/* =============================================================
   HOW TO USE — Reusable Component
   Path: wwwroot/css/shared/how_to_use.css
   Usage: <link href="~/css/shared/how_to_use.css" rel="stylesheet" />
   Compatible with: All tool pages — Calculator, Scientific, Percentage, etc.
   ============================================================= */


/* =============================================================
   1. CSS CUSTOM PROPERTIES — Light Mode Defaults
   ============================================================= */
:root {
    --htu-bg-section:         #f8fafc;
    --htu-bg-card:            #ffffff;
    --htu-bg-step-icon:       #eef2ff;
    --htu-bg-step-icon-hover: #e0e7ff;
    --htu-bg-tip:             #f0f9ff;
    --htu-border-card:        #e5e7eb;
    --htu-border-tip:         #bae6fd;
    --htu-shadow-card:        0 1px 4px rgba(0, 0, 0, 0.07);
    --htu-shadow-hover:       0 8px 28px rgba(99, 102, 241, 0.13);
    --htu-accent:             #6366f1;
    --htu-accent-soft:        rgba(99, 102, 241, 0.08);
    --htu-accent-tip:         #0284c7;
    --htu-accent-tip-bg:      #f0f9ff;
    --htu-accent-tip-border:  #bae6fd;
    --htu-step-number-bg:     #6366f1;
    --htu-step-number-color:  #ffffff;
    --htu-connector-color:    #e0e7ff;
    --htu-text-heading:       #111827;
    --htu-text-subheading:    #1f2937;
    --htu-text-body:          #6b7280;
    --htu-text-body-hover:    #4b5563;
    --htu-text-tip:           #0369a1;
    --htu-radius-section:     20px;
    --htu-radius-card:        14px;
    --htu-radius-tip:         12px;
    --htu-transition:         all 0.22s cubic-bezier(0.4, 0, 0.2, 1);
}


/* =============================================================
   2. CSS CUSTOM PROPERTIES — Dark Mode Overrides
   ============================================================= */
.dark-mode,
[data-theme="dark"],
[data-bs-theme="dark"] {
    --htu-bg-section:         #0f1117;
    --htu-bg-card:            #1a1d2e;
    --htu-bg-step-icon:       #252840;
    --htu-bg-step-icon-hover: #2d3155;
    --htu-bg-tip:             #0c1a2e;
    --htu-border-card:        #2a2d3e;
    --htu-border-tip:         #1e3a5f;
    --htu-shadow-card:        0 1px 4px rgba(0, 0, 0, 0.35);
    --htu-shadow-hover:       0 8px 28px rgba(99, 102, 241, 0.22);
    --htu-accent-soft:        rgba(99, 102, 241, 0.12);
    --htu-accent-tip:         #38bdf8;
    --htu-accent-tip-bg:      #0c1a2e;
    --htu-accent-tip-border:  #1e3a5f;
    --htu-connector-color:    #2a2d3e;
    --htu-text-heading:       #f1f5f9;
    --htu-text-subheading:    #e2e8f0;
    --htu-text-body:          #94a3b8;
    --htu-text-body-hover:    #cbd5e1;
    --htu-text-tip:           #38bdf8;
}

/* OS-level dark mode fallback */
@media (prefers-color-scheme: dark) {
    :root:not(.light-mode):not([data-theme="light"]):not([data-bs-theme="light"]) {
        --htu-bg-section:         #0f1117;
        --htu-bg-card:            #1a1d2e;
        --htu-bg-step-icon:       #252840;
        --htu-bg-step-icon-hover: #2d3155;
        --htu-bg-tip:             #0c1a2e;
        --htu-border-card:        #2a2d3e;
        --htu-border-tip:         #1e3a5f;
        --htu-shadow-card:        0 1px 4px rgba(0, 0, 0, 0.35);
        --htu-shadow-hover:       0 8px 28px rgba(99, 102, 241, 0.22);
        --htu-accent-soft:        rgba(99, 102, 241, 0.12);
        --htu-accent-tip:         #38bdf8;
        --htu-accent-tip-bg:      #0c1a2e;
        --htu-accent-tip-border:  #1e3a5f;
        --htu-connector-color:    #2a2d3e;
        --htu-text-heading:       #f1f5f9;
        --htu-text-subheading:    #e2e8f0;
        --htu-text-body:          #94a3b8;
        --htu-text-body-hover:    #cbd5e1;
        --htu-text-tip:           #38bdf8;
    }
}


