/* Reset & Base */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    /* Professional Color Palette - Deep Ocean */
    --primary: #0066cc;
    --primary-dark: #0052a3;
    --primary-light: #3385d6;
    --secondary: #00b4d8;
    --accent: #06d6a0;

    /* Semantic Colors */
    --success: #06d6a0;
    --warning: #ffd166;
    --error: #ef476f;

    /* Typography */
    --text-primary: #0a1128;
    --text-secondary: #4a5568;
    --text-tertiary: #718096;

    /* Backgrounds */
    --bg-primary: #ffffff;
    --bg-secondary: #f7fafc;
    --bg-tertiary: #edf2f7;

    /* Borders & Dividers */
    --border: #e2e8f0;
    --border-light: #f1f5f9;

    /* Gradients */
    --gradient-primary: linear-gradient(135deg, #0066cc 0%, #00b4d8 100%);
    --gradient-accent: linear-gradient(135deg, #00b4d8 0%, #06d6a0 100%);

    /* Shadows - Professional depth */
    --shadow-xs: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-sm: 0 2px 4px 0 rgba(0, 0, 0, 0.06);
    --shadow-md: 0 4px 8px -2px rgba(0, 0, 0, 0.08);
    --shadow-lg: 0 12px 24px -4px rgba(0, 0, 0, 0.12);
    --shadow-xl: 0 20px 40px -8px rgba(0, 0, 0, 0.15);

    /* Spacing scale */
    --space-xs: 0.25rem;
    --space-sm: 0.5rem;
    --space-md: 1rem;
    --space-lg: 1.5rem;
    --space-xl: 2rem;
    --space-2xl: 3rem;

    /* Border radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;

    /* Transitions */
    --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-base: 250ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-slow: 350ms cubic-bezier(0.4, 0, 0.2, 1);
}

body {
    /* Professional font stack */
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Noto Sans KR', sans-serif;
    color: var(--text-primary);
    background: var(--bg-primary);
    line-height: 1.65;
    font-weight: 400;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* Skip Link for Accessibility */
.skip-link {
    position: absolute;
    top: -40px;
    left: 0;
    background: var(--primary);
    color: white;
    padding: 8px 16px;
    text-decoration: none;
    border-radius: 0 0 var(--radius-md) 0;
    font-weight: 600;
    z-index: 100;
    transition: top var(--transition-fast);
}

.skip-link:focus {
    top: 0;
}

/* Typography scale */
h1, h2, h3, h4, h5, h6 {
    font-weight: 800;
    line-height: 1.2;
    letter-spacing: -0.02em;
}

/* Accessibility improvements */
*:focus {
    outline: 2px solid var(--primary);
    outline-offset: 2px;
}

*:focus:not(:focus-visible) {
    outline: none;
}

*:focus-visible {
    outline: 2px solid var(--primary);
    outline-offset: 2px;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
}

/* Hero Section */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    background:
        radial-gradient(circle at 20% 30%, rgba(0, 180, 216, 0.08) 0%, transparent 50%),
        radial-gradient(circle at 80% 70%, rgba(6, 214, 160, 0.06) 0%, transparent 50%),
        linear-gradient(to bottom, #ffffff 0%, #f7fafc 100%);
    padding: 80px 0;
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: -50%;
    right: -10%;
    width: 600px;
    height: 600px;
    background: radial-gradient(circle, rgba(0, 102, 204, 0.1) 0%, transparent 70%);
    border-radius: 50%;
    animation: float 20s ease-in-out infinite;
}

.hero::after {
    content: '';
    position: absolute;
    bottom: -30%;
    left: -5%;
    width: 500px;
    height: 500px;
    background: radial-gradient(circle, rgba(0, 180, 216, 0.08) 0%, transparent 70%);
    border-radius: 50%;
    animation: float 25s ease-in-out infinite reverse;
}

.hero .container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 60px;
    align-items: center;
}

.hero-content {
    animation: fadeInUp 0.8s ease-out;
}

.hero-title {
    font-size: 3.5rem;
    font-weight: 800;
    line-height: 1.1;
    margin-bottom: 24px;
    color: var(--text-primary);
}

