:root {
    --color-primary: #1e3a8a;
    --color-primary-light: #3b82f6;
    --color-primary-dark: #1e40af;
    --color-secondary: #0ea5e9;
    --color-accent: #06b6d4;

    --color-bg: #ffffff;
    --color-bg-secondary: #f8fafc;
    --color-bg-tertiary: #f1f5f9;
    --color-card: #ffffff;

    --color-text: #0f172a;
    --color-text-secondary: #475569;
    --color-text-muted: #64748b;

    --color-border: #e2e8f0;
    --color-border-hover: #cbd5e1;

    --color-success: #10b981;
    --color-warning: #f59e0b;
    --color-error: #ef4444;

    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
    --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.1);

    --border-radius: 12px;
    --border-radius-lg: 16px;
    --border-radius-full: 9999px;

    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

[data-theme="dark"] {
    --color-primary: #3b82f6;
    --color-primary-light: #60a5fa;
    --color-primary-dark: #2563eb;

    --color-bg: #0f172a;
    --color-bg-secondary: #1e293b;
    --color-bg-tertiary: #334155;
    --color-card: #1e293b;

    --color-text: #f1f5f9;
    --color-text-secondary: #cbd5e1;
    --color-text-muted: #94a3b8;

    --color-border: #334155;
    --color-border-hover: #475569;

    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.3);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.3), 0 2px 4px -2px rgb(0 0 0 / 0.3);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.3), 0 4px 6px -4px rgb(0 0 0 / 0.3);
    --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.3), 0 8px 10px -6px rgb(0 0 0 / 0.3);
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen', 'Ubuntu', 'Cantarell', 'Fira Sans', 'Droid Sans', 'Helvetica Neue', sans-serif;
    line-height: 1.6;
    color: var(--color-text);
    background-color: var(--color-bg);
    transition: var(--transition);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1.5rem;
}

.header {
    background-color: var(--color-card);
    border-bottom: 1px solid var(--color-border);
    padding: 1.25rem 0;
    position: sticky;
    top: 0;
    z-index: 100;
    backdrop-filter: blur(10px);
    background-color: rgba(255, 255, 255, 0.9);
    transition: var(--transition);
}

[data-theme="dark"] .header {
    background-color: rgba(30, 41, 59, 0.9);
}

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

.logo {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.logo-icon {
    width: 32px;
    height: 32px;
    color: var(--color-primary);
}

.logo h1 {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--color-text);
    letter-spacing: -0.025em;
}

.theme-toggle {
    background: none;
    border: 2px solid var(--color-border);
    width: 48px;
    height: 48px;
    border-radius: var(--border-radius);
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: var(--transition);
    color: var(--color-text);
}

.theme-toggle:hover {
    border-color: var(--color-primary);
    background-color: var(--color-bg-secondary);
}

.theme-toggle svg {
    width: 24px;
    height: 24px;
}

.sun-icon {
    display: block;
}

.moon-icon {
    display: none;
}

[data-theme="dark"] .sun-icon {
    display: none;
}

[data-theme="dark"] .moon-icon {
    display: block;
}

.main {
    min-height: calc(100vh - 200px);
    padding: 3rem 0;
}

.hero {
    text-align: center;
    margin-bottom: 3rem;
}

.hero-title {
    font-size: 2.5rem;
    font-weight: 800;
    color: var(--color-text);
    margin-bottom: 1rem;
    letter-spacing: -0.025em;
    line-height: 1.2;
}

.hero-subtitle {
    font-size: 1.25rem;
    color: var(--color-text-secondary);
    max-width: 700px;
    margin: 0 auto;
    line-height: 1.5;
}

.calculator-section {
    margin-bottom: 4rem;
}

.calculator-card {
    background-color: var(--color-card);
    border-radius: var(--border-radius-lg);
    padding: 2.5rem;
    box-shadow: var(--shadow-xl);
    border: 1px solid var(--color-border);
    max-width: 700px;
    margin: 0 auto;
}