/* =============================================================
   3. SECTION WRAPPER
   ============================================================= */
.how-to-use-section {
    background: var(--htu-bg-section);
    border-radius: var(--htu-radius-section);
    padding: 3rem 2.5rem;
    margin: 2.5rem 0;
    transition: background 0.2s ease;
}


/* =============================================================
   4. SECTION HEADER
   ============================================================= */
.htu-header {
    text-align: center;
    margin-bottom: 2.5rem;
}

.htu-header h2 {
    font-size: 1.75rem;
    font-weight: 800;
    color: var(--htu-text-heading);
    margin: 0 0 0.5rem;
    letter-spacing: -0.02em;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    transition: color 0.2s ease;
}

.htu-header h2 i {
    color: var(--htu-accent);
    font-size: 1.5rem;
}

.htu-subheading {
    font-size: 1rem;
    color: var(--htu-text-body);
    margin: 0;
    transition: color 0.2s ease;
}


/* =============================================================
   5. STEPS GRID
   ============================================================= */
.htu-steps {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 1.25rem;
    position: relative;
    margin-bottom: 2rem;
}

/* Horizontal connector line between steps */
.htu-steps::before {
    content: '';
    position: absolute;
    top: 2.25rem;                        /* vertically centered on step icons */
    left: calc(12.5% + 1rem);           /* starts after first icon center */
    right: calc(12.5% + 1rem);          /* ends before last icon center */
    height: 2px;
    background: var(--htu-connector-color);
    z-index: 0;
    transition: background 0.2s ease;
}


/* =============================================================
   6. INDIVIDUAL STEP CARD
   ============================================================= */
.htu-step {
    position: relative;
    z-index: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
    background: var(--htu-bg-card);
    border: 1px solid var(--htu-border-card);
    border-radius: var(--htu-radius-card);
    padding: 1.5rem 1rem 1.25rem;
    box-shadow: var(--htu-shadow-card);
    transition: var(--htu-transition);
    cursor: default;
}

.htu-step:hover {
    box-shadow: var(--htu-shadow-hover);
    border-color: var(--htu-accent);
    transform: translateY(-3px);
}

/* Step number badge */
.htu-step-number {
    width: 2.75rem;
    height: 2.75rem;
    border-radius: 50%;
    background: var(--htu-step-number-bg);
    color: var(--htu-step-number-color);
    font-size: 1rem;
    font-weight: 700;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 0.875rem;
    flex-shrink: 0;
    box-shadow: 0 2px 8px rgba(99, 102, 241, 0.3);
    transition: var(--htu-transition);
}

.htu-step:hover .htu-step-number {
    box-shadow: 0 4px 14px rgba(99, 102, 241, 0.45);
    transform: scale(1.08);
}

/* Step icon */
.htu-step-icon {
    width: 3rem;
    height: 3rem;
    border-radius: 12px;
    background: var(--htu-bg-step-icon);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 0.875rem;
    transition: var(--htu-transition);
}

.htu-step-icon i {
    font-size: 1.375rem;
    color: var(--htu-accent);
    transition: var(--htu-transition);
}

.htu-step:hover .htu-step-icon {
    background: var(--htu-bg-step-icon-hover);
}

.htu-step:hover .htu-step-icon i {
    transform: scale(1.1);
}

/* Step title */
.htu-step-title {
    font-size: 0.9375rem;
    font-weight: 700;
    color: var(--htu-text-subheading);
    margin: 0 0 0.4rem;
    transition: color 0.2s ease;
}

.htu-step:hover .htu-step-title {
    color: var(--htu-accent);
}

/* Step description */
.htu-step-desc {
    font-size: 0.85rem;
    color: var(--htu-text-body);
    line-height: 1.6;
    margin: 0;
    transition: color 0.2s ease;
}

.htu-step:hover .htu-step-desc {
    color: var(--htu-text-body-hover);
}

/* Step keyboard hint badge */
.htu-step-kbd {
    display: inline-flex;
    align-items: center;
    gap: 0.25rem;
    margin-top: 0.625rem;
    font-size: 0.75rem;
    color: var(--htu-text-body);
}

