/* ==========================================================================
   Variables & Reset
   ========================================================================== */
:root {
    /* Color Palette */
    --color-bg-primary: #ffffff;
    --color-bg-secondary: #f8f9fa;
    --color-text-main: #212529;
    --color-text-muted: #6c757d;
    --color-accent: #3b82f6;      /* Modern Blue */
    --color-accent-hover: #2563eb;
    --color-border: #e9ecef;
    --color-card-bg: #ffffff;
    
    /* Typography */
    --font-primary: 'Noto Sans JP', 'Montserrat', sans-serif;
    
    /* Layout */
    --container-max-width: 1000px;
    --transition-speed: 0.3s;
}

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

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: var(--font-primary);
    background-color: var(--color-bg-primary);
    color: var(--color-text-main);
    line-height: 1.7;
    -webkit-font-smoothing: antialiased;
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

a {
    color: inherit;
    text-decoration: none;
    transition: color var(--transition-speed) ease;
}

ul {
    list-style: none;
}

/* ==========================================================================
   Reusable Components
   ========================================================================== */
.container {
    width: 100%;
    max-width: var(--container-max-width);
    margin: 0 auto;
    padding: 0 1.5rem;
}

.section {
    padding: 6rem 0;
}

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

.section-title {
    font-size: 2rem;
    font-weight: 700;
    letter-spacing: 0.05em;
    margin-bottom: 3rem;
    position: relative;
    display: inline-block;
}

.section-title::after {
    content: '';
    position: absolute;
    left: 0;
    bottom: -8px;
    width: 40px;
    height: 3px;
    background-color: var(--color-accent);
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 0.8rem 1.8rem;
    font-size: 0.95rem;
    font-weight: 500;
    border-radius: 6px;
    transition: all var(--transition-speed) ease;
    cursor: pointer;
}

.btn-primary {
    background-color: var(--color-accent);
    color: #ffffff;
    border: 1px solid var(--color-accent);
}

.btn-primary:hover {
    background-color: var(--color-accent-hover);
    border-color: var(--color-accent-hover);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(59, 130, 246, 0.2);
}

.btn-secondary {
    background-color: transparent;
    color: var(--color-text-main);
    border: 1px solid var(--color-border);
    margin-left: 1rem;
}

.btn-secondary:hover {
    background-color: var(--color-bg-secondary);
    border-color: var(--color-text-muted);
    transform: translateY(-2px);
}

/* ==========================================================================
   Header
   ========================================================================== */
.header {
    position: sticky;
    top: 0;
    background-color: rgba(255, 255, 255, 0.9);
    backdrop-filter: blur(8px);
    border-bottom: 1px solid var(--color-border);
    z-index: 100;
}

.header-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 70px;
}

.logo {
    font-family: 'Montserrat', sans-serif;
    font-size: 1.25rem;
    font-weight: 600;
    letter-spacing: 0.05em;
}

.nav ul {
    display: flex;
    gap: 2rem;
}

.nav a {
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--color-text-muted);
}

.nav a:hover {
    color: var(--color-accent);
}

/* ==========================================================================
   Hero Section
   ========================================================================== */
.hero {
    padding: 8rem 0;
    display: flex;
    align-items: center;
    background: radial-gradient(circle at top right, rgba(59, 130, 246, 0.05), transparent 40%);
}

.hero-container {
    display: grid;
    grid-template-columns: 1.2fr 0.8fr;
    gap: 4rem;
    align-items: center;
}

.hero-sub {
    font-family: 'Montserrat', sans-serif;
    font-size: 0.95rem;
    color: var(--color-accent);
    font-weight: 600;
    letter-spacing: 0.1em;
    margin-bottom: 1rem;
    text-transform: uppercase;
}

.hero-title {
    font-size: 2.5rem;
    font-weight: 700;
    line-height: 1.4;
    margin-bottom: 1.5rem;
    color: var(--color-text-main);
}

.hero-desc {
    color: var(--color-text-muted);
    font-size: 1.05rem;
    margin-bottom: 2.5rem;
    max-width: 540px;
}

.hero-cta {
    display: flex;
    align-items: center;
}

.avatar-placeholder {
    width: 280px;
    height: 280px;
    border-radius: 50%;
    background: linear-gradient(135deg, #e0f2fe 0%, #3b82f6 100%);
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto;
    box-shadow: 0 10px 30px rgba(59, 130, 246, 0.15);
}

.avatar-placeholder span {
    font-family: 'Montserrat', sans-serif;
    font-size: 4rem;
    font-weight: 600;
    color: #ffffff;
    letter-spacing: 0.05em;
}

/* ==========================================================================
   About Section
   ========================================================================== */
.about-grid {
    display: grid;
    grid-template-columns: 1.1fr 0.9fr;
    gap: 4rem;
}

.about-text h4 {
    font-size: 1.4rem;
    font-weight: 600;
    margin-bottom: 1.5rem;
}

.about-text p {
    color: var(--color-text-muted);
    margin-bottom: 1.2rem;
}

.about-details {
    background-color: var(--color-bg-secondary);
    padding: 2.5rem;
    border-radius: 12px;
    border: 1px solid var(--color-border);
    display: flex;
    flex-direction: column;
    justify-content: center;
    gap: 1.5rem;
}

