/* ============================
   CSS Variables & Design Tokens
   ============================ */
:root {
    /* Color Palette - Dark Theme */
    --color-bg-primary: hsl(230, 25%, 8%);
    --color-bg-secondary: hsl(230, 20%, 12%);
    --color-bg-card: hsla(230, 20%, 18%, 0.6);
    --color-bg-input: hsla(230, 15%, 15%, 0.8);
    
    /* Accent Colors */
    --color-accent-primary: hsl(280, 85%, 65%);
    --color-accent-secondary: hsl(200, 85%, 55%);
    --color-accent-gradient: linear-gradient(135deg, hsl(280, 85%, 65%), hsl(200, 85%, 55%));
    
    /* Text Colors */
    --color-text-primary: hsl(0, 0%, 95%);
    --color-text-secondary: hsl(0, 0%, 70%);
    --color-text-muted: hsl(0, 0%, 50%);
    
    /* Effects */
    --shadow-sm: 0 2px 8px hsla(0, 0%, 0%, 0.3);
    --shadow-md: 0 4px 16px hsla(0, 0%, 0%, 0.4);
    --shadow-lg: 0 8px 32px hsla(0, 0%, 0%, 0.5);
    --shadow-glow: 0 0 20px hsla(280, 85%, 65%, 0.3);
    
    /* Glassmorphism */
    --glass-bg: hsla(230, 20%, 18%, 0.4);
    --glass-border: hsla(0, 0%, 100%, 0.1);
    --glass-blur: blur(12px);
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 0.75rem;
    --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: 1.5rem;
    --font-size-2xl: 2rem;
    --font-size-3xl: 2.5rem;
    
    /* Border Radius */
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-xl: 24px;
    
    /* Transitions */
    --transition-fast: 150ms ease-in-out;
    --transition-base: 250ms ease-in-out;
    --transition-slow: 400ms ease-in-out;
}

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

body {
    font-family: var(--font-family);
    font-size: var(--font-size-base);
    line-height: 1.6;
    color: var(--color-text-primary);
    background: var(--color-bg-primary);
    background-image: 
        radial-gradient(circle at 20% 20%, hsla(280, 85%, 65%, 0.1) 0%, transparent 50%),
        radial-gradient(circle at 80% 80%, hsla(200, 85%, 55%, 0.1) 0%, transparent 50%);
    background-attachment: fixed;
    min-height: 100vh;
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* ============================
   Layout Components
   ============================ */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: var(--spacing-lg);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.header {
    text-align: center;
    margin-bottom: var(--spacing-2xl);
    animation: fadeInDown 0.6s ease-out;
}

.header h1 {
    font-size: var(--font-size-3xl);
    font-weight: 700;
    background: var(--color-accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: var(--spacing-sm);
}

.subtitle {
    font-size: var(--font-size-lg);
    color: var(--color-text-secondary);
    font-weight: 400;
}

.main-content {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xl);
}

/* ============================
   Card Components
   ============================ */
.input-card,
.controls-card,
.results-card {
    background: var(--glass-bg);
    backdrop-filter: var(--glass-blur);
    -webkit-backdrop-filter: var(--glass-blur);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    box-shadow: var(--shadow-md);
    transition: all var(--transition-base);
    animation: fadeInUp 0.6s ease-out;
}

.input-card:hover,
.controls-card:hover,
.results-card:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg), var(--shadow-glow);
}


/* ============================
   Collapsible Sections (Details/Summary)
   ============================ */
.advanced-options,
.secondary-results {
    width: 100%;
}

.advanced-summary,
.details-title {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-md) var(--spacing-lg);
    background: var(--color-bg-input);
    border-radius: var(--radius-md);
    cursor: pointer;
    list-style: none; /* Hide default arrow */
    transition: all var(--transition-base);
    border: 1px solid var(--glass-border);
}

.advanced-summary::-webkit-details-marker {
    display: none; /* Hide default arrow Chrome/Safari */
}

.advanced-summary:hover,
.details-title:hover {
    background: var(--color-bg-secondary);
    border-color: var(--color-accent-primary);
}

.summary-text {
    font-weight: 600;
    color: var(--color-text-secondary);
}

.summary-icon {
    font-size: 1.2rem;
    color: var(--color-accent-primary);
    transition: transform var(--transition-base);
}

details[open] .summary-icon {
    transform: rotate(180deg);
}

.controls-grid {
    margin-top: var(--spacing-lg);
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(100px, 1fr));
    gap: var(--spacing-lg);
}

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

.secondary-results .result-details {
    margin-top: var(--spacing-lg);
}


/* ============================
   Input Grid
   ============================ */
.inputs-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--spacing-lg);
}

.input-group {
    margin-bottom: var(--spacing-md);
}

.input-group label {
    display: block;
    font-size: var(--font-size-sm);
    font-weight: 500;
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-xs);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

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

.date-input:focus,
.time-input:focus {
    outline: none;
    border-color: var(--color-accent-primary);
    box-shadow: 0 0 0 3px hsla(280, 85%, 65%, 0.2);
    background: var(--color-bg-secondary);
}

