/*
 * Pure Ocean - Conrad Challenge Innovation Website Styles
 * File: styles.css
 */

/* === 0. Variables & Reset === */
:root {
    --color-ocean-dark: #001f3f; /* Deep Navy */
    --color-ocean-medium: #0077b6; /* Primary Blue */
    --color-ocean-light: #00b4d8; /* Secondary Teal/Cyan */
    --color-sky-light: #e0f7fa; /* Light Background */
    --color-white: #ffffff;
    --color-text-body: #495057; /* Dark Gray */
    --color-text-header: var(--color-ocean-dark);
    --font-primary: 'Inter', 'Segoe UI', 'Helvetica Neue', Arial, sans-serif;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-primary);
    line-height: 1.6;
    color: var(--color-text-body);
    background-color: var(--color-sky-light);
    font-size: 16px;
}

/* === 1. Layout & Structure === */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

section {
    padding: 80px 0;
    border-bottom: 1px solid rgba(0, 0, 0, 0.05);
    background-color: var(--color-white); /* 默认背景为白色，以提高可读性 */
    
    /* 滚动动画效果 */
    opacity: 0;
    transform: translateY(20px);
    transition: opacity 0.8s ease-out, transform 0.8s ease-out;
}

section:nth-child(even) { /* 交替背景色 */
    background-color: var(--color-sky-light);
}

.section-title {
    font-size: 2.5rem;
    font-weight: 800;
    color: var(--color-text-header);
    text-align: center;
    margin-bottom: 50px;
    position: relative;
}

.section-title span {
    color: var(--color-ocean-medium);
}

.section-title::after {
    content: '';
    display: block;
    width: 60px;
    height: 4px;
    background-color: var(--color-ocean-light);
    margin: 10px auto 0;
    border-radius: 2px;
}

.intro-paragraph {
    font-size: 1.25rem;
    font-weight: 500;
    max-width: 900px;
    margin: 0 auto 40px;
    text-align: center;
    color: var(--color-ocean-dark);
}

/* === 2. Navigation Bar (Sticky Header) === */
header {
    background-color: var(--color-white);
    border-bottom: 2px solid var(--color-ocean-light);
    padding: 15px 0;
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.05);
}

nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.6rem;
    font-weight: 900;
    color: var(--color-ocean-dark);
    text-decoration: none;
}

.nav-links a {
    color: var(--color-text-body);
    text-decoration: none;
    margin-left: 20px;
    font-weight: 600;
    padding: 5px 10px;
    border-radius: 4px;
    transition: color 0.3s, background-color 0.3s;
}

.nav-links a:hover {
    color: var(--color-white);
    background-color: var(--color-ocean-medium);
}


/* === 3. HERO SECTION === */
#hero {
    padding: 180px 0;
    text-align: center;
    background: linear-gradient(145deg, var(--color-sky-light) 0%, var(--color-white) 100%);
    min-height: 80vh; 
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 1; 
    transform: translateY(0);
}

.meta-info {
    font-size: 0.9rem;
    color: var(--color-ocean-medium);
    font-weight: 600;
    margin-bottom: 25px;
    letter-spacing: 1px;
    text-transform: uppercase;
}

.hero-title {
    font-size: 4rem;
    font-weight: 900;
    color: var(--color-ocean-dark);
    margin-bottom: 25px;
    line-height: 1.1;
}

.hero-subtitle {
    font-size: 1.5rem;
    color: var(--color-text-body);
    margin-bottom: 50px;
    max-width: 800px;
    margin-left: auto;
    margin-right: auto;
}

.cta-buttons a {
    text-decoration: none;
    padding: 14px 35px;
    border-radius: 30px; /* Pill shape */
    font-weight: 700;
    margin: 0 10px;
    display: inline-block;
    transition: all 0.3s ease;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
}

.btn-primary {
    background-color: var(--color-ocean-medium);
    color: var(--color-white);
    border: 2px solid var(--color-ocean-medium);
}

.btn-primary:hover {
    background-color: var(--color-ocean-dark);
    border-color: var(--color-ocean-dark);
    transform: translateY(-2px);
}

/* === 4. Problem & Cards Styling === */
#problem .intro-paragraph, #problem p {
    text-align: left;
}

.problem-grid {
    display: grid;
    grid-template-columns: 2fr 1fr; /* 主文本区和引文区 */
    gap: 40px;
    max-width: 1000px;
    margin: 0 auto 50px;
    align-items: start;
}

.problem-details {
    font-size: 1.1rem;
    line-height: 1.8;
}

.framing-question {
    background-color: var(--color-ocean-medium);
    color: var(--color-white);
    padding: 30px;
    border-radius: 8px;
    font-style: italic;
    font-weight: 600;
    font-size: 1.1rem;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.2);
}

.card-container {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 20px;
    margin-top: 50px;
}

.problem-card {
    background-color: var(--color-white);
    padding: 25px;
    border-radius: 10px;
    box-shadow: 0 3px 10px rgba(0, 0, 0, 0.08);
    border-top: 5px solid var(--color-ocean-light);
}

.problem-card h4 {
    color: var(--color-ocean-medium);
    margin-bottom: 10px;
    font-size: 1.1rem;
    font-weight: 700;
}


/* === 5. How It Works (Steps) Styling === */
.workflow {
    display: flex;
    justify-content: space-between;
    gap: 30px;
    margin-top: 40px;
    text-align: center;
}

.step {
    flex: 1;
    padding: 30px;
    background-color: var(--color-white);
    border-radius: 10px;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.05);
    position: relative;
}