.htu-step-kbd kbd {
    font-size: 0.7rem;
    padding: 0.1rem 0.4rem;
    border-radius: 4px;
    background: var(--htu-bg-step-icon);
    border: 1px solid var(--htu-border-card);
    color: var(--htu-accent);
    font-weight: 600;
    font-family: monospace;
}


/* =============================================================
   7. PRO TIP BANNER
   ============================================================= */
.htu-tip {
    display: flex;
    align-items: flex-start;
    gap: 0.875rem;
    background: var(--htu-accent-tip-bg);
    border: 1px solid var(--htu-accent-tip-border);
    border-radius: var(--htu-radius-tip);
    padding: 1rem 1.25rem;
    margin-top: 0.5rem;
    transition: var(--htu-transition);
}

.htu-tip:hover {
    box-shadow: 0 4px 16px rgba(2, 132, 199, 0.1);
}

.htu-tip-icon {
    font-size: 1.25rem;
    color: var(--htu-accent-tip);
    flex-shrink: 0;
    margin-top: 0.1rem;
    transition: color 0.2s ease;
}

.htu-tip-body {
    font-size: 0.9rem;
    color: var(--htu-text-tip);
    line-height: 1.65;
    margin: 0;
    transition: color 0.2s ease;
}

.htu-tip-body strong {
    font-weight: 700;
    color: var(--htu-accent-tip);
}

.htu-tip-body a {
    color: var(--htu-accent-tip);
    font-weight: 600;
    text-decoration: underline;
    text-underline-offset: 2px;
    transition: opacity 0.2s ease;
}

.htu-tip-body a:hover {
    opacity: 0.8;
}


/* =============================================================
   8. KEYBOARD SHORTCUTS STRIP (optional inline row)
   ============================================================= */
.htu-shortcuts {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    justify-content: center;
    gap: 0.5rem 1.25rem;
    margin-top: 1.5rem;
    padding-top: 1.5rem;
    border-top: 1px solid var(--htu-border-card);
}

.htu-shortcuts-label {
    font-size: 0.8125rem;
    font-weight: 600;
    color: var(--htu-text-body);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    width: 100%;
    text-align: center;
    margin-bottom: 0.25rem;
}

.htu-shortcut-item {
    display: inline-flex;
    align-items: center;
    gap: 0.35rem;
    font-size: 0.8125rem;
    color: var(--htu-text-body);
}

.htu-shortcut-item kbd {
    font-size: 0.7rem;
    padding: 0.15rem 0.45rem;
    border-radius: 5px;
    background: var(--htu-bg-step-icon);
    border: 1px solid var(--htu-border-card);
    color: var(--htu-accent);
    font-weight: 700;
    font-family: monospace;
    box-shadow: 0 1px 2px rgba(0,0,0,0.08);
}


/* =============================================================
   9. RESPONSIVE
   ============================================================= */

/* Tablet — 2 columns */
@media (max-width: 991px) {
    .htu-steps {
        grid-template-columns: repeat(2, 1fr);
    }

    /* Hide connector on 2-col layout */
    .htu-steps::before {
        display: none;
    }

    .how-to-use-section {
        padding: 2.5rem 1.75rem;
    }
}

/* Mobile — 1 column */
@media (max-width: 575px) {
    .htu-steps {
        grid-template-columns: 1fr;
    }

    .htu-step {
        flex-direction: row;
        text-align: left;
        gap: 1rem;
        padding: 1rem 1.125rem;
    }

    .htu-step-number {
        margin-bottom: 0;
        flex-shrink: 0;
    }

    .htu-step-icon {
        display: none;          /* hide icon on mobile — number badge is enough */
    }

    .htu-step-content {
        flex: 1;
    }

    .htu-header h2 {
        font-size: 1.4rem;
    }

    .how-to-use-section {
        padding: 1.75rem 1.25rem;
        border-radius: 14px;
    }

    .htu-tip {
        flex-direction: column;
        gap: 0.5rem;
    }

    .htu-shortcuts {
        gap: 0.4rem 0.875rem;
    }
}