/*--------------------------------------------------------------------------------------
                                        ROOT / BASE
--------------------------------------------------------------------------------------*/
:root {
    --primary-blue: #0052cc;
    --primary-blue-dark: #003d99;
    --hero-gradient: linear-gradient(135deg, #0061ff 0%, #0033aa 100%);
    --bg-light: #f8fafc;
    --white: #ffffff;
    --text-main: #1e293b;
    --text-muted: #64748b;
    --border-color: #e2e8f0;
    --border-soft: rgba(255, 255, 255, 0.18);
    --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 10px 15px -3px rgba(0, 0, 0, 0.10);
    --shadow-lg: 0 20px 25px -5px rgba(0, 0, 0, 0.12);
    --radius: 12px;
    --radius-lg: 18px;
    --transition: all 0.3s ease;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', sans-serif;
    color: var(--text-main);
    background: var(--white);
    line-height: 1.7;
}

.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 16px;
}

.section-padding {
    padding: 80px 0;
}

.bg-light {
    background: var(--bg-light);
}

.bg-white {
    background: var(--white);
}

a {
    color: var(--primary-blue);
    text-decoration: none;
    transition: var(--transition);
}

a:hover {
    color: var(--primary-blue-dark);
}

p {
    margin: 0 0 16px;
    color: var(--text-muted);
}

h1, h2, h3 {
    color: var(--text-main);
    line-height: 1.2;
    margin: 0 0 16px;
}

.section-header {
    margin-bottom: 32px;
}

.section-header.text-left {
    text-align: left;
}

.section-label {
    display: inline-block;
    margin-bottom: 10px;
    font-size: 0.78rem;
    font-weight: 700;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    color: var(--primary-blue);
}

.content-flow p:last-child {
    margin-bottom: 0;
}

/*--------------------------------------------------------------------------------------
                                           HERO
--------------------------------------------------------------------------------------*/
.advanced-hero {
    background: var(--hero-gradient);
    color: var(--white);
    padding: 56px 0 72px;
}

.hero-container {
    display: flex;
    flex-direction: column;
    gap: 28px;
}

.breadcrumb {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    font-size: 0.92rem;
    color: rgba(255, 255, 255, 0.82);
}

.breadcrumb a,
.breadcrumb span {
    color: rgba(255, 255, 255, 0.88);
}

.hero-content {
    display: grid;
    gap: 28px;
    align-items: start;
}

.hero-text h1 {
    font-size: clamp(2rem, 4vw, 3.3rem);
    font-weight: 800;
    color: var(--white);
    margin-bottom: 18px;
}

.hero-intro,
.hero-support {
    color: rgba(255, 255, 255, 0.94);
    font-size: 1.03rem;
    max-width: 760px;
}

.hero-actions {
    display: flex;
    flex-wrap: wrap;
    gap: 14px;
    margin-top: 26px;
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-height: 48px;
    padding: 0 20px;
    border-radius: 10px;
    font-weight: 700;
    text-align: center;
    transition: var(--transition);
    border: 1px solid transparent;
}

.btn-primary,
.btn-solid {
    background: var(--white);
    color: var(--primary-blue);
    box-shadow: var(--shadow-sm);
}

.btn-primary:hover,
.btn-solid:hover {
    transform: translateY(-2px);
    color: var(--primary-blue-dark);
}

.btn-secondary,
.btn-outline {
    background: transparent;
    color: var(--white);
    border-color: rgba(255, 255, 255, 0.4);
}

.btn-secondary:hover,
.btn-outline:hover {
    background: rgba(255, 255, 255, 0.1);
    color: var(--white);
}

/*--------------------------------------------------------------------------------------
                                      PAGE SHELL / LAYOUT
--------------------------------------------------------------------------------------*/
.page-shell {
    display: grid;
    grid-template-columns: minmax(0, 1.7fr) 320px;
    gap: 28px;
    align-items: start;
}

.main-content,
.side-panel {
    min-width: 0;
}

/*--------------------------------------------------------------------------------------
                                     CALCULATOR GRID / CARDS
--------------------------------------------------------------------------------------*/
.calculator-grid {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 18px;
}

.tool-card {
    background: var(--white);
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    padding: 22px;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
}

.tool-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-md);
    border-color: rgba(0, 82, 204, 0.22);
}

.tool-icon {
    width: 42px;
    height: 42px;
    border-radius: 10px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 16px;
    background: rgba(0, 82, 204, 0.08);
    color: var(--primary-blue);
    font-size: 1rem;
}