.step:not(:last-child)::after {
    content: '→';
    position: absolute;
    right: -25px;
    top: 50px;
    font-size: 2.5rem;
    color: var(--color-ocean-medium);
    font-weight: 200;
}

.step-number {
    font-size: 2rem;
    font-weight: 900;
    color: var(--color-ocean-light);
    background-color: var(--color-ocean-dark);
    width: 50px;
    height: 50px;
    line-height: 50px;
    border-radius: 50%;
    margin: 0 auto 20px;
}

.step h4 {
    color: var(--color-ocean-dark);
    font-size: 1.3rem;
    margin-bottom: 10px;
}

/* === 6. Target Users Styling === */
.stakeholder-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 30px;
    margin-top: 50px;
}

.stakeholder-card {
    padding: 30px;
    background-color: var(--color-white);
    border-radius: 10px;
    box-shadow: 0 5px 20px rgba(0, 0, 0, 0.05);
    border-bottom: 5px solid var(--color-ocean-medium);
}

.stakeholder-card h3 {
    color: var(--color-ocean-medium);
    font-size: 1.5rem;
    margin-bottom: 15px;
    display: flex;
    align-items: center;
}

.stakeholder-card ul {
    list-style: none;
    padding: 0;
    margin-top: 15px;
}

.stakeholder-card ul li {
    padding-left: 20px;
    position: relative;
    margin-bottom: 8px;
    color: var(--color-text-body);
}

.stakeholder-card ul li::before {
    content: '✓';
    color: var(--color-ocean-light);
    position: absolute;
    left: 0;
    font-weight: 900;
}

/* === 7. Technology & Innovation === */
.tech-grid {
    display: grid;
    grid-template-columns: 1.5fr 1fr;
    gap: 50px;
    margin-top: 50px;
    align-items: center;
}

.innovation-point {
    margin-bottom: 30px;
    padding-left: 20px;
    border-left: 4px solid var(--color-ocean-light);
}

.innovation-point h4 {
    color: var(--color-ocean-dark);
    font-size: 1.3rem;
    margin-bottom: 8px;
}

/* iframe 容器样式 */
.embedded-demo-container {
    padding: 30px;
    background-color: var(--color-ocean-dark);
    border-radius: 10px;
    text-align: center;
}

.embedded-demo-container h4 {
    color: var(--color-white);
    margin-bottom: 15px;
}

.embedded-demo-container iframe {
    width: 100%;
    height: 300px; 
    border: 4px solid var(--color-ocean-light);
    border-radius: 6px;
    background-color: var(--color-white);
}

/* === 8. Impact Section === */
.impact-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 40px;
    margin-top: 40px;
}

.impact-card {
    padding: 30px;
    border-radius: 10px;
    background-color: var(--color-white);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.05);
}

.impact-card h4 {
    color: var(--color-ocean-medium);
    font-size: 1.3rem;
    margin-bottom: 15px;
    font-weight: 700;
}

.metrics-list {
    margin-top: 20px;
    list-style-type: '→ ';
    padding-left: 20px;
}

.metrics-list li {
    margin-bottom: 10px;
}

/* === 9. Team & Story === */
#team {
    background-color: var(--color-sky-light);
}

.story-text {
    max-width: 900px;
    margin: 0 auto 50px;
    font-size: 1.1rem;
    line-height: 1.8;
}

.team-grid {
    display: flex;
    justify-content: center;
    gap: 30px;
    margin-top: 40px;
    flex-wrap: wrap;
}

.team-member-card {
    background-color: var(--color-white);
    padding: 20px;
    border-radius: 10px;
    text-align: center;
    width: 200px;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.08);
}

.member-image-placeholder {
    width: 100%;
    height: 150px;
    background-color: #f0f8ff;
    border-radius: 8px;
    margin-bottom: 15px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--color-ocean-medium);
    font-size: 0.9rem;
    border: 2px dashed var(--color-ocean-light);
}

.team-member-card h5 {
    font-size: 1.2rem;
    color: var(--color-ocean-dark);
    margin-bottom: 5px;
}

.team-member-card p {
    font-size: 0.95rem;
    color: var(--color-ocean-medium);
}

/* === 10. Roadmap & Contact === */
.roadmap-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 20px;
    margin-bottom: 50px;
}

.roadmap-phase {
    padding: 20px;
    background-color: var(--color-white);
    border-radius: 8px;
    border-top: 4px solid var(--color-ocean-medium);
    box-shadow: 0 3px 10px rgba(0, 0, 0, 0.05);
}

.roadmap-phase h4 {
    color: var(--color-ocean-medium);
    font-size: 1.1rem;
    margin-bottom: 10px;
}

.collaboration-box {
    text-align: center;
    padding: 40px;
    background-color: var(--color-ocean-dark);
    color: var(--color-white);
    border-radius: 10px;
}

.collaboration-box p {
    font-size: 1.1rem;
    margin-bottom: 20px;
}

/* === 11. Footer === */
footer {
    background-color: var(--color-ocean-dark);
    color: var(--color-sky-light);
    text-align: center;
    padding: 30px 0;
    font-size: 0.9rem;
}


/* === 12. Media Queries (Responsiveness) === */
@media (max-width: 992px) {
    .problem-grid, .stakeholder-grid, .tech-grid, .impact-grid, .roadmap-grid {
        grid-template-columns: 1fr;
    }
    .workflow {
        flex-direction: column;
        align-items: center;
    }
    .step:not(:last-child)::after {
        content: '↓';
        right: 50%;
        left: auto;
        bottom: -20px;
        top: auto;
        transform: translateX(50%);
    }
    .step {
        width: 80%;
        max-width: 400px;
        margin-bottom: 40px;
    }
    .hero-title {
        font-size: 3rem;
    }
}