/* ===== RESET & BASE STYLES ===== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: "Cascadia Mono", monospace;
}

body {
    background-color: #eefff2;
    color: #2d3e3f;
    transition: all 0.3s ease;
}

/* ===== HEADER SECTION ===== */
.header {
    min-height: 100vh;
    width: 100%;
    background-image: linear-gradient(rgba(80, 118, 95, 0.731), rgba(15, 57, 32, 0.7)), url(images/background.jpg);
    background-position: center;
    background-size: cover;
    position: relative;
}
.credit {
    min-height: 50vh;
    width: 100%;
    background-color:rgba(70, 120, 90, 0.7);
    background-position: center;
    background-size: cover;
    position: relative;
}

/* Navigation */
nav {
    display: flex;
    padding: 2% 6%;
    justify-content: space-between;
    align-items: center;
}

nav img {
    width: 150px;
}

.nav-links {
    flex: 1;
    text-align: right;
}

.nav-links ul li {
    list-style: none;
    display: inline-block;
    padding: 8px 12px;
    position: relative;
}

.nav-links ul li a {
    color: #fff;
    text-decoration: none;
    font-size: 13px;
}

.nav-links ul li::after {
    content: '';
    width: 0%;
    height: 2px;
    background: #79d191;
    display: block;
    margin: auto;
    transition: 0.5s;
}

.nav-links ul li:hover::after {
    width: 100%;
}

/* Hero text */
.text-box {
    width: 90%;
    color: #fff;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    text-align: center;
    text-shadow: 2px 2px 10px rgba(0, 0, 0, 0.5),
                 0 0 15px rgba(51, 94, 70, 0.8);
}

.text-box h1 {
    font-size: 62px;
}

.text-box p {
    margin: 10px 0 40px;
    font-size: 20px;
    color: #fff;
}

.hero-btn {
    display: inline-block;
    text-decoration: none;
    border-color: #89a293;
    color: #e6f2f3;
    background-color: rgba(255, 255, 255, 0.2);
    border: 1px solid #456b4f;
    padding: 12px 34px;
    font-size: 13px;
    background: transparent;
    position: relative;
    cursor: pointer;
    transition: 1s;
    box-shadow:rgba(0, 0, 0, 0.2) 0px 10px 20px;
}

.hero-btn:hover {
    background: #456b4f;
}

/* ===== MAIN CONTENT SECTIONS ===== */
.home {
    width: 100%;
    margin: auto;
    text-align: left;
    padding-top: 100px;
}

.course {
    width: 80%;
    margin: auto;
    text-align: center;
    padding-top: 100px;
}

/* Typography */
h1 {
    font-size: 36px;
    font-weight: 600;
}

h2, h3{
    font-weight: 600;
    margin: 10px 0;
    text-align: center;
    color: #1c422d;
}

p, ul {
    color: #335e46;
    font-size: 14px;
    font-weight: 500;
    line-height: 22px;
    padding: 10px;
}

/* Layout components */
.container {
    display: flex;
    justify-content: space-between;
    margin-top: 5%;
    max-width: 1000px;
    margin-left: auto;
    margin-right: auto;
    gap: 50px;
    align-items: flex-start;
}

.column{
    flex: 1;
    background: #93c9a8; /* Thêm màu nền cho column */
    border-radius: 10px;
    padding: 20px;
    backdrop-filter: blur(5px);
    transition: all 0.3s ease;
}
.column:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 20px rgba(0,0,0,0.1);
}
.row {
    margin-top: 5%;
    display: flex;
    justify-content: space-between;
}

.course-col {
    flex: 1;
    flex-basis: 21%;
    background: #93c9a8;
    border-radius: 10px;
    margin-bottom: 5%;
    padding: 20px 12px;
    transition: 1s;
}
.course-col p{
    color: #335e46 !important;
}

.course-col:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 20px rgba(0,0,0,0.1);
}