.calculator-mode {
    display: flex;
    gap: 0.75rem;
    margin-bottom: 2rem;
    background-color: var(--color-bg-secondary);
    padding: 0.5rem;
    border-radius: var(--border-radius);
}

.mode-button {
    flex: 1;
    padding: 0.875rem 1.5rem;
    background: none;
    border: none;
    border-radius: calc(var(--border-radius) - 4px);
    font-size: 1rem;
    font-weight: 600;
    color: var(--color-text-secondary);
    cursor: pointer;
    transition: var(--transition);
}

.mode-button:hover {
    color: var(--color-text);
}

.mode-button.active {
    background-color: var(--color-primary);
    color: white;
    box-shadow: var(--shadow-md);
}

.calculator-form {
    display: flex;
    flex-direction: column;
    gap: 1.75rem;
}

.input-group {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.input-label {
    font-size: 0.975rem;
    font-weight: 600;
    color: var(--color-text);
}

.time-input {
    width: 100%;
    padding: 1rem 1.25rem;
    border: 2px solid var(--color-border);
    border-radius: var(--border-radius);
    font-size: 1.125rem;
    color: var(--color-text);
    background-color: var(--color-bg);
    transition: var(--transition);
}

.time-input:hover {
    border-color: var(--color-border-hover);
}

.time-input:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
}

.sleep-time-options {
    display: flex;
    gap: 0.75rem;
}

.radio-option {
    flex: 1;
    position: relative;
    cursor: pointer;
}

.radio-option input[type="radio"] {
    position: absolute;
    opacity: 0;
    width: 0;
    height: 0;
}

.radio-option span {
    display: block;
    padding: 0.875rem;
    text-align: center;
    border: 2px solid var(--color-border);
    border-radius: var(--border-radius);
    font-weight: 600;
    color: var(--color-text-secondary);
    transition: var(--transition);
    background-color: var(--color-bg);
}

.radio-option:hover span {
    border-color: var(--color-border-hover);
}

.radio-option input[type="radio"]:checked + span {
    border-color: var(--color-primary);
    background-color: var(--color-primary);
    color: white;
}

.calculate-button {
    padding: 1.125rem 2rem;
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-light) 100%);
    color: white;
    border: none;
    border-radius: var(--border-radius);
    font-size: 1.125rem;
    font-weight: 700;
    cursor: pointer;
    transition: var(--transition);
    box-shadow: var(--shadow-md);
}

.calculate-button:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.calculate-button:active {
    transform: translateY(0);
}

.results {
    margin-top: 2.5rem;
    padding-top: 2.5rem;
    border-top: 2px solid var(--color-border);
    animation: fadeIn 0.5s ease;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.results-title {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--color-text);
    margin-bottom: 0.5rem;
}

.results-subtitle {
    color: var(--color-text-secondary);
    margin-bottom: 1.5rem;
    font-size: 1rem;
}

.results-list {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
    margin-bottom: 1.5rem;
}

.result-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1.125rem 1.5rem;
    background-color: var(--color-bg-secondary);
    border: 2px solid var(--color-border);
    border-radius: var(--border-radius);
    transition: var(--transition);
}

.result-item:hover {
    border-color: var(--color-primary);
    transform: translateX(4px);
}

.result-item.recommended {
    background: linear-gradient(135deg, rgba(59, 130, 246, 0.1) 0%, rgba(14, 165, 233, 0.1) 100%);
    border-color: var(--color-primary);
    box-shadow: var(--shadow-md);
}

.result-time {
    font-size: 1.375rem;
    font-weight: 700;
    color: var(--color-text);
}

.result-cycles {
    font-size: 0.925rem;
    color: var(--color-text-secondary);
    font-weight: 600;
}

