/**
 * Database Design Course - Unified Theme
 * Inspired by ER diagrams, UML schemas, and database design tools
 * Version: 2.0
 */

/* ============================================
   FONT IMPORTS
   ============================================ */
@import url('https://fonts.googleapis.com/css2?family=JetBrains+Mono:wght@300;400;500;600;700&family=IBM+Plex+Mono:wght@300;400;500;600;700&display=swap');

/* ============================================
   CSS VARIABLES - DATABASE SCHEMA PALETTE
   ============================================ */
:root {
    /* ========== Core Database Colors ========== */
    /* Inspired by database design tools and ER diagrams */

    /* Primary Schema Colors */
    --db-entity: #1e3a8a;           /* Deep blue - Primary entities (rectangles) */
    --db-relationship: #0891b2;     /* Cyan - Relationships (diamonds) */
    --db-attribute: #059669;        /* Green - Attributes (ovals) */
    --db-primary-key: #f59e0b;      /* Amber - Primary keys */
    --db-foreign-key: #8b5cf6;      /* Purple - Foreign keys */

    /* Constraint Colors */
    --db-constraint: #dc2626;       /* Red - Constraints/errors */
    --db-nullable: #6b7280;         /* Gray - Nullable/optional */
    --db-required: #1e3a8a;         /* Blue - Required fields */

    /* Background Scheme */
    --db-canvas: #ffffff;           /* White - Main canvas (like schema diagrams) */
    --db-grid: #f8fafc;             /* Light gray - Grid background */
    --db-paper: #fefefe;            /* Off-white - Card backgrounds */
    --db-border: #e2e8f0;           /* Light border - Subtle separators */
    --db-divider: #cbd5e1;          /* Medium border - Prominent separators */

    /* Text Hierarchy */
    --db-text-primary: #0f172a;     /* Near black - Primary text (high contrast) */
    --db-text-secondary: #334155;   /* Dark gray - Secondary text */
    --db-text-muted: #64748b;       /* Medium gray - Muted text */
    --db-text-light: #94a3b8;       /* Light gray - Disabled/placeholder */

    /* Semantic Colors (High Contrast) */
    --db-success: #059669;          /* Green - Success states */
    --db-success-bg: #d1fae5;       /* Light green bg */
    --db-warning: #d97706;          /* Orange - Warnings */
    --db-warning-bg: #fef3c7;       /* Light orange bg */
    --db-error: #dc2626;            /* Red - Errors */
    --db-error-bg: #fee2e2;         /* Light red bg */
    --db-info: #0891b2;             /* Cyan - Info */
    --db-info-bg: #cffafe;          /* Light cyan bg */

    /* Interactive States */
    --db-hover: #eff6ff;            /* Light blue hover */
    --db-active: #dbeafe;           /* Darker blue active */
    --db-focus: #3b82f6;            /* Bright blue focus ring */

    /* Shadows & Elevation */
    --db-shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --db-shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px -1px rgba(0, 0, 0, 0.1);
    --db-shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -2px rgba(0, 0, 0, 0.1);
    --db-shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -4px rgba(0, 0, 0, 0.1);
    --db-shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 8px 10px -6px rgba(0, 0, 0, 0.1);

    /* Spacing Scale (based on 4px base unit) */
    --db-space-1: 0.25rem;  /* 4px */
    --db-space-2: 0.5rem;   /* 8px */
    --db-space-3: 0.75rem;  /* 12px */
    --db-space-4: 1rem;     /* 16px */
    --db-space-5: 1.25rem;  /* 20px */
    --db-space-6: 1.5rem;   /* 24px */
    --db-space-8: 2rem;     /* 32px */
    --db-space-10: 2.5rem;  /* 40px */
    --db-space-12: 3rem;    /* 48px */
    --db-space-16: 4rem;    /* 64px */

    /* Border Radius Scale */
    --db-radius-sm: 0.25rem;   /* 4px - Small elements */
    --db-radius: 0.5rem;       /* 8px - Default */
    --db-radius-md: 0.75rem;   /* 12px - Cards */
    --db-radius-lg: 1rem;      /* 16px - Large cards */
    --db-radius-xl: 1.5rem;    /* 24px - Modals */
    --db-radius-full: 9999px;  /* Fully rounded */

