/* ========================================
   CSS Custom Properties & Root Variables
   ======================================== */

:root {
    --columns: 12;
    --gutter: 1.5rem;
    --column-width: calc((100% - (var(--columns) - 1) * var(--gutter)) / var(--columns));
    --base-unit: 4rem;
    --baseline: 1rem;

    /* Colors */
    --color-bg: #F8F8F8;
    --color-text-primary: #2C2C2C;
    --color-text-secondary: #4A4A4A;
    --color-grid: #D8D8D8;
    --color-grid-emphasis: #3C3C3C;
    --color-accent-1: #4A90E2;
    --color-accent-2: #E68A4A;
    --color-accent-3: #4AE68A;
    --color-accent-4: #8A4AE6;

    /* Typography */
    --font-display: 'Courier Prime', monospace;
    --font-body: 'IBM Plex Sans', sans-serif;
    --font-mono: 'JetBrains Mono', monospace;

    --font-size-h1: clamp(2.4rem, 6vw, 4.8rem);
    --font-size-h2: clamp(1.6rem, 4vw, 3.2rem);
    --font-size-h3: clamp(1.2rem, 2.5vw, 2rem);
    --font-size-body: clamp(1rem, 1.1vw, 1.15rem);
    --font-size-sm: 0.875rem;
    --font-size-xs: 0.75rem;

    --line-height-tight: 1.1;
    --line-height-normal: 1.6;
    --line-height-loose: 1.9;
}

/* ========================================
   Reset & Global Styles
   ======================================== */

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    background-color: var(--color-bg);
    color: var(--color-text-primary);
    font-family: var(--font-body);
    font-size: var(--font-size-body);
    line-height: var(--line-height-normal);
    position: relative;
    overflow-x: hidden;
}

/* Grid Overlay */
body::before {
    content: '';
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-image: repeating-linear-gradient(
        90deg,
        var(--color-grid) 0px,
        var(--color-grid) 1px,
        transparent 1px,
        transparent calc(100% / 12 + var(--gutter))
    );
    background-size: 100% 100%;
    pointer-events: none;
    z-index: 1;
    opacity: 0.12;
}

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

h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-display);
    font-weight: 400;
    line-height: var(--line-height-tight);
    letter-spacing: 0.08em;
}

h1 {
    font-size: var(--font-size-h1);
}

h2 {
    font-size: var(--font-size-h2);
}

h3 {
    font-size: var(--font-size-h3);
}

p {
    margin-bottom: 1.5rem;
}

a {
    color: var(--color-accent-1);
    text-decoration: none;
    border-bottom: 1px solid var(--color-accent-1);
    transition: color 0.3s, border-color 0.3s;
}

a:hover {
    color: var(--color-accent-2);
    border-color: var(--color-accent-2);
}

/* ========================================
   Layout & Structure
   ======================================== */

section {
    min-height: 100vh;
    padding: 4rem var(--gutter);
    display: flex;
    align-items: center;
    justify-content: space-between;
    position: relative;
    z-index: 2;
    gap: 2rem;
}

section.header-anchor {
    flex-direction: column;
    justify-content: center;
    align-items: center;
    text-align: center;
}

section.principle {
    flex-direction: row;
}

section.system-exhibition {
    flex-direction: column;
    align-items: flex-start;
    justify-content: flex-start;
}

/* ========================================
   Header Anchor
   ======================================== */

.header-anchor {
    background: linear-gradient(180deg, var(--color-bg) 0%, #F5F5F5 100%);
}

.center-box {
    width: 100vmin;
    height: 100vmin;
    max-width: 60vw;
    max-height: 60vw;
    border: 2px solid var(--color-grid-emphasis);
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
}

.center-box::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    border: 1px solid var(--color-grid);
    opacity: 0.5;
}

.main-title {
    font-size: var(--font-size-h1);
    letter-spacing: 0.12em;
    animation: title-fade-in 2s ease-out 0.3s both;
}

.tagline {
    margin-top: 3rem;
    font-family: var(--font-body);
    font-size: var(--font-size-sm);
    letter-spacing: 0.1em;
    text-transform: uppercase;
    color: var(--color-text-secondary);
    animation: tagline-fade-in 2s ease-out 1s both;
}

@keyframes title-fade-in {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes tagline-fade-in {
    from {
        opacity: 0;
        transform: translateX(-20px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

/* ========================================
   Principle Sections
   ======================================== */

.principle-card {
    flex: 0 0 35%;
    padding: 2rem;
    background: rgba(248, 248, 248, 0.9);
    backdrop-filter: blur(8px);
    border: 2px solid var(--color-grid);
    border-left: 3px solid;
    position: relative;
}

.principle[data-principle="grid"] .principle-card {
    border-left-color: var(--color-accent-1);
}

.principle[data-principle="hierarchy"] .principle-card {
    border-left-color: var(--color-accent-2);
}

.principle[data-principle="contrast"] .principle-card {
    border-left-color: var(--color-accent-3);
}