/* Lesson buttons */
.toggle-btn {
    width: 100%;
    padding: 15px;
    margin-bottom: 10px;
    font-size: 18px;
    font-weight: bold;
    background-color: #78ae8d;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    transition: all 0.3s;
    color: #fff;
}

.toggle-btn:hover {
    background-color: #5cb87c;
}

.lesson-list {
    display: none;
    width: 100%;
}

.lesson-btn {
    width: 100%;
    padding: 12px;
    margin: 5px 0;
    text-align: left;
    background-color: #c8e6d5;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    transition: all 0.3s;
}

.didnt-complete {
    width: 100%;
    padding: 12px;
    margin: 5px 0;
    text-align: left;
    background-color: #89a293;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    transition: all 0.3s;
    color: white;
}

.lesson-btn:hover {
    background-color: #c8f0d5;
}
.image-gallery{
    width: 80%;
    margin: auto;
    text-align: center;
    padding-top: 50px;
}
.image-col{
    flex-basis: 32%;
    border-radius: 10px;
    margin-bottom: 30px;
    position: relative;
    overflow: hidden;
}
.image-col img {
    width: 100%;
    display: block;
}
.layer{
    background: transparent;
    height: 100%;
    width: 100%;
    position: absolute;
    top:0;
    left: 0;
    transition: 0.5s;
}
.layer:hover{
    background: rgba(73, 138, 126, 0.7)
}
.layer h3{
    width: 100%;
    font-weight: 500;
    color: #fff;
    font-size: 26px;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    position: absolute;
    opacity: 0;
    transition: 0.5s;
}
.layer:hover h3{
    bottom: 50%;
    opacity: 1;
}

/* ===== DARK MODE ===== */
body.dark-mode {
    background-color: #1a2e22;
    color: #e0f7e9;
}

body.dark-mode ul,
body.dark-mode h2, h3, p {
    color: #c8e6d5;
}

body.dark-mode .course-col {
    background: #2d4a3a;
}
body.dark-mode .course-col p {
    color: #c8e6d5 !important;
}
body.dark-mode .course-col:hover {
    box-shadow: 0 0 20px rgba(100, 150, 120, 0.3);
}

body.dark-mode .toggle-btn {
    background-color: #3a5a4a;
    color: white;
}

body.dark-mode .toggle-btn:hover {
    background-color: #5a665b;
}

body.dark-mode .lesson-btn {
    background-color: #3a5a4a;
    color: white;
}

body.dark-mode .lesson-btn:hover {
    background-color: #6a7a6b;
}
body.dark-mode .column {
    background: #2d4a3a;
}
body.dark-mode .header {
    background-image: linear-gradient(rgba(19, 70, 44, 0.591), rgba(9, 49, 32, 0.767)), url(images/background.jpg);
}

body.dark-mode .hero-btn {
    border-color: #295740;
    color: #e0f7e9;
}

body.dark-mode .hero-btn:hover {
    background-color: #295740;
}

body.dark-mode .didnt-complete {
    background-color: #3a4a3a;
    color: #e0f7e9;
}

body.dark-mode .didnt-complete:hover {
    background-color: #4a4a4a;
}
body.dark-mode #toggle-theme{
    background-color: #3a5a4a;
}
/* ===== RESPONSIVE DESIGN ===== */
@media (max-width: 700px) {
    /* Header */
    .text-box h1 {
        font-size: 20px;
    }
    
    /* Navigation */
    .nav-links {
        position: absolute;
        background: #79d191;
        height: 100vh;
        width: 150px;
        top: 0;
        right: -200px;
        text-align: left;
        z-index: 2;
        transition: 1s;
    }
    
    .nav-links ul li {
        display: block;
    }
    
    .nav-links ul {
        padding: 30px;
    }
    
    nav .fa {
        display: block;
        color: #fff;
        margin: 10px;
        font-size: 22px;
        cursor: pointer;
    }
    