.result-item.recommended .result-cycles {
    color: var(--color-primary);
}

.results-note {
    padding: 1rem 1.25rem;
    background-color: var(--color-bg-tertiary);
    border-radius: var(--border-radius);
    font-size: 0.925rem;
    color: var(--color-text-secondary);
    border-left: 4px solid var(--color-primary);
}

.info-section {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin-bottom: 4rem;
}

.info-card {
    background-color: var(--color-card);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius-lg);
    padding: 2.5rem;
    box-shadow: var(--shadow-lg);
    transition: var(--transition);
}

.info-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-xl);
}

.info-icon {
    width: 56px;
    height: 56px;
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-light) 100%);
    border-radius: var(--border-radius);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 1.5rem;
    color: white;
}

.info-icon svg {
    width: 32px;
    height: 32px;
}

.info-card h2 {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--color-text);
    margin-bottom: 1rem;
    line-height: 1.2;
}

.info-card p {
    color: var(--color-text-secondary);
    line-height: 1.7;
    margin-bottom: 1rem;
}

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

.faq-section {
    margin-bottom: 4rem;
}

.section-title {
    font-size: 2rem;
    font-weight: 800;
    color: var(--color-text);
    text-align: center;
    margin-bottom: 2.5rem;
    letter-spacing: -0.025em;
}

.faq-list {
    max-width: 800px;
    margin: 0 auto;
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.faq-item {
    background-color: var(--color-card);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius);
    overflow: hidden;
    transition: var(--transition);
}

.faq-item:hover {
    box-shadow: var(--shadow-md);
}

.faq-question {
    width: 100%;
    padding: 1.5rem;
    background: none;
    border: none;
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 1rem;
    cursor: pointer;
    text-align: left;
    font-size: 1.075rem;
    font-weight: 600;
    color: var(--color-text);
    transition: var(--transition);
}

.faq-question:hover {
    color: var(--color-primary);
}

.faq-icon {
    width: 24px;
    height: 24px;
    color: var(--color-text-secondary);
    transition: var(--transition);
    flex-shrink: 0;
}

.faq-question[aria-expanded="true"] .faq-icon {
    transform: rotate(180deg);
    color: var(--color-primary);
}

.faq-answer {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.3s ease;
}

.faq-answer p {
    padding: 0 1.5rem 1.5rem 1.5rem;
    color: var(--color-text-secondary);
    line-height: 1.7;
}

.footer {
    background-color: var(--color-card);
    border-top: 1px solid var(--color-border);
    padding: 3rem 0 1.5rem;
    margin-top: 4rem;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2.5rem;
    margin-bottom: 2rem;
}

.footer-section h3 {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--color-text);
    margin-bottom: 1rem;
}

.footer-section h4 {
    font-size: 1rem;
    font-weight: 700;
    color: var(--color-text);
    margin-bottom: 1rem;
}

.footer-section p {
    color: var(--color-text-secondary);
    line-height: 1.6;
}

.footer-links {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.footer-links a {
    color: var(--color-text-secondary);
    text-decoration: none;
    transition: var(--transition);
}

.footer-links a:hover {
    color: var(--color-primary);
}

.footer-bottom {
    padding-top: 2rem;
    border-top: 1px solid var(--color-border);
    text-align: center;
}

.footer-bottom p {
    color: var(--color-text-muted);
    font-size: 0.925rem;
}

@media (max-width: 768px) {
    .hero-title {
        font-size: 2rem;
    }

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

    .calculator-card {
        padding: 1.75rem;
    }

    .calculator-mode {
        flex-direction: column;
        gap: 0.5rem;
    }

    .sleep-time-options {
        flex-direction: column;
    }

    .info-section {
        grid-template-columns: 1fr;
    }

    .footer-content {
        grid-template-columns: 1fr;
        gap: 2rem;
    }

    .logo h1 {
        font-size: 1.25rem;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 1rem;
    }

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

    .calculator-card {
        padding: 1.5rem;
    }

    .result-item {
        flex-direction: column;
        align-items: flex-start;
        gap: 0.5rem;
    }
}