.principle[data-principle="rhythm"] .principle-card {
    border-left-color: var(--color-accent-4);
}

.principle[data-principle="balance"] .principle-card {
    border-left-color: var(--color-accent-1);
}

.principle-card h2 {
    font-size: var(--font-size-xs);
    letter-spacing: 0.15em;
    text-transform: uppercase;
    color: var(--color-text-secondary);
    margin-bottom: 0.5rem;
    font-weight: 400;
}

.principle-title {
    font-size: var(--font-size-h3);
    margin-bottom: 1rem;
    font-family: var(--font-display);
    letter-spacing: 0.1em;
}

.principle-text {
    font-size: var(--font-size-body);
    line-height: var(--line-height-loose);
    color: var(--color-text-secondary);
    margin-bottom: 2rem;
}

.metric {
    display: flex;
    justify-content: space-between;
    align-items: baseline;
    padding: 0.75rem 0;
    border-bottom: 1px solid var(--color-grid);
    font-family: var(--font-mono);
    font-size: var(--font-size-xs);
}

.metric:last-of-type {
    border-bottom: none;
}

.metric-label {
    color: var(--color-text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.08em;
}

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

.demo-area {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 2rem;
    background: rgba(255, 255, 255, 0.5);
    border: 1px solid var(--color-grid);
}

/* Demo Styles */

.grid-demo {
    width: 100%;
    height: auto;
    max-width: 400px;
}

.hierarchy-demo {
    width: 100%;
}

.ruler {
    width: 100%;
    height: 1px;
    background: repeating-linear-gradient(
        90deg,
        var(--color-grid) 0px,
        var(--color-grid) 6px,
        transparent 6px,
        transparent 12px
    );
    margin: 0.5rem 0;
}

.contrast-pairs {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 1rem;
    width: 100%;
}

.contrast-pair {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.5rem;
}

.color-box {
    width: 100%;
    aspect-ratio: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    border: 1px solid var(--color-grid);
    font-weight: 600;
    font-size: var(--font-size-xs);
    font-family: var(--font-mono);
    transition: transform 0.3s;
}

.color-box:hover {
    transform: scale(1.02);
}

.color-box.good {
    border-color: var(--color-accent-3);
}

.color-box.warning {
    border-color: var(--color-accent-2);
}

.color-box.poor {
    border-color: #999;
    opacity: 0.6;
}

.contrast-label {
    font-family: var(--font-mono);
    font-size: var(--font-size-xs);
    color: var(--color-text-secondary);
}

.rhythm-demo {
    display: flex;
    align-items: flex-end;
    justify-content: space-around;
    width: 100%;
    height: 200px;
    gap: 0.5rem;
}

.rhythm-item {
    flex: 1;
    height: 100%;
    border: 2px solid var(--color-grid);
    transition: transform 0.3s, opacity 0.3s;
}

.rhythm-item:hover {
    transform: scaleY(1.1);
    opacity: 0.8;
}

.rhythm-spacer {
    width: 40%;
    border-bottom: 2px dashed var(--color-grid);
}

.balance-demo {
    width: 100%;
    max-width: 400px;
    height: auto;
}

/* ========================================
   System Exhibition
   ======================================== */

.system-exhibition {
    background: linear-gradient(180deg, #F5F5F5 0%, var(--color-bg) 100%);
}

.exhibition-header {
    width: 100%;
    text-align: center;
    margin-bottom: 4rem;
}

.exhibition-header h2 {
    margin-bottom: 1rem;
}

.exhibition-header p {
    color: var(--color-text-secondary);
    font-size: var(--font-size-body);
}

.component-grid {
    width: 100%;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.component-section {
    padding: 2rem;
    border: 1px solid var(--color-grid);
    background: rgba(255, 255, 255, 0.6);
}

.component-section h3 {
    font-size: var(--font-size-h3);
    margin-bottom: 1.5rem;
    font-family: var(--font-display);
}

/* Button Showcase */

.button-showcase {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.btn {
    padding: 0.75rem 1.5rem;
    border: 2px solid var(--color-accent-1);
    background: transparent;
    color: var(--color-accent-1);
    font-family: var(--font-body);
    font-size: var(--font-size-sm);
    cursor: pointer;
    transition: all 0.3s;
    text-transform: uppercase;
    letter-spacing: 0.08em;
}

.btn:not(:disabled):hover {
    background: var(--color-accent-1);
    color: var(--color-bg);
    transform: scale(1.02);
}

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.btn-secondary {
    border-color: var(--color-accent-2);
    color: var(--color-accent-2);
}

.btn-secondary:not(:disabled):hover {
    background: var(--color-accent-2);
    color: var(--color-bg);
}

/* Card Showcase */

.card-showcase {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.card-minimal,
.card-emphasis {
    padding: 1.5rem;
    border: 1px solid var(--color-grid);
    background: white;
    transition: all 0.3s;
}

.card-minimal:hover,
.card-emphasis:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
}

.card-emphasis {
    border-left: 3px solid var(--color-accent-1);
    background: rgba(74, 144, 226, 0.02);
}