    /* Layout */
    .container {
        flex-direction: column;
        align-items: center;
        gap: 15px;
        padding: 0 20px;
    }
    
    .column {
        width: 100%;
        max-width: 100%;
        padding: 0 20px;
    }
    .course-col {
        width: 100%;
        flex-basis: auto;
        margin-bottom: 15px;
    }
    
    /* Typography */
    .column h2 {
        text-align: center;
    }
    
    ul {
        padding-left: 20px;
    }
    
    /* Buttons */
    .toggle-btn {
        padding: 12px;
        font-size: 16px;
    }
    
    .lesson-btn {
        padding: 10px;
        font-size: 14px;
    }
    
    /* Dark mode mobile */
    body.dark-mode .nav-links {
        background: #424843;
    }
}

/* Utility classes */
.hidden {
    display: none !important;
}

/* ===== TOGGLE THEME BUTTON ===== */
#toggle-theme {
    position: fixed;
    left: 10px;
    bottom: 19px;
    z-index: 100;
    padding: 15px 20px;
    background-color: #89a293;
    color: white;
    border: none;
    border-radius: 30px;
    cursor: pointer;
    box-shadow: 0 2px 10px rgba(0,0,0,0.2);
    transition: all 0.3s ease;
}

#toggle-theme:hover {
    background-color: #78ae8d;
    transform: translateY(-2px);
}

body.dark-mode #toggle-theme {
    background-color: #4d7a62;
    color: white;
}

/* ===== ANIMATIONS ===== */
@keyframes slideDown {
    from {
        opacity: 0;
        transform: translateY(-20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.lesson-list.showing {
    display: block;
    animation: slideDown 0.4s ease-out forwards;
}

.toggle-btn.clicked {
    transform: scale(0.98);
    background-color: #5cb87c;
}

/* Dark mode adjustments for animations */
body.dark-mode .toggle-btn.clicked {
    background-color: #5a665b;
}
/* ===== CREDIT SECTION ===== */
.credit-section {
    width: 100%;
    padding: 80px;
    background-color: #93c9a8;
    text-align: center;
}

.credit-section .container {
    display: flex;
    flex-direction: column;
    align-items: center;
}

.section-title {
    color: white;
    font-size: 2.5rem;
    margin-top: -100px;
    position: relative;
    display: inline-block;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: -15px;
    left: 50%;
    transform: translateX(-50%);
    width: 80px;
    height: 3px;
    background-color: white;
}

.credit-content {
    display: flex;
    justify-content: center;
    gap: 60px;
    max-width: 900px;
    width: 100%;
}

.credit-group {
    flex: 1;
    background: #78ae8d;
    border-radius: 15px;
    padding: 30px;
    backdrop-filter: blur(5px);
    transition: all 0.3s ease;
    max-width: 400px;
}

.credit-group:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 20px rgba(0,0,0,0.1);
}

.credit-subtitle {
    color: white;
    font-size: 1.5rem;
    margin-bottom: 20px;
    position: relative;
    padding-bottom: 10px;
}

.credit-subtitle::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 50px;
    height: 2px;
    background-color: rgba(255,255,255,0.5);
}

.credit-list {
    list-style: none;
    text-align: center;
}

.credit-list li {
    color: white;
    padding: 10px 0;
    font-size: 1.1rem;
    position: relative;
}

.credit-list li:not(:last-child)::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 80%;
    height: 1px;
    background-color: rgba(255,255,255,0.2);
}

/* Dark mode */
body.dark-mode .credit-section {
    background-color: #2d4a3a;
}

body.dark-mode .credit-group {
    background: rgba(0, 0, 0, 0.2);
}

/* Responsive */
@media (max-width: 768px) {
    .credit-content {
        flex-direction: column;
        align-items: center;
        gap: 30px;
    }
    
    .credit-group {
        width: 90%;
        max-width: 100%;
    }
    
    .section-title {
        font-size: 2rem;
        margin-bottom: 30px;
    }
}