@import url('https://fonts.googleapis.com/css2?family=Noto+Sans+JP:wght@300;400;700&family=Zen+Old+Mincho&display=swap');

:root {
    --color-bg-primary: #F7F3E9; 
    --color-bg-secondary: rgba(255, 255, 255, 0.95); 
    --color-text-dark: #333C45; 
    --color-text-light: #F7F3E9; 
    --color-accent-red: #C73E1D; 
    --color-accent-gold: #B8860B; 
    --color-border: #D1CFC7; 
    --color-shadow: rgba(0, 0, 0, 0.1);

    --daily-card-bg-gradient: linear-gradient(135deg, #FF7E5F, #FEB47B);

    --font-heading: 'Zen Old Mincho', serif;
    --font-body: 'Noto Sans JP', sans-serif;

    --border-radius-soft: 8px;
    --border-radius-card: 15px;
    --box-shadow-soft: 0 4px 8px var(--color-shadow);
    --box-shadow-medium: 0 8px 16px var(--color-shadow);
}

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

body {
    font-family: var(--font-body);
    line-height: 1.6;
    color: var(--color-text-dark);
    background-color: var(--color-bg-primary);
    overflow-x: hidden;
    position: relative;
    min-height: 100vh;
}

.container {
    max-width: 1200px;
    margin: 2rem auto;
    padding: 0 1.5rem;
    position: relative;
    z-index: 1;
}

.header {
    width: 100%;
    height: 450px;
    background-image: url('../image/back.gif');
    background-size: cover;
    background-position: center;
    background-repeat: no-repeat;
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
    overflow: hidden;
    box-shadow: 0 10px 20px rgba(0, 0, 0, 0.3);
    text-align: center;
}

.header::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    backdrop-filter: blur(2px);
    z-index: 0;
}

.header-content {
    position: relative;
    z-index: 1; 
    color: var(--color-text-light);
    padding: 2rem;
}

.header h1 {
    font-family: var(--font-heading);
    font-size: 5rem;
    margin-bottom: 0.8rem;
    letter-spacing: 5px; 
    text-shadow: 4px 4px 8px rgba(0, 0, 0, 0.6); 
    animation: fadeInDown 1s ease-out; 
}

.header p {
    font-size: 2rem; 
    opacity: 0.9;
    font-style: italic;
    margin-bottom: 3rem;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.5);
    animation: fadeInUp 1s ease-out 0.2s; 
}

.contact-button {
    display: inline-block;
    background-color: var(--color-accent-red);
    color: var(--color-text-light);
    padding: 0.35rem 1.5rem; 
    border-radius: var(--border-radius-soft);
    text-decoration: none;
    font-size: 0.8rem; 
    font-weight: 500;
    transition: background-color 0.3s ease, transform 0.2s ease, box-shadow 0.3s ease;
    box-shadow: 0 6px 15px rgba(0, 0, 0, 0.4); 
    border: 2px solid var(--color-accent-red);
    animation: zoomIn 1s ease-out 0.4s; 
}

.contact-button:hover {
    background-color: #A03117;
    transform: translateY(-5px) scale(1.05);
    box-shadow: 0 10px 20px rgba(0, 0, 0, 0.5);
}

.back-link {
    display: inline-flex;
    align-items: center;
    color: var(--color-text-light);
    text-decoration: none;
    font-size: 1.1rem;
    padding: 0.8rem 1.5rem;
    background-color: rgba(0, 0, 0, 0.5);
    border-radius: var(--border-radius-soft);
    transition: background-color 0.3s ease, transform 0.2s ease;
    position: absolute;
    top: 20px;
    left: 20px;
    z-index: 2; 
    border: 1px solid rgba(255, 255, 255, 0.4);
}

.back-link:hover {
    background-color: rgba(0, 0, 0, 0.7);
    transform: translateX(-5px);
}
.back-link::before {
    content: '\2190';
    display: inline-block;
    margin-right: 0.5em;
    font-size: 1.2em;
}