.detail-item {
    display: flex;
    flex-direction: column;
    gap: 0.25rem;
}

.detail-label {
    font-size: 0.8rem;
    color: var(--color-text-muted);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.detail-value {
    font-size: 0.95rem;
    font-weight: 500;
}

/* ==========================================================================
   Skills Section
   ========================================================================== */
.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
}

.skill-card {
    background-color: var(--color-card-bg);
    padding: 2.5rem;
    border-radius: 12px;
    border: 1px solid var(--color-border);
    transition: all var(--transition-speed) ease;
}

.skill-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 20px rgba(0, 0, 0, 0.03);
    border-color: rgba(59, 130, 246, 0.3);
}

.skill-icon {
    font-size: 2rem;
    margin-bottom: 1.5rem;
}

.skill-name {
    font-size: 1.2rem;
    font-weight: 600;
    margin-bottom: 1rem;
}

.skill-desc {
    font-size: 0.9rem;
    color: var(--color-text-muted);
}

/* ==========================================================================
   Projects Section
   ========================================================================== */
.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2.5rem;
}

.project-card {
    background-color: var(--color-card-bg);
    border-radius: 12px;
    border: 1px solid var(--color-border);
    overflow: hidden;
    transition: all var(--transition-speed) ease;
    display: flex;
    flex-direction: column;
}

.project-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 15px 30px rgba(0, 0, 0, 0.05);
    border-color: rgba(59, 130, 246, 0.2);
}

.project-img-placeholder {
    height: 180px;
    background: linear-gradient(135deg, #f1f5f9 0%, #e2e8f0 100%);
    color: #94a3b8;
    display: flex;
    align-items: center;
    justify-content: center;
    font-family: 'Montserrat', sans-serif;
    font-size: 1.1rem;
    font-weight: 600;
    letter-spacing: 0.05em;
    border-bottom: 1px solid var(--color-border);
}

.project-content {
    padding: 2rem;
    display: flex;
    flex-direction: column;
    flex-grow: 1;
}

.project-name {
    font-size: 1.15rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
}

.project-desc {
    font-size: 0.9rem;
    color: var(--color-text-muted);
    margin-bottom: 1.5rem;
    flex-grow: 1;
}

.project-tech {
    font-family: 'Montserrat', sans-serif;
    font-size: 0.75rem;
    font-weight: 500;
    color: var(--color-accent);
    background-color: rgba(59, 130, 246, 0.08);
    padding: 0.25rem 0.75rem;
    border-radius: 20px;
    align-self: flex-start;
}

/* ==========================================================================
   Contact Section
   ========================================================================== */
.contact-container {
    text-align: center;
    max-width: 600px;
}

.contact-lead {
    font-size: 1.05rem;
    color: var(--color-text-muted);
    margin-bottom: 2.5rem;
}

.contact-methods {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 1.5rem;
}

.contact-link {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--color-text-main);
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    border-bottom: 2px solid transparent;
    padding-bottom: 0.2rem;
}

.contact-link:hover {
    color: var(--color-accent);
    border-color: var(--color-accent);
}

.social-links {
    display: flex;
    gap: 1.5rem;
    margin-top: 1rem;
}

.social-link {
    font-size: 0.9rem;
    color: var(--color-text-muted);
    border-bottom: 1px solid transparent;
}

.social-link:hover {
    color: var(--color-accent);
    border-color: var(--color-accent);
}

/* ==========================================================================
   Footer
   ========================================================================== */
.footer {
    padding: 2.5rem 0;
    text-align: center;
    font-size: 0.85rem;
    color: var(--color-text-muted);
    border-top: 1px solid var(--color-border);
}

/* ==========================================================================
   Responsive Design
   ========================================================================== */
@media (max-width: 900px) {
    .hero-container {
        grid-template-columns: 1fr;
        gap: 3rem;
        text-align: center;
    }

    .hero-content {
        order: 1;
    }

    .hero-image {
        order: 0;
    }

    .hero-desc {
        margin-left: auto;
        margin-right: auto;
    }

    .hero-cta {
        justify-content: center;
    }

    .avatar-placeholder {
        width: 220px;
        height: 220px;
    }

    .avatar-placeholder span {
        font-size: 3rem;
    }

    .about-grid {
        grid-template-columns: 1fr;
        gap: 3rem;
    }
}

@media (max-width: 600px) {
    html {
        font-size: 15px;
    }

    .section {
        padding: 4.5rem 0;
    }

    .header-container {
        flex-direction: column;
        justify-content: center;
        gap: 0.5rem;
        height: auto;
        padding: 1rem;
    }

    .nav ul {
        gap: 1.2rem;
    }

    .hero {
        padding: 4rem 0;
    }

    .hero-title {
        font-size: 2rem;
    }

    .btn {
        width: 100%;
        text-align: center;
    }

    .btn-secondary {
        margin-left: 0;
        margin-top: 0.75rem;
    }

    .hero-cta {
        flex-direction: column;
    }
}