.tool-card h3 {
    font-size: 1.08rem;
    margin-bottom: 10px;
}

.tool-card p {
    font-size: 0.95rem;
    margin-bottom: 16px;
}

.tool-link {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    font-weight: 700;
    font-size: 0.95rem;
}

/*--------------------------------------------------------------------------------------
                                          SIDE PANEL
--------------------------------------------------------------------------------------*/
.side-panel {
    display: flex;
    flex-direction: column;
    gap: 18px;
    position: sticky;
    top: 100px;
}

.side-card {
    background: var(--white);
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    padding: 22px;
    box-shadow: var(--shadow-sm);
}

.side-card-icon {
    width: 38px;
    height: 38px;
    border-radius: 10px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    background: rgba(0, 82, 204, 0.08);
    color: var(--primary-blue);
    margin-bottom: 14px;
}

.side-card h3 {
    font-size: 1.08rem;
    margin-bottom: 12px;
}

.side-links {
    list-style: none;
    padding: 0;
    margin: 16px 0 0;
}

.side-links li {
    margin-bottom: 12px;
}

.side-links a {
    color: var(--primary-blue);
    font-weight: 600;
}

.tip-list {
    margin-top: 14px;
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.tip-row {
    display: flex;
    justify-content: space-between;
    gap: 12px;
    padding: 10px 0;
    border-bottom: 1px solid var(--border-color);
}

.tip-row:last-child {
    border-bottom: 0;
    padding-bottom: 0;
}

.tip-row span {
    color: var(--text-muted);
    font-size: 0.93rem;
}

.tip-row strong {
    color: var(--text-main);
    font-size: 0.93rem;
}

/*--------------------------------------------------------------------------------------
                                      FEATURE PANEL / CONTENT
--------------------------------------------------------------------------------------*/
.feature-panel {
    background: var(--white);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 28px;
    box-shadow: var(--shadow-sm);
}

/*--------------------------------------------------------------------------------------
                                          FORMULA CARDS
--------------------------------------------------------------------------------------*/
.formula-grid {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 18px;
    margin-top: 30px;
}

.formula-card {
    background: var(--white);
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    padding: 22px;
    box-shadow: var(--shadow-sm);
}

.formula-card h3 {
    font-size: 1rem;
    margin-bottom: 14px;
}

.formula-box {
    margin-bottom: 14px;
    padding: 16px;
    border-radius: 12px;
    background: rgba(0, 82, 204, 0.06);
    color: var(--primary-blue);
    font-weight: 800;
    text-align: center;
    overflow-wrap: anywhere;
}

/*--------------------------------------------------------------------------------------
                                         INFO / METHOD GRID
--------------------------------------------------------------------------------------*/
.method-grid {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 18px;
}

.info-card {
    background: var(--white);
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    padding: 22px;
    box-shadow: var(--shadow-sm);
}

.info-card h3 {
    font-size: 1.05rem;
    margin-bottom: 12px;
}

.info-card p:last-child {
    margin-bottom: 0;
}

/*--------------------------------------------------------------------------------------
                                            STEPS GRID
--------------------------------------------------------------------------------------*/
.steps-grid {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 18px;
}

.step-card {
    background: var(--white);
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    padding: 22px;
    box-shadow: var(--shadow-sm);
}

.step-number {
    width: 34px;
    height: 34px;
    border-radius: 50%;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 14px;
    background: rgba(0, 82, 204, 0.10);
    color: var(--primary-blue);
    font-weight: 800;
    font-size: 0.94rem;
}

.step-card h3 {
    font-size: 1rem;
    margin-bottom: 10px;
}

/*--------------------------------------------------------------------------------------
                                       BENEFITS / MISTAKES
--------------------------------------------------------------------------------------*/
.benefits-grid,
.mistakes-grid {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 18px;
}

.benefit-card,
.mistake-card {
    background: var(--white);
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    padding: 22px;
    box-shadow: var(--shadow-sm);
}

.benefit-card i {
    font-size: 1rem;
    color: var(--primary-blue);
    margin-bottom: 14px;
}

.benefit-card h3,
.mistake-card h3 {
    font-size: 1rem;
    margin-bottom: 10px;
}

/*--------------------------------------------------------------------------------------
                                        AUDIENCE SECTION
--------------------------------------------------------------------------------------*/
.audience-intro {
    margin-bottom: 22px;
}

.audience-grid {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 14px;
}

.audience-item {
    display: flex;
    align-items: center;
    gap: 12px;
    background: var(--white);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 16px 18px;
    box-shadow: var(--shadow-sm);
}

.audience-item i {
    color: var(--primary-blue);
    font-size: 1rem;
    flex-shrink: 0;
}