@keyframes fadeInDown {
    from { opacity: 0; transform: translateY(-50px); }
    to { opacity: 1; transform: translateY(0); }
}

@keyframes fadeInUp {
    from { opacity: 0; transform: translateY(50px); }
    to { opacity: 1; transform: translateY(0); }
}

@keyframes zoomIn {
    from { opacity: 0; transform: scale(0.8); }
    to { opacity: 1; transform: scale(1); }
}

section {
    background-color: var(--color-bg-secondary);
    padding: 2.5rem;
    border-radius: var(--border-radius-card);
    box-shadow: var(--box-shadow-medium);
    margin-bottom: 2.5rem;
    border: 1px solid var(--color-border);
}

section h2 {
    font-family: var(--font-heading);
    font-size: 3rem;
    color: var(--color-accent-red);
    text-align: center;
    margin-bottom: 2rem;
    position: relative;
}

section h2::after {
    content: '';
    display: block;
    width: 60px;
    height: 3px;
    background-color: var(--color-accent-gold);
    margin: 1rem auto 0;
    border-radius: 2px;
}

.daily-task-section {
    text-align: center;
}

.daily-task-card {
    background: var(--daily-card-bg-gradient);
    color: var(--color-text-light);
    border-radius: var(--border-radius-card);
    padding: 3rem;
    box-shadow: var(--box-shadow-medium);
    border: 3px solid var(--color-accent-gold);
    transition: transform 0.4s ease, box-shadow 0.4s ease;
    cursor: pointer;
    max-width: 900px;
    margin: 0 auto;
    position: relative;
    overflow: hidden;
}

.daily-task-card::before {
    content: '今日';
    position: absolute;
    top: 15px;
    right: 15px;
    font-family: var(--font-heading);
    font-size: 3.5rem;
    color: rgba(255, 255, 255, 0.2);
    transform: rotate(15deg);
    pointer-events: none;
    z-index: 0;
}

.daily-task-card:hover {
    transform: translateY(-10px) scale(1.01);
    box-shadow: 0 18px 36px rgba(0, 0, 0, 0.3);
}

.daily-task-card h3 {
    font-family: var(--font-heading);
    font-size: 2.8rem;
    margin-bottom: 1rem;
    color: var(--color-text-light);
    text-shadow: 1px 1px 2px rgba(0,0,0,0.4);
    position: relative;
    z-index: 1;
}

.filters-section h3 {
    font-family: var(--font-heading);
    font-size: 2rem;
    color: var(--color-accent-red);
    margin-bottom: 1.5rem;
    text-align: center;
}

.filters {
    display: flex;
    flex-wrap: wrap;
    gap: 1.2rem;
    justify-content: center;
    align-items: center;
}

.filters select,
.filters input[type="text"],
.filters button {
    padding: 0.9rem 1.5rem;
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius-soft);
    font-family: var(--font-body);
    font-size: 1.1rem;
    outline: none;
    background-color: var(--color-bg-primary);
    color: var(--color-text-dark);
    box-shadow: inset 0 1px 3px rgba(0,0,0,0.1);
}

.filters select {
    appearance: none;
    background-image: url('data:image/svg+xml;charset=US-ASCII,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20width%3D%22292.4%22%20height%3D%22292.4%22%3E%3Cpath%20fill%3D%22%23333C45%22%20d%3D%22M287%2C197.3L159.2%2C69.5c-3.1-3.1-8.2-3.1-11.3,0L5.4,197.3c-3.1,3.1-3.1,8.2,0,11.3s8.2,3.1,11.3,0l136.1-136.1c-0.1,0.1-0.1,0.1,0,0l136.1,136.1c3.1,3.1,8.2,3.1,11.3,0S290.1,200.4,287,197.3z%22%2F%3E%3C%2Fsvg%3E');
    background-repeat: no-repeat;
    background-position: right 0.7em top 50%;
    background-size: 0.65em auto;
    cursor: pointer;
}