    /* Typography Scale */
    --db-text-xs: 0.75rem;     /* 12px */
    --db-text-sm: 0.875rem;    /* 14px */
    --db-text-base: 1rem;      /* 16px */
    --db-text-lg: 1.125rem;    /* 18px */
    --db-text-xl: 1.25rem;     /* 20px */
    --db-text-2xl: 1.5rem;     /* 24px */
    --db-text-3xl: 1.875rem;   /* 30px */
    --db-text-4xl: 2.25rem;    /* 36px */
    --db-text-5xl: 3rem;       /* 48px */

    /* Line Heights */
    --db-leading-tight: 1.25;
    --db-leading-normal: 1.5;
    --db-leading-relaxed: 1.75;

    /* Font Families */
    --db-font-mono: 'JetBrains Mono', 'IBM Plex Mono', 'Consolas', 'Monaco', 'Courier New', monospace;
    --db-font-sans: system-ui, -apple-system, 'Segoe UI', sans-serif;

    /* Transitions */
    --db-transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
    --db-transition: 200ms cubic-bezier(0.4, 0, 0.2, 1);
    --db-transition-slow: 300ms cubic-bezier(0.4, 0, 0.2, 1);

    /* Z-Index Scale */
    --db-z-base: 0;
    --db-z-dropdown: 1000;
    --db-z-sticky: 1100;
    --db-z-fixed: 1200;
    --db-z-modal: 1300;
    --db-z-popover: 1400;
    --db-z-tooltip: 1500;
}

/* ========== Dark Mode Variables ========== */
[data-theme="dark"] {
    /* Dark mode color adjustments */
    --db-entity: #3b82f6;
    --db-relationship: #06b6d4;
    --db-attribute: #10b981;
    --db-primary-key: #fbbf24;
    --db-foreign-key: #a78bfa;

    --db-canvas: #0f172a;
    --db-grid: #1e293b;
    --db-paper: #1e293b;
    --db-border: #334155;
    --db-divider: #475569;

    --db-text-primary: #f1f5f9;
    --db-text-secondary: #cbd5e1;
    --db-text-muted: #94a3b8;
    --db-text-light: #64748b;

    --db-hover: #1e293b;
    --db-active: #334155;

    --db-shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
    --db-shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.4), 0 1px 2px -1px rgba(0, 0, 0, 0.4);
    --db-shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.4), 0 2px 4px -2px rgba(0, 0, 0, 0.4);
    --db-shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.4), 0 4px 6px -4px rgba(0, 0, 0, 0.4);
    --db-shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.4), 0 8px 10px -6px rgba(0, 0, 0, 0.4);
}

/* ============================================
   BASE RESET & DEFAULTS
   ============================================ */
*,
*::before,
*::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: var(--db-font-mono);
    font-size: var(--db-text-base);
    line-height: var(--db-leading-normal);
    color: var(--db-text-primary);
    background: var(--db-canvas);
    transition: background-color var(--db-transition), color var(--db-transition);
}

/* ============================================
   TYPOGRAPHY
   ============================================ */

/* Headings with database schema styling */
h1, h2, h3, h4, h5, h6 {
    font-family: var(--db-font-mono);
    font-weight: 600;
    line-height: var(--db-leading-tight);
    color: var(--db-text-primary);
    letter-spacing: -0.025em;
}

h1 {
    font-size: var(--db-text-4xl);
    font-weight: 700;
    margin-bottom: var(--db-space-6);
    padding-bottom: var(--db-space-4);
    border-bottom: 2px solid var(--db-entity);
    color: var(--db-entity);
}

h2 {
    font-size: var(--db-text-3xl);
    margin-bottom: var(--db-space-5);
    margin-top: var(--db-space-8);
    color: var(--db-entity);
}

h3 {
    font-size: var(--db-text-2xl);
    margin-bottom: var(--db-space-4);
    margin-top: var(--db-space-6);
    color: var(--db-relationship);
}

h4 {
    font-size: var(--db-text-xl);
    margin-bottom: var(--db-space-3);
    margin-top: var(--db-space-4);
}

h5 {
    font-size: var(--db-text-lg);
    margin-bottom: var(--db-space-2);
}

h6 {
    font-size: var(--db-text-base);
    margin-bottom: var(--db-space-2);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