.audience-item span {
    color: var(--text-main);
    font-weight: 500;
    font-size: 0.95rem;
}

/*--------------------------------------------------------------------------------------
                                         RELATED TOOLS
--------------------------------------------------------------------------------------*/
.related-grid {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 18px;
}

.related-card {
    display: block;
    background: var(--white);
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    padding: 22px;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
}

.related-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-md);
    border-color: rgba(0, 82, 204, 0.22);
}

.related-card h3 {
    font-size: 1rem;
    margin-bottom: 10px;
}

.related-card p {
    font-size: 0.94rem;
    margin-bottom: 14px;
}

.related-card span {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    font-weight: 700;
    color: var(--primary-blue);
}

/*--------------------------------------------------------------------------------------
                                              FAQ
--------------------------------------------------------------------------------------*/

.faq-list {
    display: flex;
    flex-direction: column;
    gap: 14px;
}

.faq-item {
    background: var(--white);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    box-shadow: var(--shadow-sm);
    overflow: hidden;
}

.faq-item details {
    padding: 0;
}

.faq-item summary {
    list-style: none;
    cursor: pointer;
    padding: 18px 22px;
    font-weight: 700;
    color: var(--text-main);
    position: relative;
}

.faq-item summary::-webkit-details-marker {
    display: none;
}

.faq-item summary::after {
    content: "+";
    position: absolute;
    right: 22px;
    top: 50%;
    transform: translateY(-50%);
    color: var(--primary-blue);
    font-size: 1.1rem;
    font-weight: 800;
}

.faq-item details[open] summary::after {
    content: "−";
}

.faq-item details p {
    padding: 0 22px 20px;
    margin: 0;
}

/*--------------------------------------------------------------------------------------
                                        DISCLAIMER / CTA
--------------------------------------------------------------------------------------*/
.disclaimer-card,
.cta-card {
    background: var(--white);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 28px;
    box-shadow: var(--shadow-sm);
}

.disclaimer-card {
    display: flex;
    gap: 18px;
    align-items: flex-start;
}

.disclaimer-icon {
    width: 42px;
    height: 42px;
    border-radius: 12px;
    flex-shrink: 0;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    background: rgba(0, 82, 204, 0.10);
    color: var(--primary-blue);
}

.disclaimer-content h2,
.cta-card h2 {
    font-size: 1.5rem;
    margin-bottom: 12px;
}

.cta-card {
    text-align: center;
    background: linear-gradient(180deg, #ffffff 0%, #f8fbff 100%);
}

.cta-card p {
    max-width: 760px;
    margin: 0 auto 20px;
}

.cta-actions {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: 14px;
}

.cta-card .btn-solid {
    background: var(--primary-blue);
    color: var(--white);
}

.cta-card .btn-solid:hover {
    background: var(--primary-blue-dark);
    color: var(--white);
}

.cta-card .btn-outline {
    color: var(--primary-blue);
    border-color: rgba(0, 82, 204, 0.22);
    background: transparent;
}

.cta-card .btn-outline:hover {
    background: rgba(0, 82, 204, 0.06);
    color: var(--primary-blue-dark);
}

/*--------------------------------------------------------------------------------------
                                           RESPONSIVE
--------------------------------------------------------------------------------------*/
@media (max-width: 1100px) {
    .page-shell {
        grid-template-columns: 1fr;
    }

    .side-panel {
        position: static;
    }

    .hero-content {
        grid-template-columns: 1fr;
    }

    .formula-grid,
    .method-grid,
    .steps-grid,
    .benefits-grid,
    .mistakes-grid,
    .related-grid {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }
}

@media (max-width: 768px) {
    .section-padding {
        padding: 64px 0;
    }

    .advanced-hero {
        padding: 44px 0 60px;
    }

    .hero-text h1 {
        font-size: 2.2rem;
    }

    .calculator-grid,
    .formula-grid,
    .method-grid,
    .steps-grid,
    .benefits-grid,
    .mistakes-grid,
    .audience-grid,
    .related-grid {
        grid-template-columns: 1fr;
    }

    .feature-panel,
    .tool-card,
    .info-card,
    .step-card,
    .benefit-card,
    .mistake-card,
    .side-card,
    .related-card,
    .disclaimer-card,
    .cta-card,
    .formula-card {
        padding: 20px;
    }

    .disclaimer-card {
        flex-direction: column;
    }

    .hero-actions,
    .cta-actions {
        flex-direction: column;
        align-items: stretch;
    }

    .btn {
        width: 100%;
    }

    .breadcrumb {
        font-size: 0.85rem;
    }
}