.gradient-text {
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    display: inline-block;
}

.hero-subtitle {
    font-size: 1.25rem;
    color: var(--text-secondary);
    margin-bottom: 40px;
    line-height: 1.8;
}

.hero-cta {
    display: flex;
    gap: 16px;
    margin-bottom: 60px;
}

.btn {
    padding: 16px 36px;
    border-radius: var(--radius-lg);
    font-size: 1.0625rem;
    font-weight: 600;
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    transition: all var(--transition-base);
    border: none;
    cursor: pointer;
    position: relative;
    overflow: hidden;
}

.btn::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 0;
    height: 0;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.2);
    transform: translate(-50%, -50%);
    transition: width var(--transition-slow), height var(--transition-slow);
}

.btn:hover::before {
    width: 300px;
    height: 300px;
}

.btn-primary {
    background: var(--gradient-primary);
    color: white;
    box-shadow: var(--shadow-md);
}

.btn-primary:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-xl);
}

.btn-primary:active {
    transform: translateY(-1px);
    box-shadow: var(--shadow-lg);
}

.btn-secondary {
    background: white;
    color: var(--primary);
    border: 2px solid var(--primary);
    box-shadow: var(--shadow-sm);
}

.btn-secondary:hover {
    background: var(--bg-secondary);
    border-color: var(--primary-dark);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.btn-secondary:active {
    transform: translateY(0);
}

/* Touch-friendly target sizes (minimum 44x44px for mobile) */
@media (hover: none) and (pointer: coarse) {
    .btn {
        min-height: 44px;
        padding: 12px 32px;
    }

    .hero-cta .btn {
        min-height: 48px;
    }

    a,
    button {
        min-height: 44px;
        display: inline-flex;
        align-items: center;
        justify-content: center;
    }
}

.hero-stats {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 32px;
}

.stat {
    text-align: center;
}

.stat-number {
    font-size: 2.5rem;
    font-weight: 800;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 8px;
    display: inline-block;
}

.stat-label {
    font-size: 0.875rem;
    color: var(--text-secondary);
}

/* Hero Visual */
.hero-visual {
    display: flex;
    align-items: center;
    gap: 20px;
    animation: fadeInRight 0.8s ease-out 0.2s both;
    position: relative;
    z-index: 1;
}

/* Glassmorphism Effect */
.visual-card {
    flex: 1;
    background: rgba(255, 255, 255, 0.7);
    backdrop-filter: blur(20px) saturate(180%);
    -webkit-backdrop-filter: blur(20px) saturate(180%);
    border-radius: var(--radius-xl);
    border: 1px solid rgba(255, 255, 255, 0.8);
    box-shadow:
        0 8px 32px 0 rgba(0, 102, 204, 0.12),
        inset 0 1px 0 0 rgba(255, 255, 255, 0.8);
    overflow: hidden;
    animation: float 6s ease-in-out infinite;
}

.visual-card:nth-child(3) {
    animation-delay: 1s;
}

.visual-card:hover {
    transform: translateY(-8px);
    box-shadow:
        0 12px 40px 0 rgba(0, 102, 204, 0.18),
        inset 0 1px 0 0 rgba(255, 255, 255, 0.9);
    border-color: rgba(0, 102, 204, 0.3);
}

.card-header {
    background: linear-gradient(135deg, rgba(0, 102, 204, 0.9) 0%, rgba(0, 180, 216, 0.9) 100%);
    backdrop-filter: blur(10px);
    color: white;
    padding: 14px 20px;
    font-weight: 600;
    font-size: 0.875rem;
    letter-spacing: 0.02em;
    box-shadow: 0 2px 8px rgba(0, 102, 204, 0.2);
}

.card-body {
    padding: 20px;
}

.todo-item {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 12px 0;
    border-bottom: 1px solid var(--border);
}

.todo-item:last-child {
    border-bottom: none;
}

.status {
    font-size: 1.2rem;
}

.task {
    font-size: 0.875rem;
    color: var(--text-secondary);
}

.visual-arrow {
    font-size: 2rem;
    color: var(--primary);
    font-weight: bold;
    background: rgba(255, 255, 255, 0.5);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    width: 60px;
    height: 60px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: var(--shadow-md);
    border: 1px solid rgba(255, 255, 255, 0.6);
    animation: float 8s ease-in-out infinite;
    animation-delay: 0.5s;
}

