/* ============================================================================
   AHP Matrix Calculator — Modern Design System
   Sans-serif first, clean, accessible, light/dark ready
   ========================================================================== */

:root {
    /* Colors — Light Mode (Monochrome + Semantic) */
    --bg: #f6f5f4;
    --surface: #ffffff;
    --surface-hover: #EFEFED;
    --border: #E8E8E5;
    --text-primary: #1A1A19;
    --text-secondary: #6B6B68;
    --text-disabled: #AFAFAC;
    --accent: #0F7DDB;
    --accent-hover: #0A65B8;
    --accent-muted: #E6F4FF;

    /* Semantic Palette */
    --success: #548164;
    --success-hover: #3E6B52;
    --success-muted: #DCEFE0;
    --warning: #C29343;
    --warning-hover: #A87C34;
    --warning-muted: #FAF1E6;
    --error: #C4554D;
    --error-hover: #A63D37;
    --error-muted: #F9E6E5;
    --info: #2E7DB5;
    --info-hover: #236592;
    --info-muted: #E6F4FB;
    
    /* Spacing — 8px base grid */
    --xs: 4px;
    --sm: 8px;
    --md: 16px;
    --lg: 24px;
    --xl: 32px;
    --2xl: 48px;
    --section-gap: 48px;
    
    /* Typography */
    --font-sans: Inter, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-mono: Menlo, Consolas, 'Courier New', monospace;
    
    /* Line Heights */
    --lh-tight: 1.15;
    --lh-body: 1.6;
}

/* ============================================================================
   Reset & Base Styles
   ========================================================================== */

* {
    box-sizing: border-box;
}

html, body {
    margin: 0;
    padding: 0;
    font-family: var(--font-sans);
    color: var(--text-primary);
    background-color: var(--bg);
    font-size: 16px;
}

body {
    line-height: var(--lh-body);
    font-size: 0.9375rem;
    font-weight: 400;
    letter-spacing: -0.01em;
    padding-bottom: 96px;
}

/* ============================================================================
   Typography
   ========================================================================== */

h1 {
    font-family: var(--font-sans);
    font-size: 1.75rem;
    font-weight: 700;
    line-height: var(--lh-tight);
    letter-spacing: -0.03em;
    margin: 0;
    color: var(--text-primary);
}

h2 {
    font-family: var(--font-sans);
    font-size: 1rem;
    font-weight: 600;
    line-height: var(--lh-tight);
    letter-spacing: -0.02em;
    margin: 0 0 var(--md) 0;
    color: var(--text-primary);
}

h3 {
    font-family: var(--font-sans);
    font-size: 1.25rem;
    font-weight: 600;
    line-height: var(--lh-tight);
    letter-spacing: -0.02em;
    margin: 0 0 var(--md) 0;
    color: var(--text-primary);
}

p {
    margin: 0;
    line-height: var(--lh-body);
}

small, .text-small {
    font-size: 0.875rem;
    font-weight: 400;
    color: var(--text-secondary);
    line-height: var(--lh-body);
}

code, .code {
    font-family: var(--font-mono);
    font-size: 0.875rem;
    font-weight: 400;
    line-height: var(--lh-body);
}

/* ============================================================================
   Buttons
   ========================================================================== */

button {
    font-family: var(--font-sans);
    cursor: pointer;
    border: none;
    transition: all 120ms ease-out;
    outline: none;
}

/* Primary Button */
.btn-primary {
    background-color: var(--text-primary);
    color: #FFFFFF;
    padding: 8px 18px;
    border-radius: 6px;
    font-size: 0.875rem;
    font-weight: 500;
    letter-spacing: -0.01em;
}

.btn-primary:hover {
    background-color: #333;
}

.btn-primary:disabled {
    background-color: var(--text-disabled);
    color: #FFFFFF;
    cursor: not-allowed;
    opacity: 0.6;
}

/* Secondary / Ghost Button */
.btn-secondary {
    background-color: transparent;
    border: none;
    color: var(--text-secondary);
    padding: 8px 18px;
    border-radius: 6px;
    font-size: 0.875rem;
    font-weight: 500;
    letter-spacing: -0.01em;
}

.btn-secondary:hover {
    color: var(--text-primary);
}

/* ============================================================================
   Inputs
   ========================================================================== */

input[type="text"],
input[type="number"],
input[type="email"],
textarea,
select {
    font-family: var(--font-sans);
    font-size: 1rem;
    padding: 7px 12px;
    border: 1px solid transparent;
    border-radius: 6px;
    background-color: var(--surface);
    color: var(--text-primary);
    transition: border-color 120ms ease-out, box-shadow 120ms ease-out;
    letter-spacing: -0.01em;
}

input[type="text"]::placeholder,
input[type="number"]::placeholder,
input[type="email"]::placeholder,
textarea::placeholder {
    color: var(--text-disabled);
}

input[type="text"]:focus,
input[type="number"]:focus,
input[type="email"]:focus,
textarea:focus,
select:focus {
    outline: none;
    border-color: var(--accent);
    background-color: var(--bg);
    box-shadow: 0 0 0 3px rgba(15, 125, 219, 0.1);
}

/* ============================================================================
   Spacing Utilities
   ========================================================================== */

.space-xs { margin: var(--xs); }
.space-sm { margin: var(--sm); }
.space-md { margin: var(--md); }
.space-lg { margin: var(--lg); }
.space-xl { margin: var(--xl); }
.space-2xl { margin: var(--2xl); }

.gap-xs { gap: var(--xs); }
.gap-sm { gap: var(--sm); }
.gap-md { gap: var(--md); }
.gap-lg { gap: var(--lg); }
.gap-xl { gap: var(--xl); }