.card-minimal h4,
.card-emphasis h4 {
    font-size: var(--font-size-h3);
    margin-bottom: 0.5rem;
}

.card-minimal p,
.card-emphasis p {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
    margin-bottom: 0;
}

/* Color Application */

.color-application {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 1rem;
}

.color-sample {
    aspect-ratio: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--accent);
    color: white;
    font-weight: 600;
    font-size: var(--font-size-sm);
    border: 2px solid var(--accent);
    transition: transform 0.3s;
}

.color-sample:hover {
    transform: scale(1.05);
}

/* Spacing Scale */

.spacing-scale {
    display: flex;
    flex-direction: column;
    gap: 1rem;
    width: 100%;
}

.space-item {
    display: flex;
    align-items: center;
    gap: 1rem;
    background: var(--color-accent-1);
    height: 2rem;
    opacity: 0.3;
    transition: opacity 0.3s;
}

.space-item:hover {
    opacity: 0.6;
}

.space-item span {
    margin-left: 0.5rem;
    font-family: var(--font-mono);
    font-size: var(--font-size-xs);
    color: var(--color-text-primary);
    white-space: nowrap;
}

/* ========================================
   Scroll Indicator
   ======================================== */

.scroll-indicator {
    position: fixed;
    top: 2rem;
    left: 2rem;
    z-index: 10;
    font-family: var(--font-mono);
    font-size: var(--font-size-xs);
    color: var(--color-text-secondary);
    letter-spacing: 0.1em;
}

.percentage {
    display: inline-block;
    width: 3em;
    text-align: right;
}

/* ========================================
   Footer
   ======================================== */

.site-footer {
    min-height: auto;
    padding: 4rem var(--gutter);
    text-align: center;
    background: #F5F5F5;
    flex-direction: column;
    justify-content: center;
}

.site-footer p {
    color: var(--color-text-secondary);
    margin-bottom: 2rem;
}

.grid-indicators {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 2rem;
    font-family: var(--font-mono);
    font-size: var(--font-size-xs);
    letter-spacing: 0.08em;
}

.grid-stat {
    color: var(--color-text-secondary);
}

/* ========================================
   Accessibility
   ======================================== */

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

    html {
        scroll-behavior: auto;
    }
}

/* ========================================
   Responsive Design
   ======================================== */

@media (max-width: 1024px) {
    :root {
        --gutter: 1rem;
        --font-size-h1: clamp(2rem, 5vw, 3.5rem);
        --font-size-h2: clamp(1.4rem, 3.5vw, 2.5rem);
        --font-size-h3: clamp(1rem, 2vw, 1.5rem);
    }

    section {
        flex-direction: column;
    }

    .principle-card {
        flex: 0 0 100%;
    }

    .demo-area {
        flex: 1 0 auto;
        width: 100%;
        min-height: 300px;
    }

    .center-box {
        max-width: 80vw;
        max-height: 80vw;
    }

    .component-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 768px) {
    :root {
        --gutter: 0.75rem;
        --font-size-body: clamp(0.95rem, 1vw, 1rem);
        --font-size-h3: clamp(0.9rem, 1.8vw, 1.3rem);
    }

    body::before {
        opacity: 0.08;
    }

    section {
        padding: 2rem var(--gutter);
        min-height: auto;
    }

    .header-anchor {
        min-height: 80vh;
    }

    .center-box {
        max-width: 70vw;
        max-height: 70vw;
    }

    .main-title {
        font-size: clamp(1.5rem, 8vw, 2.5rem);
    }

    .principle-card {
        padding: 1.5rem;
    }

    .metric {
        font-size: var(--font-size-xs);
        padding: 0.5rem 0;
    }

    .contrast-pairs {
        grid-template-columns: 1fr;
    }

    .rhythm-demo {
        height: 150px;
    }

    .scroll-indicator {
        top: 1rem;
        left: 1rem;
        font-size: 0.65rem;
    }

    .site-footer {
        padding: 2rem var(--gutter);
    }

    .grid-indicators {
        gap: 1rem;
        flex-direction: column;
    }
}

@media (max-width: 480px) {
    :root {
        --gutter: 0.5rem;
    }

    section {
        padding: 1.5rem var(--gutter);
    }

    .header-anchor {
        min-height: 70vh;
    }

    .center-box {
        max-width: 90vw;
        max-height: 90vw;
    }

    .main-title {
        font-size: clamp(1.2rem, 7vw, 2rem);
    }

    .tagline {
        font-size: 0.7rem;
    }

    .principle-card {
        padding: 1rem;
    }

    .metric {
        font-size: 0.65rem;
    }

    .scroll-indicator {
        top: 0.75rem;
        left: 0.75rem;
        font-size: 0.6rem;
    }
}

/* ========================================
   Print Styles
   ======================================== */

@media print {
    body::before {
        display: none;
    }

    section {
        page-break-inside: avoid;
        min-height: auto;
    }

    .scroll-indicator {
        display: none;
    }

    a {
        border-bottom: none;
    }
}