.filters button {
    background-color: var(--color-accent-red);
    color: var(--color-text-light);
    cursor: pointer;
    transition: background-color 0.3s ease, transform 0.2s ease;
    border: none;
    text-transform: uppercase;
    font-weight: 700;
}

.filters button:hover {
    background-color: #A03117;
    transform: translateY(-2px);
}

.tasks-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: 2rem;
}

.task-card {
    background: var(--color-bg-secondary);
    border-radius: var(--border-radius-card);
    padding: 2rem;
    box-shadow: var(--box-shadow-medium);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    cursor: pointer;
    border: 1px solid var(--color-border);
    position: relative;
    overflow: hidden;
}

.task-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 5px;
    background: linear-gradient(to right, var(--color-accent-gold), var(--color-accent-red));
    transform: translateY(-100%);
    transition: transform 0.3s ease-out;
}

.task-card:hover::before {
    transform: translateY(0);
}

.task-card:hover {
    transform: translateY(-8px);
    box-shadow: 0 12px 24px rgba(0, 0, 0, 0.2);
}

.task-card h3 {
    font-family: var(--font-heading);
    font-size: 1.8rem;
    margin-bottom: 0.8rem;
    color: var(--color-text-dark);
    line-height: 1.3;
}

.task-card p {
    font-size: 1rem;
    color: #555;
    margin-bottom: 1rem;
}

.task-card .difficulty {
    font-weight: 700;
    padding: 0.4em 0.9em;
    border-radius: var(--border-radius-soft);
    display: inline-block;
    margin-bottom: 1rem;
    color: var(--color-text-light);
    box-shadow: 0 2px 4px rgba(0,0,0,0.2);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.difficulty.Beginner { background-color: #4B974B; } 
.difficulty.AdvancedBeginner { background-color: #9B9B00; } 
.difficulty.Intermediate { background-color: #9B4B00; } 
.difficulty.Advanced { background-color: #923535; } 
.difficulty.Expert { background-color: #C10000; } 


.detailed-card {
    background: var(--color-bg-secondary);
    border-radius: var(--border-radius-card);
    padding: 3.5rem;
    box-shadow: var(--box-shadow-medium);
    max-width: 1000px;
    margin: 0 auto;
    text-align: left;
    border: 1px solid var(--color-border);
}

.detailed-card h3 {
    font-family: var(--font-heading);
    font-size: 3.5rem;
    margin-bottom: 1.5rem;
    color: var(--color-accent-red);
    text-align: center;
    position: relative;
    padding-bottom: 1rem;
}

.detailed-card h3::after {
    content: '';
    display: block;
    width: 80px;
    height: 4px;
    background-color: var(--color-accent-gold);
    margin: 0.5rem auto 0;
    border-radius: 2px;
}

.detailed-card p {
    font-size: 1.15rem;
    margin-bottom: 1.5rem;
    color: var(--color-text-dark);
}

.detailed-card .difficulty {
    font-size: 1.2rem;
    padding: 0.6em 1.2em;
    margin-bottom: 2rem;
    display: table;
    margin-left: auto;
    margin-right: auto;
}

.detailed-card .tech-stack,
.detailed-card .features,
.detailed-card .learning-path,
.detailed-card .open-source-focus {
    margin-top: 2rem;
    font-size: 1.05rem;
    color: #444;
    background-color: #fff;
    padding: 1.5rem;
    border-radius: var(--border-radius-soft);
    border: 1px solid var(--color-border);
    box-shadow: 0 2px 5px rgba(0,0,0,0.05);
}

.detailed-card .tech-stack strong,
.detailed-card .features strong,
.detailed-card .learning-path strong,
.detailed-card .open-source-focus strong {
    font-family: var(--font-heading);
    color: var(--color-accent-red);
    display: block;
    margin-bottom: 1rem;
    font-size: 1.5rem;
    text-transform: uppercase;
    letter-spacing: 1px;
}

.detailed-card ul {
    list-style: none;
    padding-left: 0;
    margin-top: 0.5rem;
}