.p-sm { padding: var(--sm); }
.p-md { padding: var(--md); }
.p-lg { padding: var(--lg); }
.p-xl { padding: var(--xl); }

.mt-sm { margin-top: var(--sm); }
.mt-md { margin-top: var(--md); }
.mt-lg { margin-top: var(--lg); }
.mt-xl { margin-top: var(--xl); }

.mb-sm { margin-bottom: var(--sm); }
.mb-md { margin-bottom: var(--md); }
.mb-lg { margin-bottom: var(--lg); }
.mb-xl { margin-bottom: var(--xl); }

/* ============================================================================
   Cards & Containers
   ========================================================================== */

.card {
    background-color: var(--bg);
    border-radius: 8px;
    padding: var(--lg);
    box-shadow: none;
}

.card-surface {
    background-color: var(--surface);
    border-radius: 8px;
    padding: var(--lg);
    box-shadow: none;
}

.surface {
    background-color: var(--surface);
}

/* ============================================================================
   Borders & Dividers
   ========================================================================== */

.border-subtle {
    border: 1px solid var(--border);
}

.border-top-subtle {
    border-top: 1px solid var(--border);
}

/* ============================================================================
   Shadows — Notion Style (subtle, only when needed)
   ========================================================================== */

.shadow-low {
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
}

.shadow-mid {
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.12);
}

/* ============================================================================
   Accent Colors (used sparingly)
   ========================================================================== */

.text-accent { color: var(--accent); }
.text-accent-hover:hover { color: var(--accent-hover); }
.text-accent-muted { color: var(--accent-muted); }

.bg-accent { background-color: var(--accent); }

.bg-accent-hover:hover { background-color: var(--accent-hover); }
.bg-accent-muted { background-color: var(--accent-muted); }

.text-success { color: var(--success); }
.text-success-hover:hover { color: var(--success-hover); }
.text-success-muted { color: var(--success-muted); }
.bg-success { background-color: var(--success); }
.bg-success-hover:hover { background-color: var(--success-hover); }
.bg-success-muted { background-color: var(--success-muted); }

.text-warning { color: var(--warning); }
.text-warning-hover:hover { color: var(--warning-hover); }
.text-warning-muted { color: var(--warning-muted); }
.bg-warning { background-color: var(--warning); }
.bg-warning-hover:hover { background-color: var(--warning-hover); }
.bg-warning-muted { background-color: var(--warning-muted); }

.text-error { color: var(--error); }
.text-error-hover:hover { color: var(--error-hover); }
.text-error-muted { color: var(--error-muted); }
.bg-error { background-color: var(--error); }
.bg-error-hover:hover { background-color: var(--error-hover); }
.bg-error-muted { background-color: var(--error-muted); }

.text-info { color: var(--info); }
.text-info-hover:hover { color: var(--info-hover); }
.text-info-muted { color: var(--info-muted); }
.bg-info { background-color: var(--info); }
.bg-info-hover:hover { background-color: var(--info-hover); }
.bg-info-muted { background-color: var(--info-muted); }

/* Muted / Inactive utilities */
.text-disabled { color: var(--text-disabled); }
.bg-disabled { background-color: var(--surface-hover); }

/* ============================================================================
   Utility Classes
   ========================================================================== */

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

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

.flex-row {
    display: flex;
    flex-direction: row;
}

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

.items-start {
    align-items: flex-start;
}

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

.rounded-md { border-radius: 6px; }
.rounded-lg { border-radius: 8px; }
.rounded-full { border-radius: 9999px; }

.opacity-50 { opacity: 0.5; }
.opacity-75 { opacity: 0.75; }

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

/* ============================================================================
   Page Layout
   ========================================================================== */

.container {
    max-width: 680px;
    margin: 0 auto;
    padding: 0 var(--md);
}

/* Bottom navigation fixed bar */
.step-indicator {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    height: 48px;
    background-color: var(--bg);
    border-top: 1px solid var(--border);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 100;
}

.step-indicator-content {
    max-width: 680px;
    width: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 24px;
    padding: 0 var(--md);
}

.step-indicator-step {
    display: flex;
    align-items: center;
    gap: 4px;
    font-size: 0.8125rem;
}

.step-indicator-step.inactive {
    color: var(--text-disabled);
}

.step-indicator-step.active {
    color: var(--text-primary);
    font-weight: 600;
}

.step-indicator-step.completed {
    color: var(--text-disabled);
    text-decoration: line-through;
}

.step-indicator-connector {
    color: var(--text-disabled);
}

/* ============================================================================
    Range Slider Styling
    ========================================================================== */

input[type="range"] {
    -webkit-appearance: none;
    appearance: none;
    width: 100%;
    height: 1.5px;
    background: var(--border);
    border-radius: 0;
    outline: none;
    cursor: pointer;
}

input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 16px;
    height: 16px;
    border-radius: 50%;
    background-color: var(--bg);
    border: 1.5px solid var(--text-primary);
    cursor: pointer;
    margin-top: -7.25px;
}

input[type="range"]::-moz-range-thumb {
    width: 16px;
    height: 16px;
    border-radius: 50%;
    background-color: var(--bg);
    border: 1.5px solid var(--text-primary);
    cursor: pointer;
}

input[type="range"]::-webkit-slider-runnable-track {
    background: var(--border);
    height: 1.5px;
    border-radius: 0;
}

input[type="range"]::-moz-range-track {
    background: var(--border);
    height: 1.5px;
    border-radius: 0;
    border: none;
}

input[type="range"]::-moz-range-progress {
    background-color: var(--text-disabled);
    height: 1.5px;
}