.pr-item {
    padding: 12px 0;
}

.pr-title {
    font-size: 0.875rem;
    font-weight: 600;
    margin-bottom: 8px;
    color: var(--text-primary);
}

.pr-meta {
    display: flex;
    gap: 12px;
    font-size: 0.75rem;
}

.pr-status {
    color: #10b981;
    font-weight: 600;
}

.pr-author {
    color: var(--text-secondary);
}

/* Features Section */
.features {
    padding: 100px 0;
    background: white;
}

.section-title {
    font-size: 2.5rem;
    font-weight: 800;
    text-align: center;
    margin-bottom: 16px;
    color: var(--text-primary);
}

.section-subtitle {
    text-align: center;
    color: var(--text-secondary);
    font-size: 1.125rem;
    margin-bottom: 64px;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 32px;
    max-width: 1000px;
    margin: 0 auto;
}

.feature-card {
    background: white;
    border-radius: var(--radius-xl);
    padding: var(--space-2xl);
    transition: all var(--transition-base);
    border: 2px solid var(--border-light);
    box-shadow: var(--shadow-sm);
    position: relative;
    overflow: hidden;
}

.feature-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: var(--gradient-accent);
    transform: scaleX(0);
    transform-origin: left;
    transition: transform var(--transition-slow);
}

.feature-card:hover::before {
    transform: scaleX(1);
}

.feature-card:hover {
    transform: translateY(-12px);
    box-shadow: var(--shadow-xl);
    border-color: var(--primary-light);
}

.feature-icon {
    font-size: 3rem;
    margin-bottom: var(--space-lg);
    display: inline-block;
    transition: transform var(--transition-base);
}

.feature-card:hover .feature-icon {
    transform: scale(1.1) rotate(5deg);
}

.feature-title {
    font-size: 1.5rem;
    font-weight: 800;
    margin-bottom: 16px;
    color: var(--text-primary);
}

.feature-description {
    color: var(--text-secondary);
    line-height: 1.7;
    margin-bottom: 24px;
}

.feature-list {
    list-style: none;
    padding: 0;
}

.feature-list li {
    padding: 8px 0;
    color: var(--text-secondary);
    font-size: 0.95rem;
}

.feature-list li::before {
    content: '';
    display: inline-block;
    width: 4px;
    height: 4px;
    background: var(--primary);
    border-radius: 50%;
    margin-right: 12px;
}

/* Demo Form Section */
.demo-form {
    padding: 80px 0;
    background: var(--bg-secondary);
}

.demo-form h2 {
    font-size: 2.5rem;
    font-weight: 800;
    text-align: center;
    margin-bottom: 16px;
}

.section-subtitle {
    text-align: center;
    color: var(--text-secondary);
    font-size: 1.125rem;
    margin-bottom: 48px;
}

.form {
    max-width: 600px;
    margin: 0 auto;
    background: white;
    padding: 48px;
    border-radius: 12px;
    box-shadow: var(--shadow-md);
}

.form-group {
    margin-bottom: 24px;
}

.form-group label {
    display: block;
    font-weight: 600;
    margin-bottom: 8px;
    color: var(--text-primary);
}

.required {
    color: var(--error);
    font-weight: 800;
    margin-left: 2px;
}

.form-group input,
.form-group textarea {
    width: 100%;
    padding: 12px 16px;
    border: 1px solid var(--border);
    border-radius: 8px;
    font-size: 1rem;
    transition: border-color 0.2s;
}

.form-group input:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--primary);
}

.btn-large {
    width: 100%;
    padding: 16px 32px;
    font-size: 1.125rem;
}

.form-notice {
    text-align: center;
    color: var(--text-secondary);
    font-size: 0.875rem;
    margin-top: 24px;
}

/* Animations */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes fadeInRight {
    from {
        opacity: 0;
        transform: translateX(30px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

@keyframes float {
    0%, 100% {
        transform: translateY(0);
    }
    50% {
        transform: translateY(-20px);
    }
}