/* Paragraph and text */
p {
    margin-bottom: var(--db-space-4);
    color: var(--db-text-secondary);
}

/* Lists with ER diagram styling */
ul, ol {
    margin-left: var(--db-space-6);
    margin-bottom: var(--db-space-4);
}

li {
    margin-bottom: var(--db-space-2);
    color: var(--db-text-secondary);
}

/* Database relationship list style */
ul.db-list {
    list-style: none;
    margin-left: 0;
}

ul.db-list li {
    padding-left: var(--db-space-6);
    position: relative;
}

ul.db-list li::before {
    content: "├─";
    position: absolute;
    left: 0;
    color: var(--db-relationship);
    font-weight: 600;
}

ul.db-list li:last-child::before {
    content: "└─";
}

/* Inline code */
code {
    font-family: var(--db-font-mono);
    font-size: 0.9em;
    padding: 0.125rem 0.375rem;
    background: var(--db-info-bg);
    color: var(--db-entity);
    border-radius: var(--db-radius-sm);
    font-weight: 500;
    border: 1px solid var(--db-border);
}

[data-theme="dark"] code {
    background: var(--db-grid);
    color: var(--db-relationship);
}

/* Code blocks */
pre {
    font-family: var(--db-font-mono);
    font-size: var(--db-text-sm);
    line-height: var(--db-leading-relaxed);
    padding: var(--db-space-4);
    background: var(--db-grid);
    border: 1px solid var(--db-border);
    border-left: 3px solid var(--db-entity);
    border-radius: var(--db-radius);
    overflow-x: auto;
    margin-bottom: var(--db-space-4);
}

pre code {
    background: transparent;
    padding: 0;
    border: none;
    color: var(--db-text-primary);
}

/* Links */
a {
    color: var(--db-entity);
    text-decoration: underline;
    text-decoration-thickness: 1px;
    text-underline-offset: 2px;
    transition: color var(--db-transition-fast);
}

a:hover {
    color: var(--db-relationship);
}

a:focus-visible {
    outline: 2px solid var(--db-focus);
    outline-offset: 2px;
    border-radius: var(--db-radius-sm);
}

/* ============================================
   COMPONENTS - Entity Boxes (Cards)
   ============================================ */

/* Base entity card (like ER diagram rectangles) */
.db-entity-card,
.card {
    background: var(--db-paper);
    border: 2px solid var(--db-border);
    border-radius: var(--db-radius-md);
    padding: var(--db-space-6);
    margin-bottom: var(--db-space-6);
    box-shadow: var(--db-shadow);
    transition: all var(--db-transition);
}

.db-entity-card:hover,
.card:hover {
    border-color: var(--db-entity);
    box-shadow: var(--db-shadow-md);
    transform: translateY(-2px);
}

/* Primary entity (emphasized) */
.db-entity-card.primary {
    border-color: var(--db-entity);
    border-width: 3px;
    border-left-width: 6px;
}

/* Relationship card (diamond shape hint via styling) */
.db-relationship-card {
    background: linear-gradient(135deg, var(--db-paper) 0%, var(--db-grid) 100%);
    border: 2px dashed var(--db-relationship);
    border-radius: var(--db-radius-md);
    padding: var(--db-space-6);
    margin-bottom: var(--db-space-6);
}

/* ============================================
   COMPONENTS - Buttons
   ============================================ */

.btn,
button:not(.unstyled) {
    font-family: var(--db-font-mono);
    font-size: var(--db-text-sm);
    font-weight: 600;
    padding: var(--db-space-3) var(--db-space-5);
    border-radius: var(--db-radius);
    border: 2px solid transparent;
    cursor: pointer;
    transition: all var(--db-transition-fast);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--db-space-2);
    text-decoration: none;
}

/* Primary button (entity blue) */
.btn-primary,
button.btn-primary {
    background: var(--db-entity);
    color: white;
    border-color: var(--db-entity);
}

.btn-primary:hover {
    background: var(--db-relationship);
    border-color: var(--db-relationship);
    transform: translateY(-1px);
    box-shadow: var(--db-shadow-md);
}

