;
    top: 100px;
    max-height: calc(100vh - 120px);
    overflow-y: auto;
}

.history-item {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-sm);
    padding: var(--spacing-md);
    margin-bottom: var(--spacing-md);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.history-item:hover {
    background: var(--bg-hover);
    transform: translateX(-4px);
}

.history-date {
    font-size: var(--font-size-xs);
    color: var(--text-tertiary);
    margin-bottom: var(--spacing-xs);
}

.history-task {
    font-size: var(--font-size-sm);
    color: var(--text-primary);
    font-weight: 500;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

/* ============================================
   Modal
   ============================================ */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.5);
    backdrop-filter: blur(4px);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    opacity: 0;
    visibility: hidden;
    transition: all var(--transition-base);
}

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

.modal {
    background: var(--bg-card);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-2xl);
    max-width: 500px;
    width: 90%;
    box-shadow: var(--shadow-xl);
    transform: scale(0.9);
    transition: transform var(--transition-base);
}

.modal-overlay.active .modal {
    transform: scale(1);
}

.modal-header {
    margin-bottom: var(--spacing-xl);
}

.modal-title {
    font-size: var(--font-size-2xl);
    font-weight: 700;
    margin-bottom: var(--spacing-sm);
}

.modal-description {
    color: var(--text-secondary);
    font-size: var(--font-size-sm);
}

/* ============================================
   Loading State
   ============================================ */
.loading-spinner {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 3px solid var(--border-color);
    border-top-color: var(--accent-primary);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

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

.loading-overlay {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(255, 255, 255, 0.8);
    backdrop-filter: blur(2px);
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: var(--border-radius);
}

[data-theme="dark"] .loading-overlay {
    background: rgba(15, 23, 42, 0.8);
}

/* ============================================
   Utilities
   ============================================ */
.hidden {
    display: none !important;
}

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

.mt-lg {
    margin-top: var(--spacing-lg);
}

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

/* ============================================
   Responsive Design
   ============================================ */
@media (max-width: 768px) {
    .container {
        padding: 0 var(--spacing-md);
    }

    .main-layout {
        grid-template-columns: 1fr;
    }

    .history-panel {
        position: static;
        max-height: none;
    }

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

/* ============================================
   Animations
   ============================================ */
@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }

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

@keyframes slideIn {
    from {
        opacity: 0;
        transform: translateX(100px);
    }

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

.fade-in {
    animation: fadeIn var(--transition-base) ease-out;
}

/* ============================================
   Accessibility - Focus Styles
   ============================================ */
button:focus-visible,
input:focus-visible,
textarea:focus-visible,
select:focus-visible {
    outline: 2px solid var(--accent-primary);
    outline-offset: 2px;
}

/* ============================================
   Scrollbar Styling
   ============================================ */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

::-webkit-scrollbar-track {
    background: var(--bg-secondary);
}

::-webkit-scrollbar-thumb {
    background: var(--border-color);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--text-tertiary);
}