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

/* Responsive Design - Mobile First Approach */

/* Tablet (768px - 968px) */
@media (max-width: 968px) {
    .container {
        padding: 0 20px;
    }

    .hero {
        padding: 60px 0;
    }

    .hero .container {
        grid-template-columns: 1fr;
        gap: 40px;
    }

    .hero-title {
        font-size: 2.5rem;
    }

    .hero-subtitle {
        font-size: 1.125rem;
    }

    .hero-visual {
        flex-direction: column;
        gap: 24px;
    }

    .visual-arrow {
        transform: rotate(90deg);
        width: 50px;
        height: 50px;
        font-size: 1.75rem;
    }

    .visual-card {
        width: 100%;
        max-width: 500px;
        margin: 0 auto;
    }

    .hero-stats {
        grid-template-columns: repeat(3, 1fr);
        gap: 20px;
    }

    .stat-number {
        font-size: 2rem;
    }

    .features {
        padding: 80px 0;
    }

    .features-grid {
        grid-template-columns: 1fr;
        gap: 24px;
    }

    .feature-card {
        padding: 32px;
    }

    .demo-form {
        padding: 60px 0;
    }

    .form {
        padding: 40px 32px;
    }
}

/* Mobile (320px - 640px) */
@media (max-width: 640px) {
    .container {
        padding: 0 16px;
    }

    .hero {
        min-height: auto;
        padding: 40px 0;
    }

    .hero-title {
        font-size: 1.875rem;
        line-height: 1.2;
        margin-bottom: 20px;
    }

    .hero-subtitle {
        font-size: 1rem;
        line-height: 1.6;
        margin-bottom: 32px;
    }

    .hero-cta {
        flex-direction: column;
        gap: 12px;
        margin-bottom: 48px;
    }

    .btn {
        width: 100%;
        text-align: center;
        padding: 14px 28px;
        font-size: 1rem;
    }

    .hero-stats {
        grid-template-columns: 1fr;
        gap: 24px;
    }

    .stat-number {
        font-size: 2.25rem;
    }

    .stat-label {
        font-size: 0.8125rem;
    }

    .visual-card {
        max-width: 100%;
    }

    .card-header {
        padding: 12px 16px;
        font-size: 0.8125rem;
    }

    .card-body {
        padding: 16px;
    }

    .todo-item,
    .pr-item {
        padding: 10px 0;
    }

    .task,
    .pr-title {
        font-size: 0.8125rem;
    }

    .visual-arrow {
        width: 40px;
        height: 40px;
        font-size: 1.5rem;
    }

    .features {
        padding: 60px 0;
    }

    .section-title {
        font-size: 2rem;
        margin-bottom: 12px;
    }

    .section-subtitle {
        font-size: 1rem;
        margin-bottom: 48px;
    }

    .feature-card {
        padding: 24px;
    }

    .feature-icon {
        font-size: 2.5rem;
        margin-bottom: 16px;
    }

    .feature-title {
        font-size: 1.25rem;
        margin-bottom: 12px;
    }

    .feature-description {
        font-size: 0.9375rem;
        margin-bottom: 20px;
    }

    .feature-list li {
        font-size: 0.875rem;
        padding: 6px 0;
    }

    .demo-form {
        padding: 48px 0;
    }

    .demo-form h2 {
        font-size: 2rem;
        margin-bottom: 12px;
    }

    .form {
        padding: 32px 20px;
    }

    .form-group {
        margin-bottom: 20px;
    }

    .form-group label {
        font-size: 0.9375rem;
        margin-bottom: 6px;
    }

    .form-group input,
    .form-group textarea {
        padding: 12px 14px;
        font-size: 0.9375rem;
    }

    .btn-large {
        padding: 14px 28px;
        font-size: 1rem;
    }

    .form-notice {
        font-size: 0.8125rem;
        margin-top: 20px;
    }
}

/* Small Mobile (< 375px) */
@media (max-width: 374px) {
    .hero-title {
        font-size: 1.625rem;
    }

    .stat-number {
        font-size: 2rem;
    }

    .section-title {
        font-size: 1.75rem;
    }

    .feature-card {
        padding: 20px;
    }
}