/* Secondary button (outlined) */
.btn-secondary,
button.btn-secondary {
    background: transparent;
    color: var(--db-entity);
    border-color: var(--db-entity);
}

.btn-secondary:hover {
    background: var(--db-entity);
    color: white;
}

/* Success button (green) */
.btn-success {
    background: var(--db-success);
    color: white;
    border-color: var(--db-success);
}

.btn-success:hover {
    background: var(--db-attribute);
    border-color: var(--db-attribute);
}

/* Danger button (red) */
.btn-danger {
    background: var(--db-error);
    color: white;
    border-color: var(--db-error);
}

.btn-danger:hover {
    background: #b91c1c;
    border-color: #b91c1c;
}

/* Disabled state */
.btn:disabled,
button:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none !important;
}

/* ============================================
   COMPONENTS - Forms & Inputs
   ============================================ */

input[type="text"],
input[type="email"],
input[type="password"],
input[type="number"],
input[type="date"],
input[type="time"],
select,
textarea {
    font-family: var(--db-font-mono);
    font-size: var(--db-text-base);
    padding: var(--db-space-3);
    border: 2px solid var(--db-border);
    border-radius: var(--db-radius);
    background: var(--db-canvas);
    color: var(--db-text-primary);
    transition: all var(--db-transition-fast);
    width: 100%;
}

input:focus,
select:focus,
textarea:focus {
    outline: none;
    border-color: var(--db-focus);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
}

label {
    font-size: var(--db-text-sm);
    font-weight: 600;
    color: var(--db-text-secondary);
    margin-bottom: var(--db-space-2);
    display: block;
}

/* ============================================
   COMPONENTS - Badges & Tags
   ============================================ */

/* Primary key badge (gold) */
.badge-pk,
.db-badge-primary {
    display: inline-flex;
    align-items: center;
    padding: var(--db-space-1) var(--db-space-3);
    background: var(--db-primary-key);
    color: white;
    border-radius: var(--db-radius-full);
    font-size: var(--db-text-xs);
    font-weight: 600;
    letter-spacing: 0.025em;
}

/* Foreign key badge (purple) */
.badge-fk,
.db-badge-secondary {
    display: inline-flex;
    align-items: center;
    padding: var(--db-space-1) var(--db-space-3);
    background: var(--db-foreign-key);
    color: white;
    border-radius: var(--db-radius-full);
    font-size: var(--db-text-xs);
    font-weight: 600;
}

/* Status badges */
.badge-success {
    background: var(--db-success-bg);
    color: var(--db-success);
    border: 1px solid var(--db-success);
}

.badge-warning {
    background: var(--db-warning-bg);
    color: var(--db-warning);
    border: 1px solid var(--db-warning);
}

.badge-error {
    background: var(--db-error-bg);
    color: var(--db-error);
    border: 1px solid var(--db-error);
}

/* ============================================
   COMPONENTS - Alerts & Notifications
   ============================================ */

.alert {
    padding: var(--db-space-4);
    border-radius: var(--db-radius);
    border-left: 4px solid;
    margin-bottom: var(--db-space-4);
}

.alert-info {
    background: var(--db-info-bg);
    border-color: var(--db-info);
    color: var(--db-text-primary);
}

.alert-success {
    background: var(--db-success-bg);
    border-color: var(--db-success);
    color: var(--db-text-primary);
}

.alert-warning {
    background: var(--db-warning-bg);
    border-color: var(--db-warning);
    color: var(--db-text-primary);
}

.alert-error {
    background: var(--db-error-bg);
    border-color: var(--db-error);
    color: var(--db-text-primary);
}

/* ============================================
   LAYOUT UTILITIES
   ============================================ */

.container {
    width: 100%;
    max-width: 1400px;
    margin: 0 auto;
    padding: var(--db-space-4);
}

.container-sm {
    max-width: 640px;
}

.container-md {
    max-width: 768px;
}

.container-lg {
    max-width: 1024px;
}

/* Grid layouts (schema-like) */
.db-grid {
    display: grid;
    gap: var(--db-space-4);
}

.db-grid-2 {
    grid-template-columns: repeat(2, 1fr);
}

.db-grid-3 {
    grid-template-columns: repeat(3, 1fr);
}

.db-grid-4 {
    grid-template-columns: repeat(4, 1fr);
}

/* Responsive grid */
.db-grid-auto {
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
}