/* Custom date/time input styling */
.date-input::-webkit-calendar-picker-indicator,
.time-input::-webkit-calendar-picker-indicator {
    filter: invert(1);
    cursor: pointer;
    opacity: 0.7;
    transition: opacity var(--transition-fast);
}

.date-input::-webkit-calendar-picker-indicator:hover,
.time-input::-webkit-calendar-picker-indicator:hover {
    opacity: 1;
}

.now-button {
    width: 100%;
    padding: var(--spacing-md);
    background: var(--color-accent-gradient);
    border: none;
    border-radius: var(--radius-sm);
    color: white;
    font-size: var(--font-size-base);
    font-weight: 600;
    font-family: var(--font-family);
    cursor: pointer;
    transition: all var(--transition-base);
    box-shadow: var(--shadow-sm);
    margin-bottom: var(--spacing-sm);
}

.now-button:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.now-button:active {
    transform: translateY(0);
}

.current-time {
    font-size: var(--font-size-xs);
    color: var(--color-text-muted);
    text-align: center;
    font-style: italic;
}

/* ============================
   Controls
   ============================ */
/* controls-grid moved to Collapsible Sections for better flow */

.control-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-sm);
}

.control-buttons {
    display: flex;
    gap: var(--spacing-xs);
}

.control-btn {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    border: 2px solid var(--glass-border);
    background: var(--color-bg-input);
    color: var(--color-text-primary);
    font-size: var(--font-size-lg);
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-fast);
    display: flex;
    align-items: center;
    justify-content: center;
}

.control-btn:hover {
    background: var(--color-accent-primary);
    border-color: var(--color-accent-primary);
    transform: scale(1.1);
    box-shadow: var(--shadow-glow);
}

.control-btn:active {
    transform: scale(0.95);
}

.control-btn.plus {
    background: hsla(280, 85%, 65%, 0.2);
}

.control-btn.minus {
    background: hsla(200, 85%, 55%, 0.2);
}

.control-input {
    width: 80px;
    padding: var(--spacing-sm);
    background: var(--color-bg-input);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-sm);
    color: var(--color-text-primary);
    font-size: var(--font-size-base);
    font-family: var(--font-family);
    text-align: center;
    font-weight: 600;
    transition: all var(--transition-base);
}

.control-input:focus {
    outline: none;
    border-color: var(--color-accent-primary);
    box-shadow: 0 0 0 3px hsla(280, 85%, 65%, 0.2);
}

.control-label {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
    font-weight: 500;
    text-transform: capitalize;
}

/* ============================
   Results Display
   ============================ */
.result-summary {
    font-size: var(--font-size-2xl);
    font-weight: 600;
    text-align: center;
    padding: var(--spacing-xl);
    background: var(--color-accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: var(--spacing-xl);
    line-height: 1.4;
}

.result-value {
    font-weight: 700;
    color: var(--color-accent-primary);
    display: inline-block;
}

#final-result-text {
    display: block;
    font-size: 1.2em;
    background: var(--color-accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    font-weight: 800;
}


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

.details-title {
    font-size: var(--font-size-lg);
    font-weight: 600;
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-sm);
    text-align: center;
}

.detail-item {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-md);
    background: var(--color-bg-input);
    border-radius: var(--radius-sm);
    border-left: 3px solid var(--color-accent-primary);
    transition: all var(--transition-base);
}

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

.detail-value {
    font-size: var(--font-size-lg);
    font-weight: 600;
    color: var(--color-text-primary);
}

.detail-label {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
}

/* ============================
   Footer
   ============================ */
.footer {
    margin-top: var(--spacing-2xl);
    padding: var(--spacing-lg);
    text-align: center;
    color: var(--color-text-muted);
    font-size: var(--font-size-sm);
}

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

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

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

/* ============================
   Responsive Design
   ============================ */
@media (max-width: 768px) {
    :root {
        --font-size-3xl: 2rem;
        --font-size-2xl: 1.5rem;
        --font-size-xl: 1.25rem;
        --spacing-xl: 1.5rem;
        --spacing-2xl: 2rem;
    }
    
    .container {
        padding: var(--spacing-md);
    }
    
    .input-card,
    .controls-card,
    .results-card {
        padding: var(--spacing-lg);
    }
    
    .inputs-grid {
        grid-template-columns: 1fr;
    }
    
    .controls-grid {
        grid-template-columns: repeat(auto-fit, minmax(80px, 1fr));
        gap: var(--spacing-md);
    }
    
    .result-summary {
        font-size: var(--font-size-xl);
        padding: var(--spacing-lg);
    }
    
    .detail-value {
        font-size: var(--font-size-base);
    }
}

@media (max-width: 480px) {
    .controls-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .control-item {
        gap: var(--spacing-xs);
    }
    
    .control-btn {
        width: 36px;
        height: 36px;
        font-size: var(--font-size-base);
    }
}

/* ============================
   Accessibility
   ============================ */
@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

/* Focus visible for keyboard navigation */
*:focus-visible {
    outline: 2px solid var(--color-accent-primary);
    outline-offset: 2px;
}