.detailed-card ul li {
    margin-bottom: 0.8rem;
    padding-left: 1.5em;
    position: relative;
}

.detailed-card ul li:before {
    content: '\2022';
    color: var(--color-accent-gold);
    font-weight: bold;
    font-size: 1.5em;
    line-height: 1;
    position: absolute;
    left: 0;
    top: 0.2em;
}

.footer {
    background: linear-gradient(to right, #4B0082, #8A2BE2);
    color: var(--color-text-light);
    text-align: center;
    padding: 2rem 0;
    font-size: 1rem;
    box-shadow: 0 -4px 8px rgba(0, 0, 0, 0.1);
    position: relative;
    z-index: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 1rem;
}

.footer .social-icons {
    margin-top: 1rem;
}

.footer .social-icons a {
    color: var(--color-text-light);
    font-size: 1.8rem;
    margin: 0 0.8rem;
    transition: color 0.3s ease, transform 0.2s ease;
}

.footer .social-icons a:hover {
    color: var(--color-accent-gold);
    transform: translateY(-3px) scale(1.1);
}

@media (max-width: 768px) {
    .header {
        height: 350px;
    }
    .header h1 {
        font-size: 3.5rem;
    }
    .header p {
        font-size: 1.5rem;
    }
    .contact-button {
        padding: 0.8rem 2rem;
        font-size: 1rem;
    }

    .back-link {
        top: 10px;
        left: 10px;
        font-size: 1rem;
        padding: 0.6rem 1rem;
    }

    .footer .social-icons a {
        font-size: 1.5rem;
        margin: 0 0.6rem;
    }

    section {
        padding: 1.5rem;
        margin-bottom: 2rem;
    }
    section h2 {
        font-size: 2.2rem;
        margin-bottom: 1.5rem;
    }

    .daily-task-card {
        padding: 2rem;
    }
    .daily-task-card h3 {
        font-size: 2rem;
    }
    .daily-task-card::before {
        font-size: 2.5rem;
        top: 10px;
        right: 10px;
    }

    .filters {
        flex-direction: column;
        gap: 1rem;
    }
    .filters select,
    .filters input[type="text"],
    .filters button {
        width: 100%;
    }

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

    .task-card {
        padding: 1.5rem;
    }
    .task-card h3 {
        font-size: 1.5rem;
    }

    .detailed-card {
        padding: 2rem;
    }
    .detailed-card h3 {
        font-size: 2.5rem;
        margin-bottom: 1rem;
    }
    .detailed-card .difficulty {
        margin-bottom: 1.5rem;
    }
    .detailed-card p {
        font-size: 1rem;
        margin-bottom: 1rem;
    }
    .detailed-card .tech-stack,
    .detailed-card .features,
    .detailed-card .learning-path,
    .detailed-card .open-source-focus {
        margin-top: 1.5rem;
        padding: 1rem;
    }
    .detailed-card .tech-stack strong,
    .detailed-card .features strong,
    .detailed-card .learning-path strong,
    .detailed-card .open-source-focus strong {
        font-size: 1.3rem;
        margin-bottom: 0.8rem;
    }
}

@media (max-width: 480px) {
    .header {
        height: 300px;
    }
    .header h1 {
        font-size: 2.2rem;
    }
    .header p {
        font-size: 1.2rem;
    }
}

.difficulty-legend {
  display: flex;
  gap: 10px;
  margin: 10px 0 20px;
  flex-wrap: wrap;
}

.difficulty {
  color: white;
  padding: 5px 10px;
  border-radius: 6px;
  font-size: 0.9rem;
  font-weight: bold;
  white-space: nowrap;
}

.difficulty.Beginner {
  background-color: #4B974B;
}
.difficulty.AdvancedBeginner {
  background-color: #9B9B00;
}
.difficulty.Intermediate {
  background-color: #9B4B00;
}
.difficulty.Advanced {
  background-color: #923535;
}
.difficulty.Expert {
  background-color: #C10000;
}