/* Flexbox utilities */
.flex {
    display: flex;
}

.flex-col {
    flex-direction: column;
}

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

.justify-between {
    justify-content: space-between;
}

.gap-2 { gap: var(--db-space-2); }
.gap-4 { gap: var(--db-space-4); }
.gap-6 { gap: var(--db-space-6); }

/* ============================================
   THEME TOGGLE
   ============================================ */

.theme-toggle {
    position: fixed;
    top: var(--db-space-4);
    right: var(--db-space-4);
    z-index: var(--db-z-fixed);
    background: var(--db-paper);
    padding: var(--db-space-2) var(--db-space-3);
    border-radius: var(--db-radius-full);
    border: 2px solid var(--db-border);
    box-shadow: var(--db-shadow);
    display: flex;
    align-items: center;
    gap: var(--db-space-2);
}

.theme-switch {
    position: relative;
    width: 48px;
    height: 24px;
}

.theme-switch input {
    opacity: 0;
    width: 0;
    height: 0;
}

.theme-slider {
    position: absolute;
    cursor: pointer;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: var(--db-border);
    transition: var(--db-transition);
    border-radius: var(--db-radius-full);
}

.theme-slider::before {
    content: "";
    position: absolute;
    height: 18px;
    width: 18px;
    left: 3px;
    bottom: 3px;
    background: white;
    transition: var(--db-transition);
    border-radius: 50%;
}

input:checked + .theme-slider {
    background: var(--db-entity);
}

input:checked + .theme-slider::before {
    transform: translateX(24px);
}

/* ============================================
   RESPONSIVE DESIGN
   ============================================ */

@media (max-width: 768px) {
    :root {
        font-size: 14px;
    }

    .db-grid-2,
    .db-grid-3,
    .db-grid-4 {
        grid-template-columns: 1fr;
    }

    .container {
        padding: var(--db-space-3);
    }
}

/* ============================================
   UTILITY CLASSES
   ============================================ */

/* Spacing */
.mt-2 { margin-top: var(--db-space-2); }
.mt-4 { margin-top: var(--db-space-4); }
.mt-6 { margin-top: var(--db-space-6); }
.mb-2 { margin-bottom: var(--db-space-2); }
.mb-4 { margin-bottom: var(--db-space-4); }
.mb-6 { margin-bottom: var(--db-space-6); }
.p-4 { padding: var(--db-space-4); }
.p-6 { padding: var(--db-space-6); }

/* Text alignment */
.text-left { text-align: left; }
.text-center { text-align: center; }
.text-right { text-align: right; }

/* Font weights */
.font-normal { font-weight: 400; }
.font-medium { font-weight: 500; }
.font-semibold { font-weight: 600; }
.font-bold { font-weight: 700; }

/* Colors */
.text-primary { color: var(--db-text-primary); }
.text-secondary { color: var(--db-text-secondary); }
.text-muted { color: var(--db-text-muted); }
.text-entity { color: var(--db-entity); }
.text-relationship { color: var(--db-relationship); }
.text-success { color: var(--db-success); }
.text-error { color: var(--db-error); }

/* Background colors */
.bg-paper { background: var(--db-paper); }
.bg-grid { background: var(--db-grid); }
.bg-entity { background: var(--db-entity); color: white; }
.bg-success { background: var(--db-success); color: white; }
.bg-error { background: var(--db-error); color: white; }

/* Borders */
.border { border: 1px solid var(--db-border); }
.border-2 { border: 2px solid var(--db-border); }
.border-entity { border-color: var(--db-entity); }
.rounded { border-radius: var(--db-radius); }
.rounded-lg { border-radius: var(--db-radius-lg); }

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

/* Display */
.hidden { display: none; }
.block { display: block; }
.inline-block { display: inline-block; }

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

::-webkit-scrollbar-track {
    background: var(--db-grid);
    border-radius: var(--db-radius);
}

::-webkit-scrollbar-thumb {
    background: var(--db-border);
    border-radius: var(--db-radius);
}

::-webkit-scrollbar-thumb:hover {
    background: var(--db-divider);
}